Incomplete Count Recovery Research Articles

Phase I Study of Ixazomib with Conventional Chemotherapy in the Treatment of Acute Myeloid Leukemia in Older Adults

Introduction: Outcome in acute myeloid leukemia (AML) for patients aged >60 years is poor with a median survival of approximately 11 months. Targeting the proteasome in AML is attractive, since leukemia stem cells demonstrate sensitivity to proteasome inhibition in preclinical models, perhaps through down regulation of nuclear NF-KB or MCL-1 through stabilizing effects on NOXA. AML cell lines are susceptible to synergistic cytotoxicity when bortezomib, a proteasome inhibitor, is combined with daunorubicin and cytarabine. We have shown that adding bortezomib to standard treatment in AML results in a high remission rate. A newer generation proteasome inhibitor, ixazomib, is less frequently associated with neurotoxicity, and, therefore, was selected for combination with conventional chemotherapy in this phase I trial. The primary objective of this study was to determine the recommended phase II dose (RP2D) of ixazomib in combination with intensive induction and consolidation chemotherapy for AML. A secondary objective was to determine if the level of CD74 in blasts correlated with response, since prior studies showed that CD74 may be a poor prognostic indicator, but its effect might be diminished with proteasome inhibition. Methods: Adults >60 years of age with newly diagnosed AML were screened for eligibility. Patients with secondary AML were eligible, including those with prior hypomethylating agent (HMA) therapy for myelodysplastic syndromes (MDS). We excluded those with promyelocytic leukemia. There were 2 phases in this study. In the first phase (A), the induction treatment consisted of the following: cytarabine 100 mg/m2/day by continuous IV infusion, Days 1-7; daunorubicin 60 mg/m2/day IV, Days 1, 2, 3, and ixazomib was provided orally at the cohort dose, Days 2, 5, 9, and 12. Consolidation or transplant in this phase was at the discretion of the treating physician. In the second phase (B), induction was administered with the established RP2D of ixazomib in phase A. All patients were to be treated with the following consolidation: cytarabine at 2 g/m2/day, days 1-5 with ixazomib on days 2, 5, 9, and 12 at the cohort dose for consolidation. A classical 3 + 3 patient cohort dose escalation design was used to determine whether the dose of ixazomib could be safely escalated in 3 cohorts (1.5 mg/day, 2.3 mg/day, 3.0 mg/day), initially in induction (phase A) and subsequently in consolidation (phase B). Secondary objectives included rate of complete remission (CR), disease-free survival (DFS), overall survival (OS), and outcome relationship with CD74. Results: Thirty-nine patients were enrolled, including 15 (38%) patients with secondary AML, either with antecedent myeloid malignancy or therapy-related AML. Twenty-six patients (67%) were male, and the median age was 68 years (range 61-80 years). There were no grade 5 toxicities attributed to study drug. Four patients died before day 30 with persistent leukemia, 3 of whom were replaced for assessment of the MTD. Three other patients were not evaluable and were replaced. Nearly all grade 3 and 4 toxicities were hematologic (Table). There was 1 DLT (grade 4 platelet count decrease extending beyond Day 42). There were no grade 3 or 4 neurotoxicity events attributable to ixazomib. Among the 38 patients evaluable for response, 26 achieved CR, and 2 achieved CR with incomplete count recovery (CRi), for a composite remission rate (CCR) of 74%. Among the 15 patients with secondary AML, 9 achieved CR and 2 achieved CRi, for a CCR of 73%. The median OS for the 39 patients is 40.8 months [95% CI, 17.6, Inf]. The 18-month OS estimate was 63% [95% CI, 49-80%]. Of note, 30 patients underwent stem cell transplantation. There was no significant association between level of CD74 expression on blasts at baseline and response. Conclusions: The highest dose level (3 mg) of ixazomib planned for induction and consolidation in this trial has been reached safely and is the recommended phase 2 dose for both. Notably, to date, no grade 3 or 4 neurotoxicity has been encountered. The remission rate for this regimen in this older adult population appears favorable. With ixazomib added in treatment, we saw no association of response rate with level of CD74 in blasts. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Outcomes of Adults Treated with a Hypomethylating Agent Plus Venetoclax for Relapsed/Refractory Acute Myeloid Leukemia: A Multicenter Retrospective Study

BACKGROUND: Despite recent advances in treatment options for relapsed/refractory (R/R) acute myeloid leukemia (AML), prognosis remains poor for patients who do not proceed to allogeneic stem cell transplant. In the frontline setting, the combination of a hypomethylating agent with venetoclax (HMA + ven) has emerged as a new standard of care for adults who are unfit for intensive chemotherapy. However, data on response rates with HMA + ven in the R/R setting is limited. In this multicenter retrospective analysis, we sought to estimate the response rate associated with HMA + ven as salvage therapy for R/R AML and to explore predictors of response. METHODS: We conducted a multicenter retrospective study through COMMAND (Consortium on Myeloid Malignancies and Neoplastic Diseases), a collaboration involving 10 academic institutions. A total of 93 patients treated with HMA + ven for R/R AML at 3 sites (University of Pittsburgh Medical Center, Yale, Mayo Clinic Florida) were evaluated. We summarized clinical characteristics of the study population using descriptive statistics. We reported the best response at any point after starting therapy by summarizing complete remission (CR) rate, CR with incomplete count recovery (CRi) rate and rate of CR + CRi + morphologic leukemia free state (MLFS) by frequency (percentage) and its exact 95% confidence interval (CI). The association of CR rate with continuous variables was examined using t-tests for normally distributed variables and Wilcoxon rank sum tests for non-normally distributed variables, as well as Fisher's exact test for categorical variables. Overall survival (OS), defined as the time from start of HMA + ven to death from any cause or the last follow-up, was analyzed by the Kaplan-Meier method, and the median OS was calculated along with its 95% CI. RESULTS: Among the 93 patients in our analysis, 63% (n=59) received azacitidine + ven and 37% (n=34) received decitabine + ven. Median age at AML diagnosis was 61 years (IQR 54-69). Most patients had de novo AML (59%, n=55), followed by 31% (n=29) with secondary AML and 10% (n=9) with therapy-related AML. The distribution of cytogenetic/molecular abnormalities was as follows: 61% (n=57) with complex cytogenetics, 10% (n=10) with FLT3 mutation (ITD or TKD), 9% (n=8) with NPM1 mutation, 35% (n=33) with TP53 mutation, and 19% (n=18) with IDH1/ IDH2 mutation. Among a subset of 25 patients for whom data on lines of therapy prior to HMA + ven was available, 28% (n=7) received 1 prior line of therapy, 44% (n=11) received 2 prior lines and 28% (n=7) received 3 prior lines. The median time from diagnosis to start of salvage therapy with HMA + ven was 15 months (IQR 2-17 months). Of 75 evaluable patients, 26 achieved a CR, for a CR rate of 35% (95% CI 24-47%). The MRD-negative CR rate was 24% (95% CI 15-35%, n=18) and the MRD-positive CR rate was 11% (95% CI 5-20%, n=8). The CRi rate was 4% (95% CI 1-11%, n=3), and the rate of CR + CRi + MLFS was 47% (95% CI 35-59%, n=35). Median OS was 8 months (95% CI 6-10 months), and 1-year and 2-year OS rates were 33% and 16%, respectively. There were no associations between CR rate and cytogenetic/molecular profile or type of AML. Age was associated with CR rate (median [IQR] age at HMA + ven in patients who achieved a CR was 65 [61-72] years versus 58 [48-69] years in patients who did not achieve a CR, p=0.05). CONCULSIONS: In this multicenter retrospective analysis, CR and OS rates with HMA + ven were comparable to historical CR rates reported with other regimens used to treat R/R AML. We did not find an association between CR rate and cytogenetic/molecular profile or type of AML, suggesting that HMA + ven can be used broadly in this setting. Further prospective studies are needed to determine populations that may benefit most from this regimen and additional outcomes such as time to response and duration of response that may guide clinical decision making.

Time-Dependent Prediction of Relapse in Patients with Acute Myeloid Leukemia

Background: Although most patients with newly diagnosed acute myeloid leukemia (AML) obtain a complete remission (CR) following induction chemotherapy, most subsequently relapse. Previous studies have demonstrated the importance of various prognostic factors for relapse-free survival, including age, cytogenetics, prior antecedent hematologic disorder (AHD), and prior cancer-related therapy. However, assessments of treatment response now include additional factors such as measurable residual disease (MRD) status, time to count recovery, and remission type (CR vs. CR with incomplete count recovery [CRi]). Among patients in complete remission, we set out to examine the impact of additional initial response variables on relapse or death at various time points up to 3 years, a time point after which AML relapses become very uncommon. Methods: Of 972 patients who had a confirmed diagnosis of AML or other high-grade myeloid neoplasm (≥10% blasts) underwent initial induction treatment at University of Washington / Fred Hutchinson Cancer Center between November 2008 and December 2018, 656 achieved a morphologic remission (CR or CRi) and were included in our analysis. The primary outcomes were survival without relapse after 1, 2, or 3 years. Multivariable logistic regression models controlled for the following covariates: age, ELN 2017 risk classification, presence of MRD determined by multiparameter flow cytometry at first remission, gender, WBC count at diagnosis, prior AHD and/or therapy-related disease, performance status, treatment-related mortality (TRM) score, induction intensity (high: CLAG-M, FLAG-ida, or similar; intermediate: 7+3 or similar; low: hypomethylating agent with or without venetoclax), CR vs CRi, and count recovery within 30 days. Time to relapse was estimated using relapse-free survival curves. Results: The median age at diagnosis was 60 years (range 18-91). De novo AML was found in 373 patients (57%) with the remainder a mix of antecedent AHD and therapy-related AML. ELN2017 risk classification was favorable in 181 patients (28%), intermediate in 206 (41%), and adverse in 203 (31%). Performance status was 0-1 in 538 patients (82%). Most patients received high or intermediate-intensity induction (88%). After induction, 540 patients (82%) achieved a CR and 116 patients (18%) CRi. MRD following induction therapy was found in 173 patients (26%). In multivariable analysis, age, remission type (CRi), and MRD status were the strongest predictors of being alive without relapse at years 1, 2, and 3 (year 3 summarized in Table 1). In the year 3 model, CR MRD+ after induction was associated with the largest decrease in odds of being alive without relapse (CR MRD+: odds ratio [OR] 0.15, 95% confidence interval [CI] 0.08-0.27). 3-year relapse-free survival (RFS) of 18.5% (95% CI 13.5-25.5%) for MRD+ patients versus 36.4% (95% CI 31.3-42.4%) for MRD- patients (Figure 1). CRi MRD+/MRD- were both also associated with decreased survival with CRi MRD- (OR 0.33, 95% CI 0.16-0.65) and CRi MRD+ (OR 0.40, 95% CI 0.18-0.87). Increasing age was the second strongest predictor across the models (year 3 OR 0.78, 95% CI 0.67-0.89). Conclusions: Our study identified remission category (CR vs CRi), MRD status, and age as the strongest predictors of being alive without relapse at years 1, 2, or year 3 following induction for patients with AML and other high-grade myeloid neoplasms. Patients with older age or those with evidence of residual detectable disease with MRD or CRi and/or MRD have an increased risk of relapse or death in the first 3 years after initial CR. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Post-Remission Outcomes in Patients with Acute Myeloid Leukemia (AML) Are Similar between Hypomethylating Agent/Venetoclax Therapy and Intensive Chemotherapy after Accounting for Measurable Residual Disease (MRD) Status

Background: Intensive chemotherapy regimens (IC; e.g., 7+3 or CPX-351) broadly target leukemic blast populations in acute myeloid leukemia (AML) by interfering with DNA replication, whereas hypomethylating agent/venetoclax therapy (HMA/ven) takes advantage of metabolic vulnerabilities in leukemic stem cells via inhibition of anti-apoptotic pathways. IC regimens are often targeted to 'fit', younger patients, while HMA/ven is typically used in patients who are older or who have significant comorbidities. Both therapeutic paradigms can induce morphologic remission, with resultant measurable residual disease (MRD) status remaining a prognostically significant factor. Here, we aim to determine whether post-remission outcomes in AML patients depend mainly on MRD status or are further modified by chosen induction (IC vs HMA/ven). Methods: Retrospective chart review was performed on adult (age 18 years and older) patients newly diagnosed with AML and treated at Johns Hopkins Hospital, Baltimore, MD between September 2014 and June 2021. Patients were excluded if they had promyelocytic or mixed phenotype leukemia. Complete remission (CR) was defined by <5% medullary blasts with no extramedullary disease and count recovery. Primary covariates of interest included age in years, performance status (PS; ECOG 0-1 for good vs 2-4 for poor), European LeukemiaNet (ELN) 2022 risk group, number of HMA/ven cycles to best response, hematopoietic stem cell transplantation (HCT) status, chemotherapy type (IC vs HMA/ven), and MRD status by multiparametric flow cytometry (MFC). Groups were compared using Wilcoxon rank sum, Kruskal-Wallis, and Fisher's exact tests. Laplace regression models were used to estimate subgroup median overall survivals (OS) in order to compare them using the Wald test. Associations between OS and the above covariates were examined in Cox models; one multivariable model included an interaction term for therapy type and MRD status. Analyses were performed using Stata version 17. Results: Of the 388 patients initially reviewed, 214 (55%) achieved a CR or CR with incomplete count recovery and were included in further analysis. Most (103 of 159) IC patients received 7+3; 20 received CPX-351 and 36 received a high-dose cytarabine-based regimen. Fifty-five patients received HMA/ven. The HMA/ven patients were significantly older than those receiving IC regardless of MRD status (median age 72 vs 58 years, respectively, P<0.001). MRD negative (MRD-) remission was achieved in 134 (84.3%) patients after IC and 44 (80.0%) patients after HMA/ven. Patients who achieved MRD- CRs after IC were more likely to undergo HCT than those with identical MRD status after HMA/ven (77.6% vs 40.9%, P<0.001) and were younger (median age 60 vs 73 years, P<0.001). Univariate analysis showed significantly decreased hazard of death in patients with favorable ELN 2022 risk score, MRD- status in first CR, and HCT (Table 1). Kaplan-Meier curves showed patients with MRD- remissions had superior survival to those with MRD positive (MRD+) remissions (median OS not reached vs. 21.9 months, P<0.05), whereas there was no statistically significant difference in median OS between therapies (36.1 months HMA/ven vs. 61.2 months IC). Patients in the IC, MRD- group and HMA/ven, MRD- group had similar outcomes (median OS not reached for both); both groups had superior survival to MRD+ groups (P<0.05; Figure 1). Multivariable analysis showed decreased hazards of death for ELN favorable risk patients (hazard ratio [HR] 0.49, 95% confidence interval [CI] 0.28-0.85) and those MRD- in first CR (HR 0.47, 95% CI 0.28-0.77) after adjusting for age, PS, therapy type, and cycles. In a subsequent model, an interaction term between therapy type and MRD status was not significant (HR=0.96, suggesting no difference in impact of MRD between therapy types). Conclusions: In this retrospective study evaluating outcomes in patients with AML, chemotherapy type does not appear to differentially impact survival by MRD status in those achieving remission. MRD status as measured by MFC significantly impacts survival when adjusting for relevant baseline covariates. These results suggest that obtaining deep, MRD- remissions matters regardless of whether these are achieved with HMA/venetoclax or intensive therapy. Ultimately, randomized controlled trials are needed to better determine the value of MRD in AML after different induction strategies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Prognostic Impact of the 2022 European Leukemia Net Risk Classification in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation

Introduction: For most acute myeloid leukemia (AML) patients (pts) an allogeneic stem cell transplantation (HSCT) offers the highest chance of cure. Recently, the European LeukemiaNet (ELN) published updated recommendations on the risk classification in AML pts. In addition to the risk at diagnosis, which is now based on cytogenetics and the mutation status of several genes, a dynamic adjustment according to the measurable residual disease (MRD) status in favorable (fav) and intermediate (int) risk pts at informative time points - such as prior to an allogeneic HSCT - was recommended. A validation of the new ELN2022 risk classification has not been reported. Methods: We retrospectively analyzed 522 AML pts who received an allogeneic HSCT between 2000 and 2021 in first complete remission (CR, 54%), second CR (11%), CR with incomplete count recovery (CRi, 13%), or relapsed/refractory (22%) at our center. Median age at HSCT was 59 (range 16-76) years (y), 53% of pts were younger than 60 y. Conditioning regimens were myeloablative (27%), reduced-intensity (23%) or non-myeloablative (50%). At diagnosis, cytogenetics, and the mutation status of CEBPA, NPM1, and FLT3-ITD were assessed. Using next-generation sequencing we analyzed a panel of 54 recurrently mutated genes in myeloid malignancies (MiSeq platform, Illumina). In pts with material available in remission prior to HSCT, the MRD status based on NPM1mutations, BAALC, MN1, and WT1 expression was evaluated as published previously (Jentzsch 2021). MRD positivity (MRDpos) was defined as positivity of any of the analyzed markers. Median follow up after HSCT was 3.0 y. Results: ELN2022 risk at diagnosis was 22% fav, 26% int, and 52% adverse (adv). Older pts (≥ 60 y at HSCT) had significantly worse ELN2022 genetic risk (P<.001). Comparing the ELN2017 and the new ELN2022, 83% (fav), 70% (int), and 90% (adv) of pts kept their allocation, while 15% and 2% of fav ELN2017 risk pts changed to int and adv ELN2022, 30% of int ELN2017 risk pts changed to adv ELN2022 & 1% and 10% of adv ELN2017 risk pts changed to fav and int ELN2022. Analyzing the c-statistic (area under the curves [AUC]) produced by the ELN2017 and ELN2022 for relapse (AUC2017 = 0.64 vs AUC2022 = 0.64, P=.21) and overall survival (OS) prediction (AUC2017 = 0.60 vsAUC2022 = 0.57, P=.06), the ELN2022 did not perform significantly better. However, the ELN2022 risk at diagnosis impacted cumulative incidence of relapse/progression (CIR, P<.001) and OS (P<.001, Figure 1), which was especially seen in pts < 60 y (CIR P<.001, OFS P<.001), but less so in pts ≥ 60 y at HSCT (CIR P=.002, OS P=.10). At diagnosis, outcomes did not differ significantly with respect to the specific genetic abnormality defining the ELN2022 fav or the ELN2022 int risk. Also a high or low FLT3-ITD allelic ratio (0.5 cut) within the ELN2022 int risk did not result in distinct outcomes (CIR P=.13, OS P=.30). In contrast, within pts harboring adv ELN2022 risk, CIR (P=.05) and OS (P<.001) significantly differed according to the presence of specific genetic abnormalities; i.e. a complex karyotype (at 3 y: CIR 59%, OS 30%), other adverse cytogenetic aberrations (at 3 y: CIR 50%, OS 54%), adverse-risk gene mutation (i.e.ASXL1, RUNX1, or TP53, at 3 y: CIR 47%, OS 58%), or secondary AML-like gene mutations (at 3 y: CIR 30%, OS 73%). When we adjusted fav and int risk pts according to the MRD status at HSCT as proposed by the ELN2022 recommendations, 49% of fav risk pts at diagnosis had persisting MRD and were reclassified as int risk at HSCT while 53% of int risk pts at diagnosis were MRD negative and reclassified as fav risk at HSCT. Outcomes of MRD-adjusted fav risk pts improved (at 3 y: CIR 12%, OS 75%), while that of MRD-adjusted int risk pts (at 3 y: CIR 53%, OS 49%) was similar to that of adv risk pts transplanted in morphologic CR/CRi (at 3 y: CIR 47%, OS 54%). Conclusion: In the context of an allogeneic HSCT, the proposed risk assessments by the ELN2022 significantly impacted outcomes at diagnosis as well as after adjustment according to MRD status prior to HSCT of AML pts. However, it did not perform significantly better than the previous ELN2017 risk stratification. The FLT3-ITD allelic ratio did not significantly impacted outcomes within the ELN2022 int risk, justifying the removal from the risk stratification. Noteworthy, in pts receiving allogeneic HSCT, secondary AML-like gene mutations did not associate with adverse outcomes when no other adverse-risk characteristics were present. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Gemtuzumab Ozogamicin Plus Standard Induction Chemotherapy Improves Outcomes in Intermediate Risk Cytogenetic Acute Myeloid Leukemia

Background: Gemtuzumab ozogamicin (GO) is a CD33-directed antibody-drug conjugate approved for the treatment of newly diagnosed (ND) and refractory/relapsed CD33-positive acute myeloid leukemia (AML). Meta-analysis of individual patient (pt) data from 5 randomized controlled trials (n=3325) confirmed a significant survival benefit of GO added to intensive induction chemotherapy for pts with AML without adverse cytogenetics. While favorable-risk ND-AML pts, specifically core-binding factor AML (CBF-AML), particularly benefited with a 5-year overall survival (OS) improvement of 20.7% (log rank p= 0.0006), pts with intermediate-risk AML also showed a significant 5-yr survival improvement of 5.7% (p=0.005) (Hills RK et al Lancet Oncol 2014: 15, 986). However, the smaller difference in these latter pts coupled with apprehension for risk of sinusoidal obstruction syndrome (SOS) following hematopoietic stem cell transplantation (HSCT) has led many clinicians to not use 7+3 plus GO in the intermediate-risk AML population. Aim/Objective: To perform a retrospective analysis of outcomes of 7+3 plus GO vs 7+3 in ND intermediate-risk cytogenetic AML pts treated at a single comprehensive cancer center. Methods: We studied the demographic, clinical and genetic data of intermediate risk ND-AML pts treated at Roswell Park Comprehensive Cancer Center (n=113) between 2015-2022. Conventional cytogenetics and fluorescence in situ hybridization (FISH) were performed. Genomic profiling was performed using next-generation sequencing methods (FoundationOne®CDx). Risk stratification was defined per the European LeukemiaNet (ELN)-2017 classification. 7+3 plus GO pts received at least one dose of GO 3 mg/m2 (up to one 4.5 mg vial) plus cytarabine 100 mg/m² continuous IV infusion on days 1-7, and daunorubicin 60 mg/m² IV on days 1-3 (7+3). Control pts received 7+3 alone. Prophylactic heparin was administered to prevent hepatic SOS based on institutional standards if not thrombocytopenic. Outcomes included response rate to induction, successful bridging to HSCT, relapse rate, and overall survival. Results: 113 intermediate-risk ND-AML pts were studied: 33 received 7+3 plus GO and 80 received 7+3. Median age was 57 vs. 59 years, respectively (range: 19-76 years). Moreover, there was no significant difference in the percentage of pts > 60 yrs (45% vs 48%). Gender was equally distributed. Pts treated with 7+3 plus GO had a significantly higher rate (p=0.019) of complete remission (CR) and complete remission with incomplete count recovery (CRi) (27/33, 82%) than 7+3 (44/80, 55%; Figure 1A). Among pts with available minimal residual disease (MRD) status detected by multiparameter flow cytometry, 100% achieved MRD-negative status after 7+3 plus GO (18/18) compared to 86% with 7+3 (12/14). Non-responders to 7+3 plus GO were enriched for ASXL1, DNMT3A, TET2, and TP53 mutations as compared to responders who harbored more FLT3, IDH1/2, KRAS/NRAS and RUNX1 mutations. Among pts achieving CR/CRi, 48% after 7+3 plus GO vs 30% after 7+3 (p=0.13) were successfully bridged to HSCT. Cumulative incidence of relapse after CR/CRi was significantly lower after 7+3 plus GO (11%) than 7+3 (43%; p=0.007). Finally, 7+3 plus GO pts demonstrated a superior, yet not statistically significant, median overall survival (OS) benefit (median OS not reached) compared to 7+3 alone (median OS = 35 months; Figure 1B). No pts receiving 7+3 plus GO developed SOS. Conclusions: Intermediate risk ND-AML pts treated with 7+3 plus GO at our academic center had significantly higher rates of MRD-negative CR and CRi, lower rates of relapse, and higher percentage of pts receiving HSCT as compared with 7+3 alone. Non-responders in the 7+3 plus GO group harbored adverse risk genetic mutations that likely dictated the failure to response. Although addition of GO was associated with a non-significant trend towards improved overall survival, longer follow-up is warranted to decipher an absolute survival advantage of this regimen. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Frida Study: An Option for Mutated FLT3 Relapsed/Refractory Acute Myeloid Leukemia Patients with a Novel Iadademstat and Gilteritinib Combination Therapy

Background: Epigenetic dysregulation is a hallmark of acute myeloid leukemia (AML) and is caused by recurrent translocations and/or mutations in chromatin regulators and transcription factors, resulting in myeloid differentiation blockade and leukemic stem cell renewal. Accordingly, about 70% of recurring mutations in AML patients target regulators of gene expression, underscoring the potential of epigenetic therapies to change the natural history of the disease. Iadademstat (iada/ORY-1001) is a specific, oral, potent, covalent inhibitor of the epigenetic Lysine-Specific Demethylase 1 (LSD1/KDMA1) enzyme. Preclinical models demonstrate that exposure to iada decreases leukemic stem cell survival and preclinical and clinical studies shows iada's effect on inducing macrophage/monocytic differentiation of blast cells. Furthermore, a Phase 2 ongoing study of iada in combination with azacitidine (ALICE) shows high complete remission (CR)/ CR with incomplete count recovery (CRi) and durable responses in treatment naïve, unfit AML patients (pts) without exacerbating the toxicity profile of azacitidine (Salamero et al., Abstract P586 EHA 2022). Despite improvements in AML therapy, relapses remain a common challenge, contributing to the death of more than 50% of pts, particularly in those subpopulations with higher risk genetics, the largest of which (up to 30-40% of AML pts) harbor mutations in the fms-like tyrosine kinase 3 (FLT3) gene. Use of the FLT3 inhibitor (FLT3i) gilteritinib as monotherapy for relapsed/refractory (R/R) pts has resulted in improved outcomes but the duration of remission achieved is transient and often brief. The Phase 3 randomized ADMIRAL trial of gilteritinib revealed a CR rate of 20%; and an event-free-survival (EFS) of 2.8 months (Perl, et al., NEJM 2019). Preclinically, iada produces marked synergy with FLT3i, including gilteritinib, in FLT3 wild-type and mutated (FLT3 mut+) AML cells and in derived cell lines resistant to venetoclax, azacitidine and other FLT3is. The novel MOAs generating this synergy of the combination include activation of a pro-differentiative epigenetic and transcriptional program with simultaneous suppression of the activity of MYC target genes (Yashar, et al. 2022, https://doi.org/10.1101/2022.01.17.476469). The FRIDA clinical trial is designed to establish the safety, tolerability of the combination of iada plus gilteritinib and to identify the recommended phase 2 dose (RP2D) in FLT3 mut+ R/R AML specifically according to FDA's Project Optimus. Methods: Adult pts with body weight ≥50 Kg and ECOG 0-2, with FLT3 mut+ R/R AML, after 1 or 2 prior lines of therapy, will be enrolled. Up to 18 pts, in a 3+3 escalation phase, will receive iada at doses of 75 to 150 ug, orally, in 5 days ON - 2 days OFF schedule, with continuous gilteritinib, at 120 mg/day orally. In the expansion phase, up to 14 pts at the selected safe and pharmacologically active dose/s (determined based on all available data from escalation pts including PK, target engagement (TE), safety, tolerability, and emerging activity) will be enrolled. TE will be assessed with a proprietary validated chemo-probe assay for LSD1 occupancy in PBMCs. Primary endpoints of the study are safety and RP2D determination, based on the same 5 criteria outlined above. Bayesian posterior probability efficacy monitoring will be performed periodically for each dose cohort starting from the first 6 additional pts in the expansion phase (total of 12). Bayesian efficacy futility and early stopping boundary will be applied during the monitoring. Posterior probability criterion (Prob (θ>0.3) ≥ 0.60) at the end of the study will warrant additional development. The safety of the combination treatment will be also continuously evaluated during expansion following a Bayesian design stopping rule. Secondary endpoints include overall survival, EFS, CR, CR/CR with partial hematologic recovery (CRh), overall response rates, time to response, duration of response, and transfusion rate. Exploratory endpoints include measurable residual disease and gene mutational analysis. Pts who achieve a response can undergo hematopoietic stem cell transplant. The study plans to have 15 sites enrolling in the US. Additional sites will be added for a subsequent randomized controlled double-blinded FRIDA 2 study to assess the efficacy of the iada and gilteritinib combination in R/R FLT3 mut+ AML.

Real-World Outcomes of IDH Mutant AML Patients Treated with or without IDH Inhibitors

Background: The molecular landscape of acute myeloid Leukemia (AML) is heterogeneous, yet only a few mutations are targetable. Mutations in the isocitrate dehydrogenase genes (IDH1, IDH2) are heterozygous gain of function point mutations with an approximate frequency of 20%. FDA approved IDH2 inhibitor enasidenib in 2017 and IDH1 inhibitor ivosidenib in 2018 for adults with relapsed/refractory (R/R) IDH2 and IDH1MT AML. In May 2022, FDA approved ivosidenib combined with azacitidine for adults aged 75 years or older with newly diagnosed AML who cannot undergo intensive induction chemotherapy. Since IDH inhibitors (IDHi) have been in clinical use within and outside clinical trials for the last few years, we sought to retrospectively analyze our experience and clinical outcomes of patients with IDH mutations who were treated with/without IDHi at our center, especially there is some recent evidence of better response to venetoclax based therapy for patients with IDH mutations. Methods: We included all patients diagnosed with a myeloid neoplasm with IDH1 or IDH2 or both mutations as identified by targeted Next Generation Sequencing using the commercially available Illumina TruSight Myeloid Panel and were treated between October 2014 and September 2021. Baseline demographic and clinical characteristics were noted. The Chi-square test was used to study various parameters as described in the results, and Kaplan-Meier curves were used for survival analyses. Results: Among 65 patients with myeloid neoplasms, 53 (82%) had AML, 8 (12%) had Myelodysplastic syndrome, 2 (3%) had Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN), 1 (1.5%) had essential thrombocythemia, and 1 (1.5%) had myelofibrosis secondary to polycythemia vera. Of the 65, 54% (35/65) were male, and the median age at disease diagnosis was 65 years [range, 35-97]. 42% (27/65) in the cohort had IDH1 mutation, 55% (36/65) had IDH2 mutation, and 3% (2/65) had both. Only 29% (19/65) of patients in the cohort received IDHi therapy, and all had AML. 12 (63%) were female. 15 (79%) patients received IDHi therapy in the R/R setting and 4 (21%) in the first line. The median age of patients receiving IDHi was 66 years [range, 44-80]. Of the 19 patients who received IDHi, 6 (32%) achieved complete remission (CR), 2 (10%) achieved complete remission with incomplete count recovery (CRi), 1 (5%) had a partial response (PR), and 10 (53%) had refractory disease. The median time to best response was 3.5 months [range, 0.3-11.25]. IDHi-induced differentiation syndrome (DS) was reported in 6 patients (32%); 4 (21%) who developed DS received Olutasidenib, and 2 (11%) received Enasidenib. Three patients (50%) developed severe DS, two of which died from it. One had moderate DS, and 2 had indeterminate DS. All patients with DS were treated with medication discontinuation and intravenous dexamethasone. Median overall survival for the IDHi group was 28.6 months (95% CI 16.0-41.3) and 30.4 months (95% CI 5.9-54.9) for the non-IDHi group (p = 0.363). Conclusion: Only a minority of patients with IDHMT AML had received IDHi-based therapy, which is attributed to patients diagnosed and treated before the FDA approval. Surprisingly, the median survival for patients who didn't receive IDHi therapy seemed not different, underscoring the other therapies' effects, including the influence of the venetoclax-based regimen. More extensive randomized studies are needed to compare the efficacy of IDHi to other therapies in treating IDHMT AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Phase I Study of Uproleselan Combined with Azacitidine and Venetoclax for the Treatment of Older or Unfit Patients with Treatment Naïve Acute Myeloid Leukemia

Introduction: VIALE-A established azacitidine (AZA) with venetoclax (VEN) as a standard of care for AML ineligible for induction chemotherapy (IC). Patients (Pts) who achieved a measurable residual disease (MRD) negative complete remission (CR) or CR with incomplete count recovery (CRi) by multiparameter flow cytometry (MFC) had improved outcomes; however, only 41% of CR/CRi responders achieved MRD negativity. Uproleselan (UPRO) is a novel E-selectin antagonist that disrupts cell survival pathways and improves chemotherapy responses in preclinical models, including in combination with AZA +/- VEN. A Phase I/II study of UPRO combining with IC in AML pts established a recommended Phase II dose (RP2D). UPRO was associated with higher CR/CRi and MRD negative (MRD-ve) rates, lower induction mortality, and less severe mucositis compared to historical controls. We are exploring the combination of UPRO with AZA/VEN to improve outcomes in pts with untreated AML ineligible for standard IC. Methods: This ongoing single center Phase I trial of frontline UPRO in combination with AZA/VEN in older or unfit AML pts (NCT04964505) consists of a dose optimization portion, using a modified 3+3 dose optimization design to confirm the RP2D UPRO dose level (800 mg IV q12h for 7 days), and a dose expansion cohort. We report results of the dose optimization portion and initial expansion phase subjects. Key eligibility criteria included age ≥18 years, AML diagnosis by WHO criteria, and eligibility for frontline AZA/VEN. Pts received UPRO 800 mg IV q12h and AZA 75 mg/m2 IV/SC q24h for 7 days, and VEN 400 mg PO daily for 28 days in 28-day cycles. Treatment continued until progression, intolerance, or patient decision to stop. Pts had a VEN ramp-up in cycle 1 including tumor lysis syndrome monitoring and prophylaxis. A bone marrow biopsy was done after every cycle until morphologic leukemia-free state or better response (MLFS+). UPRO was given for up to 6 cycles with dosing decreased to daily after achieving MLFS+. The primary objective was to determine safety and tolerability. Adverse events (AE) were monitored throughout treatment, and dose-limited toxicities (DLT) assessed in cycle 1. The secondary objective was to evaluate preliminary efficacy, notably MRD-ve CR/CRi rate, as measured by MFC. Results: As of June 26, 2022, 8 pts [75% female, median age 78 (range 70-81)] were enrolled in the dose optimization (n=6) and dose expansion (n=2) portions of the study. Four (50%) had de novo AML and four (50%) had secondary AML, including 3 (38%) with therapy-related AML. Six (75%) had ELN 2017 adverse risk disease; 3 (38%) had complex cytogenetics. The most common mutations identified were RUNX1 (n=4), BCOR (n=2) and TET2 (n=2), and one patient each had TP53, NPM1, FLT3-ITD, or IDH2 mutations. All pts completed cycle 1. Median time on study is currently 126 days (range 32-179). Pts received a median of 3 treatment cycles (range 1-6). No DLTs were observed. There were no deaths in the first 30 days from treatment initiation; there was one death from sepsis in the first 60 days. All pts had at least one treatment-emergent AE (TEAE). The most common TEAE regardless of grade and attribution included anemia (n=6), thrombocytopenia (n=6), anorexia (n=4), nausea (n=4), neutropenia (n=4), fatigue (n=3), hypocalcemia (n=3), and hyponatremia (n=3). All pts experienced at least one ≥grade 3 TEAE, with anemia (n=6), thrombocytopenia (n=6), neutropenia (n=4), and febrile neutropenia (n=2) most common. Four pts (50%) experienced nine total serious AEs (SAEs), including thrombocytopenia (n=2). There were two grade 5 events, sepsis and AML disease progression, both unrelated to UPRO. Two pts remain on study treatment, and six have discontinued study therapy [patient decision (n=4) and death (n=2)]. All pts with an MLFS+ had dose modifications and/or cycle delays. All 8 pts had a MLFS+ response. Five (63%) achieved CR and one CRi, for a total CR/CRi rate of 75%, and two achieved MLFS. Five CR/CRi responses occurred with cycle 1. Four of the CR/CRi responses were MFC MRD-ve, for an overall MRD-ve CR/CRi rate of 50% and 67% among the CR/CRi responders. Conclusions: Preliminary results from this Phase I study reveals a tolerable safety profile of UPRO with AZA/VEN in pts with untreated AML ineligible for IC. No DLTs were observed, and the most common Grade 3-4 AE and SAE were hematologic. The combination shows promising preliminary efficacy, including a 50% rate of MRD-ve CR/CRi.

Quantitative Cytogenetic Analysis with karyoParser Allows for More Precise Identification of Disease Biology, Clonal Evolution, and Etiology of Relapse in Acute Myeloid Leukemia

Introduction: Clinical risk assessment in AML relies on high quality cytogenetic data, often reported as a modal karyotype in International System for Human Cytogenomic Nomenclature format (ISCN). Here we show that quantitative assessment of clonal hierarchy is feasible for both internal and public datasets and reveals cytogenetic signatures reflective of disease biology both at diagnosis and relapse. Methods We built karyoParser as an R package to facilitate automated analysis. Using the ISCN string, it builds a quantitative clonal hierarchy for downstream analysis including automated AML assessment using leukNLP (Abstract id: 170203). To quantitatively assess relationships between different karyotypes, each alteration was assigned a value reflecting the degree of change. Translocations were assigned +3, full additions +1, full deletions -1, p arm additions +0.3, p arm deletions -0.3, q arm additions + 0.7, and q arm deletions -0.7. Hierarchical clustering was then performed on cases with cytogenetic abnormalities using Euclidean distance and Ward's method. Clusters were identified by cutting the dendrogram at a distance balancing intercluster homogeneity with intracluster heterogeneity. Cluster labels were assigned according to dominant cytogenetic features. Clinical annotation of prior MDS cases at Memorial Sloan Kettering (MSK) were obtained through a manually curated database. MPN cases were identified using a composite of JAK2/CALR/MPL mutation presence as well as leukNLP annotation. Prior treatment information and AML therapy were also obtained through leukNLP annotation. Clinical annotation of TCGA and Beat AML cases were obtained from the respective publications. Enrichment for these features and molecular features in specific clusters was assessed using a logistic regression model. The impact of diagnostic abnormal clone count was determined by Cox Proportional Hazards survival modeling. In the MSK cohort, response to therapy was obtained through leukNLP annotation and included complete response (CR), CR without minimal residual disease (CR MRD-), CR with incomplete count recovery (CRi), morphologic leukemia free state (MLFS), partial response (PR), and no response (NR). Patterns of clonal evolution were analyzed using a Cox Proportional Hazards event free survival model. Results We applied karyoParser to a dataset consisting of AML patients from MSK (N= 599), the public TCGA AML cohort (N=195) 5 and public Beat AML cohort (N=466). Unsupervised analysis revealed 14 clusters, 8 of which were defined by well characterized AML translocations (Figure 1). Clusters 6 and 7 were enriched for prior chemotherapy (p<0.01, p<0.01). Clusters 2, 7, and 8 were associated with prior MDS or MPN (p<0.01, p< 0.01, p=0.01). Cluster 4 was negatively correlated with prior malignancy (p<0.01). Clusters 7, 5, and 11 were significantly enriched for TP53 mutations, exhibiting the diverse modalities of AML progression following this mutation (p < 0.01). We also note a significant enrichment of SF3B1 in the inv(3) cluster (p < 0.01) which was only recently described in AML. In addition, we note enrichment of KIT mutations in t(8;21) and FLT3-ITD in APL (p < 0.01, p = 0.04), which have been previously described. We next sought to assess the impact of abnormal clones on clinical outcomes. In the combined cohort, increased abnormal clone count at diagnosis was associated with poorer overall survival (3 clones: HR: 3.2, p<0.01, 4+ clones: HR: 3.0, p <0.01). For the subset of patients at MSK with longitudinal data we found that depth of response was also influenced by abnormal clone count. Achievement of a CR decreased significantly with higher numbers of abnormal clones (p = 0.05) and NR increased (p < 0.01). CR MRD- also showed a trend toward decline with increasing abnormal clone count (p=0.10) (Figure 2). Time to relapse also differed based on the pattern of clonal evolution. Compared to normal karyotype cases, emergence of new clones had a significantly longer disease free interval (16.4 months; p=0.01) and relapse with an identical clone showed a trend toward a shorter interval (6.4 months; p=0.053). Conclusion Quantitative assessment of hierarchically structured karyotypes in AML fills a void in the analysis of AML biology. Using karyoParser, we show that joint analysis of both public and local datasets is feasible in a way that defines novel disease biology, prognosis, and patterns of relapse. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Treatment Response and Impact Factor of Venetoclax Based Regimens in the Frontline Treatment of Newly Diagnosed Unfit Acute Myeloid Leukemia in the Real World of China

Purpose: Aim to assess the efficacy and safety of venetoclax (VEN) based regimens in the frontline treatment of newly diagnosed (ND) unfit acute myeloid leukemia (AML), and then explore the impact factors of the efficacy in the real world of China. Method: All patients with ND-unfit-AML being frontline treated with VEN-based regimens from July 2019 to February 2022 in Nanfang Hospital were included and analyzed their treatment response, safety and the impact factors of efficacy. Results: Totally 73 patients with a median age of 64(13-84) years old (54(74.0%) patients with Eastern Cooperative Oncology Group (ECOG) performance score (PS) of 0-2 and 19(26.0%) with ECOG PS of 3-4) were frontline treated with a median of 2(1-8) cycles of VEN-based therapy, including 68(93.2%) with VEN+azacytidine and 5(6.8%) with VEN+decitabine. 32(43.8%) patients terminated VEN-based therapy, including 26(35.6%) cases were adjusted their treatment strategy, and 20(27.4%) patients were bridged to allogeneic hematopoietic stem cell transplantation (allo-HSCT). With a median follow-up of 8.0(1.0-31.0) months, a total of 56(76.7%) patients acquired treatment response, including 48(65.8%) with complete remission (CR)/CR with incomplete count recovery (CRi) and 30/71(42.3%) with measurable residual disease (MRD) negative. The median time of acquiring CR/CRi was 1(1-5) cycle of therapy. The rate of CR/CRi and MRD negative were increasing with rising cycles of therapy. Patients with low risk (vs intermediate risk and high risk) according to European Leukemia Net stratification, mutation of IDH1/2, NPM1 and FLT3-ITD/TKD, and 28 days of VEN (vs 14-21 days) had better response to VEN-based therapy. There were not significantly different in the rate CR/CRi and MRD negative between the patients with de novo versus secondary/treatment-related AML, the dose of VEN with 400mg/d versus 100-200mg/d (co-administered with posaconazoleorvoriconazole). The median overall survival (mOS) was 20.3±1.8 months. The rate of one year OS was 62.5%±7.5%. The patients with acquiring CR/CRi (P<0.001) or MRD negative (P=0.001 had significantly better mOS than those without. The patients with treatment strategy adjustment had much longer mOS (P=0.011) and lower rate of relapse (p=0,020) than those with continuous VEN-based therapy, especially remarkably in the patients with the age <60 years old or high risk. Bridging to allo-HSCT further improved mOS versus those without (P=0.010). The safety of VEN-based therapy was well tolerated and the incidence of ≥3 grade adverse events was low. Conclusion: VEN-based therapy as the frontline treatment of ND-unfit-AML in the real world was effective and safe. Molecular abnormalities, treatment strategy and whether standardized use of VEN or not could significantly impact the efficacy of VEN-based therapy. Key words: Venetoclax, unfit, acute myeloid leukemia, efficacy, safety

Allogeneic Donor-Derived Myeloid Antigen Directed CAR-T Cells - for Relapsed/Refractory Acute Myeloid Leukemia in Children after Allogeneic Hematopoietic Stem Cell Transplantation: Report of Three Cases

Introduction The outcome of HSCT among children with chemorefractory acute myeloid leukemia (AML) is poor. The incidence of relapse exceeds 50%. We hypothesized that myeloid antigen-directed CAR-T cell therapy may induce remission in children with refractory AML. Patients and methods Three pediatric patients with R/R AML were enrolled in a compassionate-use program. All cases had AML, relapsing after multiple lines of treatment, including previous HSCT (n=3). One patient had CD123-positive leukemia cell population in the bone marrow, 2 pts had CD33-positive population. At the time of allogeneic CAR-T application disease burden was overt leukemia (n=3), all patients had full donor chimerism in the CD3 cells. Baseline characteristics of the pts are summarized in table 1. Allo-CAR-T were derived from previous HSCT donors (haplo n=2, MRD n=1). The FlA chemotherapy regimen was used to reduce tumor burden, followed by the fludarabine and cyclophosphamide for lymphodepletion before CAR-T cell infusion in all patients. One patient received CD123 directed allo-CAR-T cells, 2 pts - CD33 CAR-T cells. Both CD33 and CD123 constructs were 2-nd generation 4-1BBz CARs, modified based on the published Ukrainskaya et al. Clinical grade manufacturing was performed on Prodigy bioreactor platform with retroviral transduction. Results Cytokine release syndrome (CRS) occurred in 3 patients and was grade ≤3, all pts received tocilizumab with good effect. Two patients had neurologic events (ICANS grade 1-2). In one patient rash and liver toxicity coincided with CRS, potentially representing aGVHD, with full response to corticosteroids. All pts had grade III/IV hematological toxicities. The median time to CAR-T cell peak expansion was 14 days. At 4 weeks after CAR-T infusion two patients achieved complete MRD negative remission with incomplete count recovery and good CAR-T cell expansion. One pt. had MRD positive remission with CD33 loss on residual blast cells. Two patients (#1 and #2) on d +37 and +45 receivedTotal body irradiation (TBI) at 4 Gy and TCRαβ+ depleted graft from original donors. Abatacept on d 0, +7, +14 was used as GVHD prophylaxis. One pt. (#3) received second HSCT on d +30 from haploidentical donor with full intensity TBI-based regimen. All patients engrafted recovered hematopoietic function) and had MRD-negative remission with full donors chimerism on d+30. Two patients, #1 and #2, relapsed after 4 and 2 months after graft infusion, respectively. Patient #3 remains in MRD-negative remission on day +100. All patients alive with median follow up 164 days (102-196). Conclusion Our early experience suggests that allogeneic myeloid antigen-directed CAR-T cells are effective as cytoreduction and have manageable toxicity. Myeloid antigen-directed CAR-T therapy can be used as a bridge to allo HSCT in r/r AML. We have documented CAR-T expansion and persistence. Prospective testing of the approach is warranted. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Phase 2 Study of ASTX727 (cedazuridine/decitabine) Plus Venetoclax in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML) or Previously Untreated, Elderly Patients with AML Unfit for Chemotherapy

Background: ASTX727, an oral formulation of the fixed dose combination of decitabine and cytidine deaminase inhibitor cedazuridine (35 mg/100 mg), has been recently approved for the treatment of patients (pts) with myelodysplastic syndrome. Combination of the hypomethylating agents (decitabine or azacytidine) with venetoclax (Ven), an orally bioavailable BCL-2 inhibitor, is the standard of care for treating pts with AML unfit for intensive induction chemotherapy based on age and/or comorbidity. We are investigating whether a total oral therapy regimen of ASTX727+ven is feasible and safe. Methods: Pts aged ≥18 years with relapsed/refractory AML (R/R) or pts with AML (excluding acute promyelocytic leukemia) aged ≥ 75 or 18 -74 with comorbid conditions prohibiting intensive chemotherapy (frontline, FL) are eligible to participate. Other eligibility criteria included adequate renal and hepatic function and absence of uncontrolled infections or other uncontrolled comorbidities and an ECOG performance status (PS) of ≤2. ASTX727 is administered orally daily on days 1-5 of each treatment cycle and Ven on days 1-28 of the first cycle after a dose ramp up of 100-200-400 mg over 3 days (with tumor lysis prophylaxis precautions and with ven dose adjustments as needed based on concurrent CYP3A4 inhibitor therapy such as azole antifungals). A bone marrow exam is performed on day 21±3 days of first cycle and ven is held if blasts cleared to <5% to allow count recovery. Bone marrow exam is repeated on day 28±7 days to document response. Cycles are repeated every 4-8 weeks depending on count recovery and venetoclax is administered for 21 days in subsequent cycles. Dose adjustments of both ASTX727 and ven are permitted depending on tolerance. Results: As of July 11th, 2022, a total of 37 pts (21 FL, 16 R/R) have been enrolled on the study. The median age is 75 years (range, 46-92); 73 in the FL cohort and 75.5 in the R/R cohort. Nine (43%) frontline pts were older than 75 years including 8 pts (38%) ≥80 years. In the R/R cohort, 11 pts (69%) were 70-80 years. The median PS was 1 (range 0-3). The R/R cohort had a median 2 of prior treatments (range, 1-4). In the frontline cohort, 4 pts (19%) had normal cytogenetics, 9 (43%) a complex karyotype; and 7 (33%) other abnormalities including trisomy 8 and miscellaneous. In the R/R cohort, 44% had normal karyotype, 38% complex karyotype and 13% other. Mutations of note in the frontline cohort were TET2 (35%), ASXL1 (30%), RUNX1 (24%), TP53 (16%), and DNMT3A (11%). The overall response including complete response (CR), CR with incomplete count recovery (CRi) and morphological leukemia free state (MLFS) in the frontline cohort is 65% (4 CR, 6 CRi, 1 MLFS and 4 non-responders and 2 not evaluable). 2 pts received only one day of therapy for severe adverse events unrelated to therapy (1 due to ischemic stroke, 1 due to septic shock) and were not evaluable for response. In the R/R cohort, the overall response rate is 53% (6 CR, 1 CRi, 1 MLFS with 7 non-responders). Both cohorts received a median of 3 cycles (range for both cohorts, 1-8). With a median follow-up of 7 months, the median survival for the FL cohort is 9.5 months (range, 0.6 - 11.1) and has not been reached for the R/R cohort (range, 0.6 - 13). Grade 3 or higher adverse events related to study drugs were mainly myelosuppression-related; 4 patients (11%) had infection complications, including 1 pt with life-threatening pneumonia, and 1 pt (3%) who had liver enzyme abnormality. Conclusion: ASTX727 and venetoclax combination is safe and feasible particularly in the advanced elderly population and demonstrates significant efficacy in pts unfit for chemotherapy both in the FL and R/R settings. Total oral therapy of ASTX727 and venetoclax combination appears to be a promising strategy for older and unfit patients with AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Phase 1 Study Evaluating the Safety, Tolerability, Pharmacokinetics, and Preliminary Antitumor Activity of Bcl-2 Inhibitor Bgb-11417 in Adult Patients with Mature B-Cell Malignancies: Preliminary Data

Background/Introduction: The efficacy of Bcl-2 inhibitors in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) was established by the approval of agents such as venetoclax across all lines of therapy. However, adverse events (AEs) related to venetoclax and the development of BCL2 mutations leading to resistance may limit the utility of venetoclax in the clinic. Compared to venetoclax, BGB-11417 is a more potent (>10 fold in biochemical assays) and highly selective Bcl-2 inhibitor with the potential to achieve deeper target inhibition and clinical responses. Here, we report preliminary data from a phase 1 trial of BGB-11417 in patients with mature B-cell malignancies. Methods: BGB-11417-102 (NCT04883957) is a multicenter, phase 1, open-label, dose-finding study conducted in China. The primary objectives were to determine the safety, maximum tolerated dose (MTD) or maximum administered dose, and the recommended phase 2 dose (RP2D) of BGB-11417 monotherapy for the selected B-cell malignancy dose-finding cohorts. Patients with relapsed/refractory (R/R) B-cell malignancies received escalating doses of BGB-11417 monotherapy (80, 160, 320, or 640 mg once daily) with a weekly or daily ramp-up to the intended target dose. Dose-limiting toxicity for each dose cohort was evaluated by a Bayesian logistic regression model during dose ramp-up through day 21 at intended dose. AEs were reported per Common Terminology Criteria for AEs v5.0. Results: As of June 16, 2022, 41 patients were treated. Twenty-seven with R/R non-Hodgkin lymphoma (NHL; 13 diffuse large B-cell lymphoma, 7 follicular lymphoma, 4 marginal zone lymphoma, and 3 transformed NHL) received BGB-11417 ≤640 mg/d and 14 with R/R CLL/SLL received ≤320 mg/d. MTD has not yet been reached. The median values were as follows: age, 62 years (range 31-84); lines of prior systemic therapy, 2 (range 1-7); and follow-up, 5.7 months (range 0.7-9.5). A total of 19 patients (18 NHL and 1 CLL/SLL) discontinued the study treatment (14 progressive disease, 4 withdrawal by subject, and 1 investigator decision). At least 1 treatment-emergent AE (TEAE) was reported by 97.6% of patients and grade ≥3 AEs were reported by 51.2%. The most common TEAEs (reported in ≥10% of patients) across all dose levels are listed in the Table. Dose-limiting toxicity events were reported in 7.3% of patients (grade 3 febrile neutropenia and grade 3 platelet count decrease at 80 mg/d dose level each; grade 3 bone pain at 160 mg/d dose level). Serious TEAEs were reported in 9.8% of patients, and TEAEs leading to drug interruption were reported in 12.2%. No patients reported TEAEs leading to death or treatment discontinuation. Laboratory tumor lysis syndrome (TLS) events were reported in 4.9% of patients, and all were controlled without dose modification. No clinical TLS events were reported. Of the 31 patients available for tumor assessment (23 NHL and 8 CLL/SLL), 4 patients with NHL and 5 patients with CLL/SLL achieved responses (NHL: 3 partial responses [PR] at 160 mg/d dose level and 1 PR at 320 mg/d dose level; CLL/SLL: 2 complete responses [CRs]/CR with incomplete count recovery, 1 PR at 80 mg/d dose level, and 2 PR at 160 mg/d dose level). One patient with CLL had a CLL count of less than 10-4 in both blood and bone marrow aspirate after 4.5 months of treatment with 80 mg/d dose, as measured by European Research Initiative in CLL flow cytometry assay with 10-4 sensitivity. Conclusion: These results demonstrated that BGB-11417 is effective and well tolerated at all tested doses, with no increase in AEs with increasing dose. Dose escalation is still ongoing because an MTD has not yet been reached in any dose-escalation cohort as of the data cutoff date, with patients being recruited. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Evaluation of Emergent FLT3 Mutations (FLT3m) at Relapse in Patients (Pts) with Wild-Type FLT3 Acute Myeloid Leukemia (AML)

Background:FLT3 mutations (FLT3m) are detected in approximately 30% of newly diagnosed (ND) pts with AML and are associated with poor prognosis. FLT3m can also emerge in relapse in pts with previously wild-type FLT3 AML; however, their frequency and clinical implications are not well studied. Our objective was to identify pts who relapsed with emergent FLT3m and compare their clinical and pathological characteristics to those who relapse without FLT3m. Methods: We identified 686 pts with ND AML treated at our institution between 12/2005 and 01/2020, who achieved complete remission (CR) / CR with incomplete count recovery (CRi) and subsequent relapse of AML. Pts with available FLT3 status (ITD and TKD) at diagnosis and within 4 weeks of first relapse were included (N=300). A multiplex fluorescent-based PCR analysis followed by capillary electrophoresis for detection of FLT3 ITD and/or TKD was performed on DNA isolated from BM aspirate samples. Next-generation sequencing (NGS) at baseline was performed using the Illumina MiSeq platform with multigene panels (either 28-gene, 53-gene, or 81-gene) interrogating genes recurrently mutated in myeloid neoplasms. Results: Among 300 pts who achieved CR/CRi after induction and eventually relapsed, 216 (72%) had FLT3 wild-type (WT) AML and 84 (28%) had FLT3m AML at diagnosis. Baseline clinical features are shown in Table 1. 43 (14%) pts had a change of FLT3 status between baseline and relapse: 30 pts had FLT3m at baseline that wasn't detected at relapse, and 13 pts with FLT3 WT AML at baseline experienced relapse with FLT3m AML. The median remission duration (until 1st relapse) for the entire study cohort pts withFLT3 WT and pts with FLT3m AML was 7.8 months (range, 0.2-147.2), 9 months (0.2-147.2), and 6.1 months (range, 0.5-79.6), respectively. FLT3 wild-type at Diagnosis Among 216 pts with FLT3 WT AML at baseline, 203 (94%) and 13 (6%) experienced relapse with FLT3 wild-type and FLT3m AML, respectively. Comparison of baseline molecular features of FLT3 WT and FLT3m cohorts showed that pts who had relapsed AML with a positive FLT3m had more frequent concomitant NRAS mutations compared with pts who had FLT3 WT AML at relapse (60% vs 5%; p=0.003). No significant difference was seen in the frequency of TP53 (49% vs. 20%; p=0.36), NPM1 (15% vs. 40%; p=0.19), DNMT3A (16% vs. 40%; p=0.21), KRAS (5% vs. 0%; p=1), or PTPN11 (3% v. 0%; p=1) mutations between the two cohorts, respectively. Among 13 pts with AML with emergent FLT3m, 12 had diploid cytogenetics at diagnosis, but only 6 maintained the diploid status at relapse. The remaining 6 pts developed karyotypic clonal evolution at relapse (complex, n=1; KMT2A rearrangement, n=1; trisomy 8, n=1; other alterations, n=3). We had paired baseline and relapse NGS performed in 5 of 13 pts with relapsed AML, among these AMLs acquired new mutations. Nine newly acquired mutations were detected in the following genes: NPM1 (n=1), KRAS (n=1), RUNX1 (n=1), IDH2 (n=1), DNMT3A (n=1), ZRSR2 (n=1), WT1 (n=2), and STAG2 (n=1). Two of 5 pts had AML with no mutations at baseline, and 1 pt had AML with the same mutation profile at baseline and relapse. The median OS after relapse was 5.3 months and 5.5 months in pts with WT vs. FLT3m AML, respectively (P=0.29) (Figure 1). FLT3 mutant at diagnosis Among 84 pts with FLT3m AML at diagnosis, 52 (62%) and 32 (38%) pts experienced relapse with FLT3m and WT AML, respectively. Comparison of baseline molecular features of FLT3 WT and FLT3m AML showed a trend towards a higher frequency of NPM1 (77% vs. 47%; p=0.09) and DNMT3A mutations (55% vs. 21%; p=0.08) in patients who experienced relapse with FLT3m AML compared with FLT3 WT AML. No difference in the frequency TP53 (0% vs. 23%; p=0.13), KRAS (0% vs. 14%; p=0.27), NRAS (14% vs. 9%; p=0.63) and PTPN11 (7% vs. 14%; p=1) mutations was observed among both cohorts, respectively. The median OS after relapse was 8.1 months vs. 3.9 months in pts with FLT3 WT vs. FLT3m AML, respectively (p=0.005) (Figure 2). Conclusion: Our data suggest that FLT3m are more likely to emerge at AML relapse with concomitant NRAS mutations and indicate that FLT3m testing should be performed at relapse, irrespective of FLT3status at diagnosis. It is common for the FLT3 status to change, either from mutant to WT or vice versa. FLT3 status has immediate and clinically important implications for selection of appropriate therapeutic agents in the setting of salvage therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Clinical Predictors for Relapse Among Patients with AML Who Responded to Venetoclax-Based Treatment - a Real-World Prospective Analysis from the Revive Study Group

Background: Venetoclax (VEN)-based low intensity combinations are approved for the treatment of patients with acute myeloid leukemia (AML) ineligible for intensive chemotherapy. Despite the encouraging composite complete remission rates demonstrated in the VIALE-A trial, disease relapse remains a frequent event with dismal outcome. The aim of the current analysis is to characterize patterns and clinical predictors of relapse in a real-world setting. Methods: The REVIVE study is a prospective, real-life, observational study that assesses patterns of patient selection, efficacy and toxicity. 189 newly diagnosed AML patients from 12 medical centers in Israel were enrolled at initiation of VEN-based low-intensity therapy, between August 12, 2019, and April 15, 2022 (data cut). Demographic, clinical and patient-related baseline characteristics, as well as treatment patterns, safety and efficacy outcomes were collected. For the current analysis, remission was defined as either achieving complete remission (CR), CR with incomplete count recovery (CRi) or morphological leukemia-free state (MLFS). Relapse-free survival (RFS) was calculated from the date of first response to the date of progression of disease or death from any cause, whichever occurs first or lost follow-up in the population of responding patients (CR, CRi, MLFS). A cox proportional hazards model was used to compare relapse-free survival between subgroups of baseline characteristics. Results: Of the 189 patients recruited to the study, 110 (58.2%) achieved a response (CR- 55.5%, CRi- 39.1%, MLFS- 5.5%). The median age of these patients was 75 years, 58.2% were males and 69.1% had ECOG performance status of 0-1. The median time to remission was 35 (0-193) days. As of data cut, with a median follow-up of 278 (31-878) days, 50 patients (45% of responding patients) who achieved response have relapsed. Median RFS was 425 (275-588) days. 1-year after achieving remission 53.3% (42.3%-64.2%) of the patients remained in remission. The estimated OS of the patients who responded was 509 (302-680) days. In univariate analysis, there was a statistically significant association of age (p=0.005) and baseline neutrophil counts (p=0.001) with RFS. The expected hazard of relapse in patients <75 of age was 0.4 times the hazard in patients ≥75 (median RFS of 588 vs. 275 days, respectively). The expected hazard of relapse in patients with baseline neutrophils ≥1,000 cells/µl was 2.7 times the expected hazard in patients <1,000 cells/µl. Patients with a normal BMI (<25) had a hazard of relapse that was higher than those with an overweight BMI (≥25) (p=0.06). There was no statistical association of gender, ECOG performance status, type of AML, cytogenetic risk group, and prior HMA exposure with RFS. On a multivariate analysis, only age and baseline neutrophil counts remained significant in the cox proportional hazards model. A comparison of responding patients with prior myeloproliferative neoplasms (MPNs) (n=14), patients who were excluded from registrational clinical studies, to patients with therapy-related AML/ prior MDS (n=40) demonstrated a significant association with RFS. The median RFS was 154 days (range 76-not reached) in the MPN group compared to not reached in the other group (range 298-not reached, KM estimation for 1 year of 25% vs. 63.8%, respectively p=0.0119). Conclusions: In a real-world, prospective analysis, newly diagnosed AML patients who responded to treatment demonstrated a median relapse free survival of more than 1 year (425 days). Clinical factors significantly associated with shorter RFS were age≥75 and baseline neutrophil counts (≥1,000 cells/µl). AML patients with prior MPN have a shorter RFS compared to other secondary AML patients. Analysis of patterns of post-relapse salvage approaches and survival is planned for future analysis. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Venetoclax (VEN) Plus Intensive Chemotherapy (IC) with FLAG-IDA in Patients (Pts) with Newly Diagnosed (ND) and Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML)

Background: Despite the high complete remission (CR) rates achieved with IC, relapse rates remain high underscoring the need for novel combination regimens capable of inducing deeper remissions via eradicating measurable residual disease (MRD). Recently, several studies have shown promising clinical activity of VEN when combined with different IC regimens in pts with ND AML with composite CR rates (CRc) above 90% and MRD-ve rates exceeding 80% (Wang 2022; Kadia 2021). FLAG-IDA + VEN has also shown significant clinical activity in pts with ND AML with a CRc rate of 89% and MRD-ve remission rate of 93% (DiNardo 2022). Methods: We conducted a single-center retrospective study to assess the clinical activity of FLAG-IDA + VEN in pts with AML. During induction, VEN was initially given for 14 days which was later on reduced to 7 days due to encouraging results by Kadia et al. Standard cytogenetic (CN) analysis was performed and molecular data was obtained using a 40-gene NGS platform. Responses were assessed using the modified International Working Group response criteria and included CR, CR with incomplete count recovery (CRi), morphologic leukemia-free state (MLFS), and partial remission (PR). Time-to-event analyses were estimated using the Kaplan-Meier method and compared using the log rank test. Results: From March 2020 to May 2022, 24 pts with AML (17 ND and 7 R/R) were treated using FLAG-IDA + VEN (Table 1). Median age was 48 years (range, 21-68) with male predominance (67%). Among the 17 pts with ND AML (8 de novo, 5 AML-MRC, 2 treated-secondary, 2 therapy-related), 3 had extramedullary disease (EMD). The most common ELN CN risk groups were complex (N=5), KMT2A-rearranged (N=4), other adverse (N=3), and diploid (N=3). Eight pts (47%) harbored a RAS mutation. Median time to initiation of therapy was 5 days (range, 2-14). Twelve pts (71%) [KMT2A-rearranged, N=4; complex CN, N=3; diploid, N=3; other adverse, N=1; other intermediate, N=1] achieved CR/CRi including 1 pt with EMD. Median time to ANC (≥ 500) and platelet (≥ 50,000) recovery were 29 days (range, 19- 42) and 25 days (range, 17- 42), respectively. Median number of consolidation cycles given were 1.5 (range, 1- 5). MRD status was available in 6 out of 12 pts and all 6 pts achieved MRD negativity using flow cytometry (<10-3). Median follow-up among ND AML pts was 4.3 months (mths) (range, 0.7- 13.2). Among the 12 responders: (1) 3 pts received allo-SCT [KMT2A-rearranged, N=2; (-7), N=1] after 7, 4, and 3 mths, respectively, and remain alive in CR 10+, 7.5+, and 3+ mths, respectively, after initiation of therapy, (2) 6 pts with ELN favorable (N=3), intermediate (N=2), and adverse (N=1) risk AML remain in CR/CRi for 6+, 4+, 1+, 3+, 2+, and 2+ mths, respectively, (3) 3 pts with ELN adverse risk AML (including 1 pt with de novo MLLr AML and EMD) achieved CR and relapsed after 0.7, 1.7, and 7.6 mths, respectively. One pt died due to progressive disease (PD) 4.7 mths after relapse and the remaining 2 pts are receiving salvage therapy and alive 4.3+ and 5.2+ mths after relapse, respectively. All nonresponders (N=5) had ELN adverse risk AML including 2 pts with EMD and 2 pts with treated secondary AML. All 5 nonresponders died due to PD including 3 pts who had no response to HMA+VEN based salvage therapy. Among the 7 pts with R/R AML, 6 were in salvage 1 and 1 pt received prior allo-SCT. Responses were observed in all pts: 4 CR, 1 CRi, 1 MLFS, and 1 PR. Median time to count recovery in R/R AML pts was 33 days (range, 24-78). Median follow-up in R/R AML pts was 6.2 mths (range, 1.5- 15.6). Of the 5 pts who achieved CR/CRi, 4 were bridged to allo-SCT and 1 pt died in CR after 3 cycles of consolidation due to sepsis. Of the 4 SCT recipients: (1) 2 pts relapsed 2 mths after allo-SCT and died 4 and 6.5 mths, respectively, after allo-SCT; (2) 2 pts (KMT2A-rearranged and NPM1mut) remain alive in CR for 8+ and 14+ mths, respectively. Two pts with complex CN achieved MLFS and PR after 1 cycle of therapy and died due to PD and fungal pneumonia after 5.3 and 1.5 mths of starting therapy, respectively. Median overall survival (OS) for pts with ND AML and R/R AML were 13.2 mths (95% CI: Not reached) and 6.2 mths (95% CI: 5-7), respectively (p=0.62; Figure 1). Among pts with ND AML, median OS was not reached among responders and was 2.6 mths in non-responders (p=0.002). Conclusion: FLAG-IDA + VEN is a feasible and active regimen in AML. Longer follow-up and larger multicenter studies are needed to confirm the efficacy of this regimen. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Long-Term Outcomes of a Clinical Trial of Molecular and Functional Drug Screening for Individualized Therapy in Relapsed and Refractory (R/R) Acute Leukemia (AL)

Background. Outcome of patients (pts) with R/R AL is dismal. While traditional precision medicine basket trials have assigned treatment based on targeted inhibitors for certain mutations, this approach has limited use for pts without such mutations or with co-occurring mutations. In contrast, we developed a clinical trial for which treatment was assigned based on molecular characteristics and functional drug testing. Patient cell samples were analyzed for 194 recurring mutations and by high throughput screening (HTS) for a custom panel of drugs and drug combinations to comprehensively select the best treatment for each individual patient. Here we report the final analysis and long-term outcomes of this individualized approach. (NCT02551718) Methods. Eligibility criteria included diagnosis of AL, relapsed or refractory to at least 2 lines of treatment, ECOG <4 and adequate organ function. Blood/bone marrow (BM) and/or fluid or tissue involved by leukemic blasts was subjected to cell enrichment using magnetic beads, then assayed for drug sensitivity using the CLIA approved Cancer Drug Sensitivity Test (CDST) performed at the University of Washington Quellos High Throughput Core (method described in Lee et al. Nat Commun 2018), mutations by MyAML®, RNAseq and single cell mutation analysis (MissionBio). The HTS included 170 drugs and drug combinations, both FDA-approved and investigational. Drug recommendations were provided by the study to the patient's physician based on the lowest IC50, percentile rankings compared to other tested patients, no history of failed prior use, and insurance authorization. The patient's physician made the final decision about treatment. Results. 60 pts were enrolled: 51 acute myeloid leukemia (AML), 7 acute lymphoblastic leukemia (ALL), 1 undifferentiated, 1 mixed phenotype. The median age was 58 years (range 22-82). For AML pts, ELN 2017 was favorable, intermediate and adverse in 8 (16%), 14 (28%) and 28 (56%) pts, respectively. Median prior lines of therapy were 4 (range 1-8); 15 pts (25%) had primary induction failure and 23 pts (40%) had relapsed post allogeneic transplant, 10 in the first 100 days (d). For those who had relapsed disease, median duration of 1st CR was 6.8 months (range 0.5-52.6). Final HTS test results were obtained within 5 d (4-13), and each patient exhibited a unique pattern of drug response (Figure 1). 35 patients were treated with a single drug (N=12) or combination (2-4 agents; N=23) recommended by the trial. 25 of the patients did not complete treatment on this study because of transition to supportive care (6), treatment with other therapy (10), travel out of state to local care (4), participation on another trial (CAR-T cell-2, investigational agent-2), and pneumonia (1). 30 patients had at least 1 mutation for which targeted inhibitors [FLT3 (11), KIT (2), IDH1/2 (7), NRAS/KRAS (20), ABL1 (3), JAK2 (1)] were available, and seven patients received one. Additionally, 35 pts (4 had more than 1) had a mutation that could now be considered for investigational therapy, including TP53 (12), NPM1 (8), KMT2A rearrangement (4), WT1 (10), or spliceosome mutation (5). Median follow up duration was 2.7 months (range 0.3-36.3). Of 27 pts for whom a post-treatment BM was performed, overall response rate was 33% including 2 complete remission (CR), 1 CR with incomplete count recovery (CRi) and 6 partial remissions (PRs). Of 22 pts with circulating blasts, 21 (95%) exhibited decline with chosen regimen, and 7 (31.8%) exhibited resolution. Median overall survival (OS) for those receiving assay guided therapy was 135 days (d) (95%CI 79-213), compared to 34 d (95%CI 26-63) for enrolled patients not treated on study with corresponding 100 day-OS of 57% (95%CI 39-72%) and 24% (95%CI 10-42), respectively (P<0.001) (Figure 2). Median survival post consent was 109 d (95%CI 79-341) for the subset of post-allogeneic transplant relapsed pts who then received assay guided therapy vs. 30 d (95%CI 8-92) for the those not treated on this trial (P 0.003). Assay guided therapy can decrease risk of death by 83% after adjusted by age, sex, type of leukemia, cytogenetic risk, number of lines of previous treatment (HR 0.17, 95%CI 0.08-0.35, P <0.001) for this group of pts with extensive prior therapy. Conclusion. Genomic analysis and functional screening of enriched leukemia cells can comprehensively predict in vivo efficacy and individualize optimal treatment for patients with R/R AL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Utility of Flow Cytometry in Monitoring of Measurable Residual Disease in Patients with Hairy Cell Leukemia

Background: Hairy cell leukemia (HCL) is a rare lymphoproliferative disorder with an excellent prognosis following cladribine-based therapies. However, not all patients achieve complete remission and a significant proportion relapse after prior response. The addition of rituximab to cladribine deepens responses and whether this can prolong remission duration has not been established. Interestingly, some patients remain relapse-free despite having detectable residual hairy cells with long term follow-up. Objective: Evaluate the correlation between peripheral blood (PB) and bone marrow (BM) measurable residual disease (MRD) assessment at one and three months into therapy and examine the role of PB flow cytometry (FCM) as an MRD tool during long term follow-up. Methods: We retrospectively reviewed adult patients with HCL treated on a clinical trial with cladribine and rituximab at our institution between June 2004 and October 2020. Cladribine was administered at the dose of 5.6 mg/m2 daily for 5 days, and rituximab 375 mg/m2 weekly for 8 weeks, starting 28 days after the administration of cladribine. The correlation and concordance between FCM results obtained from BM and PB were evaluated using Pearson correlation and Bland Altman test, with linear regression performed to assess for proportional bias between the 2 techniques. Overall survival (OS) was calculated from the time of diagnosis to the time of death or last follow-up. Results: 120 patients were analyzed, with a median age of 55 years (range, 29-91); 83% were males. Among 119 evaluable patients, 118 patients achieved complete remission (CR) and 1 patient CR with incomplete count recovery (CRi) as best response after a median of 81 days (range, 24-244). 101 patients were assessed for MRD by FCM on BM samples at best response, and 55% were found to be MRD negative. At diagnosis, the mean percentage of detectable hairy cells assessed by flow cytometry on BM and PB samples was 19% (range, 0.3%-93%) and 16% (range, 0%-99%) respectively. There was a good concordance between the two sample sources (R=0.82, P<0.0001) and no proportional bias (unstandardized coefficient=-0.16, P=0.10) (Figure 1). At 1 month, those respective levels were 1.4% (range, 0%-41%) and 1.8% (range, 0%-50%), with a strong correlation between sample sources (R=0.99, P<0.0001); however, proportional bias was observed (unstandardized coefficient=-0.30, P<0.0001). At 3 months, the median MRD level by BM was 0.27% (range, 0%-19%) and 0.14% by PB (range, 0%-6%), with good correlation between sample sources (R=0.98, P<0.0001). From year 1 onwards after diagnosis, patients were monitored by FCM testing on PB for the evaluation of MRD (Figure 2). The mean MRD values at years 1, 3, 5, and 10 were 0.0003% (range, 0%-0.02%), 0.01% (range, 0%-0.4%), 0.10% (range, 0%-2.3%), and 0.11% (range, 0%-0.5%), respectively. Five patients relapsed: 4 patients with abnormal counts and 1 patient with BM showing relapsed disease in the setting of normal counts. None of the patients who relapsed had FCM at 1 year; one patient had positive MRD at 0.4% at 3 years and 0.25% at 5 years but relapsed at 8 years after diagnosis; and one patient had MRD at 0.15% at 10 years but his relapse manifested after 11 years from diagnosis. Two patients did not have any FCM measurements. Among the 115 patients who did not relapse, 78 had FCM tests at 1 year that were negative except for one positive result at 0.02% (became negative at 3 years), and 38 had FCM at 3 years with only two positive results at 0.01% (became negative at 5 years) and 0.03%. At 5 years, 24 patients had FCM assessment: one patient had a positive result at 0.03% (previously negative) and one at 2.3%. Four patients had FCM at 10 years and with no evidence of disease. After a median follow-up of 101 months (range, 84-119), the median OS of the entire cohort was not reached, with a 10-year OS rate of 93%. Conclusion: There is good concordance between FCM MRD assessed on BM and PB samples in patients with HCL particularly early in the course of therapy. Late relapses have been observed among patients in remission, justifying the use of FCM on PB as a reliable tool for long term MRD monitoring, with most relapsing patients having levels >0.1%. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Efficacy of Chidamide Maintenance Therapy after CAR-T Therapy for Refractory or Relapsed B-Cell Acute Lymphoblastic Leukemia

Introduction Anti-CD19 chimeric antigen receptor (CAR) T-cells therapy has achieved unprecedented efficacy in refractory or relapsed (R/R) B-cell acute lymphoblastic leukemia (B-ALL) patients, with up to a 90% complete remission (CR) rate. However, a large body of clinical data has shown that the relapse rate post CD19 CAR-T therapy remains high. Our published study of 254 patients with R/R B-ALL treated with CD19 CAR-T showed the median time to relapse following CAR-T cells infusion was 100 days. Patients who received consolidative allogeneic hematopoietic stem cell transplantation (allo-HSCT) post CAR-T therapy demonstrated much higher overall survival (OS) and leukemia-free survival (LFS) compared to those who received CAR-T therapy alone (1-year OS of 77.8% vs. 35.4%, p<0.0001; 1-year LFS of 70.9% vs. 33.3%, p<0.0001, respectively). However, there are still many patients who cannot undergo allo-HSCT, including those who have relapsed following allo-HSCT and elderly patients. Prolonging disease-free survival (DFS) after CAR-T therapy in these patients remains a challenge for physicians. Studies have shown that the histone deacetylase (HDAC) inhibitor chidamide can up-regulate T-cell activity and down-regulate derived suppressor cell (MDSC) expression. Chidamide also promotes the expression of CD22 on the surface of B-cell tumor cells in vitro and in vivo, and enhances CAR-T function. Here we explore the efficacy of chidamide as maintenance therapy post CAR-T in B-ALL. Patients and methods We analyzed 19 patients with R/R B-ALL who received CD19 CAR-T at our center (NCT04546893) between October 2019 and July 2022. All patients achieved CR on day 30 following CD19 CAR-T cells infusion and were unable to bridge to allo-HSCT within 3 months. We administered chidamide as maintenance therapy to all 19 patients between 30 to 90 days after CAR-T infusion. Chidamide was continuously administered until the patient relapsed, transferred to transplant, or had intolerable side effects. Results On Day 30 post CD19 CAR-T, 19/19 (100%) patients achieved CR or CR with incomplete count recovery (CRi)(Figure 1). Sixteen of 18 (88.89%) who had bone marrow involvement achieved minimal residual disease (MRD)-negative CR. The median time from CAR-T cell infusion to start chidamide therapy was 30 days (range: 30-90 days) and the median duration of chidamide administration was 90 days (range: 12-420 days). No patient experienced cytokine release syndrome (CRS) or encephalopathy while taking chidamide. All side effects that occurred were mild. Two patients experienced nausea and vomiting and one patient had mild bone marrow suppression. No other side effects occurred. The median follow-up time was 12 months (range: 1-33 months), the 12-month OS rate was 83.1% and the 12-month DFS rate was 62.4% (Figure 2). Five patients received allo-HSCT following chidamide maintenance and 13 patients who did not undergo transplantation had 12-month OS of 83.3%, 12-month DFS of 62.9%. Six patients were monitored for the proportion of CAR-T cells in T lymphocytes following chidamide therapy. In all six patients, the proportion of CAR-T cells increased but to different degrees. Conclusions For those patients with R/R B-ALL for whom allo-HSCT is not available following CD19 CAR-T therapy, HDAC inhibitor chidamide as maintenance therapy is a viable option to reduce the risk of relapse rate following CD19 CAR-T therapy. This study demonstrated that chidamide could prolong OS and DFS in some patients who achieved CR after CD19 CAR-T therapy. Chidamide was safe, inexpensive and convenient to take orally. The inclusion of more patients and extended observation time is needed for further evaluation of chidamide maintenance therapy following CAR-T cell therapy in patients with R/R B-ALL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal