High MRD Research Articles

Combined Ibrutinib and Venetoclax for First-Line Treatment of Patients with Chronic Lymphocytic Leukemia (CLL): Focus on Long-Term MRD Results

Combined Ibrutinib and Venetoclax for First-Line Treatment of Patients with Chronic Lymphocytic Leukemia (CLL): Focus on Long-Term MRD Results

Predictors of Relapse Risk Do Not Influence Time to “Cure” in Children and Young Adults with Acute Lymphoblastic Leukaemia

After how many years from diagnosis/completing treatment should children and young adults with acute lymphoblastic leukaemia be considered “cured”? Clinical trials generally report 5 year event free survival because the risk of relapse after that time-point is very low and this is assumed to mean cure. Indeed, the risk of relapse after four years from completing therapy was <1% for patients treated on St Jude's trial Total Therapy XV and they proposed that length of follow-up should be considered to be the “time to cure”. The group had previously shown that excess deaths beyond ten years in non-irradiated patients was similar to the general population whereas irradiated patients had a greater risk of excess mortality due to the development of secondary neoplasms. However, there was limited information about the time to cure and relative survival in sub-groups with variable relapse risk. We examined the long-term outcome of patients treated on an MRD stratified protocol UKALL 2003 that recruited patients between 2003-2011 to determine time to cure for the overall trial population and prognostic sub-groups defined by age, sex, immunophenotype, cytogenetics and MRD response.There were a total of 3113 patients eligible for analysis with a median follow up of 9.4 years (only 20 patients received cranial irradiation). Relative survival rates were estimated using nationwide population mortality rates as the baseline accounting for age, sex and calendar year (Office of National Statistics 2018 release). The relative survival of UKALL2003 patients compared to equivalent children in the UK population was 96% (95% CI 95.5-96.7). Relative survival did not differ by sex but was significantly worse for patients >10 years compared with younger patients (p<0.001). As expected, patients with good risk cytogenetics ( ETV6-RUNX1, and high hyperdiploidy) and negative bone marrow Ig/TCR MRD at end of induction (EOI) had better relative survival rates and lower excess mortality (all p<0.001) compared with patients who had adverse risk factors (high risk genetics and EOI MRD+).To estimate the time to a cure, we calculated the conditional probability of relapse at 12 years for patients who had survived event to the start of each follow-up year. Although the initial risk of relapse differ significantly by sex, age, MRD and genetics the risk of relapse for all subgroups quickly coalesced at around 5-6 years (Figure 1). Furthermore, the time to cure, defined as a relapse risk <1% (dashed blue line of figure), was similar across all the subgroups at 6-7 years.In conclusion, the relative survival of young patients with good risk cytogenetics and EOI MRD negative status approaches that of their normal peers. However, regardless of prognosis, the time to cure is similar across risk groups. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Lintuzumab-Ac225 in Combination with CLAG-M Yields High MRD (-) Responses in R/R AML with Adverse Features: Interim Results of a Phase I Study

Background:Lintuzumab-Ac225 (Actimab-A) is a humanized CD33 antibody, lintuzumab, conjugated to an alpha emitting isotope, actinium (Ac225), with potent single agent activity against AML. We hypothesized that a low dose infusion of lintuzumab-Ac225, after salvage chemotherapy, would effectively eliminate residual leukemia and improve remission rates, and depth of remission.Patients and Methods:Adult patients with relapsed/refractory AML (RR-AML), and with adequate organ function and performance status were eligible for screening. On screening, we assessed CD33 expression, greater than 25% of leukemic blasts must have expressed CD33 antigen by flow cytometry for inclusion. Induction consisted of G-CSF, 300mcg/d, given D1-6, cladribine 5mg/m2, given D2-6, cytarabine 2g/m2, given D2-6, and mitoxantrone 10mg/m2, given D2-4. Lintuzumab-Ac225 was administered as a single dose on either day 7, 8, or 9. This trial enrolled to 4 cohorts, administering lintuzumab-ac225 at a dose of 0.25uCi/kg, 0.50uCi/kg, 0.75uCi/kg, and 1.0uCi/kg. Treatment consisted of one induction cycle. Disease assessment, including MRD assessment by flow, was performed between Days 29-42.Results:Sixteen patients with a median age of 64 yrs were evaluable for toxicity and response. Three pts were treated in cohort 1 (0.25uCi/kg), nine pts were treated in cohort 2 (0.5uCi/kg), three pts were treated in cohort 3 (0.75uCi/kg), and one pt was treated in cohort 4 (1.0uCi/kg). Patient characteristics include 63% (n=10) pts with adverse cytogenetics, mutations involving TP53 in 44% (n=7) pts, and secondary/therapy-related AML in 50% (n=8) of patients. Patients received a median 2 lines of therapy, and 50% (n=8) received a venetoclax combination regimen prior to enrollment. Table 1 summarizes patient characteristics.No undue non-hematologic toxicities were observed in this trial. Commonest AEs were neutropenic fever and infection. Among responders, an ANC>1000 was achieved in 9/10 patients, at a median of 33 days, and a platelet count >50k was achieved in 6/10 patients at a median of 37 days. Of note, two patients proceeded to HCT prior to platelet recovery.Overall, among patients enrolled in cohorts 1-3, CR/CRi was observed in 67% (n=10) pts. One patient enrolled in cohort 4 achieved an aplastic marrow by D+42, with subsequent stem cell boost and neutrophil recovery. Of responders, 70% (7/10) had no measurable disease (MRD(-)) by flow cytometry. Among patients receiving <4 lines of prior therapy, 71% (n=5) pts with adverse cytogenetics, 80% (n=4) pts with TP53 mutation, and 80% (n=4) pts receiving a prior venetoclax combination achieved a remission. Estimated 6-month OS was 60%.Conclusions:Lintuzumab-Ac225 at a low dose appears to be safe in combination with the salvage chemotherapy regimen CLAG-M. Furthermore, this combination has demonstrated promising efficacy results among high risk RR-AML patients, namely patients with adverse molecular/cytogenetic features and patients previously receiving venetoclax. Updated Cohort 4 results will be presented at ASH.Upon determination of MTD, we plan to explore the combination of lintuzumab-Ac225 with other salvage regimens (e.g. FLAG, FLAG-Ida, MEC) to determine whether adding this novel agent can generally improve salvage outcomes in hard to treat patients. [Display omitted] DisclosuresAbedin: Helsinn: Research Funding; Agios: Honoraria; AltruBio: Research Funding; Pfizer: Research Funding; Amgen: Honoraria; Actinium: Research Funding; Astellas Pharma Inc.: Research Funding. Guru Murthy: Guidepoint: Consultancy; Cancerexpertnow: Honoraria; Techspert: Consultancy; Qessential: Consultancy; Cardinal Health Inc.: Honoraria; TG therapeutics: Other: Advisory board. Hamadani: Sanofi, Genzyme, AstraZeneca, BeiGene: Speakers Bureau; Takeda, Spectrum Pharmaceuticals and Astellas Pharma: Research Funding; Janssen, Incyte, ADC Therapeutics, Omeros, Morphosys, Kite: Consultancy. Atallah: Pfizer: Consultancy, Research Funding; BMS: Honoraria, Speakers Bureau; Takeda: Consultancy, Research Funding; Abbvie: Consultancy, Speakers Bureau; Amgen: Consultancy; Novartis: Consultancy, Honoraria, Research Funding.

Upfront Autologous Stem Cell Transplantation (ASCT) Vs Carfilzomib-Cyclophosphamide-Dexamethasone (KCd) Consolidation in Transplant-Eligible, Newly Diagnosed (NDTE) Multiple Myeloma (MM): Results of the Cardamon Study According to Cytogenetic Risk

Upfront Autologous Stem Cell Transplantation (ASCT) Vs Carfilzomib-Cyclophosphamide-Dexamethasone (KCd) Consolidation in Transplant-Eligible, Newly Diagnosed (NDTE) Multiple Myeloma (MM): Results of the Cardamon Study According to Cytogenetic Risk

First Line Chemo-Free Therapy with the BRAF Inhibitor Vemurafenib Combined with Obinutuzumab Is Effective in Patients with Hcl

First Line Chemo-Free Therapy with the BRAF Inhibitor Vemurafenib Combined with Obinutuzumab Is Effective in Patients with Hcl

OAB-003: CARDAMON:Carfilzomib (K) maintenance following Autologous Stem Cell Transplant (ASCT) or carfilzomib-cyclophosphamide-dexamethasone (KCd) consolidation for newly diagnosed (NDTE) multiple myeloma (MM)

<h3>Background</h3> The role of upfront ASCT for NDTE MM remains under evaluation with high MRD rates following novel induction and consolidation (cons) strategies. K maintenance represents an alternative strategy to lenalidomide maintenance. The CARDAMON trial investigated K maintenance following KCd induction plus either ASCT or KCd cons. <h3>Methods</h3> NDTE pts received 4 x KCd induction (K 20/56 mg/m2 biweekly, C 500 mg D 1,8,15, d 40mg weekly) before 1:1 randomisation to ASCT or 4 x KCd cons followed by 18 cycles K maintenance (56mg/m² D1,8,15). Flow cytometric MRD (10-5) was assessed post induction, pre-maintenance and at 6 months maintenance. Primary endpoints were ≥VGPR post induction and 2-year PFS from randomisation. Secondary endpoints included improvements in disease response and MRD conversion following ASCT/ cons and maintenance. <h3>Results</h3> 281 patients were registered, with 218 randomised to either ASCT or cons. The median PFS for ASCT was not yet reached vs 3.4 years for cons, with cons failing to show non-inferiority (difference in 2-year PFS 6.5%, 70% CI 1.0% to 11.1%). 196 patients received K maintenance (99 ASCT, 97 cons), 17 remain on treatment. A median of 16 cycles (1-18) were given over a median of 15.9 months (0-21.5). COVID-19 led to maintenance treatment interruptions in 41 (8 ASCT, 6 Cons) and treatment discontinuation in 15 (9 ASCT, 6 Cons). The median K dose given was 50.6mg/m2 and was similar across both arms (51.2 vs 49.4mg/m2, p=0.03). K maintenance was discontinued for PD in 14.1% (ASCT) vs 22.7% (cons), and for adverse events (AEs) in 7.1% (ASCT) vs 4.1% (cons). Most common AEs were hypertension and infections and more ≥G3 AEs were noted in ASCT vs cons (p=0.01). Patient/ clinician withdrawals from maintenance were low but occurred more in the ASCT arm (9.1% vs 1%). MRD neg patients post ASCT/ Cons had a longer PFS than MRD pos (p=0.002); with a higher MRD neg rate in the ASCT arm (53.6% vs 35.1% in Cons, p=0.01). MRD neg patients at 6 months post maintenance also had longer PFS (p=0.004 cf MRD pos patients); again with higher MRD neg rates in the ASCT arm (58.1% ASCT vs 40.5% Cons, p=0.02). There was no difference in PFS for MRD neg patients according to treatment arm from PBSCH, post-ASCT/ Cons or 6 months maintenance timepoints. Overall, 27.8% of MRD pos patients converted to MRD neg post ASCT/ Cons with more converting with ASCT (39.1% ASCT vs 16.1%, p=0.004). 23.5% of MRD pos patients converted to neg during maintenance (30.6% ASCT, 17.8%: p=0.2). Maintenance of MRD negativity over the first 6 months was similar between ASCT and Cons arms (p=0.3). There was no evidence that the timing of achievement of MRD negativity impacted PFS. <h3>Conclusions</h3> K maintenance at 56mg/m2 weekly was deliverable and tolerable, with continued higher MRD neg rates at 6 months post-ASCT compared to post-Cons. However more ≥G3 AEs and discontinuations for AEs/ patient choice were noted for K maintenance after ASCT.

Minimal residual disease, long-term outcome, and IKZF1 deletions in children and adolescents with Down syndrome and acute lymphocytic leukaemia: a matched cohort study

SummaryBackgroundPatients with Down syndrome and acute lymphocytic leukaemia are at an increased risk of treatment-related mortality and relapse, which is influenced by unfavourable genetic aberrations (eg, IKZF1 deletion). We aimed to investigate the potential underlying effect of Down syndrome versus the effects of adverse cancer genetics on clinical outcome.MethodPatients (aged 1–23 years) with Down syndrome and acute lymphocytic leukaemia and matched non-Down syndrome patients with acute lymphocytic leukaemia (matched controls) from eight trials (DCOG ALL10 and ALL11, ANZCHOG ALL8, AIEOP-BFM ALL2009, UKALL2003, NOPHO ALL2008, CoALL 07-03, and CoALL 08-09) done between 2002 and 2018 across various countries (the Netherlands, the UK, Australia, Denmark, Finland, Iceland, Norway, Sweden, and Germany) were included. Participants were matched (1:3) for clinical risk factors and genetics, including IKZF1 deletion. The primary endpoint was the comparison of MRD levels (absolute MRD levels were categorised into two groups, low [<0·0001] and high [≥0·0001]) between patients with Down syndrome and acute lymphocytic leukaemia and matched controls, and the secondary outcomes were comparison of long-term outcomes (event-free survival, overall survival, relapse, and treatment-related mortality [TRM]) between patients with Down syndrome and acute lymphocytic leukaemia and matched controls. Two matched cohorts were formed: for MRD analyses and for long-term outcome analyses. For both cohorts, matching was based on induction regimen; for the long-term outcome cohort, matching also included MRD-guided treatment group. We used mixed-effect models, Cox models, and competing risk for statistical analyses.FindingsOf 251 children and adolescents with Down syndrome and acute lymphocytic leukaemia, 136 were eligible for analyses and matched to 407 (of 8426) non-Down syndrome patients with acute lymphocytic leukaemia (matched controls). 113 patients with Down syndrome and acute lymphocytic leukaemia were excluded from matching in accordance with predefined rules, no match was available for two patients with Down syndrome and acute lymphocytic leukaemia. The proportion of patients with high MRD at the end of induction treatment was similar for patients with Down syndrome and acute lymphocytic leukaemia (52 [38%] of 136) and matched controls (157 [39%] of 403; OR 0·97 [95% CI 0·64–1·46]; p=0·88). Patients with Down syndrome and acute lymphocytic leukaemia had a higher relapse risk than did matched controls in the IKZF1 deleted group (relapse at 5 years 37·1% [17·1–57·2] vs 13·2% [6·1–23·1]; cause-specific hazard ratio [HRcs] 4·3 [1·6–11·0]; p=0·0028), but not in the IKZF1 wild-type group (relapse at 5 years 5·8% [2·1–12·2] vs 8·1% [5·1–12·0]; HRcs 1·0 [0·5–2·1]; p=0·99). In addition to increased induction deaths (15 [6%] of 251 vs 69 [0·8%] of 8426), Down syndrome and acute lymphocytic leukaemia was associated with a higher risk of post-induction TRM compared with matched controls (TRM at 5 years 12·2% [7·0–18·9] vs 2·7% [1·3–4·9]; HRcs 5·0 [2·3–10·8]; p<0·0001).InterpretationInduction treatment is equivalently effective for patients with Down syndrome and acute lymphocytic leukaemia and for matched patients without Down syndrome. Down syndrome itself provides an additional risk in individuals with IKZF1 deletions, suggesting an interplay between the germline environment and this poor risk somatic aberration. Different treatment strategies are warranted considering both inherent risk of relapse and high risk of TRM.FundingStichting Kinder Oncologisch Centrum Rotterdam and the Princess Máxima Center Foundation, NHMRC Australia, The Cancer Council NSW, Tour de Cure, Blood Cancer UK, UK Medical Research Council, Children with Cancer, Swedish Society for Pediatric Cancer, Swedish Childhood Cancer Fund, Danish Cancer Society and the Danish Childhood Cancer Foundation.

B-Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL) with t(5;14)(q31;q32)/ IL3-IGH Rearrangement and Eosinophilia: A Peculiar IGH BCP-ALL

Introduction: BCP-ALL associated with t(5;14)(q31;q32) is an exceptional cause of eosinophilia. The IL3 gene expression becomes regulated by the IGH enhancer leading to an overproduction of IL3 causing eosinophilia. Clinical, biological and outcome data are extremely scarce in the literature.Methods: We recruited 2 newly diagnosed patients (pts) with t(5;14)(q31;q32) in our centers. A retrospective search in the French protocol FRALLE 2000 data base and collaboration with the GFCH (Groupe Francophone de Cytogénétique Hématologique) added 4 other pts. Array CGH, MLPA or genomic PCR search for IKZF1 deletion were performed in these 6 pts. We further analysed the 12 pts with t(5;14)(q31;q32) described in the literature with our 6 newly described pts, leading to a meaningful series of 18 pts.Results: Main features at onset are displayed in table 1. Median age at diagnosis is 16.5 years. Male/female ratio is 4.6. Eosinophilia-related symptoms are common with neurologic, thromboembolic or lung involvement (respectively 4/13, 4/13 and 6/13 pts). No pt exhibits blast cells in CSF at diagnosis. Median WBC count is high (48x109/L), mainly due to a high rate of eosinophils (median: 30.5x109/L). Blood eosinophilia preceded ALL diagnosis from 6 and 12 months in 2 cases. Peripheral blast cells are low or undetectable (median: 0x109/L; range: 0-18.7x109/L). A high basophilia is frequent (median: 0.55x109/L). Bone marrow morphology is marked by a low blast infiltration (median: 47%) and increased eosinophil-lineage cells (median: 24%) with dysplastic features in 6/10 pts. All cases are of the B lineage. All 18 pts but one present the t(5;14)(q31;q32) translocation. For the remaining pt, it was revealed by sequencing as karyotype was normal in a context of eosinophilia. Six out of 18 pts have additional cytogenetic abnormalities. For the first time, we report an IKZF1 deletion which is present in 4 out of 6 pts. Few other deletions are found in more than one pt (PAX5, ETV6, MEF2C, CDKN2A). Remission and outcome data are available for 11 pts (our 6 newly described pts and 5 from the literature). Median follow-up (FU) at point date is 18 months (range: 4 days-30 months). Only 5 pts achieve a first complete remission (CR1) at first attempt. The 6 newly described pts are currently alive: 4 are in continuous CR1 (CCR1) including 2 after hematopoietic stem cell transplantation (HSCT) and 2 are in CCR2 (including 1 after HSCT). The 5 pts from the literature died, 1 from cardiac arrest secondary to eosinophilia and the 4 others from disease progression and / or sepsis.Discussion and Conclusion : 1) t(5;14)(q31;q32)-associated BCP-ALL has remarkable features including some which are shared with other IGH BCP-ALL, according to data from a comprehensive UK retrospective study using IGH FISH screening1. Both conditions affect preferentially teenagers and young adults (median age: 16 years1). The highly biased male to female ratio reported here is milder in other IGH BCP-ALL (1.441). In both entities a low blast count (<50 G/L in 119/158 pts1) is observed. Our new data revealed a high rate of IKZF1 deletion in 4/6 pts (66%) also observed in 35/88 pts (40%) in IGH BCP-ALL1. Differences obviously include the eosinophilia and related symptoms but also the low rate of cytopenias possibly linked to the partial bone marrow infiltration, prevailing in t(5;14)(q31;q32)-associated BCP-ALL. 2) In pediatric IGH BCP-ALL pts, 5-year overall survival is 84%1. The lower published survival rate in t(5;14)(q31;q32)-associated BCP-ALL should be balanced by a 100% survival in CR in our 6 newly described pts with obviously a limited sample size and a shorter FU. This may reflect new treatment strategies, including pediatric intensive chemotherapy and MRD-based stratification. HSCT seems to be an option for pts with suboptimal response (induction failure, high MRD) or relapse. 3) Despite being a specific WHO recognized entity, many common clinical and biological features allow to suggest that t(5;14)(q31;q32)-associated BCP-ALL may be considered as a very rare subset of IGH BCP-ALL. Nevertheless depending on its kinetics and severity, the specific eosinophilia can render difficult both diagnosis and management.1. Russell LJ, Enshaei A, Jones L, et al. IGH@ translocations are prevalent in teenagers and young adults with acute lymphoblastic leukemia and are associated with a poor outcome. J. Clin. Oncol. Off. J. Am. Soc. Clin. Oncol. 2014;32(14):1453-1462. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Peg-Asparaginase Administration on Day 3 of Remission Induction Accelerates MRD Response in Children with B-Cell Precursor Acute Lymphoblastic Leukemia

To improve the outcome of children with standard and intermediate risk acute lymphoblastic leukemia (ALL) by the addition of PEG-asparaginase (PEG) on day 3 of remission induction was one of the key aims of trial ALL MB-2008 (J. Roumjantseva et al, Pediatriya, 2009). Therapy was designed based on previous MB-group studies (A. Karachunsky et al, Leukemia, 2008). Aim of the present study was to evaluate the influence of day 3 PEG on the end-induction MRD-status which is one of the significant predictors of outcome in children with B-cell precursor ALL (BCP-ALL).Patients and methods. In total, 474 patients (242 boys and 232 girls aged 1 to 17 years (median 5 years 8 months) were studied. Inclusion criteria were: BCP-ALL, treatment according to protocol ALL MB-2008, compliance with standard risk group (SRG, n=266) and intermediate risk group (ImRG, n=208) criteria according to the protocol stratification system, and availability of end-induction (day 36) bone marrow (BM) samples. Remission induction of ALL MB-2008 consisted of oral dexamethasone (6mg/m2 daily), 5 injections of vincristine (1,5 mg/m2), 0-2 injections of daunorubicin (DNR, 45 mg/m2) and 6 triple intrathecal injections. Patients were randomized in respect to PEG administration on day 3. SRG patients were divided into three groups (PEG+DNR+, PEG+DNR- and PEG-DNR+); ImRG patients were split into two (PEG+DNR+ and PEG-DNR+). MRD detection was performed by multicolor flow cytometry (MFC) in three reference laboratories. Samples with a tumor cell level above 0.01% were considered MRD-positive. Outcome parameters were event-free survival (EFS) and cumulative incidence of relapse (CIR). Median of follow up was 5 years.Results. Outcome in 474 study group patients was not significantly different from outcome of 2310 children with BCP-ALL enrolled in SRG and ImRG of ALL MB-2008 trial in whom MRD was not studied: EFS was 0.86±0.02 and 0.84±0.01, respectively, p=0.14, and CIR was 0.12±0.02 and 0.09±0.01, p=0.38.MFC MRD data obtained at day 36 had a significant impact on prognosis in SRG patients. EFS as well as CIR were worse for patients with MRD >0.1% (n=26; EFS 0.47±0.15, CIR 0.49±0.17) compared with 248 patients with low/negative MRD (EFS 0.94±0.2, CIR 0.05±0.02, p<0.001). Nevertheless, the distribution of MRD levels was completely different dependent on randomization arms: in arm PEG-DNR+ (n=92) 18.5% of patients belonged to the group with unfavorable MRD compared with only 6.2% in arm PEG+DNR- (n=80, p=0.017) and 4.3% in arm PEG+DNR+ (n=94, p=0.002). Interestingly, in two PEG+ arms the number of patients with high MRD was not significantly different (p=0.558). Despite the lower proportion of high MRD levels in PEG+ arms MRD maintained its prognostic significance also in these patients. EFS was 0.65±0.16 and CIR 0.35±0.18 in 9 children with MRD ≥0.1 compared with EFS 0.94±0.02 and CIR 0.05±0.02 in 165 patients of the low MRD group (p<0.001 for both EFS and CIR).In ImRG, MFC MRD data disclosed a prognostic value, as well. EFS was 0.92±0.03 and CIR 0.06±0.02 for 143 patients with MRD-negativity on day 36; in contrast, outcome of 78 MRD-positive patients was significantly inferior (EFS 0.73±0.06, CIR 0.25±0.06, p<0.001 for both comparisons). Like in SRG, in ImRG the distribution of MRD levels was different between two randomization arms. In PEG-DNR+ group (n=93) only 54.8% of patients were MRD-negative at the end of remission induction. In contrast, in PEG+DNR+ group (n=115) the proportion of patients with favorable MRD results was significantly higher (76.5%, p=0.001). Again even with low number of MRD-positive cases in PEG+ arm, day 36 MRD disclosed a significant influence on outcome: In 88 MRD-negative patients EFS was 0.93±0.03 and CIR 0.05+0.03, significantly better than in 27 MRD-positive patients (EFS 0.80+0.08 and CIR 0.17+0.08, p=0.025 and p=0.019, respectively).Conclusions. Administration of PEG at day 3 of remission induction leads to a more rapid MRD response in children both with standard-risk and intermediate-risk BCP-ALL. In SRG, rapidity of MRD clearance in PEG+ arms was independent of the additional administration of daunorubicin. We conclude that end-induction MRD data are independent predictors of outcome despite the small proportion of MRD-positive patients after the implementation PEG during induction. DisclosuresNo relevant conflicts of interest to declare.

Immune Recovery Refines the Prognostic Impact of Minimal Residual Disease on Overall and Progression Free Survivals after Frontline Fludarabine, Cyclophosphamide and Rituximab (FCR) in CLL Patients

Introduction: in chronic lymphocytic leukemia (CLL), treatment with FCR is the standard of care for treatment-naive and fit enough patients (pts). MRD threshold assessed 3 months after end of treatment (EOT) is considered as a surrogate for both progression free survival (PFS) and overall survival (OS). On the other hand, antibiotic prophylaxis is often started and maintained until CD4>200/mm3. We hypothesized that a monitoring of MRD versus normal immune cells recovery kinetics during follow-up (FU) could help refine the predictive power of MRD EOT evaluation, and allow identification of patients with increased risk of either infection and/or relapse.Methods: we prospectively collected fresh peripheral blood (PB) samples of 162 pts from 2 institutions in France (2006-2017) at the end of treatment (EOT), then every 6 months until month 24 (M24). We used 4-color flow cytometry to quantify both MRD (classified as 3 clusters: low (<10-4), intermediate (≥10-4 but <10-2) or high (≥10-2) level) and the reconstitution of normal lymphocyte subsets (CD4, CD8, NK). We plotted survival curves using Kaplan-Meier method and landmark analyses at different time points (9-15-21 months from day 1 cycle 1 FCR). Cox proportional model with time-dependent covariates (MRD, CD4, CD8 and NK counts) was also used to evaluate the correlation of covariates with outcomes.Results: one hundred and sixty-two pts (69% male, median age 58y) received a median of 6 courses of FCR. IGHV was mutated in 36.6%, and del13q was the most frequent cytogenetic abnormality (37.4%). Only 7 pts had del17p and/or mutation of TP53. After a median follow-up of 60.5 months, 46.3 % of pts have relapsed and/or died (median PFS estimation: 65.7 months, median OS not reached). At EOT, 65.3%, 27.2% and 7.5 % of pts achieved low, intermediate and high MRD respectively; 64.2% of pts had CD4≤200/mm3 while 35.8% had CD4>200/mm3.At landmark analysis of EOT, multivariate Cox model identified IgHV unmutated (HR 2.46), MRD intermediate (HR 3.3) or high (HR 19.57) (Figure 1), CD4 level (HR 1.22) as factors associated with PFS, and only MRD (HR 1.1) and CD4 counts (HR 1.2) were found to be associated with improved OS (Figure 2). In EOT intermediate MRD pts (n=34), those having EOT CD4≤200/mm3 had better 5-year PFS than those having CD4>200/mm3 (53.5% vs 7.7%, p=0.001) (Figure 3). This difference was not significant for low MRD pts (65% vs 58.9%, p=0.7). In landmark analysis at 21 months (=one year after EOT assessment), intermediate MRD pts (n=44) having CD4≤200/mm3 had significantly better 5-year PFS (85.7% vs 52.8%, p=0.0138). When performing successive landmark analyses on the whole population, CD4>200/mm3 was associated with worse 5-year PFS at EOT (34.1% vs 59.6%, p=0.016), 6 months (49.5% vs 58.8%, p=0.017) and 12 months (46.7% vs 68.3%, p=0.008) (Figure 4). In total, 20.4% of patients developed opportunistic infections, not correlated to CD4/CD8/NK counts.Conclusion: complementarily with MRD, CD4 count is an independent predictive factor of PFS and OS after FCR. As expected, MRD increase during FU is independently associated with worse PFS and OS, but CD4 counts at EOT and the first year post-FCR refine prognosis of the “MRD detectable” risk group (independently of CLL associated risk factors such as del17p/IgHV status). This is important in the interpretation and design of clinical trials dedicated to prolong PFS/OS using consolidation regimens based on MRD detection>10-4 in CLL. On the other hand, CD4>200/mm3 was not predictive of infectious events. [Display omitted] DisclosuresRecher:Celgene, Sunesis, Amgen, Novartis: Research Funding; Novartis, Celgene, Jazz, Sunesis, Amgen: Consultancy. Ysebaert:Janssen: Consultancy, Research Funding, Speakers Bureau.

Improving Depth of Response with Continued Ibrutinib Therapy in CLL Patients

Introduction: Minimal residual disease negativity (MRD-) predicts long-term survival of CLL patients after chemoimmunotherapy. Data on depth of response and its clinical significance in patients receiving ibrutinib is limited. The fact that ibrutinib is a time-indefinite therapy, as opposed to the time-limited approach with classic chemoimmunotherapy, raises the question of temporal MRD changes during continued treatment. We sequentially quantified MRD in peripheral blood (PB) and bone marrow (BM) by flow cytometry in CLL patients on ibrutinib.Methods and Patients: 86 CLL patients received single-agent ibrutinib 420mg once daily under a phase II investigator-initiated trial (NCT01500733). 3-year safety and efficacy results from this trial were previously reported [Farooqui et al, 2015 ASH Abstract 2937]. Briefly, eligible patients had either TP53 aberration or were ≥65 years old. The study included both treatment-naïve and relapsed/refractory patients. The primary endpoint was response at 6 months according to 2008 International Workshop on Chronic Lymphocytic Leukemia (iwCLL) criteria incorporating 2012 clarifications. Response assessments at 6 and 12 months and annually thereafter included PB and BM flow cytometry and BM biopsy. MRD- was defined as <10-4 CLL cells per leukocytes based on 8-color flow cytometry. Spearman's analysis was used to assess the correlation between PB and BM MRD. Linear mixed models for repeated measures were used to estimate annual reduction of disease burden. Statistical analyses were performed using R (version 3.4.0).Result: Of 86 patients enrolled, 51 (59.3%) patients had TP53 aberration and 35 (40.7%) patients were ≥65 years old. More than half of the patients had previously untreated CLL (53 [62.6%]), advanced Rai stage (58 [67.4%]), and unmutated IGHV (U- IGHV) status (57 [66.3%]). At the median follow-up of 48 months, 52 (60.5%) remained on study. CLL disease burden significantly and continuously decreased with therapy in both PB and BM. Comparison of the paired PB and BM MRD levels revealed strong correlation between the two compartments (P <0.0001). Past the first year, residual CLL burden decreased by 36% in PB and 28% in BM with each additional year of treatment. Median MRD at 3 years was 5.3x10-2 in PB and 7.3x10-2 in BM. Although depth of response significantly improved over time, MRD- (<10-4) was rare even with long-term therapy. Three patients achieved MRD- in PB (each at 2, 3 and 4 years) and three patients achieved MRD- in BM (two at 3 years and one at 4 years, respectively). Low MRD (<10-2) was achieved by 16 (25.4%) of 63 patients at 3 years. We correlated MRD levels to iwCLL response. The CR rate of 38% in the low MRD group was not significantly different from 23% in the high MRD group (P=0.33). Likewise, both MRD groups showed comparable levels of residual disease in lymph nodes, spleen, and BM. Next, we performed subgroup analyses using baseline characteristics to identify factors associated with differential levels of MRD. MRD levels were similar between subgroups stratified by TP53 aberration and prior treatment status. Notably, patients with U- IGHV had significantly lower MRD in PB than patients with mutated IGHV (M- IGHV) starting from the first year on ibrutinib (P <0.05; Figure 1). However, BM MRD levels were similar between IGHV subgroups.Conclusion: Depth of response improved with continued ibrutinib, leading to low levels of MRD. PB and BM MRD levels were highly correlated, suggesting non-invasive testing could replace BM assessments on ibrutinib. Patients with M- IGHV had significantly higher levels of PB MRD than those with U- IGHV, consistent with known differences in redistribution lymphocytosis between two subgroups. Studies using MRD as a decision point for treatment duration with ibrutinib need to take into consideration the different levels of PB MRD achieved in the two IGHV subgroups. [Display omitted] DisclosuresWiestner:Pharmacyclics: Research Funding; Acerta Pharma: Research Funding.

Long Term Follow up of Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplant Cyclophosphamide in Children and Teenagers < 18 Years Old with High-Risk Acute Leukemia. Very Good Results in CR1 and CR2 Patients but Unexpected High Incidence of Severe Acute Graft Versus Host Disease in Children < 10 Years

IntroductionSeveral reports have been published showing that T cell replete haploidentical stem cell transplantation (TCR-Haplo-SCT) with post-transplantation cyclophosphamide (PTCy) is feasible and achieves good results in children and young adults with hematologic malignancies, however most of them have included patients until 21 years, a variety of malignancies and the follow up informed have been short, indeed, only one described outcomes until 36 months. Here we present the long term follow up of 39 patients, < 18 years old, with high-risk leukemia, transplanted with TCR-Haplo-SCT and PTCy in one institutionMethods and Patients:The cellular source was PBSC, the mobilization was done with filgrastim and the cells were collected with one apheresis procedure. Two conditioning were used: fludarabine 30 mg/m2/day for 5 days, oral busulfan 4-8 mg/kg/split in 1-2 days and total body irradiation 400 cGy on day - 1 (Flu Bu TBI) or fludarabine, same dose, melphalan 100-140 mg/m2, one day and TBI 200-400 cGy on day - 1 (Flu Mel TBI). The patients received PTCy 50 mg/kg/day on D+3 and D+4, followed by cyclosporine and oral mycophenolate starting on day + 5.After a signed informed consent, 39 patients were transplanted. The diagnoses were: acute lymphoblastic leukemia (ALL): 22, acute myeloid leukemia (AML): 14, juvenile myelomonocytic leukemia (JMML): 2, blastic phase of chronic myeloid leukemia (CML blastic): 1. Eleven out of 39 (28%) were in first remission (CR1), 18/39 (46%) in second (CR2), and 10/39 (26%) in third or with refractory disease (CR3). The indication for transplantation of patients in CR1 was: JMML: 2 cases, ALL with high MRD levels after induction: 3, CML blastic: 1, AML without CR after induction: 4 or with complex karyotype: 1.Median age was 7.6 years (range 2-17), 17 out of 39 were younger than 10 year s and, 18 were female.Results:All the donors shared 4 out of 8 alleles; in 61% of the cases the donor was the mother, in 26% the father and in 13% a sibling. 17 patients (38%) were given Flu Bu TBI and 22 (56%) received Flu Mel TBI.A median of 14 million of CD34+ cells/kg was infused (range 7-38). For patients younger than 10 years the median was 17 million (range 7-38) and for older 12 million (range 8-19) P: 0.08. The engraftment rate in 38 patients alive at d+30 was 100%, median time to reach 500 neutrophil or more and a self- sustained platelet count of 20.000 was 14 days for both (range 12-20 and 8-48). Chimerism at day + 100 was available in 35 cases; all of them had full donor hematopoiesis.The median follow-up of the whole group was 20 months (range 3- 52), while for alive and deceased patients were 26 and 7.7 months respectively. The accumulative incidence of acute graft versus host disease (aGVHD) II-IV and III-IV was 25 and 13%, it was unexpected higher in patients younger than 10 years; indeed, all the severe cases belong to this group (Tab 1). The incidence of extensive chronic graft versus host disease was 16.6%The overall relapsed rate was 23%, the transplant related mortality (TRM) at 1 year was 15.4%. The overall (OS) and event free survival (EFS) at 36 months (Kaplan Meier) for the whole group was 51 and 48%. When OS and EFS were discriminated by state of the disease, the results were excellent for CR1 patients; 87 and 75%, also good for CR2; 46 and 43 %, and still acceptable for CR3 or advance disease group; 30% for both. In the CR2 group there were 4 late relapses at 19, 24, 27 and 37 months post transplant. Fig 1ConclusionThis study included only patients younger than 18 years with high risk leukemia transplanted with haplo PBSC and with PTCy. After a follow up of 26 months for surviving patients, the OS is outstanding for patients in CR1, encouraging for CR2 and satisfactory for advance disease, the TRM is not high and the overall incidence of acute and chronic GVHD acceptable, this confirm the value of this procedure in the population studied. However late relapsed occurred and we noticed, similar to an Indian report, (Biol Blood Marrow Transplant 2016; 22:499) a high incidence of severe aGVHD in children < 10 years, it seem that this group may needs innovative approaches for the prevention of this complication [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The combination of venetoclax, lenalidomide, and rituximab in patients with newly diagnosed mantle cell lymphoma induces high response rates and MRD undetectability.

7505 Background: MCL is a rare lymphoma without a standard of care but several regimens have demonstrated clinical activity, the majority based on traditional chemotherapy. We hypothesized that adding venetoclax (V) to R2 would be safe and effective in MCL pts irrespective of age, morphology or stage. Here we present safety and efficacy data from the on-going phase 1b study of R2 + V in pts with newly diagnosed MCL. Methods: This multi-center phase 1 study (NCT03523975) enrolled pts aged ≥18 yrs with untreated MCL. The primary objective was to characterize the safety and tolerability of R2 + V and determine the MTD. During induction (12 months (m)) pts received lenalidomide (L) 20 mg daily on day 1-21, Rituximab (R) was given weekly during c1 then on day 1 of every even cycle, V was escalated over 4 weeks to 400 mg beginning day 8. Each cycle is 28 days (d). The DLT period was 42 d beginning C1D8. In maintenance, R every 8 weeks for 36m, L at 10 mg or half of last dose during induction for 24 m and V for minimum 12 m. No pts have been transplanted. Pts with progression (PD) came off study. MRD was analyzed in parallel with scans during induction by clonoSEQ assay (Adaptive Biotechnologies). Results: As of Feb. 1st, 2021, we have enrolled all 28 planned pts on study. Pt characteristics/responses are summarized in Table. Among the 28 pts who have received at least one dose, the median treatment duration so far is 278d (IQR 170-560), with 24 pts still on treatment (Tx). 1 pt is off from a unrelated condition. All pts escalated to V 400 mg w/o any DLTs noted. Treatment-emergent adverse events (TEAEs) were reported in 100% of pts, and grade 3+ TEAEs were reported in 26 (93%) patients. The most common all-grade TEAEs (≥50% of pts), regardless of relationship to study Tx, were fatigue, neutropenia and diarrhea. Grade ≥3 TEAEs reported in ≥50% pts were neutropenia (68%) and thrombocytopenia (50%). No pts have withdrawn or d/c Tx due to AEs. There was one grade 5 event, in a non-evaluable pt, related to a PE that occurred prior to DLT period. In the 28 evaluable pts the ORR (CR/PR) was 96% (27/28 pts) with CR/CRu of 89%. Of the responding pts, two had PD, one w/ CR and one w/ PR. All pts with PD had baseline TP53 mutation. MRD testing was successful in all pts. At time of submission 20 of 28 (71%) were MRD - at 10-6. Conclusions: Interim results show that at the MTD the combination of V 400 mg daily, L 20 mg, with R is safe with a manageable toxicity profile and a high ORR and MRD - in pts with newly diagnosed MCL. Safety data is consistent with the AE profile noted for each drug without any unexpected or unique AEs. Updated results including BH3 profiling will be presented at the meeting. Clinical trial information: NCT03523975. [Table: see text]

Upfront autologous stem cell transplantation (ASCT) versus carfilzomib-cyclophosphamide-dexamethasone (KCd) consolidation with K maintenance in transplant-eligible, newly diagnosed (NDTE) multiple myeloma (MM).

8000 Background: Upfront ASCT for NDTE MM remains under evaluation with high MRD rates following novel induction and consolidation (cons) strategies. Current phase 3 trials support ASCT, however these employ lenalidomide maintenance which predominantly benefits standard risk (SR) patients (pts). The CARDAMON trial investigated the role of ASCT using K based induction and maintenance. Methods: NDTE pts received 4 x KCd induction (K 20/56 mg/m2 biweekly, C 500 mg D 1,8,15, d 40mg weekly) before 1:1 randomisation to ASCT or 4 x KCd cons. All received 18 months K maintenance (56mg/m2 D1,8,15). Flow cytometric MRD (10-5) was assessed post induction, pre-maintenance and at 6 months maintenance. Primary endpoints were ≥VGPR post induction and 2-year PFS from randomisation. 210 randomised pts were needed to exclude a 10% non-inferiority margin with 15% 1-sided alpha, 80% power. Results: 281 pts were registered, median age 59y (33–74), 24% high risk [t(4;14), t(14;16), t(14;20) or del(17p)]. Post induction, ≥VGPR rate was 58.5%, ORR was 87% with similar responses for high risk vs SR. 52 pts did not proceed to PBSCH (6 MR, 16 PD, 19 toxicity, 4 deaths: 3 infection, 1 cardiac event, 7 other). 109 were randomised to ASCT, 109 to KCd cons. ≥VGPR rate was 78.5% after cons and 80.0% after ASCT (p = 0.8). Median KCd cons dose was 55.5 mg/m2, 99 (90.8%) pts completed 4 cycles, 104 (95.4%) pts received ASCT. After 2.6 years follow-up, median PFS was not reached for ASCT vs 3.8 years for cons (HR: 0.82 (70% CI 0.65, 1.05, p = 0.4). Observed 2-year PFS for ASCT was 75.5% vs 70.7% for cons; calculated difference in 2-year PFS rate (cons vs ASCT) was -4.5% (70% CI -9.2%, +1.1%, non-inferior). High risk pts had inferior outcomes to SR overall regardless of randomisation (2-year PFS ASCT: 52% vs 82% (HR 4.09); cons 48% vs 77% (HR 2.83)). 2 year PFS did not differ according to randomisation: SR 82% (ASCT) vs 77% (cons) HR: 1.29 (0.71-2.35); high risk: 52% (ASCT) vs 48% (cons) HR: 1.06 (0.50-2.23). MRD negativity post induction was 24.3% and similar by genetic risk. MRD negative rates were higher post ASCT (53.1%) than cons (35.8%) (p = 0.02) independent of genetics: SR 49% (ASCT) vs 36% (cons); high risk: 57% (ASCT) vs 32% (cons). G3+ adverse events to induction were infections (18.7%), hypertension (11.2%), anaemia (10.4%), cardiac disorders (3.6%), vomiting (2.2%), fatigue (2.2%), diarrhoea (1.8%). Conclusions: In NDMM receiving KCd induction and K maintenance, KCd cons was non-inferior to ASCT. High risk pts had inferior outcomes, that were not influenced by ASCT or cons randomisation. Clinical trial information: NCT02315716. [Table: see text]

Long-term follow-up results of a multicenter first-in-human study of the dual BCMA/CD19 Targeted FasT CAR-T GC012F for patients with relapsed/refractory multiple myeloma.

8014 Background: The dual CAR-T GC012F developed on the novel FasT CAR-T platform targeting B cell maturation antigen (BCMA), and CD19 was designed to improve depth of response and overall efficacy for CAR-T as therapy for Multiple Myeloma. Here, we present updated data for study (NCT04236011; NCT04182581) including additional pts treated. Methods: From October 2019 to July 2020, 19 heavily pretreated Relapsed/Refractory Multiple Myeloma (RRMM) pts (age 27-71) with a median of 5 prior lines (range 2-9) received a single infusion of GC012F. 94.7% (18/19) were high risk (HR- defined by mSMART), 5 pts had extramedullary disease, 1 pts presented with plasma cell leukemia, and 15/19 were refractory to last therapy. 4/19 pts had received prior anti- CD38, 18/19 pts prior IMiD. 18/19 pts were refractory to PI, 17 pts to IMiD, 3 pts being primary refractory. After lymphodepletion over 2-3 days (30 mg/m2/d, 300mg/ m2/d Flu/Cy) CAR-T cells were administered as single infusion at 3 dose levels: 1x105/kg (DL1) n=1, 2x105/kg (DL2) n=9 and 3x105/kg (DL3) n=9. Results: As of Jan 12, 2021 cut-off, 19 pts were evaluated for response. Overall response rate (ORR) was 94.7% - all responses VGPR or better (94.7% - 16/18 sCR, 2/18 VGPR) with all pts MRD- by flow cytometry (10-4-10-6) - earliest response d 28 post infusion. 100% of pts achieved a reduction of paraprotein, 18/19 a 100% reduction. Best response was MRD- sCR in 16/19 patients (84.2%). In DL3 (n=9) 4 additional pts were response evaluable for 6 mth follow-up: 100% (9/9) of pts achieved MRD-sCR as best response, 87.5% (7/8) of response evaluable pts maintained MRD-sCR at landmark analysis of 6 mths. At data cut off, the median time to follow up was 13.8 mths (6.1-16.4) – median duration of response not yet reached. Cytokine Release Syndrome (CRS) and ICANs were graded by ASBMT criteria: grade 1-2 n=16 (84.2%), grade 3 n=2 (10.5%). Median duration of CRS was 4 d (1-8 d). No grade 4/5 CRS or ICANS were observed. 2 deaths occurred on study and were assessed as not related to therapy – one reported previously; one patient was diagnosed with pseudomonas pneumonia on Day 52, refused life-saving treatment and passed. CAR-T median Tmax was 10 d (range 8-14d), median peak copy number (Cmax) was 127548 (16,011-374,346) copies /ug DNA with long duration of persistence of up to 60 weeks at time of data cut off. Patients continue to be monitored for safety and efficacy. Conclusions: BCMA-CD19 dual FasT CAR-T GC012F showed early, deep and durable responses with a high ORR (94.7% - VGPR and better) including a high MRD- sCR rate (DL3=100%, n=9) in high risk RRMM pts including those refractory to anti-CD38, PI and IMIDs with a favorable safety profile consistent with previous findings. BCMA-CD19 dual FasT CAR-T GC012F may present a new treatment approach for patients with RRMM including those with high-risk features refractory to standard of care. Clinical trial information: NCT04236011; NCT04182581.

Combined Ibrutinib and Venetoclax for First-Line Treatment for Patients with Chronic Lymphocytic Leukemia (CLL): Focus on MRD Results

Combined Ibrutinib and Venetoclax for First-Line Treatment for Patients with Chronic Lymphocytic Leukemia (CLL): Focus on MRD Results

Efficacy and Safety of Front-Line Venetoclax and Rituximab (VenR) for the Treatment of Young Patients with Chronic Lymphocytic Leukemia and an Unfavorable Biologic Profile. Preliminary Results of the Gimema Study ‘Veritas‘

Efficacy and Safety of Front-Line Venetoclax and Rituximab (VenR) for the Treatment of Young Patients with Chronic Lymphocytic Leukemia and an Unfavorable Biologic Profile. Preliminary Results of the Gimema Study ‘Veritas‘

Clofarabine Significantly Increases Eradication of Minimal Residual Disease of B-Precursor ALL Compared to High-Dose Cytarabine in Randomized Trial Coall 08-09

Background Since the FDA approval of clofarabine for the treatment of relapsed or refractory acute lymphoblastic leukemia (ALL) at childhood, several studies have been launched which put clofarabine under scrutiny in combination with other cytostatic drugs as second or third line therapy. As a novel treatment-strategy we introduced the combination of clofarabine with pegylated asparaginase (PEG-ASP) in a randomized fashion in comparison to the standard consolidation course with high dose cytarabine (Hidac) combined with PEG-ASP into the frontline management of ALL within the CoALL 08-09 protocol. The primary objective of the study was to compare the MRD based assessment of the cytotoxic efficacy of the randomized courses in pediatric ALL. Patients and methods CoALL 08-09 was an open, interventional, multi-center, prospective, and randomized clinical trial for patients with newly diagnosed ALL. In March 2010 the trial had been opened for enrollment of patients under 18 years with confirmed diagnosis of acute B- or T-cell precursor leukemia. After a stratified phase I/II, in which patients with high-risk features and high post-induction MRD received the combination of clofarabine and PEG-ASP, the randomized trial started in November 2013. All patients with a measurable MRD at the end of induction (EOI), as measured by RQ-PCR according to EURO-MRD guidelines, were eligible for randomization to receive either the combination of clofarabine 5 x 40 mg/m2 or high dose cytarabine (HIDAC) 4 x 3g/m2 bothin combination with PEG-ASP 2.500 IU/m2 at the beginning of the consolidation phase. Until December 2019 303 study patients were randomized allocating 151 patients towards the clofarabine and 152 patients to the HIDAC arm. Patient characteristics and MRD burden prior to this treatment element were highly comparable. Results The reduction of minimal residual disease was significantly more profound after clofarabine compared to cytarabine (p(Cochran-Armitage)=.01 for BCP-ALL with 93 vs 79 patients reaching MRD negativity (Table 1). MRD status of BCP-ALL after the first randomized consolidation block (day 50) was of prognostic relevance with a statistically significant impact on EFS and relapse rate (Fig. 2a). However, no difference in outcome regarding the event-free and overall survival between the randomized arms was observed (5-year EFS: Clofarabine 85.7, SE=4.1 vs Hidac 84.8, SE=4.7 (p=.96) and OS: 95.7, SE=1.9 vs 92.2, SE=3.2(p=.59) Fig. 2b). This finding was recapitulated independent of gender, age, WBC count at diagnosis, ETV6-RUNX 1 translocation, immunophenotype or overall risk strata). Results for T-ALL patients are in the same range but because of small numbers not statistically significant. No differences in the incidence of severe or persistent toxicity btween randomized treatment elements as well as in the subsequent treatment realization were registered. Conclusion Clofarabine combined with PEG-asparaginase is highly effective and well tolerated in the frontline treatment of ALL. Although the prognostic impact of MRD is still discernible in early consolidation, the greater cytotoxic efficacy of clofarabine reflected by a more frequent eradication of MRD, did not translate into an apparent improvement of outcome likely due to a lack of power in the comparative analysis of randomized patients. Disclosures No relevant conflicts of interest to declare.

The Safety and Efficacy of a CRISPR/Cas9-Engineered Universal CAR-T Cell Product (CTA101) in Patients with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

Introduction Although autologous CAR-T therapy targeting CD19+ B-cell has proven efficacy in hematological malignancies. The challenges such as undesirable waiting time, possible manufacturing failures and high cost, remain to be solved. In addition, antigen-loss/downregulation leads to treatment failure after single-target CAR-T therapy. To tackle these issues, we developed a universal CD19/CD22-targeting CAR-T cell with the TRAC region and CD52 gene disrupted using CRISPR/Cas9 technology. Pre-clinical data demonstrated the safety of CRISPR gene editing and the anti-leukemia ability of CTA101. Method Pts with CD19+ or CD22+ r/r B-ALL received a single dose of CTA101 with traditional 3+3 dose escalation (dose level: 1, 3 and 6×106 CAR+ T cells/kg). Prior to CTA101 infusion, pts received pre-conditioning chemotherapy regimen consisting of cyclophosphamide, fludarabine and alemtuzumab. The primary endpoint is the frequency of DLTs and AEs and secondary endpoints including ORR, OS, cellular PK, etc. (NCT04227015) Results Characteristics of CTA101 CTA101 was manufactured by electroporation of ribonucleoprotein complexes (RNP) comprising Cas9 loaded with sgRNA targeting TRAC and CD52 followed by lentiviral transduction of the CAR transgene. All products were expanded above 100-folds after 10-12 days manufacturing (Fig.1a). CAR expression was detected by FCM staining, ranging from 40~80% (Fig.1b). The frequency of editing as determined by flow cytometry was consistently above 85% (88%-97%) for TRAC and above 65% (68%-83%) for CD52 (Fig.1c, 1d). The CD19/CD22 dual targeting universal CAR-T cells showed potent antigen specific cytotoxicity, and mitigated tumor antigen escape (Fig.1e). Whole genome sequencing was carried out to assess the on-target and off-target editing events. While most mutations were on target, a few off-target mutations were identified, which needed further investigation (Fig.2). QPCR assays identified no detectable rearrangements occurred with the simultaneous editing of four loci: TRAC and CD52 (TRAC-CD52) during the manufacture process. Residual Cas9 protein was quantified during the manufacturing process, showing declining levels that were 0.195 fg/cell (detection limit of sensitive ELISA) in the final product. Clinical result As of August 5th 2020, 8 adult pts were screened, and 6 adult pts were enrolled. All of 6 patients received one infusion of CTA101 (DL1: 3 pts; DL2: 3 pts), with no more than 8 days between enrollment and infusion. The median age of 6 pts was 49 years (range, 26 to 56), the median prior lines of therapies were 5 (range, 2 to 8), and the median marrow blast percentage was 52% (range, 1 to 82). 3 pts had hyperleukocytosis prior to enrollment with difficulties in apheresis for autologous CAR-T, 1 relapsed after autologous CD22 CAR-T, and 3 had high-risk genomic lesions (Table 1). All 6 pts were available for evaluation of safety and efficacy. No DLTs, GvHD, ICANS and death occurred to date. All pts experienced CRS (3 G1, 2 G2, 1 G3), and the G3 CRS recovered within 7 days with one dose of tocilizumab and glucocorticoids. Other common AEs were prolonged cytopenia (3 G3), virus reactivation/infections (CMV 1 G2, 2 G3; ADV 1 G1), bacterial pneumonia (1 G3), and fungal sepsis (1 G3). The majority of events recovered to date. No replication competent lentivirus (RCL) has been detected. On D28 after CTA101 infusion, 5/6 (83.3%) pts achieved CR/CRi, and 5/5 (100%) pts achieved MRD-. With a median follow-up of 85 days (range, 53 to 202), 4/5 pts remained MRD-, 1/5 had MRD+ CR (Fig. 3). Only 1 pt received HSCT in remission on D60. Expansion had been observed in all pts and peaked from D10 to D14 (Fig.4). The correlation among dose level, donor difference, tumor burden and degree of expansion could not be identified. The median duration of persistence was 42 days. The lowest peak expansion was detected by qPCR in the pt without response and whose T lymphocyte recovered within D7, while FCM did not detect CTA101 expansion in the pt. Conclusions CTA101 demonstrates manageable safety profile and deep response of high MRD- CR/CRi rate. No GvHD and CRISPR/Cas9 genome editing associated AEs occurred. Early data of cellular PK and efficacy illustrate that CRISPR gene editing does not curtail the expansion and anti-leukemia capacity of CAR-T. Updated data, including long term gene editing-related AEs, will be presented after further follow-up. Disclosures Zhou: Nanjing Bioheng Biotech Co., Ltd: Current Employment. Ge:Nanjing Bioheng Biotech Co., Ltd: Current Employment. Han:Nanjing Bioheng Biotech Co., Ltd: Current equity holder in private company. Wang:Nanjing Bioheng Biotech Co., Ltd: Current Employment. Zhang:Nanjing Bioheng Biotech Co., Ltd: Current Employment. Ren:Nanjing Bioheng Biotech Co., Ltd: Current equity holder in private company.

Individualized, Low Dose, Fixed Duration Lenalidomide Maintenance Is an Effective Strategy in High MRD Disease Post Chemo-Immunotherapy in CLL: Outcomes of a Randomized Controlled Trial

Introduction Chemo-immunotherapy (CIT) continues to be an acceptable treatment option in CLL without deletion 17. Patients with early progression (&lt;2 years) have poor response to second line chemoimmunotherapy and a reduced PFS with every subsequent relapse. In developed countries, novel agents like ibrutinib and venetoclax are the standard of care for relapsed CLL and are finding approval as part of frontline therapy as well. In middle to low socio demographic index (SDI) countries, these drugs cost 4 to 40 times the per capita GDP and are unlikely to be affordable to a majority in near future. Therefore, strategies to prolong PFS and the time to next treatment are still relevant in these settings. Lenalidomide has shown promise as maintenance treatment in CLL in two large randomized trials (CLLM1 and CALGB). In this randomized trial, we evaluated the efficacy and safety of individualized, low dose, fixed duration, lenalidomide maintenance versus observation in non-deletion 17p CLL. Methods The study period was from January 2018 to June 2019. CLL patients who had achieved at least partial remission (iwCLL response criteria) after frontline CIT were included in the study. Patients with deletion 17p or mutated TP53 were excluded. Baseline and follow-up bone marrow MRD assessment was done using 8-color flow cytometry with a detection threshold of 10-4. MRD was classified into three groups; nil: &lt; 10-4, intermediate: 10-4 to 10-2 and high: &gt;10-2. Patients were randomly assigned to lenalidomide maintenance or observation. Lenalidomide was started at 5 mg every alternate day and escalated to a maximum dose of 10 mg daily in a 20/28 day schedule as per patient tolerance. Maintenance therapy was given for a fixed duration of 6 cycles. PFS was defined as the time from study recruitment to progression or death due to any cause. Haematological toxicity was graded using the iwCLL guidelines for grading of toxicity and other adverse events were graded according to the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE). Results A total of 32 patients were included in the study and randomized to lenalidomide maintenance (n=19) or observation (n=13). The two arms were matched for cytogenetics, comorbidity burden, disease status and MRD at recruitment. At a median follow up of 10.5 months, median PFS was not reached for either arm with no significant difference between the two arms (p=0.338). High MRD at the end of treatment was associated with an increased risk of early progression (p=0.165). Lenalidomide showed PFS benefit in the high MRD subgroup (median PFS 7 months vs. not reached), with a trend towards statistical significance (p=0.067) (see figure). Skin toxicity was the most common adverse event and was more common in the lenalidomide arm (63.2%). Grade 3 neutropenia was reported in only 5.3% patients in the lenalidomide arm. Incidence of grade 3 or more severe infections was not different between the two arms. Conclusions Maintenance therapy with 6 cycles of dose-escalated lenalidomide is safe and may afford PFS benefit in patients with non-deletion 17p CLL and high MRD at the end of frontline chemo-immunotherapy. The CLLM1 and the CALGB trials had a fixed ramp up dosing schedule of lenalidomide and reported more adverse events (38% and 71% grade 3/4 neutropenia) compared to our individualized, low dose lenalidomide protocol. The encouraging results of this study warrant further investigation into the role of lenalidomide maintenance in CLL in larger trials, especially in low and middle SDI setting where access to novel agents is limited and is going to remain so in the foreseeable future. Figure Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Lenalidomide maintenance in CLL