Achieved MRD Negativity Research Articles

Mega-dose decitabine conditioning and prophylactic donor lymphocyte infusion for patients with relapsed/refractory AML with active disease at the time of allogeneic haematopoietic cell transplantation: A multicenter prospective phase II study.

Patients with relapsed/refractory acute myeloid leukaemia (R/R AML), especially those who failed in novel target agents are related to dismal survival. We developed a multi-institutional, single-arm, prospective phase II trial, to investigate intensified conditioning with 'Mega-Dose' decitabine (MegaDAC) following allogeneic haematopoietic cell transplantation (allo-HCT) for R/R AML. From 2019 to 2023, 70 heavily treated R/R AML patients in active disease were consecutively enrolled. Significantly, every patient (n = 18) harbouring specific mutations exhibited no response to their best available target agents (BATs). Moreover, 74.3% of the enrolled patients did not reach remission following venetoclax-based regimens. All patients underwent intravenous decitabine (400 mg/m2) along with busulfan and cyclophosphamide. Median follow-up was 26 months (8-65) after HCT. All engrafted patients achieved MRD negativity post-HCT, with a median 3.3-log reduction in recurrent genetic abnormalities. The regimen was well tolerated, without irreversible grades III-IV toxicity peri-engraftment. The estimated 2-year CIR was 29.6% (18.4%-41.7%) and the est-2-year NRM was 15.5% (7.8%-25.5%). The est-2-year LFS, OS, and GRFS were 55.0% (43.5%-69.4%), 58.6% (47.0%-73.0%), and 42.9% (31.9%-57.6%), respectively. Multivariate analysis showed that pre-HCT drug exposures had no significant impact on primary outcomes. MegaDAC is highlighted as an effective and safe option for R/R AML in the new era of targeted therapies.

OriCAR-017, a novel GPRC5D-targeting CAR-T, in patients with relapsed/refractory multiple myeloma: Long term follow-up results of phase 1 study (POLARIS).

7511 Background: OriCAR-017 is a novel GPRC5D-targeting CAR T-cells. Previously we had presented early study results (Lancet Haematol 2023: 10: e107–16) following OriCAR-017 treatment, the results of good durable response and long-term safety profile support OriCAR-017 is highly probable to be developed as a promising therapy for patients with relapsed or refractory multiple myeloma. All patients had completed at least 2-year follow-up per protocol. Methods: Ten median age of 64 years (range 41–71) pretreated RRMM pts with a median of 5.5 prior lines therapies (range 3-17) received OriCAR-017. Seven (70.0%) pts were cytogenetics high risk, 4 (40.0%) pts had EMD, 3 (30.0%) pts had ISS stage(III), 2 (20.0%) pts had received prior anti-CD38 and 2 (20.0%) pts were treated with auto-HSCT and 5 (50.0%) pts were treated with BCMA CAR-T. Patients were administrated in a single dose of intravenous OriCAR-017 at 1×10⁶CAR-T/kg (DL1,n=3), 3×10⁶CAR-T/kg(DL2,n=4), or 6×10⁶CAR-T/kg(DL3,n=3). Results: At data cut-off (Jan 16, 2024), all 10 enrolled pts had been evaluated for response with the last patient completed 24 months follow up. ORR was 100.0%, sCR was 80.0%, VGPR was 20.0%. All patients achieved MRD negativity at day 28. The mDOR was 10.43 months (95%CI, 5.00-17.00); mPFS was 11.37 months (95%CI, 5.93-18.00) while mOS has not reached (7 pts still undergo survival follow-up, 1 pt died from disease progress, 2 from COVID). The mDOR was 17.23 months (95%CI, 7.33-NR) and the mPFS was 19.10 months (95%CI, 8.30-NR) with 67% prior BCMA CAR-T pts at high dose level. Nine (90%) pts had grade 1 CRS, and 1 (10%) pt had grade 2 CRS. No ≥ G3 CRS was observed. Median time to CRS onset was 2 days (range 1–9) and median duration was 6 days (range 3–9). No ICANS, nor DLTs were observed. There were no SAE and no treatment-related deaths. No PK difference across dose levels with Cmax 7354.7 copies/μL and AUC0-28 68587 copies·day/μg. At high doses, CAR-T cells were detectable at 9 months and one responder at 21 months above the LLOQ. The patients with Tlast≧9 months had a longer PFS than those with Tlast <9 months. No correlation of antigen expression and efficacy was observed. All patients had the positive GPRC5D expression in bone marrow CD138+MMPC at baseline, compared with 50% of relapsed pts had a reduced expression measured by flow cytometry. Conclusions: The updated results showed OriCAR-017 continued to provide deep and durable responses, MRD negativity was achieved in all RRMM pts, including in pts refractory to anti-CD38, PIs and IMIDs and failure to BCMA-directed therapy with excellent safety profile. The results of long-term efficacy and safety follow up support that OriCAR-017 is highly probable to be developed as a promising therapy in RRMM. Further clinical development efforts are undertaking to confirm the clinical benefits of OriCAR-017. Clinical trial information: NCT05016778 .

Real world outcome of B ALL with t (1; 19) (q23; p13)/TCF3::PBX1 in adolescents and adults treated with intensive regimes

Significant heterogeneity has been reported in outcome of Acute lymphoblastic leukemia with t(1;19)(q23;p13)/TCF3::PBX1 in adolescents and adults leading to a lack of consensus on precise risk stratification. We evaluated clinical outcome of 17 adult ALL cases (≥15 years) with this genotype treated on intensive regimes.13/17 received COG0232 and 4/17 cases received UK-ALL protocol. All achieved CR (100%) with above treatment. End of induction MRD was evaluated in 14/17 cases of which 11 (78.5%) achieved MRD negativity. Total nine patients relapsed (7 marrows, 2 CNS). Overall survival at 2 years was 53.3%. The 2 year estimated PFS was 42.9%. The 2 years CIR was 54.2%. Adults with this genotype perform poorly despite early favorable response. Incorporation of novel immunotherapies and prompt HSCT should be strongly considered with this genotype. Targeted NGS panels for additional genetic aberrations can further help in risk stratifying and guiding therapy for this genotype.

Improved Outcome of Primary Plasma Cell Leukemia in the Current Era with the Use of Novel Agents and Autologous Bone Marrow Transplants-A Single Centre Experience.

Primary Plasma cell leukemia (pPCL) is an aggressive variant of plasma cell dyscrasias. Diagnostic criteria of plasma cell leukemia were recently updated by international myeloma working group to with more than 5% circulating plasma cells or absolute plasma cell count of more than 500/µL. We performed a retrospective analysis of patients diagnosed with pPCL in our department from 2017 to 2022. Clinical characteristics including the symptoms at presentation, organomegaly, bony involvement and extramedullary involvement were collected. Laboratory parameters including the biochemistry serum protein electrophoresis, serum immunofixation, serum free light chain assay, immunoglobulin profile were sent. Treatment and follow up data was collected. Fifteen patients were diagnosed (8 females and 7 males), median age 59 years (34-70). Six were lost to follow up and nine patients who received treatment at our hospital were analyzed for survival outcome. First line treatment was bortezomib- dexamethasone and immunomodulatory drugs (IMiD). Six (66%) achieved partial response or more and 3 had progressive disease. Five of the nine patients (55%) underwent autologous transplantation. Two out of 5 patients (40%) in the transplant group and 3 of the 4 patients (75%) in the non transplant group have died of the progressive disease. Overall survival was 45% at a median follow up of 14 months. Median OS for patients who underwent auto SCT was 16 months (12-22) versus 10 months (8-12) for patients who did not undergo transplant (Student t test; p value 0.018). Three of the patients achieved MRD negativity after transplant and post transplant consolidation therapy. Survival appears to be improved in patients who respond to initial therapy and are able to achieve MRD negativity which should be the goal of treatment in these patients.

Real-World Outcomes with CPX-351 Induction in Adults with Newly Diagnosed Acute Myeloid Leukemia

Introduction: CPX-351 is a dual-drug liposomal encapsulation of daunorubicin and cytarabine with a fixed molar ratio of 1:5. CPX-351 is approved for the treatment of newly diagnosed, therapy-related acute myeloid leukemia (t-AML) or AML with myelodysplasia related changes (AML-MRC) in the U.S. and Europe for adult patients (pts) eligible for intensive chemotherapy. In a randomized phase 3 study of older pts ages 60-75, CPX-351 induction showed improved CR rates and OS compared to conventional 7+3 induction, with the greatest benefit seen in pts with t-AML and those without prior hypomethylating agent (HMA) use. There is limited data on the use of CPX-351 in younger pts, although the U.S. FDA approval was not age-restricted. This study examined real-world CPX-351 usage, including patient selection, clinical outcomes, and complications during induction hospitalizations. Methods: We identified previously untreated AML pts who received CPX-351 induction chemotherapy at the University of Kansas Medical Center via retrospective chart review from August 2017 - May 2023. Determination of t-AML and AML-MRC was made by patient history, bone marrow morphology, and available cytogenetic and molecular information at the time of therapy selection. We excluded pts who received CPX-351 as part of a clinical trial. Data was collected for baseline demographics, disease characteristics, outcomes, and safety profile. The composite complete remission rate (CRc) was defined as CR+CRi+CRh at recovery marrow after induction. Primary refractory disease included pts who failed to achieve CR, CRi, or CRh after 2 courses of intensive induction and excluded those who died in aplasia or due to an indeterminate cause. Results: 74 pts with previously untreated AML who received CPX-351 were identified. Median age was 64 years (21-78): 29% of pts were <60 years old, 50% were males, 84% were Non-Hispanic White, 32% had t-AML, 68% had AML-MRC, 20% had prior HMA treatment, and 22% had prior anthracycline exposure. ELN 2022 risk categories were 13% favorable, 20% intermediate, and 68% adverse. 21 pts had complex karyotype (28%), and 16% were TP53 mutant (Table 1). Indications for induction with CPX-351 versus 7+3 included history of prior chemotherapy (n=24), prior MDS (n=32), or MDS-related changes in bone marrow morphology (n=50). The CRc for the total study population was 61% (45/74). Of these, 29% (13/45) achieved MRD negativity by multiparameter flow cytometry <10 -4. CRc in the ELN adverse risk group was 54% (27/50), 73% (11/15) in the intermediate-risk group, and 78% (7/9) in the favorable risk group. Among TP53 mutant pts, CRc was 42% (5/12). CRc in the t-AML group was 71% (17/24), 56% (28/50) in the AML-MRC group, and 53% (8/15) in the prior HMA treatment group. The CRc in pts ≥60 was 63%, 15% were primary refractory, and 37% underwent alloSCT in CR1. In pts <60, the CRc was 54%, 32% were primary refractory, and 27% underwent an alloSCT in CR1 (Table 2). A second course of induction therapy was given for persistent disease at day 14 or similar time point in 36% (n=27) of pts. Among those, 55% (15/27) had primary refractory disease, 20% of the cohort. At a median follow-up of 11 mos, the mOS was 10.8 mos (0.4-54). The mOS for t-AML was 13 mos, whereas the mOS for the group with prior HMA treatment was 10.4 mos. For pts that achieved CR, mOS was 13.6 mos; for pts that achieved MRD negativity, mOS was 13.8 mos. The mOS for pts <60 was 16 mos, and for pts ≥60 was 10 mos (p=0.39). The mOS for pts that achieved CRc in the group <60 was 20.3mos, and for ≥60 was 11.2 mos (p=0.27). Pts that underwent alloSCT in CR1 <60 had mOS of 25 mos; for ≥60, it was 14.2 mos (p=0.37). During induction hospitalization, febrile neutropenia was the most common adverse event in 84% (n=62). ICU treatment was required in 14% (N=5). There were 2 deaths during induction: one due to respiratory failure and one attributed to sepsis. Conclusion: The use of CPX-351 demonstrated efficacy across subgroups, especially in t-AML and pts without prior HMA exposure, as shown in larger studies. In pts <60 years, even though CRc rates were lower, CPX-351 led to longer mOS in those who achieved CRc and in those who underwent alloSCT compared to pts ≥60 years, although it didn't reach statistical significance in this small cohort. Induction therapy outcomes and treatment-related complications in our study corroborate the data for prior CPX-351 studies.

MRD Positivity Was the Poor Prognostic Factor for Adverse-Risk AML Patients with Allogeneic Hematopoietic Stem Cell Transplantation: A Multicenter Trohpy Study

Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is recommended for acute myeloid leukemia (AML) patients with adverse-risk. However, when patients within this group would proceed to allo-HSCT is controversial. We aimed to identify the optimal timepoint for allo-HSCT for adverse-risk AML patients. Methods: This is a multicenter, retrospective designed study, based on the transplant database of Wuhan Tongji Hospital, Shanghai Ruijin Hospital, and Peking University Institute of Hematology (PUIH) (TROPHY group). Consecutive AML patients receiving allo-HSCT from January 2017 to June 2022 were screened, and the eligibility criteria were as followed: (1) aged ≥ 16 years; (2) adverse-risk AML based on ELN 2022 criteria; (3) achieving CR1 before allo-HSCT. The last follow-up was June 30, 2023. MRD status was monitored after the first consolidation chemotherapy (MRDc 1), after the second consolidation chemotherapy (MRDc 2), before allo-HSCT (MRD bft), and at 1, 2, 3, 4.5, 6, 9, and 12 months after allo-HSCT and at 6-month intervals thereafter. 0.1% was used as a threshold to distinguish MRD-positivity detected by multiparameter flow cytometry (MFC). The study was approved by the institutional review board of each participated hospital and was conducted in accordance with the Declaration of Helsinki. Results: A total of 391 adverse-risk AML patients were enrolled. 114 patients showed MRDc1 positivity. The 2-year probability of relapse, leukemia-free survival (LFS), and overall survival (OS) after allo-HSCT was 26.9% (95% CI: 18.1%-35.7%) vs. 9.4% (95% CI: 5.2%-13.6%) (P < 0.001), 60.7% (95% CI: 51.7%-71.1%) vs. 81.5% (95% CI: 76.3%-87.1%) (P < 0.001), and 74.4% (95% CI: 66.3%-83.3%) vs. 88.6% (95% CI: 84.4%-93.0%) (P < 0.001), respectively, for patients with MRDc 1 positivity and MRDc 1 negativity. Among patients with MRDc 1 positivity (n = 69), 24 (34.8%) turned MRD negativity after second consolidation therapy (MRDc 2 negativity). The similar trends were observed in patients with MRDc 2 positivity. The 2-year probability of relapse, LFS, and OS after allo-HSCT was 26.4% (95% CI: 18.1%-34.7%) vs. 9.4% (95% CI: 5.4%-13.3%) (P < 0.001), 61.2% (95% CI: 52.8%-71.0%) vs. 81.6% (95% CI: 76.6%-87.0%) (P < 0.001), and 75.6% (95% CI: 68.3%-83.8%) vs. 87.6% (95% CI: 83.3%-92.0%) (P < 0.001), respectively, for patients with MRD bft positivity and MRD bft negativity. Maintenance therapy provided better protection from relapse than preemptive therapy. In multivariate analysis, MRDc 1 positivity was associated with poorer LFS, MRDc 2 positivity was associated with a higher risk of relapse, and MRD bft positivity was associated with worse EFS after allo-HSCT. Conclusion: For the adverse-risk AML patients according to ELN2022 criteria, MRD is still the most important prognostic index for survival. Patients who achieved MRD negativity after the first consolidation chemotherapy could get similar clinical outcomes compared with those who achieved MRD negativity after the additional rounds of consolidation.

Phase 1b/2 Study of Escalating Doses of the NEDD8 Activating Enzyme Inhibitor Pevonedistat Administered in Combination with Standard Induction Therapy (Cytarabine and Idarubicin) in Newly Diagnosed High Risk Acute Myeloid Leukemia

Introduction: Pevonedistat is a potent and selective small-molecule inhibitor of the NEDD8-activating enzyme that has demonstrated clinical activity in acute myeloid leukemia (AML). Preclinical studies suggest that pevonedistat synergistically enhances the activity of cytarabine in AML. We investigated the safety and efficacy of pevonedistat in combination with 7+3 cytarabine and idarubicin induction chemotherapy in adults with high-risk AML. Methods: This open-label, multicenter phase 1b/2 study (NCT03330821) enrolled patients aged ≥18 years with newly diagnosed high-risk AML, defined as therapy-related AML, AML with antecedent myelodysplastic syndrome or AML with myelodysplasia-related changes, the presence of adverse genetic features per ELN 2017 guidelines, or being age ≥55. Eligible patients had an ECOG status of 0-2. Patients were administered pevonedistat on days 1, 3, and 5 of each 28-day cycle in combination with cytarabine 100 mg/m 2 on days 1-7 and idarubicin 12 mg/m 2 on days 1-3. In the phase 1b dose-escalation part of the study, a standard 3+3 design was used to evaluate 2 dose levels of pevonedistat: 15 and 20 mg/m 2. Consolidation consisted of up to 4 cycles of cytarabine (1-3 g/m 2 q12h) on days 1, 3, and 5 or transplant. For pharmacodynamic (PD) assessment, RT-PCR assays were performed on peripheral blood samples to measure expression levels of 7 NRF-2 target genes (ATF3, GCLM, GSR, NQ01, SLC7A11, SRXN1, and TXNRD1). The primary objective for the phase 1b study was to determine the RP2D of pevonedistat in combination with cytarabine and idarubicin. The primary objective for the phase 2 study was to determine the composite complete response rate (CRc; CR+CRi). Secondary objectives included relapse-free survival (RFS), overall survival (OS), and safety and tolerability. Results: A total of 28 patients were enrolled at 5 sites in the US between August 2018 and August 2021. Six patients were enrolled in the phase 1b study and 22 patients in phase 2. Baseline patient characteristics are shown in Table 1. The median age was 61 years (range 47-74). Per the 2017 ELN risk classification, 8 of 28 patients (29%) had favorable risk, 8 (29%) had intermediate risk, and 12 (43%) had adverse risk. All 28 patients were included for safety and response assessments. In phase 1b, none of the 6 patients experienced dose-limiting toxicity at 15 or 20 mg/m 2. Thus, the RP2D of pevonedistat was determined to be 20 mg/m 2. The CRc rate was 64% (95% CI 44-81) with 17 patients achieving CR and 1 patient achieving CRi. Of the 18 patients who achieved CR or CRi, 16 (89%) achieved MRD negativity by multiparameter flow cytometry, and 7 (39%) proceeded to HSCT. The CRc rates for patients in the ELN 2017 favorable, intermediate, and adverse risk groups were 100% (95% CI 63-100), 63% (95% CI 29-89), and 42% (95% CI 18-71), respectively. Eight patients were included in the interim PD analysis. Among patients who achieved CR or CRi (n=6), 4 (ATF3, GSR, SLC7A11, and SRXN1) of the 7 NRF-2 target genes measured were significantly upregulated at 5 hours post-pevonedistat induction compared to baseline. There was no significant increase in NRF-2-regulated gene transcript levels among patients with refractory disease (n=2). The median follow-up was 31.1 months (range 19.1-55.9). The median RFS was 24.4 months (95% CI 7-54.3+) and median OS was 25 months (95% CI 11.9-55.9+). The estimated 1-year and 2-year RFS were 72% (95% CI 52-93) and 55% (95% CI 23-78), respectively. The estimated 1-year and 2-year OS were 68% (95% CI 51-85) and 53% (95% CI 34-72), respectively. The most common grade ≥3 treatment-related adverse events were anemia (61%), febrile neutropenia (25%), and hypophosphatemia (18%). No treatment-related deaths were observed. Conclusion: Pevonedistat in combination with cytarabine and idarubicin was well tolerated among adults with newly diagnosed, high-risk AML and induced deep remissions with promising RFS and OS.

Outcomes in Patients with Acute Myeloid Leukemia Treated with CLAG (cladribine, cytarabine, filgrastim) and/or Mitoxantrone with Venetoclax

Introduction: CLAG (cladribine, cytarabine, filgrastim) with or without M (mitoxantrone) has anti-leukemic activity in newly diagnosed (ND) and relapsed/refractory (R/R) AML (Wierzbowska et al. 2008, Jaglal et al. 2014, Seiter et al. 2016). Venetoclax (Ven) with hypomethylating agents (HMA), approved for patients (pts) who are not candidates for intensive chemotherapy (IC), is increasingly being employed even for pts who are fit for IC. R/R disease remains a major cause of mortality in fit pts with AML, and thus improved IC regimen is an area of active research. Various combination of IC with Ven are ongoing with promising early findings (DiNardo et al. 2021, Reville et al. 2022). In this study, we examined the outcomes of AML patients treated with CLAG and/or mitoxantrone with Ven, CLAG(M)/Ven. Methods: This was a retrospective study of pts with AML who received CLAG(M)/Ven (Days 2-8) in 2022-2023. Clinical responses were reported using ELN 2022 criteria. Kaplan-Meier analyses were used to estimate overall survival (OS) from the date of CLAG(M)/Ven initiation. Results: This cohort of 19 pts (8M/11F with median age of 60 [23-74] at diagnosis) is comprised of 68.4% (13/19) R/R and 31.6% (6/19) ND AML who had prior MDS directed therapy. There were 57.9% (11/19) with secondary/therapy-related AML and when including de novo AML pts who had mutations highly specific for secondary AML ontogeny, it increased to 78.9% (15/19). Most of the pts (68.4%, 13/19) had adverse risk disease by ELN 2022. Common mutations being TP53 (26.3%, 5/19) followed by IDH1/2 (21.1%), ASXL1 (15.8%), and RUNX1 (15.8%). There were 36.8% (7/19) who had received allogeneic hematopoietic cell transplant (alloHCT) (Table 1). Similar number of pts received CLAG/Ven (47.5%) and CLAG-M/Ven (52.6%). Pts received on average 2.6 lines of treatment prior to CLAG(M)/Ven with 1 pt received 5 prior lines of treatment after AML diagnosis. Most of the pts, 78.9% (15/19), had prior HMA/Ven. The 30-day and 60-day morality was 5.3% (1/19) (disease status unknown at the time of death) and 26.3% (5/19) (disease status: 3 yes, 1 no, 1 unknown), respectively. Among these 5 early deaths within 60 days, 3 were ND AML that were heavily pretreated for prior MDS (average 3 lines of prior therapy) and 2 were R/R AML. All of them had prior HMA/Ven. Eighty percent (4/5) had adverse risk disease and received CLAG-M/Ven. Forty percent (2/5) had TP53 mutation. Objective response rate (ORR) of the entire cohort was 26.3% (5/19) (2 CR, 1 CRi, and 2 MLFS). Among those with evaluable response (n=10), ORR was 50%. Two CR/CRi pts achieved undetectable MRD by flow cytometry. MRD was not tested in the other 3 pts. Notably, ORR was higher in pts who received CLAG/Ven (44.4%, 4/9) compared to CLAG-M/Ven (10%, 1/10). No response in ND AML and 38.5% (5/13) ORR in R/R AML. Of the 47.4% (9/19) nonevaluable pts, 6 had aplastic marrow (2 died while getting induction, 2 transitioned to alloHCT, 1 moved onto next line of treatment, and 1 lost to follow up) and 3 had recovery marrow pending. For pts who achieved a response, 60% (3/5) underwent alloHCT (all of them alive without disease at data cutoff). The median time to count recovery was 42.5 days (27 days to never recovered). Prior HMA/Ven failure, high dose cytarabine failure, and mutations did not significantly impact response in this small cohort. The median OS from the time of CLAG(M)/Ven initiation was 5.5 months with a median follow up of 8.6 months (Figure 1). OS from the date of CLAG(M)/Ven was significantly shorter in pts with TP53 mutation vs. wild-type (2 vs. 11.2 months, p=0.031). Conclusions: Our findings showed the combination regimen CLAG(M)/Ven is feasible in pts with AML. It also provided better characterization in terms of early mortality and survivals in these pts, which can help inform future clinical trial design. ORR was similar to what was previously reported with CLAG(M); however, it is encouraging that those who achieved CR/CRi and had MRD testing also achieved MRD negativity. Outcomes of TP53-mutated subset is dismal suggesting IC-based approach in this setting is limited. Larger cohort and longer follow up is needed to confirm the impact of factors such as specific regimen, mutations, and prior therapies on outcomes.

Outcomes of B-Cell Acute Lymphoblastic Leukemia Patients Who Relapse after Blinatumomab Salvage Therapy - a Tertiary Centre Experience

Introduction In recent years, the treatment of B-cell acute lymphoblastic leukemia (B-ALL) has evolved tremendously resulting in improved outcomes in patients with relapse/refractory (r/r) B-ALL and patients with measurable residual disease (MRD+). One such novel therapy is the CD3/CD19 bispecific antibody blinatumomab. There is however limited data on the outcomes and treatment options for B-ALL patients who relapse after blinatumomab was given as salvage therapy. Methods This IRB-approved study retrospectively reviewed the outcomes of all adult patients (≥18 years old) with B-ALL treated with blinatumomab at our center, Singapore General Hospital. The primary aim was to describe the incidence, risk factors and survival outcomes of B-ALL patients who relapse after blinatumomab salvage therapy. Results Between January 2017 to December 2022, a total of 27 patients were treated at our center with blinatumomab. Blinatumomab was used as salvage therapy in 13 patients and for MRD+ disease after front-line therapy in 7 patients. Characteristics of the 13 patients who received blinatumomab salvage therapy are shown in Table 1. Eight patients had received an allogenic hematopoietic stem cell transplant (alloHSCT) and 6 patients had received inotuzumab, a CD22 antibody-drug conjugate, prior to blinatumomab salvage. The median number of lines of therapy before blinatumomab salvage was 3 and the median number of cycles of blinatumomab administered was 4. All but 1 patient achieved MRD negativity after the prescribed number of blinatumomab cycles. Eight (61.5%) of 13 patients relapsed after blinatumomab salvage therapy. Median progression free survival (PFS) in this group of patients was 7 months (IQR 2-11) and overall survival (OS) of 19 months (IQR 8-26). Six (75%) of these 8 patients proceeded to receive salvage therapy with inotuzumab. Majority (5 of 6) achieved MRD negativity and 2 patients subsequently underwent alloHSCT and CAR-T therapy respectively. Unfortunately, all 6 patients eventually relapsed. Of note, 3 patients had received inotuzumab prior to blinatumomab salvage. We observed that patients (n=3) with extramedullary disease (EMD) (including central nervous system (CNS) involvement) at initiation of blinatumomab salvage therapy were associated with higher odds of both systemic and extramedullary relapse (p=0.014). These patients had inferior progression free survival (PFS) as compared to patients without EMD/CNS involvement, median PFS 2 months (95% CI 2 - 11) vs 21 months (95% CI 4 - 21), p = 0.041 (Figure 1). A trend towards inferior overall survival was also observed though statistical significance was not demonstrated, median OS 19 months (95% CI 8 - 19) vs 26 months (95% CI 14 - 26). Conclusion EMD/CNS involvement prior to blinatumomab salvage therapy was associated with higher risk for systemic and EMD/CNS relapse. Patients with B-ALL who relapsed after blinatumomab salvage could be successfully rescued by inotuzumab regardless of prior inotuzumab use. These groups of patients however represent very-high risk groups with inferior survival outcomes. Novel treatments and better sequencing of treatments may improve outcomes of these patients.

Phase I Clinical Study of Humanized BCMA-Single-Domain Antibodies-Targeting CAR T (BCMA-CART) in Patients with Relapsed/Refractory Multiple Myeloma

Background:The CAR structure adopted by CART-BCMA is composed of a single-domain antibody targeting BCMA, CD8 hinge region, transmembrane region, 4-1BB co-stimulatory domain, and CD3-ζ T cell activation domain. In the phase I clinical study (NCT05346198) carried out in China, the safety and efficacy of CART-BCMA were initially evaluated through the dose escalation + dose expansion design, and the recommended dose (RD dose) for follow-up studies was determined as well. Method:Enrolled patients with relapsed and/or refractory multiple myeloma (RRMM) had previously received at least 3 lines of therapy including at least one proteasome inhibitor and one immune modulator. After lymphatic preconditioning chemotherapy (program: fludarabine 30mg/m 2/d and cyclophosphamide 300mg/m 2/d, -5, -4, -3, for 3 consecutive days), all patients received a single dose of CART-BCMA at 2.5×10 6, 5×10 6 and 7.5×10 6 CAR-positive T cells/kg (subject body weight), according to the dose level in which they were enrolled. R esults :Up to June 26, 2023, a total of 15 cases of RRMM received 2.5×10 6 CAR-positive T cells/kg (n=3), 5×10 6 CAR-positive T cells/kg (n=11) or 7.5×10 6 CAR-positive T cells/kg (n=1) dose level of CART-BCMA cell infusion therapy on the basis of the dose level in which they were enrolled. The median follow-up time was 14.42 months (range: 10.2-26.6 months). The median age of the subjects was 63.0 years old (range: 36-73 years old) (Table 1), 73.3% of the subjects (n=11) had previously received ≥4 lines of multiple myeloma therapy, and the median line of treatment was 5 lines (range: 3-9 lines), among which, 2 subjects (13.3%) had previously received autologous hematopoietic stem cell transplantation, and 4 subjects (26.7%) had relapsed/refractory diseases after previous treatment with proteasome inhibitors, immune modulators and CD38 monoclonal antibodies (three-drug relapsed/refractory). Nine subjects (60.0%) had high-risk cytogenetic abnormalities according to sMART 3.0 criteria, and 6 subjects (40.0%) had extramedullary plasmacytoma. The most common grade ≥3 adverse events were hematological toxicity, including decreased neutrophil count (n=13, 86.7%), decreased white blood cell count (n=12, 80.0%), decreased lymphocyte count (n=10, 66.7%), anemia (n=8, 53.3%), decreased platelet count (n=4, 26.7%). The first patient in the 7.5×10 6 CAR-positive T cells/kg dose group had a dose-limiting toxicity (DLT) event of grade 4 platelet count decrease, and no DLT event occurred in the other low-dose groups (2.5 and 5×10 6 CAR-positive T cells/kg). All 15 patients (100.0%) developed grade 1-2 cytokine release syndrome (CRS), no grade ≥3 CRS occurred, and the median time to CRS was 2.0 days (range: 1-13 days) , with a median duration of 7.0 days (range: 2 to 17 days). After the occurrence of CRS, all patients recovered without sequelae after supportive treatment, and 6 patients (40%) received tocilizumab (3 subjects received 2 doses, 3 subjects received 1 dose), 4 patients (26.7%) used glucocorticoids. There was no event of immune effector cell-associated neurotoxicity syndrome (ICANS), and no death event occurred. The median time to the first response (TTR) of the patients was 0.953 months (range: 0.92 to 2.23 months). All 15 patients who received CART-BCMA infusion achieved remission, and the overall remission rate (ORR) ( At least achieve PR or better efficacy) was 100% (95%CI, 78.20%-100.00%), as shown in Figure 1, among which, the best response of 9 patients (60%) was strict complete remission ( sCR), 5 patients (33.3%) achieved very good partial response (VGPR), and 1 patient (6.7%) achieved PR. All sCR patients achieved MRD negativity. The ORR of 6 patients with extramedullary plasmacytoma was 100%, of which 2 achieved sCR and 4 achieved VGPR. Notably, gradual deepening of remission was observed in 12 patients (80%), of which 10 patients (66.7%) further deepened the depth of remission on days 60-90 after infusion, and 2 patients (13.3%) were assessed sCR at day 360. Conclusion:Data from this phase 1 clinical study showed that CART-BCMA is well tolerated and highly efficacious in patients with RRMM. Patients with extramedullary plasmacytoma had the comparable response to those without extramedullary diseases. Notably, 12 patients (80%) patients elicted deeper response after 3 months of CART-BCMA infusion

Primary Endpoint Analysis from a Response Adaptive Phase II Clinical Trial of Carfilzomib, Lenalidomide, Dexamethasone Plus Daratumumab (KRd-Dara) in Patients with Newly Diagnosed Multiple Myeloma (NDMM)

Background Minimal residual disease (MRD) status has prognostic significance for progression-free survival (PFS) and overall survival (OS) in NDMM, but its value in guiding therapy remains unclear. We conducted a 2-stage, phase II trial evaluating the quadruplet regimen of KRd-Dara as induction therapy followed by MRD adapted KRd consolidation +/- autologous stem cell transplantation (ASCT) and maintenance versus observation. We previously reported the results of our stage I analysis at ASH 2022 (n=23; Blood 2022;140:4440-4441). Here we provide an updated analysis of the primary endpoint after completed enrollment of stage 2. Methods Eligible patients had NDMM with measurable disease. The induction phase allowed 8 cycles of KRd-Dara. Post-induction treatment assignment was informed by ASCT eligibility and MRD status by next generation sequencing (NGS at 10 -5), and included Group A (MRD negative, transplant-eligible and -ineligible, optional lenalidomide maintenance), Group B (MRD positive, transplant eligible, ASCT) and Group C (MRD positive, transplant ineligible, KRd consolidation for up to 12 cycles). Patients in Group B could receive up to 12 cycles of KRd consolidation therapy after ASCT if MRD positive. All groups could receive optional lenalidomide maintenance therapy after achievement of MRD negativity after induction ± consolidation. The primary endpoint was ≥complete response (CR) rate at the end of induction. The secondary endpoints were safety, MRD status, stem cell mobilization failure, and survival outcomes. Efficacy endpoints including MRD were evaluated with the intent to treat principle. Results Thirty-nine patients were enrolled: 23 in stage 1 and 16 in stage 2. Median age was 62 (range 34-78), 31% were female and 31% were African American. R-ISS stage 3 was present in 4 (10%), high-risk cytogenetics (including 1q21 gain) in 15 (39%). At the end of induction, ≥CR was achieved in 22/39 (56%, 90% CI: 42%-70%) patients including stringent CR (sCR) in 17 (44%), VGPR in 14 (36%) and PR in 1(3%). Of note, 2 patients did not complete induction therapy; one died during cycle 2, while another was withdrawn from study after an SAE during cycle 1. Evaluating by NGS, 62% achieved MRD negativity at 10 -5 and 41% MRD negativity at 10 -6 post-induction. MRD negativity by next generation flow cytometry (NGF) was 74% at 10 -5 and 31% at 10 -6. Concordance of MRD by NGS/ NGF at 10 -5 was 26/34 (76% in agreement and 24% disagreement, Cohen's kappa: 0.436), and by NGS/ NGF at 10 -6 was 17/25 (68% in agreement and 32% disagreement, Cohen's kappa: 0.351). 39 patients (100%) experienced treatment emergent AE, with grade ≥ 3 AE in 31 (80%). The most common (≥ 25%) any grade treatment related AE (TRAE) were diarrhea (39%), fatigue (36%), neutropenia (28%), and constipation (26%). Grade 3-4 TRAE (≥10% of patients) included neutropenia (21%) and hypophosphatemia (13%). Covid infection occurred in 10 (26%); only one patient needed hospitalization. Other infections (any grade) were seen in 20 (51%) patients. Fourteen (36%) patients experienced at least one SAE, of which 8 patients had a treatment-related SAE, including one death. Thromboembolic events were observed in 3 (8%) patients. Of 23 patients who collected stem cells upon completion of induction (7-8 cycles of KRD-Dara), 7 (30%) failed to collect an optimal target (3 million CD34+ cells/kg) on first attempt. Comparatively, 0 of 11 patients who collected after 3-5 cycles experienced stem cell collection failure (Fisher's exact: p=0.07). Post-induction, 24 patients were assigned to Group A, 8 to Group B, and 5 to Group C. After a median follow up of 26 months (95% CI: 17 - 27; data cut off 7/6/2023), 28 remain on treatment, 9 are in follow up, and 2 are off study. The 2-year PFS is 85.3% (95% CI: 71.6% - 99.1%); median PFS is not reached. Updated data on the best MRD/ CR/ sCR responses achieved post-induction will be presented at the meeting. Conclusions Our data confirm high rates of sCR and MRD negativity of the quadruplet regimen of KRd-Dara in NDMM. The safety data was in alignment with known safety profile of investigational products. With modification of the protocol to allow earlier stem cell collection, we were able to reduce the rate of stem cell mobilization failure from 30% to 0%. Based on our results, we recommend further testing of this MRD-based platform in randomized studies with stem cell collection after 3-4 cycles of KRd-Dara. Clinical trial: NCT04113018

Low Levels of Circulating Tumor Cells Correlate with Favorable Clinical Outcome and Unique Biological Features in Newly Diagnosed Multiple Myeloma Patients

Introduction Circulating tumor cells (CTCs) have been proposed as a prognostic biomarker in newly-diagnosed MM (NDMM) but their low frequency questions their use in clinical practice. Lower CTC levels (cut-off <0.01-0.07%) correlate with a favorable prognostic outcomes in transplant-eligible (TE) patients (pts); however, several issues remain to be addressed. On clinical grounds, it remains unclear whether there is a similar prognostic cut-off value for transplant-ineligible (TI) pts. Furthermore, it is not clear whether the CTCs mimic the characteristics of a single (main)-site bone marrow (ΒΜ) myeloma cells or if they represent the total disease burden, i.e. in cases with extramedullary or macrofocal disease. Moreover, there is limited information of the biological factors that may lead myeloma cells to egress their primary BM site. Methods BM and matched peripheral blood (PB) samples from 550 NDMM pts (210 TE, 340 TI) were evaluated with NGF (median LOD 2.1x10 -6) for the presence of myeloma cells. Various multivariable regression models including CTCs, R-ISS, cytogenetic status and LDH were assessed to define the optimal clinical CTC cut-off. The BM niche profiling was examined with mass cytometry (CyTOF, n=15 pts, 8 with no CTCs, 7 with CTCs higher than the cut-off) and various multicolor flow cytometry panels (n=199 pts including 56 pts with no CTCs) that allowed the detection of 32 distinct immune populations. Results The median value of CTCs was 0.01% of total PB cells (range: 0.0002%-63%) and in 57/550 (10.4%) pts CTCs could not be detected. Increased levels of CTCs correlated with ISS III stage (median: 0.037%, 0.007% and 0.002% for pts with ISS-3, ISS-2 and ISS-1, respectively; p<0.0001), high risk cytogenetics (median: 0.038% vs. 0.006% in standard risk, p<0.0001), and higher levels of b2-microglobulin and BM infiltration. Median follow-up was 41 months (range: 5-66 months). PFS and OS were gradually worsened towards a CTCs log increment, independently of ISS, cytogenetic status and LDH. Hence, pts with undetectable CTCs had the most favorable prognosis with a 5-year PFS and OS of 83% and 97% respectively. The optimal clinical CTCs cut-off that stratified pts into two distinct prognostic groups was defined at the level of 0.02%, which was common for both TE (median PFS: NR in both high and low CTC subsets; p<0.01) and TI subgroups (median PFS: 47 for low vs. 23 months for high CTCs subset, p<0.0001). Importantly, this cut-off, together with the phenotypic classification of pts (MGUS-like, MM-like etc.) could be incorporated in the established R-ISS system, providing an improved ptnts' stratification. The 2-year achievement of MRD negativity was 45%, 67% and 73% for pts with high, low and undetectable CTCs and median time for MRD negativity was 34, 17 and 12 months, respectively (p<0.001). Of note, pts with high CTCs who achieved MRD negativity, modulated their unfavorable risk status and showed similar PFS with those who had low CTCs. In 73/493 (14.8%) pts with detectable CTCs, there was an obvious phenotypic inconsistency between BM myeloma cells and CTCs, either in regard to the relative ratio of the detected (sub)clones, or the appearance of ≥1 phenotypically distinct clonal populations, which were present only in BM or PB. Pts with phenotypic inconsistencies had higher CTC levels and more often diffuse MRI patterns than those with a phenotypic agreement (frequency: 40% vs. 10%; p<0.01). To better understand the heterogeneous dissemination of myeloma cells to PB, we compared the BM niche profiles of pts with high CTC levels (>10 -3) and those with no CTCs. The analyses highlighted clear differences in the BM composition of the two groups with the BM of pts with no CTCs showing significantly lower levels of T cells, NK cells, TAMs and an increased naïve/memory B cell ratio. Of note, no differences were observed in the prevalence of immunosuppressive cell subsets (Tregs, MDSCs) between the two groups. Discussion The presence of CTCs at levels >0.02% confers an adverse prognostic factor for NDMM pts, irrespective of their transplant status. On the contrary, pts with no CTCs have the more favorable outcome and share unique microenvironmental features, which may eliminate CTCs dissemination. Since the liquid biopsy seems to be a better representative of the entire tumor load than a single tissue biopsy, the CTC analysis serves as the new hallmark for the real-time evaluation of a patient's disease and immune status.

Unraveling the Mechanism of Action of Bispecific T-Cell Engagers in B-Cell Acute Lymphoblastic Leukemia Using Advanced Single-Cell Multiomics

Background Bispecific T-cell engagers (BiTEs) stimulate T lymphocytes proximate to tumor cells, inducing T-cell stimulation and tumor killing. Blinatumomab, an anti CD3-CD19, was the first to be approved with overall response rates of up to 80% in refractory B-cell Acute Lymphoblastic Leukemia (B-ALL). To overcome resistance and to develop next-generation BiTEs, we need to build on blinatumomab's success and better understand BiTEs mode of action and interaction with the tumor microenvironment (TME). Here, we apply advanced multiomics to examine blinatumomab's activation signatures and the sustained dynamics in the tumor and bone marrow (BM) immune TME. Methods Physically interacting Cells sequencing (PIC-seq) is an advanced multiomics technology deciphering the crosstalk between the cellular components of an immunological synapse (Cohen et al., 2022; Giladi et al., 2020). To assess Immediate activation signatures, we applied PIC-seq on a model of B-ALL cell lines (RS4;11, NALM-6) and lymphocytes obtained from healthy subjects, activated by blinatumomab, compared to no-treatment and activation with anti CD3-CD28 antibodies. To examine the Sustained effects on the immune TME, we performed a longitudinal single-cell RNA sequencing of the bone BM of adult B-ALL patients, before and after treatment with blinatumomab in the Division of Hematology in the Tel Aviv Sourasky Medical Center in 2021-22. Results Immediate activation Applying PIC-seq on n=16,543 CD3 and CD19+ cells, we identified the distinct gene expression of ‘blinatumomab-activated lymphocytes’ (Figure 1). Blinatumomab induced cellular synapses composed of specific T lymphocytes subsets along the activation continuum, namely: effector T cells (CCL5, GNLY, NKG7), early IFN-G activation (IRF1, GBP5), activated cytotoxic (Xcl1-2, IFN-G) and proliferating T cells (CD69, CCND2) . ‘Blinatumomab-activated lymphocytes’ were characterized by a unique activation signature: upregulation of cytotoxicity (Xcl1, IFN-G, GNLY), co-stimulation and B-T cells crosstalk (CD40, CD27, TNFRSF18), immune recruitment (CXCL10, CCL4) and antigen-presentation (TNFSF14, ITGB2) pathways. Late synapses also expressed immunoregulatory molecules (TNFAIP8L2). This signature differed from classical anti CD3-CD28 induced activation and is independent of the donor and the target-cell identity. The malignant cells' response varied: RS4;11 cells manifested cellular senescence, while NALM-6 upregulated INFG-induced apoptotic pathways, suggesting indirect killing in the mechanism of action of BiTEs. Data on the introduction of primary B-ALL patients' cells will be presented at the ASH. Sustained effects We profiled >11,000 cells from three patients: Patient 1, 31-year-old (y/o) female, primary refractory B-ALL (50% BM blasts), attaining transient MRD negativity. Patient 2, 71-y/o male, primary refractory Ph+ B-ALL (74% BM blasts) achieving reduction in MRD following first cycle. Patient 3, 71 y/o, Ph+ B-ALL, treated as consolidation therapy, achieving MRD negativity. Blinatumomab induced a dramatic perturbation in the lymphocytic and myeloid compartments of the BM and was highly patient-specific ( Figure 2). The BM lymphocytic compartment prior to initiation of blinatumomab in molecular remission (patient 3) was characterized by active T and Natural Killer cell states, compared to an abundancy of naïve lymphocytes in active disease (patients 1 and 2). There were no signs of T-cell exhaustion pre or post treatment in all patients. Post-treatment, CD8 T-Central Memory cells proliferated in all patients. Patients treated for active disease (patients 2 and 3), had an expansion of the Tregs population post-treatment. In the myeloid compartment, patients with active disease had more non-classical monocytes, known to correlate with poor prognosis. These were replaced by classical monocytes following treatment, in addition to the emergence of a macrophage-precursor population. Data on the BM and peripheral blood dynamics of an additional six patients will be presented at the ASH. Conclusions We present an advanced single cell dissection of blinatumomab-induced target-effector interaction, providing novel insights into the mechanism of action and TME dynamics to guide patient selection and next generation BiTEs. A larger patients' cohort and introduction of patients' cells to the PIC-seq in vitro model will be presented at the ASH.

GEM2017FIT Trial: Induction Therapy with Bortezomib-Melphalan and Prednisone (VMP) Followed By Lenalidomide and Dexamethasone (Rd) Versus Carfilzomib, Lenalidomide and Dexamethasone (KRd) Plus/Minus Daratumumab (D), 18 Cycles, Followed By Consolidation and Maintenance Therapy with Lenalidomide and Daratumumab: Phase III, Multicenter, Randomized Trial for Elderly Fit Newly Diagnosed Multiple Myeloma (NDMM) Patients Aged between 65 and 80 Years

Background: In transplant-ineligible patients (pts) with NDMM, VMP and Rd have been standards of care. The Spanish Myeloma Group examined induction with VMP followed by Rd, and results were particularly striking for “fit” pts aged 65-80 with a CR rate of 47% and an MRD negative rate (MRD(-)) of 20%. The median PFS was 34 months (m) and 4-years (yrs) OS rate was 70%. Pts and study design: Based on this background, we consider VMP9-Rd9 as control arm and compared with KRd or D-KRd. Induction included 18 cycles, followed by 4 D-Rd consolidation cycles for the two first arms (to evaluate if anti CD38 consolidation might compensate its absence as induction). Subsequently, pts were stratified by MRD (positive and negative) to maintenance therapy with D-R vs observation. Frailty was evaluated with Geriatric Assessment in Hematology (GAH scale) considering as fit those younger than 80 years and with a punctuation between 0 and 42. VMP and Rd were given at conventional doses and in the K-based regimens, K was given at dose of 36mg/m 2 twice weekly during C1-2 and at 56 mg/m 2 weekly since C3. R was given at standard dose and D was planned as IV but switched to SC, both at the conventional dose and schedule. The primary endpoint was to evaluate the MRD(-) rate (NGF 10 -5) at the end of induction to compare both experimental arms, KRd and D-KRd to the control-one, VMP-Rd. A step-down testing procedure was applied, whereby inference for a test in the pre-defined hierarchy was dependent upon statistical significance having been achieved for the previous tests in the hierarchy. No formal adjustment for multiplicity of contrasts is required. Secondary endpoints referred to the induction phase included the serological responses, PFS and OS probabilities at 18 cycles and safety profile. Results: 540 pts were screened and 78 were screening failures. 462 pts were randomized to VMP-Rd (154 pts), KRd (154 pts) and D-KRd (153 pts but one patient was not evaluable). Baseline characteristics of the pts were comparable in the three arms with a median age of 72 and around one third older than 75 years. Nearly one third of pts in the three arms had ISS 3 and 15% had extramedullary disease. A total of 369 out of 461 pts have completed the 18 induction cycles (128 in VMP-Rd, 122 in KRd and 119 in D-KRd) and were evaluable for the primary endpoint. The MRD(-) rate at 10 -5 was 32% for VMP-Rd, 69% for KRd (p<0.0001) and 79% for D-KRd (p<0.0001). At 10 -6, the MRD(-) rate was also significantly superior for KRd (59%) and D-KRd (75%) in comparison with VMP-Rd (24%) (p values <0.0001). The ORR at the end of induction was comparable in the three arms (87%, 89% and 89%, respectively) but the sCR/CR rate was significantly higher for KRd (59%) and D-KRd (61%) in comparison with VMP-Rd (40%) (p-values <0.0001). At 18 m, the proportion of pts alive and progression-free was 79% for VMP-Rd and 87% for KRd and D-KRd, respectively. Only two pts who achieved MRD negativity have progressed thus far. The OS at 18 m in the VMP-Rd, KRd and D-KRd arms was 91%, 95% and 90%, respectively. There were 48, 44 and 40 pts who early discontinued therapy in VMP-Rd, KRd and D-KRd, respectively, due to progressive disease (VMP-Rd: 23; KRd: 9;D-KRd: 6) or toxicity (VMP/Rd:8; KRd: 14; D-KRd: 6). Death occurred in 12 pts treated with D-KRd being infections the cause in 10 pts (Covid-19 in 3); 5 pts in the KRd arm (4 infections (Covid-19 in 1)) and 6 pts in VMP-Rd arm (infections in 4 pts). Concerning hematological toxicity during induction, G3/4 neutropenia was higher in VMP-Rd (50%) than KRd (24%) (p<0.0001) and similar to D-KRd (47%). G3/4 thrombocytopenia was also higher in VMP-Rd (34%) than the other two arms (16% and 17%, p<0.0001)). G3/4 infections rate was comparable in the three arms (12% in VMP-Rd and 15%-16% in KRd and D-KRd). Cardiovascular G3/4 events were higher in KRd (11%) and D-KRd (14%) than in VMP-Rd (5%) (p<0.0001) being hypertension and cardiac failure the most frequent-ones. Conclusions: The trial met its primary end point and the MRD(-) rates of 69% for KRd and 79% for D-KRd were significantly higher than VMP9-Rd9 (32%). Overall, the VMP-Rd arm had higher rates of neutropenia, while the D-KRd arm had higher rates of infections leading to death. The trial is ongoing to evaluate long term outcomes.

A Phase II Study of Vibecotamab, a CD3-CD123 Bispecific T-Cell Engaging Antibody, for MDS or CMML after Hypomethylating Failure and in MRD-Positive AML

Background Leukemic stem cells have high expression of CD123 compared to normal hematopoietic stem cells and is therefore a therapeutic target in multiple leukemias including acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and chronic myelomonocytic leukemia (CMML). Vibecotamab (formally XmAb14045) is a CD3-CD123 bispecific engaging antibody that has shown clinical activity in relapsed/refractory AML, particularly in low-blast disease. We therefore sought to evaluate vibecotamab in other low-blast states, including MDS or CMML after hypomethylating agent failure and MRD-positive AML. Methods In this two-arm, open-label, phase II study, adults with either MDS (IPSS-R intermediate or higher risk) or CMML (CMML-1 or CMML-2) after failure of hypomethylating agents or AML in first or second morphologic remission with detectable MRD at a level of ≥0.1% by flow cytometry were eligible. CD123 expression ≥20% on aberrant myeloid blasts was required for enrollment. Vibecotamab was given IV in a ramp-up dose schedule on days 1 (0.43µg/kg), 3 (0.75µg/kg), 5 (1.1µg/kg), and 8 (1.7µg/kg) in cycle 1, followed by weekly doses of vibecotamab at a dose of 1.7µg/kg. Patients (pts) received up to 4 cycles of vibecotamab in 28-day cycles. The primary endpoint of the MDS/CMML cohort was response rate (CR + mCR + PR + HI + clinical benefit) within 4 cycles. The primary endpoint of the AML MRD cohort was the MRD negativity rate within 4 cycles. Results Between May 2022 and July 2023, 23 pts were treated (11 MDS/CMML, 12 AML MRD). Baseline characteristics are shown in Table 1. In the MDS/CMML cohort, 7 pts (63%) had received two or more prior lines of therapy, 8 pts (73%) had prior venetoclax exposure, and 2 pts (18%) had prior hematopoietic stem cell transplant (HSCT). Six MDS pts (66%) were IPSS-R high or very high risk. In the AML cohort, 6 pts (50%) had received two or more lines of prior therapy, 11 pts (92%) had prior venetoclax exposure, and 5 pts (42%) had prior HSCT. Ten pts (83%) were ELN 2022 adverse risk. The baseline CD123 expression was 72% (range, 43%-99%) in the MDS/CMML cohort and 89% (range, 55%-99%) in the AML MRD cohort. The baseline MRD by flow cytometry in the AML MRD cohort was 1.1% (range, 0.1%-3.9%). Responses are shown in Table 2. In the MDS/CMML cohort, 7 pts responded (64%), with 6 pts (56%) achieving marrow complete remission (mCR) and 1 pt (9%) achieving hematologic improvement (HI) per International Working Group (IWG) 2006 criteria. Among the 9 MDS pts, 4 (44%) achieved mCR + HI (2 HI-N, 1 HI-P, and 1 HI-P + HI-N), and 1 (11%) achieved HI (HI-N + HI-P). Per revised IWG 2023 MDS response criteria, 5 of the 9 MDS pts (56%) achieved complete remission with limited count recovery (CR L). Two of 4 MDS pts (50%) with TP53 mutations achieved CR L. Both CMML pts achieved mCR, with one pt also achieving HI-N. Among 9 pts with baseline bone marrow blasts =>5% at trial enrollment, 6 (67%) achieved a mCR, with or without HI. Best response occurred after the first cycle in all pts. CD123 expression was not associated with likelihood of response. Of the 7 responders, 5 are in ongoing response (range 0.3-6.9 months), one died in CR L from non-hematologic complications (heart failure), and one relapsed 5 months after achieving CR L. Of the 12 pts in the AML MRD cohort, 3 (25%) achieved MRD negativity, all of which occurred after 1 cycle of vibecotamab. Among the 3 responders, all were ELN adverse risk and had prior venetoclax exposure, 2 had prior HSCT, and 1 had inv(3). The median MRD and CD123 expression in responders was 0.2% (range 0.1%-0.2%) and 98% (range 95%-99%) vs 1.8% (range 0.5%-3.9%) and 87% (range 66%-96%) in non-responders, respectively. At last follow-up, all 3 responders are still in MRD-negative remission (range 3.2-12.8 months). Vibecotamab was well-tolerated with no pts requiring dose reductions or being taken off study due to adverse events. Ten pts (44%) experienced grade 2 infusion reactions and 1 pt (4%) experienced a grade 3 infusion reaction. Myelosuppression was minimal, consistent with previous studies of vibecotamab. Conclusion Vibecotamab was safe and active in low-blast, high-risk myeloid diseases, with a response rate of 64% in MDS/CMML after HMA failure and 25% in MRD-positive AML. The clinical activity of vibecotamab, including in pts with prior venetoclax exposure and/or HSCT, and its lack of clinically significant myelosuppression provide rationale to combine it with other agents in AML, MDS, and CMML.

Philadelphia-like B-Cell Acute Lymphoblastic Leukemia in a Largely Hispanic Population: Disease Features and Outcomes in the Era of Immunotherapy a Single Institutional Study

Introduction: Philadelphia (Ph)-like B-cell acute lymphoblastic leukemia (ALL) is a high-risk subgroup of B- cell ALL with distinct genotypes, unified by a gene expression profile similar to Ph-positive ALL but lacking the BCR: ABL1 fusion. Previous studies have noted the increased prevalence of Ph-like B-cell ALL in Hispanic patients. Our study evaluates Ph-like B- cell ALL clinical/genomic features and outcomes in a predominantly Hispanic population. Methods: This is a retrospective chart review of ALL patients that underwent treatment for B-cell ALL at Norris Comprehensive Cancer Center (NCCC) between 2011 and 2023. Identification of fusions associated with Ph-like B-cell ALL was performed using cumulative results from RNA-seq, conventional cytogenetics, and fluorescence in situ hybridization (FISH) with reflex gene fusion transcript analysis. Additionally, we used the Anchored Multiplex PCR™-based multi-gene NGS assay designed to detect known and novel fusions and elevated gene expression levels using a proprietary algorithm in ALL. Cumulative incidence of relapse (CIR) was evaluated using competing risk regression (Fine-Gray method), with death as a competing outcome. Overall survival (OS) and event-free survival (EFS) were analyzed using Cox proportional hazards model. Events of interest for EFS were relapse, treatment failure, and death. Ph-negative B-cell ALL patients were set as the reference for survival analysis. Results: 253 patients were included with a median age at diagnosis of 42 years (range: 18-80). ALL subtypes included 64(25.3%) Ph-like, 77(30.4%) Ph-positive, and 112(44.3%) Ph-negative. Most were Hispanic (N = 186, 73.5%), and the median follow-up time was 27 months. The 3-year OS, EFS, and CIR were 81.3% (95% CI 75.7-87.4%), 49.1% (95% CI 42.7-56.5%), and 39.9% (95% CI 33.0-46.7%). CRLF2 related mutations constituted 44(68.8%) of Ph-like patients, with 9(14.0%) CRLF2-P2RY8, 24(37.5%) CRLF2-IGH, and 11(17.2%) CRLF2-other gene rearrangements. 19 Ph-like patients had non-CRLF2 mutations consisting of 13(20.3%) IGH, 3(4.7%) ABL1/2, 3(4.7%) JAK2, and 1(1.6%) EPOR rearrangements. Compared to Ph-negative, Ph-like patients were more likely to have a refractory disease (20.6% vs. 6.2% P=0.006) and require Blinatumomab (67.2% vs. 39.3% P<0.001), with a non-significant trend towards lower rates of CR (84.1% vs 90.9% P=0.21). Ph-like patients had significantly worse EFS (HR = 1.63; 95% CI 1.09-2.45; P=0.018), but similar OS (HR = 0.88; 95% CI 0.39-1.99; P=0.75) and CIR (HR = 1.06; 95% CI 0.65-1.70; P = 0.83). Ph-positive patients displayed improved EFS relative to Ph-negative (HR = 0.56; 95% CI 0.35-0.91; P = 0.018), similar OS (HR = 0.73; 95% CI 0.35-1.50; P = 0.39), and a trend towards improved CIR (HR = 0.67; 95% CI 0.40-1.10; P=0.11). When controlling for age, sex, and treatment type, EFS was worse in Ph-like (HR = 1.57; 95% CI 1.03-2.41; P = 0.037) and improved in Ph-positive (HR = 0.56; 95% CI 0.33-0.93; P = 0.026). Our incidences of CRLF2 mutations in Ph-like patients aged>40 compared to age ≤40 was (73.3% vs 64.7%, P=0.591). On subgroup analysis of Ph-like patients, univariate regression revealed CRLF2-related Ph-like patients had a worse CIR (HR = 5.68; 95% CI 1.91-16.9; P = 0.002) but similar OS(P=0.99) and EFS(P=0.18). PAX5 expression was also a predictor of poor OS (HR = 8.89; 95% CI 1.06-74.7; P = 0.044) and EFS (HR = 2.51; 95% CI 1.09-5.77; P = 0.031), with a trend towards increased CIR (HR = 2.30; 95% CI 0.92 -5.78; P = 0.075). Compared to non-CRLF2 mutations, CRLF2-Ph-like had worse CIR (HR = 5.68; 95% CI 1.91 -16.9; P = 0.002). Relative to Ph-like patients who achieved MRD negativity during induction, patients who remained MRD positive had worse CIR(HR = 2.92; 95% CI 1.23 -6.94; P = 0.015) and EFS (HR = 4.32; 95% CI 1.890-9.84; P < 0.001). However, after controlling for Blinatumomab administration, the effect diminished (CIR: P=0.73, EFS P=0.28). There were no differences in EFS(P=0.34), CIR(P=0.69), and OS(P=0.36) between Ph-like patients who were transplanted vs not. Conclusions: Ph-like B- Cell ALL represents a high-risk disease subtype of adult B-ALL, with poor EFS and frequent treatment failure. CRLF2 translocation confers worse CIR and EFS within Ph-like patients and requires novel treatment approaches.

Cladribine with Low Dose Cytarabine and Venetoclax Alternated with Azacytidine and Venetoclax for Acute Myeloid Leukemia: Prognostic Analysis of a Phase 2 Clinical Trial

Introduction: Hypomethylating agents (HMA) with Venetoclax (Ven) is the standard of care for patients (pts) with acute myeloid leukemia (AML) ≥ 75 yrs of age or not candidates to intensive treatment. Döhner, et al. (ASH 2022) demonstrated that the European LeukemiaNet (ELN) risk classifications do not accurately predict prognosis in HMA-Ven treated pts. A prognostic risk signature classification (PRSc) was proposed, stratifying pts by RAS, FLT3 and TP53 mutations alone. This classification has not been validated in low intensity treatments combining Ven with cladribine (CLAD) and cytarabine. Moreover, RAS mutations are common mechanisms of resistance to HMA-Ven, whilst it has been proposed that cytarabine and recently cladribine-based regimens could be effective in AML with this mutation. We report an update of pts treated with CLAD, low dose cytarabine (LDAC) and Ven, focusing on outcomes and risk group stratification. Methods: This analysis included pts with newly diagnosed AML enrolled in a phase 2 clinical trial with CLAD-LDAC-Ven induction therapy followed by a consolidation phase that alternates courses of azacytidine and Ven with courses of CLAD-LDAC-Ven (NCT03586609). The PRSc allocated pts with [ K/N]- RAS or FLT3-ITD mutations in the intermediate benefit group, pts with TP53 in the lower benefit group, whereas pts with AML lacking these mutations were allocated in the higher benefit group. Cumulative incidence (CI) was calculated for pts achieving remission with death and relapse as competing events. Results: From 11/2018 to 04/2023, 123 pts were treated on the CLAD-LDAC-Ven clinical trial. Median age was 68 yrs (range, 47-84) and 57% were male. 54% of pts had diploid cytogenetics and 16% had complex karyotype. Most frequent mutations were DNMT3A (32%), NPM1 (24%), TET2 (22%), SRSF2 (20%) and ASXL1 (19%). According to the ELN 2022 classification, 31 (25%), 22 (18%) and 69 (57%) were allocated in the favorable, intermediate and adverse risk categories, respectively. According to the PRSc, 81 (66%), 26 (21%) and 16 (13%) pts were allocated in the higher, intermediate and lower benefit group, respectively (Figure 1). The overall response rate (ORR) was 85% (105/123), including 92 pts (75%) with complete remission (CR) rate and 13 (10%) having CR with incomplete hematologic recovery (CRi). Among pts achieving response, 78% (82/105) achieved MRD negativity by flow cytometry. According to ELN 2022 classification, ORR was 97%, 82% and 81% for favorable, intermediate, and adverse risk pts, respectively. According to the PRSc, the ORR was 89%, 85% and 69% for pts allocated in the higher, intermediate and lower benefit group. The median number of treatment courses received was 2 (1-18) and 94% of pts achieved best response after first cycle. After achieving remission, 48 (39%) pts underwent allogeneic stem cell transplantation (alloSCT). The median OS and EFS were 50 months, and the 2-year cumulative incidence of relapse and death without relapse were 22% and 16%, respectively. The 1- and 2-year OS was 76% and 65%, respectively. According to the ELN 2022 classification, median OS was not reached, 39, and 25 months for favorable, intermediate and adverse risk groups (p=0.004, C-index=0.61). According to the PRSc, the median OS was 50, 25 and 15 months for the higher, intermediate and lower benefit group, respectively (p=0.36, C-index=0.56). Median EFS was 53, 15 and 19 months for ELN 2022 favorable, intermediate and adverse risk, respectively. According to the PRSc, the median EFS was 52, 25 and 17 months for months for the higher, intermediate and lower benefit group, respectively (Figure 2). The 2-yr CI of relapse was 13%, 18% and 28% for pts of allocated in the ELN favorable, intermediate and adverse group, respectively. When using the PRSc classification, the 2-yr CI of relapse was 18%, 17% and 51% for the higher, intermediate and lower benefit group, respectively. Conclusion: CLAD-LDAC-Ven combination offers an encouraging ORR with long term OS and EFS. In these pts, the ELN 2022 showed a better risk group discrimination regarding OS, compared to the PRSc. Pts of the intermediate-benefit of the PRSc (enriched in RAS/FLT3 mutations) could benefit the most of CLAD-LDAC-Ven, in which an HMA-Ven approach is associated with a mOS of 12 months.

Outcomes for Children with High Risk Acute Myeloid Leukemia on the Myechild 01 International Phase III Clinical Trial

Background: Outcomes for pediatric acute myeloid leukemia (AML) remain disappointing, particularly for patients with poor risk cytogenetic/molecular genetic abnormalities and those who fail to achieve complete remission following course 1 of induction chemotherapy. Despite upfront allogeneic hematopoietic stem cell transplantation (HSCT) for these patients, high rates of relapse persist. The optimal approach to chemotherapy intensification and timing of HSCT for high risk (HR) patients remains unknown, with variable approaches employed by cooperative trial groups. Methods: The MyeChild 01 international phase III trial (NCT02724163) in children with de novo AML allocated patients up to 3 doses of gemtuzumab ozogamicin (GO 3mg/m 2/dose) during the first course of induction chemotherapy (mitoxantrone 12 mg/m2/dose x4; cytarabine 100 mg/m2/dose x20). Patients classified as HR after course 1 received FLA-Ida for course 2 followed by allogeneic HSCT. If required, a third course of bridging therapy (FLA) was given prior to HSCT. HR patients in MyeChild 01 included those with NUP98 fusions, selected KMT2A fusions ( KMT2A::MLLT10, KMT2A::MLLT4, KMT2A::AFF1, KMT2A::ABI1), CBFA2T3::GLIS2, DEK::NUP214, MECOM ( EVI1) rearrangements and all 12p abnormalities including MNX1::ETV6, in addition to the traditional HR abnormalities -7, -5/del(5q) and FLT3-ITD (without concurrent good risk abnormalities, including NPM1 mutations). Patients with induction failure after course 1 (≥ 5% blasts confirmed by flow) and those with non-HR cytogenetics/molecular genetics who remained MRD positive after course 2 (intermediate risk cytogenetics) or 3 (good risk cytogenetics) were also classified as HR. Here, we report the estimated 2-year outcomes for patients assigned HR post course 1 who received mitoxantrone and cytarabine and at least 1 dose of GO during course 1 (MA-GO). Outcomes of trial randomisations (1 vs 2 or 3 GO doses; consolidation for standard risk patients; HSCT conditioning) will be reported separately. Results: Of 749 patients enrolled at initial diagnosis, 183 received MA-GO during course 1 and were assigned HR post course 1. Of these, 172 (94%) patients had poor risk cytogenetic/molecular genetics, of which 32 also failed to achieve CR. Additionally, 11 (6%) patients did not have poor risk cytogenetic/molecular genetics but failed to achieve CR with MA-GO and thus were assigned to the HR group. Post course 1, 140 (77%) of these HR patients achieved CR/CRi, with 102/155 (66%) patients with evaluable samples achieving MRD negativity post course 1. Following course 1, 174 (95%) remained on trial and received FLA-Ida as course 2 and 163 patients (89%) proceeded to HSCT, 55 on trial and 108 following discontinuation from the trial. Estimated event-free survival (EFS) and overall survival (OS) at 2 years was 62% (95% CI: 56-70%) and 71% (64-78%) respectively (Figure 1 & 2). Estimated cumulative incidence of relapse (CIR) and death in remission at 2 years was 26% (19-33%) and 7% (3-11%) respectively. For HR patients who received MA-GO in course 1, on trial FLA-Ida as course 2 and on or off trial HSCT (n = 156), 2 year estimated outcomes were EFS 69% (62-77%), OS 77% (70-85%) and CIR 24% (17-32%). The most common cytogenetic/molecular genetic abnormalities were rearrangements of KMT2A (50/183, 27%), with KMT2A::MLLT10 predominating (70%). FLT3-ITD (19%), NUP98 fusions (14%), -7 (13%), abn(12p) (11%), del(5q) (8%) and CBFA2T3::GLIS2 (6%) accounted for the majority of other abnormalities with outcomes varying by subtype. Collectively, KMT2A-rearranged patients had EFS and OS of 68% (55-83%) and 71% (59-86%) respectively and CIR of 26% (12-40%). For FLT3-ITD, the EFS and OS was 75% (62-92%) and 83% (69-99%) respectively with a CIR of 14% (1-26%). Of the 25 patients with a NUP98 fusion, 17 (68%) were NUP98::NSD1. The EFS and OS for patients with NUP98 fusions was 71% (55-92%) and 96% (88-100%) respectively with CIR 25% (1-48%). Conclusions: Two intensive courses of induction chemotherapy, including GO and mitoxantrone in course 1 and FLA-Ida in course 2, consolidated with allogeneic HSCT, appears to be an effective approach for most HR patients. 2 year estimated outcomes for HR patients compare favourably to recent trials of GO in pediatric AML, with particularly encouraging data for patients with KMT2A-r and FLT3-ITD.

Potential clinical impact of T-cell lymphocyte kinetics monitoring in patients with B cell precursors acute lymphoblastic leukemia treated with blinatumomab: a single-center experience.

Blinatumomab is a bispecific anti-CD3 and anti-CD19 antibody that acts as a T-cell engager: by binding CD19+ lymphoblasts, blinatumomab recruits cytotoxic CD3+ T-lymphocytes to target the cancer cells. Here we describe seven different patients affected by B-cell precursor acute lymphoblastic leukemia (Bcp-ALL) and treated with blinatumomab, on which we evaluated the potential association between the amount of different T-cells subsets and deep molecular response after the first cycle, identified as a complete remission in the absence of minimal residual disease (CR/MRD). The immune-system effector cells studied were CD3+, CD4+ effector memory (T4-EM), CD8+ effector memory (T8-EM), and T-regulatory (T-reg) lymphocytes, and myeloid-derived suppressor cells (MDSC). Measurements were performed in the peripheral blood using flow cytometry of the peripheral blood at baseline and after the first cycle of blinatumomab. The first results show that patients with a higher proportion of baseline T-lymphocytes achieved MRD negativity more frequently with no statistically significant difference (p=0.06) and without differences in the subpopulation count following the first treatment. These extremely preliminary data could potentially pave the way for future studies, including larger and less heterogeneous cohorts, in order to assess the T-cell kinetics in a specific set of patients with potential synergy effects in targeting myeloid-derived suppressor cells (MDSC), commonly known to have an immune evasion mechanism in Bcp-ALL.

Impact of residual tumor cells in the stem cell collection on multiple myeloma patients receiving autologous stem cell transplantation

Autologous stem cell transplantation (ASCT) is the standard therapy for patients with transplant-eligible multiple myeloma (TEMM). However, the ideal depth of response required before ASCT and the impact of residual tumor cells in the stem cell collection (SCC) on survival remains unclear. Here we collected data of 89 patients with TEMM undergoing ASCT and analyzed the minimal residual disease of SCC (cMRD) and bone marrow (BM) (mMRD) before transplantation. Before ASCT, 31.5% and 76.4% of patients achieved MRD negativity in BM and SCC, respectively. Tumor cells were less in SCC samples than that in BM samples. Neoplastic cells in SCC could be observed in patients with different responses after induction therapy, and there were no significant differences in the percentage and level of cMRD among these subgroups (P > 0.05). No correlation was found between the cMRD status and the response patients achieved after ASCT (P > 0.05). The median follow-up was 26.8 months. mMRD negativity before ASCT was associated with longer PFS (55.9 vs. 27.1 months; P = 0.009) but not OS (not reached vs. 58.9 months; P = 0.115). Patients with different cMRD statuses before ASCT experienced similar PFS (40.5 vs. 76.4 months for negativity vs. positivity; P = 0.685) and OS (not reached vs. 58.8 months for negativity vs. positivity; P = 0.889). These results suggested that detectable cMRD does not significantly predict the inferior post-ASCT response or shorter survival, and patients are eligible to undergo ASCT upon achieving partial response.