FDA Notified About Withdrawal of Idelisib U.S. Indication for Follicular Lymphoma and Small Lymphocytic Leukemia

Idelisib has been voluntarily withdrawn from several indications in the United States, including follicular lymphoma and small lymphocytic leukemia (SLL), according to a press release from developer Gilead Sciences.¹

The therapy received an accelerated approval from the FDA in July 2014 for patients with relapsed B-cell non-Hodgkin lymphoma and relapsed SLL.² The designation was based on findings from a phase 2 study 101-09 (NCT01282424) in which 54% of patients with follicular lymphoma and 58% of patients with SLL experienced an objective response by independent review committee. However, the continued approval required additional evidence that supported idelisib's clinical benefit across both disease types. The withdrawal took place following challenges in enrolling patients on the confirmatory study.

Idelisib also has an indication in chronic lymphocytic leukemia (CLL) in the United States, as well as several marketing authorizations for CLL and follicular lymphoma across Europe, the United Kingdom, Canada, Australia, New Zealand, and Switzerland, none of which will be impacted by the withdrawal.

The study included 72 patients with follicular lymphoma and 26 with SLL who were refractory to both rituximab (Rituxan) and a chemotherapy regimen including an alkylating agent. Idelisib was administered orally twice daily at a dose of 150 mg. The primary end point was overall response rate, with key secondary outcomes including duration of response (DOR), lymph node response rate, time to response, progression-free survival, and overall survival.

Patients were required to have a Karnofsky performance status of 60 or higher and an ECOG performance status of 0 to 2. Disease needed to be histologically confirmed and patients needed to have undergone 2 or more previous chemotherapy- or immunotherapy-based regimens. Those with central nervous system or leptomeningeal lymphoma or with know histological diffuse large B-cell lymphoma transformation were excluded from the study. Other exclusion criteria included evidence of infection at the time of initiation, pregnancy or breast feeding, active drug or alcohol addiction, previous allogeneic bone marrow progenitor cell or solid organ transplant, or previous treatment with idelisib.

Additional findings from the study indicated that 6 patients achieved complete responses in the follicular lymphoma group, and all 15 responses in the SLL cohort were partial. Investigators reported a median DOR of 11.9 months in the SLL cohort (range, 0.0-14.7). The DOR was not reached in the follicular lymphoma group (range, 0.0-14.8).

References

1. Gilead statement on Zydelig® U.S. indication for follicular lymphoma and small lymphocytic leukemia. News release. Gilead Sciences. January 14, 2022. Accessed January 18, 2022. https://bit.ly/3GIVJua
2. U.S. Food and Drug Administration approves Gilead’s Zydelig® (idelalisib) for relapsed chronic lymphocytic leukemia, follicular lymphoma and small lymphocytic lymphoma. News release. Gilead Sciences. July 23, 2014. Accessed January 18, 2022. https://bit.ly/3fDagvg