PRESS RELEASE
AB SCIENCE REPORTS COMPLETION OF THE STEP 3 OF PHASE 1, EVALUATING THE COMBINATION OF AB8939 WITH VENETOCLAX FOR THE TREATMENT OF REFRACTORY OR RELAPSED ACUTE MYELOID LEUKEMIA
THE COMBINATION OF AB8939 WITH VENETOCLAX GENERATED A 67% OVERALL RESPONSE RATE (ORR) AND A 100% DISEASE CONTROL RATE (DCR), WITH NO DOSE-LIMITING TOXICITIES (DLT) OBSERVED, IN A POOR-PROGNOSIS POPULATION WITH ADVERSE GENETICS TREATED IN THE SECOND - TO FOURTH-LINE RELAPSED OR REFRACTORY SETTING
Paris, June 29, 2026, 8am CET
AB Science SA (Euronext - FR0010557264 - AB) today provides an update on the Phase 1 study of the molecule AB8939 and the completion of Step 3, evaluating the combination of AB8939 + venetoclax in patients with acute myeloid leukemia (AML) associated with a very unfavorable genetic profile.
Step 3 evaluated the combination of AB8939 plus venetoclax administered over a 14-day cycle. A total of six patients were treated across two dose levels of AB8939 (16 mg/m² and 21.3 mg/m²), each in combination with venetoclax. The combination was well-tolerated, with no dose-limiting toxicity (DLT) and no hematological toxicity observed at either dose level, allowing selection of the recommended Phase 2 dose (RP2D).
Encouraging preliminary signs of efficacy were observed. Of the six patients treated, four achieved an objective response (one complete remission with incomplete hematologic recovery and three partial responses), corresponding to a 67% overall response rate (ORR). The two remaining patients achieved stable disease, resulting in a 100% disease control rate (CDR). These responses were achieved after a single cycle of treatment (14 days) in heavily pre-treated patients receiving second- to fourth-line therapy. Notably, two of the responding patients had previously progressed on venetoclax in combination with other chemotherapies.
The patients treated all have very difficult to treat cytogenetic profiles, including complex karyotype, TP53 mutation, NRAS mutation, monosomy 5 and 7 and MECOM-rearrangement, that typically have a poor prognosis due to their aggressive disease course and treatment resistance
This is a high response rate in a population where standard-of-care therapies achieve ORR of 10–30% in adverse-risk, multiply pre-treated AML (Gill H, et al. Cancer Med. 2020;9(10):3371-3382).
Response after the first 14 days cycle in the six patients treated in Step 3 (AB8939 + venetoclax)
Patient | AB8939 dose | Line of therapy | Key adverse genetics | Best response |
Patient 1 | 16 mg/m² | 2nd | RUNX1 and NRAS mutations | CRi |
Patient 2 | 16 mg/m² | 2nd | MECOM-rearrangement, complex karyotype, monosomy 5 and 7 | PR |
Patient 3 | 16 mg/m² | 4th | TP53 mutation, complex karyotype, monosomy 5 and 7 | PR |
Patient 4 | 21.3 mg/m² | 3rd | TP53 mutation, complex karyotype, monosomy 5 and 7 | PR |
Patient 5 | 21.3 mg/m² | 2nd | TP53 mutation | SD |
Patient 6 | 21.3 mg/m² | 2nd | TP53 mutation (very high-risk MDS) | SD |