FDA Grants Priority Review to Retifanlimab for Squamous Cell Carcinoma of the Anal Canal

The FDA has granted priority review to a biologics license application (BLA) for retifanlimab (INCMGA 0012) for the treatment of adult patients with locally advanced or metastatic squamous cell carcinoma of the anal canal (SCAC) who were intolerant of or who had progressed on platinum-based chemotherapy.¹

The application was based on findings from the phase 2 POD1UM-202 trial (NCT03597295) presented during the 2020 ESMO Virtual Congress, which showed that the investigational, humanized, proprietary anti–PD-1 monoclonal antibody showcased promising activity in patients with platinum-refractory SCAC, including those positive for human immunodeficiency virus.²

The agent elicited an objective response rate (ORR) of 13.8% (95% CI, 7.6%-22.5%) per independent central review (ICR) using RECIST v1.1 criteria, with a 1.1% complete response rate, a partial response rate of 12.8%, and a stable disease rate of 35.1%. Just under half, or 45.7%, of patients experienced disease progression. The disease control rate (DCR) in these patients was 48.9% and the median duration of response (DOR) was 9.5 months. Notably, responses were observed irrespective of PD-L1 status, presence of liver metastases, age, or HIV status.

Under the Prescription Drug User Fee Act, the FDA will make a decision on the agent by July 25, 2021.

“Patients with SCAC who have progressed after first-line chemotherapy treatment currently have no approved treatments available, and we are encouraged that the FDA’s acceptance of this BLA for priority review brings us one step closer to addressing this historically neglected, yet important, tumor,” Lance Leopold, MD, group vice president of Immuno-Oncology Clinical Development at Incyte, stated in the press release. “Despite SCAC being a rare disease, its incidence is increasing, and its impact is profound. We look forward to working with the FDA to potentially fill an unmet need and advance progress in SCAC for patients.”

The open-label, single-arm, multicenter, phase 2 trial enrolled a total of 94 patients with confirmed locally advanced or metastatic SCAC who were 18 years of age or older, experienced progressive disease on or following platinum-based chemotherapy and had measurable disease per RECIST v1.1 criteria. To be eligible for enrollment, patients had to have an ECOG performance status of 0-1. Notably, select patients with HIV positivity were permitted to participate.

In the trial, patients received intravenous retifanlimab at a dose of 500 mg once every 4 weeks as part of a 28-day treatment cycle for up to 2 years. The primary end point of the trial was ORR by ICR and RECIST v1.1 criteria, while key secondary end points comprised DOR, DCR, progression-free survival (PFS), overall survival (OS), and safety.

The median age of study participants was 64 years, 61% were female, and 77% were white. The majority of patients, or 59%, had an ECOG performance status of 1, 10% had known HIV positivity, and 42% had liver metastases. Seventy-three percent of patients received prior chemoradiation, 17% had prior radiation therapy, and 97% had previously received platinum-based treatment.

At a median follow-up of 7.1 months, the median PFS was 2.3 months (95% CI, 1.9-3.6), while the median OS was 10.1 months (95% CI, 7.9–not estimable).

Regarding safety, 58.5% of patients experienced a treatment-related toxicity; of these, 11.7% experienced one that was grade 3 or higher in severity. Approximately 4% reported an adverse effect (AE) that resulted in treatment discontinuation. Additionally, 25.5% of patients experienced an immune-related AE with retifanlimab, 6.4% of which were grade 3 or higher. About 2% of patients experienced an immune-related toxicity that resulted in discontinuation.

Notably, 4.3% of patients experienced infusion reactions with the treatment. Also, no loss of HIV control was reported among the 9 patients with HIV positivity.

Previously, retifanlimab was granted an orphan drug designation by the FDA for use in patients with anal cancer; it was also granted a priority review for that indication.

The agent is currently being examined in combination with carboplatin and paclitaxel in patients with inoperable locally recurrent or metastatic SCAC as part of the phase 3 POD1UM-303/InterAACT 2 (NCT04472429) trial.

References

1. Incyte announces acceptance and priority review of BLA for retifanlimab as a potential treatment for patients with squamous cell carcinoma of the anal canal (SCAC). News release. January 21, 2021. Accessed January 21, 2021. http://bit.ly/3p8beTB.
2. Rao S, Capdevila J, Gilbert D, et al. POD1UM-202: phase 2 study of retifanlimab in patients with squamous carcinoma of the anal canal who progressed following platinum-based chemotherapy. Ann Oncol. 2020;31(suppl 4):S1170-S1171. doi:10.1016/j.annonc.2020.08.2272