Rigel Pharmaceuticals recently received the green light from the FDA for their oral IDH1 inhibitor, REZLIDHIA™ (olutasidenib). REZLIDHIA™ is indicated for treatment of acute myeloid leukemia (AML) in a difficult to treat, relapsed or refractory (R/R) patient population who have a mutation in isocitrate dehydrogenase-1 (IDH1). Mutations of IDH1 are found in 7-14% of patients with AML and there have been few treatment options for these patients, particularly in the second line. The FDA approval was supported by data from the open-label Phase 2 registrational study evaluating REZLIDHIA™ monotherapy at a dose of 150 mg twice daily in 153 mIDH1 R/R AML patients. The efficacy-evaluable population was 147 patients who initiated REZLIDHIA™ at least six months prior to the interim analysis cutoff date of June 18, 2021, and who had a centrally confirmed IDH1 mutation. Acute myeloid leukemia (AML) is a rapidly progressing cancer of the blood and bone marrow that affects myeloid cells, which normally develop into various types of mature blood cells. AML occurs primarily in adults and accounts for about 1 percent of all adult cancers. The American Cancer Society estimates that in the United States alone, there will be about 20,050 new cases, most in adults, in 2022.1
Relapsed AML affects about half of all patients who, following treatment and remission, experience a return of leukemia cells in the bone marrow.2 Refractory AML, which affects between 10 and 40 percent of newly diagnosed patients, occurs when a patient fails to achieve remission even after intensive treatment.3 Quality of life declines for patients with each successive line of treatment for AML, and well-tolerated treatments in relapsed or refractory disease remain an unmet need.
REZLIDHIA™ provided a complete remission (CR) combined with partial hematological recovery (CRh) within less than two months (mean time to response 1.9 months) lasting for over two years (mean duration 25.9 months) and demonstrated a CR+CRh rate of 35% in patients with over 90% of those responders in complete remission.
“The 25.9 months median duration of CR+CRh is a clinically meaningful improvement for AML patients and appears to be longer than currently available treatment options,” said Jorge E. Cortes, M.D., Director, Georgia Cancer Center, Cecil F. Whitaker Jr., GRA Eminent Scholar Chair in Cancer, and Phase 2 trial investigator. “Given the limited treatment options for adult patients with mIDH1 R/R AML, who typically have a poor prognosis, REZLIDHIA™ may provide an effective, new treatment option with a well characterized safety profile.”
Complete remission was achieved for over 28 months (mean 28.1 months). Over 1/3 of patients (34%) treated with REZLIDHIA™ were able to avoid platelet and/or red blood cell transfusions at 56 days and unlike other treatments in the relapsed/refractory AML space, there is no need for cardiac monitoring. REZLIDHIA™ has a black box warning for differentiation syndrome which can be fatal; if suspected, differentiation syndrome should be treated with corticosteroids and hemodynamic monitoring.
Hats off to Rigel Pharmaceuticals for getting the FDA nod just four months after acquiring the asset. REZLIDHIA™ has the potential to address an unmet need in a niche patient population typically subject to a poor prognosis. It is motivating to see companies like Rigel invest in bringing to market therapeutic options for small, tough to treat patient populations.
Click here for the full press release from Rigel Pharmaceuticals: https://www.rigel.com/investors/news-events/press-releases/detail/349/rigel-announces-u-s-fda-approval-of-rezlidhia
Click here for full prescribing information: https://www.rezlidhia.com/downloads/pdf/REZLIDHIA-Full-Prescribing-Information.pdf
