Phase 1b OMNIVERSE trial: Safety and tolerability of oral azacitidine (Oral-AZA) in combination with venetoclax (VEN) for treatment of acute myeloid leukemia

e19011 Background: Safer and more effective lower-intensity treatment (Tx) options are needed for patients (pts) with acute myeloid leukemia (AML) ineligible for intensive chemotherapy (IC). The combination of VEN, an oral BCL-2 inhibitor, and injectable AZA (Inj AZA), a hypomethylating agent, is indicated in IC-ineligible pts with newly diagnosed (ND) AML and has shown significantly improved response and survival rates vs. Inj AZA alone (DiNardo et al., N Engl J Med 2020). Oral-AZA allows for extended dosing schedules vs. Inj AZA. Methods: OMNIVERSE (NCT04887857) is an ongoing, phase 1b, multicenter, open-label, dose-determination study evaluating Oral-AZA + VEN in pts with relapsed/refractory (R/R; part 1) and ND AML (part 2). This abstract presents data from part 1. Eligible pts are adults with R/R AML (WHO 2016 criteria) not eligible for further IC, with an ECOG performance status of ≤ 2. The Oral-AZA starting dose is 300 mg QD × 14 days (d) per 28d cycle (dose level [DL] −1), which can be de-escalated to 200 mg QD × 14d depending on dose-limiting toxicities (DLTs); VEN 400 mg QD is taken continuously (or 21d per cycle; DL −2). Dosing decisions are guided by a modified toxicity probability interval 2 (mTPI-2) design. The primary endpoint is to evaluate safety/tolerability and establish the maximum tolerated dose (MTD) of Oral-AZA + VEN in R/R AML (starting dose for part 2). Secondary endpoints are to assess preliminary investigator-determined response rates per ELN 2017 AML response criteria (Döhner et al., Blood 2017) for complete remission (CR), CR with partial hematologic recovery, CR with incomplete blood count recovery (CRi), morphologic leukemia-free state, overall response, and measurable residual disease (plus conversion rate). Results: Pt enrollment began in December 2021 and is ongoing; data from part 1 are available for 5 pts (3 female; aged 51–80 years). 3 pts had 1 prior line of Tx and 2 pts had 2. Oral-AZA + VEN was given for 1–12 cycles. Of the 5 pts, 3 reported ≥ 1 any grade (Gr) drug-related adverse event, the most common of which were Gr 1–3 diarrhea (2 pts) and Gr 1–2 nausea (2 pts). Gr 3 febrile neutropenia, which was not deemed drug related, was reported in 4 pts (6 episodes total). In 1 pt, Oral-AZA was reduced to 200 mg QD x 14d from cycle 4 due to Gr 1 diarrhea and VEN to 70 mg QD x 28d from cycle 3 due to co-Tx with a strong CYP3A inhibitor (per protocol). 3 pts died after Tx discontinuation. No DLTs were observed and MTD of Oral-AZA + VEN was determined to be Oral-AZA 300 mg QD x 14d + VEN 400 mg QD x 28d. As of January 2023, 2 pts remained on Tx and best response achieved was CRi in 2 pts and stable disease in 3 pts. Conclusions: These results indicate that a MTD of Oral-AZA 300 mg QD x 14d + VEN 400 mg QD x 28d has a manageable safety profile consistent with known profiles of the 2 agents. Further evaluation in AML is warranted. Clinical trial information: NCT04887857 .