Abstract CT060: Phase 1 study of azacitidine in combination with evorpacept for higher-risk myelodysplastic syndrome (MDS)

Abstract Background:Evorpacept (EVO) is a high affinity CD47-blocking fusion protein with an inactive human immunoglobulin Fc region designed to enhance the activity of other anti-neoplastic therapies with minimal additional toxicity. Here, we present final phase 1 results from the ASPEN-02 study. Methods:ASPEN-02 is an open-label, multicenter phase 1/2 study designed to evaluate the safety and activity of EVO in combination with azacitidine (AZA) in subjects with newly diagnosed (ND) higher-risk (HR) or relapsed/refractory (R/R) MDS. Adult subjects with ND HR (IPSS-R > 3.5) or R/R MDS were enrolled into phase 1 cohorts receiving escalating doses of EVO (20 mg/kg Q2W, 30 mg/kg Q2W, and 60 mg/kg Q4W) combined with AZA (75 mg/m2 IV/SC x 7d) in a 28-day treatment cycle. A phase 1 dose expansion portion enrolled adults with ND HR MDS into two dosing cohorts determined to be safe at EVO 40 mg/kg Q4W and 60 mg/kg Q4W. This clinical trial is registered at clinicaltrials.gov: NCT04417517. Results: As of June 2, 2023, 65 subjects were treated in the phase 1 portion, including 13 subjects with R/R MDS [EVO doses of 20 mg/kg Q2W (n=1) or 60 mg/kg Q4W (n=12)], and 52 subjects with ND HR MDS [EVO doses of 40 mg/kg Q4W (n=23) and 60 mg/kg Q4W (n=29)]. Of 52 ND HRMDS subjects, 9 (17.3%) had therapy-related MDS. Multi-hit TP53 mutations were present at baseline in 2/13 (15.4%) R/R MDS and 3/52 (5.8%) ND HR MDS patients. 13/13 (100%) R/R MDS patients had received prior hypomethylating agents or cytotoxic chemotherapy. Median age was 70 (range 24 - 88) years, and baseline ECOG scores were 0 (n=27, 41.5%), 1 (n=31, 47.7%), or 2 (n=7, 10.8%). No dose-limiting toxicity was observed, and a maximum tolerated dose (MTD) was not reached. Treatment-emergent AEs and treatment-related AEs for EVO were reported in 65/65 (100%) and 35/65 (53.8%) subjects respectively; discontinuation, however, was infrequent. Seven (10.8%) subjects experienced a serious adverse event related to EVO. There were no EVO-related deaths on study. Preliminary PK indicated dose-proportional pharmacokinetics consistent with prior studies. Objective response [complete remission (CR), partial remission (PR), marrow CR (mCR), hematologic improvement (HI)], per modified International Working Group 2006 criteria, was observed in 19/52 (36.5%) ND HR [CR=8, mCR=9, HI=2] and 2/13 (15.4%) R/R [mCR=2] MDS subjects. Conclusion:The myeloid checkpoint inhibitor EVO was well tolerated in combination with AZA with an initial safety and activity profile comparable to that of historical AZA monotherapy. Additional updated data will be provided at the time of presentation. Citation Format: Guillermo Garcia-Manero, Bart L. Scott, Ashwin Kishtagari, Srinivasa R. Sanikommu, Aref Al-Kali, Je-Hwan Lee, Juan M. Bergua Burgues, Maria Diez-Campelo, Harry P. Erba, Carmen Garcia-Hernandez, Guillermo Sanz Santillana, Casey O'Connell, Jun-Ho Jang, Dong-Yeop Shin, Hamid Sayar, Mayank Rao, Richard S. Schwartz, Grace An, Feng Jin, Alison J. Forgie, Athanasios C. Tsiatis, Jessica K. Altman. Phase 1 study of azacitidine in combination with evorpacept for higher-risk myelodysplastic syndrome (MDS) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT060.