FDA Approves Tibsovo for Frontline IDH1-Mutant Acute Myeloid Leukemia

The Food and Drug Administration (FDA) has approved a supplemental new drug application (sNDA) for Tibsovo (ivosidenib) as a single agent for the first-line treatment of adult patients with IDH1-mutant acute myeloid leukemia (AML), as detected by an FDA-approved test, who are 75 years and older or are ineligible to receive intensive chemotherapy.

The approval is based on findings from a phase 1 trial in which Tibsovo induced a 28.6% complete response (CR) rate and a CR plus CR with partial hematologic recovery (CRh) rate of 42.9%, stated Agios, the developer of Tibsovo, in a press release. The median durations of CR and CR+CRh were not estimable, and 41.7% (5 patients) of patients who achieved CR/CRh remain on Tibsovo as of the data cutoff.

“The phase 1 results for Tibsovo demonstrated that this oral, single-agent therapy can induce durable responses in newly diagnosed AML patients with an IDH1 mutation,” Gail J. Roboz, M.D., professor of medicine, Director of the Leukemia Program and a member of the Sandra and Edward Meyer Cancer Center at Weill Cornell Medicine and NewYork-Presbyterian/Weill Cornell Medical Center, said in a press release. “Many patients included in the study had features associated with particularly aggressive and challenging forms of AML, including secondary disease, adverse risk genetics and prior treatment with hypomethylating agents.”

The agency’s decision took place more than a month before the action date, which was June 21, 2019. The sNDA had been accepted under the FDA’s Real-Time Oncology Review pilot program, which is designed to have a more efficient review process to make therapies more quickly available to patients.

Agios submitted data from a phase I dose escalation/expansion study examining Tibsovo monotherapy in patients with IDH1-positive hematologic malignancies. Study results from the data cutoff date of May 11, 2018, were presented in December 2018 at the ASH Annual Meeting. At the cutoff, 258 patients had received treatment, including 34 patients with untreated AML. Of this group, nine were from the dose-escalation phase and 25 were from the expansion phase.

Among these 34 AML patients, 79.4% had secondary AML and 20.6% had de novo AML. The average patient age was 76.5 years (range, 64-87). Patients received 500 mg of Tibsovo daily, and the median treatment duration was 4.3 months (range, 0.3-40.9).

Results also showed that 58.3% of patients who achieved a CR or CRh were in remission at one year after receiving Tibsovo. The median time to CR/CRh was 2.8 months (range, 1.9-12.9). Also, among 17 patients who were dependent on red blood cell (RBC) and/or platelet transfusions at baseline, 41.2% were independent of RBC and such transfusions during any 56-day postbaseline period. Moreover, of the 11 patients who were independent of both RBC and platelet transfusions at baseline, 54.5% of them remained transfusion independent during the similar period.

Among all responders, the average time to first response was 1.9 months (range, 0.9-3.6). The estimated 12-month durations of response were 59.5%, 66.7% and 77.8%, in the ORR, CR/CRh andCR populations, respectively.

There were patients across all categories of responders who achieved transfusion independence (no transfusions for 56 or more consecutive days on treatment). Sixty-four percent (nine of 14) of the CR/CRh group had IDH1 mutation clearance, including all four patients who achieved a CRh.

Regarding safety, side effects across all grades occurring in 20% of patients were diarrhea (52.9%), fatigue (44.1%), nausea (38.2%), decreased appetite (32.4%), leukocytosis (26.5%), anemia (26.5%) and edema peripheral (26.5%). QTc interval prolongation also occurred in patients treated with Tibsovo. IDH-differentiation syndrome (IDH-DS) across all grades occurred in 25% (7 patients) of patients, of which 6 patients (86%) recovered.

The FDA previously approved Tibsovo in July 2018 for the treatment of adult patients with relapsed/refractory IDH1-mutant AML. The approval was based on a single-arm phase 1 study of 174 patients with IDH1-positive relapsed/refractory AML. In the study, the CR rate was 24.7% and the CRh rate was 8%. The median duration of CR plus CRh was 8.2 months (range, 5.6-12). Among the CR/CRh population, the median time to best response was 2.0 months (range, 0.9-5.6).

This article originally appeared on OncLive as “FDA Approves Ivosidenib for Frontline IDH1+ AML."