FDA Grants Priority Review to Balstilimab for Cervical Cancer After Chemotherapy

The anti–PD-1 antibody is being assessed as therapy for patients with recurrent or metastatic cervical cancer after positive results indicate improved responses with the monotherapy.

The FDA has granted priority review to a biologics license application (BLA) for balstilimab in the treatment of recurrent or metastatic cervical cancer with disease progression following chemotherapy, according to the agent’s developer, Agenus Inc.1

The BLA is supported by data from a phase 1/2 trial (NCT03495882) that were presented at the 2020 European Society for Medical Oncology (ESMO) Congress, showing single-agent balstilimab was active and well tolerated in the indicated patient population.2 Submission of the application to the FDA occurred in April 2020.3

“Women with recurrent or metastatic cervical cancer have a very poor prognosis and limited treatment options. Data suggest balstilimab may bring benefit to patients beyond what is available in this disease setting today,” Jennifer Buell, PhD, President and Chief Operating Officer at Agenus, said in a press release when the application was first sent to the agency. “This submission also marks a significant step in our transition to a commercial company and the advancement of our oncology combination strategy.”

The trial included 2 treatment arms of balstilimab alone (n = 161) or in combination with zalifrelimab (n = 155), with all patients having previously received platinum-based chemotherapy.

Treatment in both groups was well tolerated, with 30% in the balstilimab-alone arm and 35% in the balstilimab-plus-zalifrelimab arm experiencing immune-related adverse effects, of which 8.0% and 10.5% were grade 3 or greater, respectively.

In 160 response-evaluable patients in the balstilimab-alone group, 14% had an objective response to therapy, comprised of 2% complete responses and 12% partial responses. The duration of response was 15.4 months.

In 431 patients evaluable for response treated with balstilimab plus zalifrelimab, 22% had an objective response to therapy, 6% of which were complete responses and 16% partial responses. The duration of response was not reached.

Responses were more common in patients with PD-L1 expression with a combined positive score of 1% or higher and in those with squamous cell carcinoma histology. However, responses were seen in patients without PD-L1 expression and adenocarcinoma at lower rates.

“We expect that the potential approval of balstilimab will enable us to better pursue our oncology combination strategy for our own extensive pipeline of agents as well as for existing and future partner products,” Steven O’Day, MD, Chief Medical Officer at Agenus, said at the time of BLA submission. “In particular, we hope to use this potential approval to allow us to rapidly proceed with our anti–CTLA-4 combination strategy, which we believe can add significantly to the benefit provided by our anti–PD-1 agent. There are currently limited treatment options available for recurrent or metastatic cervical cancer patients, and our vision is to bring effective treatments to these patients.”

Previously, fast track designation was granted to balstilimab monotherapy as well as the combination with zalifrelimab to treat patients with advanced cervical cancer. The FDA has set a Prescription Drug User Fee Act (PDUFA) target action date of December 16, 2021.


1. Agenus Announces U.S. FDA Acceptance and Priority Review of Balstilimab Biologics License Application for the Treatment of Recurrent or Metastatic Cervical Cancer. News release. Agenus Inc. June 17, 2021. Accessed June 17, 2021. https://bit.ly/3zyEg4a

2. O’Malley DM, Oaknin A, Monk B, et al. Single-agent anti-PD-1 balstilimab or in combination with anti-CTLA-4 zalifrelimab for recurrent/metastatic (R/M) cervical cancer (CC): preliminary results of two independent phase II trials. Ann Oncol. 2020;31(suppl 4):S1164-S1165. doi:10.1016/j.annonc.2020.08.2264

3. Agenus Submits Balstilimab Biologics License Application to the U.S. FDA for Patients with Recurrent or Metastatic Cervical Cancer. News release. Agenus Inc. April 19, 2021. Accessed June 17, 2021. https://bit.ly/3wB5AwY

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