In the Dutch single-institution phase II PERICLES trial reported in the Journal of Clinical Oncology, de Vries et al found atezolizumab produced activity in patients with advanced squamous cell carcinoma of the penis.
Study Details
In the study, 32 patients enrolled at The Netherlands Cancer Institute between October 2018 and August 2021 received atezolizumab at 1,200 mg once every 3 weeks for up to 1 year; among these, 20 patients who were expected to benefit from radiotherapy for locoregional control also received a full course of normofractionated intensity-modulated radiotherapy concurrent with atezolizumab.
The primary endpoint was 1-year progression-free survival in the total population. The endpoint was reached if 1-year progression-free survival was ≥ 15%.
Key Findings
Median follow-up was 29.1 months (interquartile range [IQR] = 18.1–33.5 months). Progression-free survival at 1 year in the entire population was 12.5% (95% confidence interval [CI] = 5.0%–31.3%), with the endpoint not being met. Progression-free survival at 1 year was 10% (90% CI = 3.3%–30.1%) among patients receiving atezolizumab plus radiotherapy and 16.7% (90% CI = 5.8%–48.2%) among those receiving atezolizumab alone.
Improved progression-free survival was observed among 14 patients with high-risk human papillomavirus (hrHPV)–positive vs 18 with hrHPV-negative tumors (median = 5.3 vs 2.6 months, P = .003) and among 14 patients with high (above median) vs 14 with low infiltration of intratumoral CD3-positive/CD8-positive T cells (median = 5.1 vs 2.6 months, P = .037). No significant difference in progression-free survival was observed according to PD-L1 status.
Median overall survival in the total population was 11.3 months (95% CI = 5.5–18.7 months). Among 30 patients evaluable for response, objective response was observed in 5 patients (16.7% (95% CI = 6%–35%), including complete response in 2 (6.7%); median duration of response was not reached. Objective response rates were 16.7% among both patients receiving atezolizumab plus radiotherapy and those receiving atezolizumab alone, with median response durations of 6.7 months and not reached.
Grade 3 or 4 adverse events related to atezolizumab occurred in 3 (9.4%) of 32 patients and those related to radiotherapy occurred in 13 (65%) of 20.
The investigators concluded, “Although the primary endpoint of 1-year progression-free survival was not met, durable antitumor activity to atezolizumab was observed in a subset of patients. Biomarkers, such as hrHPV and intratumoral CD3+ CD8+ T-cell infiltration, may help to better select responders.”
Michiel S. van der Heijden, PhD, of The Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by Hoffmann-La Roche, the Rare Disease Fund, and Dutch Cancer Society. For full disclosures of the study authors, visit ascopubs.org.
