On June 7, 2023 Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) reported promising data from an analysis of the Phase 2 study evaluating REZLIDHIA (olutasidenib), a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase-1 (mIDH1)1, in patients with mIDH1 acute myeloid leukemia (AML) who were relapsed/refractory (R/R) to prior venetoclax-based regimens (Press release, Rigel, JUN 7, 2023, View Source [SID1234632564]). The data are being presented in a poster at the EHA (Free EHA Whitepaper)2023 Hybrid Congress.

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"We are encouraged by the strong efficacy and safety results from olutasidenib in patients with mIDH1 R/R AML who had previously been treated with venetoclax combination regimens, a standard treatment for patients unfit for chemotherapy," said Raul Rodriguez, Rigel’s president and CEO. "These data reinforce REZLIDHIA as a valuable treatment option for these patients, a historically challenging population to treat."

"The data from patients who were relapsed/refractory to prior venetoclax combination-based regimens enrolled in the Phase 2 study of REZLIDHIA (olutasidenib) in patients with mIDHl1 AML is promising and appears clinically meaningful," 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. "With the trial’s compelling data in duration of response and favorable tolerability profile, REZLIDHIA is an important treatment option for these patients, including those who have received prior venetoclax."

The poster titled "Olutasidenib in Post-Venetoclax Patients with Mutant IDH1 AML" examines a subset of 17 patients from the Phase 2 study of olutasidenib who had previously received venetoclax combination regimens. Key points from the presentation are summarized below:

Olutasidenib induced durable remissions in patients with mIDH1 R/R AML, including those failing prior treatment with a venetoclax-based regimen
Of the 17 patients with prior venetoclax treatment, 5 were ongoing and 12 discontinued treatment as of the analysis cutoff date of June 18, 2021
The best response to olutasidenib was CR/CRh in 5/17 (29.4%), of which 4 (23.5%) were CR
In the 8 patients who previously received the combination of venetoclax and azacitadine, a standard treatment for AML patients unfit for chemotherapy, 3 (37.5%) patients achieved a CR/CRh
Time to CR/CRh was median 2.1 months and median duration of CR/CRh was over 18 months, as of the cut-off date
The meeting abstract can be accessed here.

In the Phase 2 study, the registrational cohort enrolled 153 patients with mIDH1 R/R AML who received olutasidenib monotherapy 150 mg twice daily. The primary endpoint was a composite of complete remission (CR) plus complete remission with partial hematological recovery (CRh). The results demonstrated a rate of CR/CRh of 35%, with a duration of response of 25.9 months.

On December 1, 2022, the U.S. Food and Drug Administration (FDA) approved REZLIDHIA (olutasidenib) capsules for the treatment of adult patients with R/R AML with a susceptible IDH1 mutation as detected by an FDA-approved test. REZLIDHIA became commercially available in the U.S. on December 22, 2022. REZLIDHIA was added to the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for acute myeloid leukemia (AML) on January 13, 2023 as a recommended targeted therapy for adult patients with R/R AML with isocitrate dehydrogenase-1 (IDH1) mutation.

About AML
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 20,380 new cases, most in adults, in 2023.2

Relapsed AML affects about half of all patients who, following treatment and remission, experience a return of leukemia cells in the bone marrow.3 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.4 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.

About REZLIDHIA
INDICATION
REZLIDHIA is indicated for the treatment of adult patients with relapsed or refractory acute myeloid leukemia (AML) with a susceptible isocitrate dehydrogenase-1 (IDH1) mutation as detected by an FDA-approved test.

IMPORTANT SAFETY INFORMATION

WARNING: DIFFERENTIATION SYNDROME
Differentiation syndrome, which can be fatal, can occur with REZLIDHIA treatment. Symptoms may
include dyspnea, pulmonary infiltrates/pleuropericardial effusion, kidney injury, hypotension, fever,
and weight gain. If differentiation syndrome is suspected, withhold REZLIDHIA and initiate treatment
with corticosteroids and hemodynamic monitoring until symptom resolution.

WARNINGS AND PRECAUTIONS
Differentiation Syndrome
REZLIDHIA can cause differentiation syndrome. In the clinical trial of REZLIDHIA in patients with relapsed or refractory AML, differentiation syndrome occurred in 16% of patients, with grade 3 or 4 differentiation syndrome occurring in 8% of patients treated, and fatalities in 1% of patients. Differentiation syndrome is associated with rapid proliferation and differentiation of myeloid cells and may be life-threatening or fatal. Symptoms of differentiation syndrome in patients treated with REZLIDHIA included leukocytosis, dyspnea, pulmonary infiltrates/pleuropericardial effusion, kidney injury, fever, edema, pyrexia, and weight gain. Of the 25 patients who experienced differentiation syndrome, 19 (76%) recovered after treatment or after dose interruption of REZLIDHIA. Differentiation syndrome occurred as early as 1 day and up to 18 months after REZLIDHIA initiation and has been observed with or without concomitant leukocytosis.

If differentiation syndrome is suspected, temporarily withhold REZLIDHIA and initiate systemic corticosteroids (e.g., dexamethasone 10 mg IV every 12 hours) for a minimum of 3 days and until resolution of signs and symptoms. If concomitant leukocytosis is observed, initiate treatment with hydroxyurea, as clinically indicated. Taper corticosteroids and hydroxyurea after resolution of symptoms. Differentiation syndrome may recur with premature discontinuation of corticosteroids and/or hydroxyurea treatment. Institute supportive measures and hemodynamic monitoring until improvement; withhold dose of REZLIDHIA and consider dose reduction based on recurrence.

Hepatotoxicity
REZLIDHIA can cause hepatotoxicity, presenting as increased alanine aminotransferase (ALT), increased aspartate aminotransferase (AST), increased blood alkaline phosphatase, and/or elevated bilirubin. Of 153 patients with relapsed or refractory AML who received REZLIDHIA, hepatotoxicity occurred in 23% of patients; 13% experienced grade 3 or 4 hepatotoxicity. One patient treated with REZLIDHIA in combination with azacitidine in the clinical trial, a combination for which REZLIDHIA is not indicated, died from complications of drug-induced liver injury. The median time to onset of hepatotoxicity in patients with relapsed or refractory AML treated with REZLIDHIA was 1.2 months (range: 1 day to 17.5 months) after REZLIDHIA initiation, and the median time to resolution was 12 days (range: 1 day to 17 months). The most common hepatotoxicities were elevations of ALT, AST, blood alkaline phosphatase, and blood bilirubin.

Monitor patients frequently for clinical symptoms of hepatic dysfunction such as fatigue, anorexia, right upper abdominal discomfort, dark urine, or jaundice. Obtain baseline liver function tests prior to initiation of REZLIDHIA, at least once weekly for the first two months, once every other week for the third month, once in the fourth month, and once every other month for the duration of therapy. If hepatic dysfunction occurs, withhold, reduce, or permanently discontinue REZLIDHIA based on recurrence/severity.

ADVERSE REACTIONS
The most common (≥20%) adverse reactions, including laboratory abnormalities, were aspartate aminotransferase increased, alanine aminotransferase increased, potassium decreased, sodium decreased, alkaline phosphatase increased, nausea, creatinine increased, fatigue/malaise, arthralgia, constipation, lymphocytes increased, bilirubin increased, leukocytosis, uric acid increased, dyspnea, pyrexia, rash, lipase increased, mucositis, diarrhea and transaminitis.

DRUG INTERACTIONS

Avoid concomitant use of REZLIDHIA with strong or moderate CYP3A inducers.
Avoid concomitant use of REZLIDHIA with sensitive CYP3A substrates unless otherwise instructed in the substrates prescribing information. If concomitant use is unavoidable, monitor patients for loss of therapeutic effect of these drugs.
LACTATION
Advise women not to breastfeed during treatment with REZLIDHIA and for 2 weeks after the last dose.

GERIATRIC USE
No overall differences in effectiveness were observed between patients 65 years and older and younger patients. Compared to patients younger than 65 years of age, an increase in incidence of hepatotoxicity and hypertension was observed in patients ≥65 years of age.

HEPATIC IMPAIRMENT
In patients with mild or moderate hepatic impairment, closely monitor for increased probability of differentiation syndrome.

Click here for Full Prescribing Information, including Boxed WARNING.

To report side effects of prescription drugs to the FDA, visit www.fda.gov/medwatch or call 1-800-FDA-1088 (800-332-1088).

REZLIDHIA is a registered trademark of Rigel Pharmaceuticals, Inc.