Safety of pembrolizumab as adjuvant therapy in a pooled analysis of phase 3 clinical trials of melanoma, non–small cell lung cancer, and renal cell carcinoma

Background: The safety profile of adjuvant pembrolizumab was evaluated in a pooled analysis of 4 phase 3 clinical trials. Methods: Patients had completely resected stage IIIA, IIIB, or IIIC melanoma per American Joint Committee on Cancer, 7th edition, criteria (AJCC-7; KEYNOTE-054); stage IIB or IIC melanoma per AJCC-8 (KEYNOTE-716); stage IB, II, or IIIA non–small cell lung cancer per AJCC-7 (PEARLS/KEYNOTE-091); or postnephrectomy/metastasectomy clear cell renal cell carcinoma at increased risk of recurrence (KEYNOTE-564). Patients received adjuvant pembrolizumab 200 mg (2 mg/kg up to 200 mg for pediatric patients) or placebo every 3 weeks for approximately 1 year. Adverse events (AEs) were summarized for patients who received ≥ 1 dose of treatment. Results: Data were pooled from 4125 patients treated with pembrolizumab (n = 2060) or placebo (n = 2065). Median (range) duration of treatment was 11.1 months (0.0–18.9) with pembrolizumab and 11.2 months (0.0–18.1) with placebo. Treatment-related AEs occurred in 78.6 % (1620/2060) of patients in the pembrolizumab group (grade 3–5, 16.3 % [336/2060]) and 58.7 % (1212/2065) in the placebo group (grade 3–5, 3.5 % [72/2065]). Immune-mediated AEs (e.g. adrenal insufficiency, hypophysitis, and thyroiditis) occurred in 36.2 % (746/2060) of patients in the pembrolizumab group (grade 3–5, 8.6 % [177/2060]) and 8.4 % (174/2065) in the placebo group (grade 3–5, 1.1 % [23/2065]). Of patients with ≥ 1 immune-mediated AE or infusion reaction, systemic corticosteroids were required for 35.2 % (268/761) and 20.2 % (39/193) of patients in the pembrolizumab and placebo groups, respectively. Conclusions: Adjuvant pembrolizumab demonstrated a manageable safety profile that was comparable to prior reports in advanced disease.