Adjuvant pembrolizumab data published in NEJM as FDA weighs kidney cancer approval

Toni K. Choueiri, MD

Data from the phase 3 KEYNOTE-564 trial supporting a potential FDA approval of adjuvant pembrolizumab (Keytruda) in renal cell carcinoma (RCC) have been published in the New England Journal of Medicine.¹

The application for pembrolizumab the FDA is considering is specifically for the adjuvant treatment of patients with RCC at intermediate-high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions. The regulatory agency is scheduled to decide on the application on or before December 10, 2021.

The phase 3 KEYNOTE-564 trial showed that at a median follow-up of approximately 24 months, the median disease-free survival (DFS) was not reached with either adjuvant pembrolizumab (n = 496) or placebo (n = 498) as per investigator assessment; however, the hazard ratio for DFS showed that pembrolizumab induced a 32% reduction in the risk of disease recurrence or death compared with placebo (HR, 0.68; 2-sided P = .002).

The standard-of-care treatment for patients with locoregional RCC is surgery; however, nearly half of patients eventually experience disease recurrence. Currently, there is no standard adjuvant systemic therapy that is supported by high levels of evidence worldwide.

In the double-blind, multicenter, phase 3 KEYNOTE-564 study (NCT03142334), investigators explored pembrolizumab vs placebo following nephrectomy in patients with clear cell RCC. Specifically, patients’ disease had to meet criteria that categorized them as high risk for recurrence, which included: pT2, grade 4 or sarcomatoid, N0, M0; pT3, any grade, N0, M0; pT4, any grade, N0, M0; any pT, any grade, N-positive, M0; or M1 with no evidence of disease after surgery.

Patients must have undergone nephrectomy within 12 weeks prior to randomization, could not have previously received systemic treatment, had to have an ECOG performance status of 0 or 1, and a tissue sample must have been obtainable for PD-L1 assessment.

All patients were randomized 1:1 to receive pembrolizumab at 200 mg every 3 weeks or placebo every 3 weeks, both for approximately 1 year. The primary end point of the trial was investigator-assessed DFS; secondary end points were overall survival (OS) and safety.

At 1 year, the estimated DFS rates were 85.7% and 76.2% with pembrolizumab and placebo, respectively. At 2 years, these rates were 77.3% and 68.1%, respectively.

The OS data are immature, with 3.6% (n = 18) and 6.6% (n = 33) events occurring in the pembrolizumab and placebo arms, respectively. The median OS has not yet been reached in either arm but is trending favorably toward the PD-1 inhibitor (HR, 0.54; P = .0164); however, this has not cross the prespecified boundary of statistical significance.

The estimated 2-year OS rates are 96.6% for pembrolizumab and 93.5% for placebo. Additional follow-up is planned for OS.

The data cutoff date was December 14, 2020. Regarding safety, all-grade adverse effects (AEs) with pembrolizumab occurred in 96.3% of patients and in 91.1% of those on placebo; grade 3 to 5 AEs occurred in 32.4% and 17.7%, respectively. AEs led to death in 2 patients on pembrolizumab and in 1 patient on placebo.

Treatment-related AEs (TRAEs) occurred in 79.1% and 53.4% of pembrolizumab- and placebo-treated patients, respectively. A total 18.9% of patients on pembrolizumab had a grade 3 to 5 TRAE vs 1.2% of those on placebo. Notably, no TRAEs led to death in either arm. Overall, the safety profile was consistent with prior data on pembrolizumab.

Watch video of lead KEYNOTE-564 author Dr. Toni K. Choueiri discussing the trial.

Reference

1. Choueiri TK, Tomczak P, Park SH, et al. Adjuvant pembrolizumab after nephrectomy in renal-cell carcinoma. N Engl J Med. 2021;385(8):683-694. doi: 10.1056/NEJMoa2106391