Results of a Phase II Study of Cladribine, Low Dose Cytarabine and Venetoclax, Alternating with Azacitidine and Venetoclax in Patients with Higher Risk Chronic Myelomonocytic Leukemia or Myelodysplastic Syndromes
RESULTS: Between October 2022 and June 2023, 20 pts have been treated: 10, 5, 3 and 2 in cohorts A, B, C and D, respectively. Thirteen pts had MDS, and 7 had CMML. Median age was 74 years (range 52-83). Among MDS pts, 8 (62%) had int-2 and 5 (38%) had high risk by IPSS. By the Molecular IPSS, 10 (79%) had very high, 1 (8%) had high, 1 (8%) had moderate high and 1 (8%) had low risk. Among CMML pts, 4 (57%) had high, 2 (29%) had intermediate-2 and 1 (14%) had intermediate-1 risk by the CPSS Molecular score. Among HMA-F cohorts, median number of prior therapies was 1 (range 1-4), median cycles of prior HMA was 6 (range 2-63) and 4 (27%) pts had failure to prior venetoclax therapy.
Most common adverse events (AEs) were hypoalbuminemia (40%), nausea (40%), sinus bradycardia (40%), alanine aminotransferase increase (35%), constipation (35%), lower extremity edema (35%), fatigue (35%) and hypocalcemia (35%) Most common grade 3-4 AEs were leukopenia (20%) and febrile neutropenia (15%). The 4-week and 8-week cumulative incidences of mortality were 0%. Median number of cycles was 2 (range 1-6). Median cycles to best response was 1 (range 1-3). Among HMA naïve pts (cohorts C and D), the ORR was 80% (n=4): CR in 2 (40%), mCR in 2 (40%). Based on 2023 IWG response criteria, responses in cohort C (n=3) included: CR in 2 (67%) and CR bilineage (CRbi) in 1 (33%). Based on 2015 IWG MDS/MPN criteria, responses in cohort D (n=2) included optimal marrow response and clinical benefit in 1 (50%) and 1 (50%) pts, respectively. Among HMA-F pts (cohorts A and B) the ORR was 20%: 1 CR (10%) and 1 (10%) mCR with HI. Median follow up is 5.3 months (95% CI 2.4-81). Median EFS is 2.1 months in cohorts A and B and not reached in C and D (Fig 1A). Median OS has not been reached for all cohorts (Fig 1B). At the time of data cut-off, all pts in cohorts C and D discontinued study to proceed with hematopoietic stem-cell transplantation (HSCT). Among cohorts A and B, 2 pts (13%) discontinued study to proceed with HSCT, 5 (33%) due to transformation to AML, 2 (13%) due to no response, 2 (13%) due to physician choice, 1 (7%) due to patient choice and 2 (13%) pts remain on study.
CONCLUSIONS: Preliminary data suggests the use of cladribine, LDAC and venetoclax can be safely administered in pts with very high risk MDS and CMML with early promising results in pts with de novo disease.