Background: AZD5991, a human MCL-1 inhibitor, was assessed for safety, tolerability, pharmacokinetics (PK), and antitumor activity as monotherapy and in combination with venetoclax in patients with relapsed or refractory (R/R) hematologic malignancies.
Methods: In the monotherapy cohort (n=61), patients with hematologic malignancies received AZD5991 intravenously in escalating doses either once or twice weekly, following intrapatient dose escalation, on a 3-week cycle. In the combination cohort (n=17), patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) received escalating doses of AZD5991 and venetoclax on either a 3-week or 4-week cycle. Primary objectives were safety and maximum tolerated dose; secondary objectives included plasma PK and antitumor activity.
Results: The most common (≥30%) adverse events (AEs) were diarrhea (59.0%), nausea (55.1%), and vomiting (47.4%). Four deaths occurred due to AEs: cardiac arrest, sepsis, tumor lysis syndrome (TLS), and acute respiratory failure; only TLS was related to AZD5991. Dose-limiting toxicities occurred in 5 patients. Three patients with MDS achieved an objective response: 1 marrow complete remission (mCR) without hematologic improvement, 1 partial remission with AZD5991 monotherapy, and 1 mCR with AZD5991+venetoclax. Asymptomatic elevations of troponin I or T were observed in 8 (10.3%) patients. Post hoc retrospective analysis revealed elevated troponin T in 14/31 patients before any AZD5991 dose and in 54/65 patients after any AZD5991 dose at or after cycle 1. There were no associations between elevated troponin and cardiovascular risk factors.
Conclusions: Treatment with AZD5991 was associated with high incidence of laboratory troponin elevation and a low overall response rate.