P492: TAMIBAROTENE IN COMBINATION WITH VENETOCLAX AND AZACITIDINE IN PREVIOUSLY UNTREATED ADULT PATIENTS SELECTED FOR RARA-POSITIVE AML WHO ARE INELIGIBLE FOR STANDARD INDUCTION THERAPY (SELECT AML-1)

Abstract

Background: RARA-positive (RARA+) AML is a novel genomically defined patient subset with an actionable biological target for treatment with tamibarotene, an oral and selective RARα agonist (McKeown 2017). RARA+ patients can be selected by a blood-based biomarker test, with approximately 30% of newly diagnosed (ND) AML patients being RARA+ (Vigil 2017). As a biologically targeted agent for patients with RARA overexpression, tamibarotene has the potential to provide benefit irrespective of mutation or cytogenetic risk classification. In RARA+ ND AML patients ineligible for standard induction therapy, tamibarotene plus azacitidine (aza) led to a CR/CRi rate of 61% and a rapid onset of response (de Botton 2020). Approximately one-third of patients with ND unfit AML do not respond to front-line standard of care venetoclax (ven)/aza (DiNardo 2020). Translational data suggest RARA positivity enriches for monocytic features reported to be associated with ven resistance (Fiore 2020, Pei 2020). This data suggests the RARA biomarker selects for patients who may respond to tamibarotene and may be less likely to respond to ven/aza. Given that tamibarotene plus aza has been generally well tolerated, with no increase in myelosuppression compared to single agent aza (de Botton 2020), it is anticipated that tamibarotene can be administered safely in combination with ven/aza. Aims: This is a Phase 2, open-label, multi-center study in the U.S. and France comparing the clinical activity of tamibarotene/ven/aza to ven/aza in treatment-naive RARA+ AML patients ineligible for standard induction chemotherapy. The primary objectives are to characterize the safety of the combination and to compare the CR/CRi rate of tamibarotene/ven/aza vs. ven/aza, with secondary objectives to compare CR rate, CR/CRh rate, duration of response, and time to response. The overall response rate using tamibarotene/ven/aza following ven/aza treatment failure will be explored. Clinical activity will be characterized by ELN criteria (Dohner 2017). Methods: This 3-part trial includes a safety lead-in, randomized efficacy study, and salvage arm. Following the safety lead-in, approximately 80 patients will be randomized 1:1 to receive tamibarotene/ven/aza or ven/aza. In the salvage arm, tamibarotene will be added for study patients randomized to ven/aza who experience progressive disease, relapse, or treatment failure. Patients will be treated with aza at 75 mg/m2 IV/SC daily on days 1-7, ven on days 1-28 per VENCLEXA USPI, followed by tamibarotene at 6 mg twice per day by mouth on days 8-28 of each 28-day cycle. Results: Response rates and 95% exact binomial confidence intervals will be calculated by treatment group. Summary/Conclusion: The SELECT AML-1 trial (NCT04905407) opened in July 2021 with ongoing enrollment.