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.