Rigel Presents New Data in Three Posters at 2024 ASCO Meeting

Rigel Pharmaceuticals presented significant findings at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting, unveiling three posters that highlight advancements in the treatment of certain hematologic disorders. The studies focused on the long-term efficacy of REZLIDHIA® (olutasidenib) for patients with relapsed or refractory (R/R) mutated isocitrate dehydrogenase-1 (mIDH1) acute myeloid leukemia (AML), particularly those with prior venetoclax treatments, and an ongoing Phase 1b trial of R289 for lower-risk myelodysplastic syndrome (LR-MDS).

The pivotal Phase 2 trial of REZLIDHIA® revealed five-year data for patients with R/R mIDH1 AML, showcasing durable responses even in heavily pretreated cases. Among 147 efficacy-evaluable patients, 35% achieved complete remission (CR) or CR with partial hematologic recovery (CRh). The median time to CR/CRh was 1.9 months, with a median duration of 25.3 months, extending up to 54.6 months in some cases. The overall response rate stood at 48%, with a median duration of 15.5 months. Furthermore, 34% achieved transfusion independence from red blood cells, and 41% from platelets. Notably, in the subset of patients who had previously received venetoclax, 33% achieved CR/CRh with a median overall survival of 16.2 months.

A subgroup analysis focused on elderly patients with R/R mIDH1 AML, particularly those aged 75 and older. This analysis affirmed the safety and efficacy of olutasidenib in this demographic, showing that 31% achieved CR/CRh with a median duration of 25.9 months. Among patients who were refractory or resistant to prior venetoclax treatment, 80% achieved an overall response, including 40% with CR/CRh.

In addition, Rigel presented an overview of the ongoing Phase 1b trial of R289, a dual inhibitor of IRAK1 and IRAK4, aimed at treating lower-risk myelodysplastic syndrome (LR-MDS). This trial focuses on evaluating the safety, preliminary efficacy, and pharmacokinetic properties of R289. Enrollment has been completed for three dose levels with daily dosing, and two additional dose levels with twice-daily dosing are currently being recruited.

Acute myeloid leukemia (AML) is a fast-progressing blood and bone marrow cancer that primarily affects adults. Relapsed AML occurs in about half of patients, while refractory AML affects 10-40% of newly diagnosed cases. These conditions pose significant treatment challenges and unmet needs for well-tolerated therapies.

R289 is an investigational compound designed to inhibit inflammatory cytokine production, which is believed to contribute to the pro-inflammatory environment in the bone marrow of lower-risk MDS patients.

REZLIDHIA® is indicated for treating adults with relapsed or refractory AML with an mIDH1 mutation. Important safety information for REZLIDHIA® includes the risk of differentiation syndrome, hepatotoxicity, and various adverse reactions such as increased liver enzymes, fatigue, and nausea. Patients are advised to monitor for signs of hepatic dysfunction and avoid breastfeeding during treatment.

Rigel Pharmaceuticals, founded in 1996, is committed to developing novel therapies for hematologic disorders and cancer, with its headquarters in South San Francisco, California.