Add-On Cemiplimab Shows Promise as First-Line Treatment for Penile Cancer

SAN FRANCISCO — A combination of cemiplimab (Libtayo) and standard-of-care chemotherapy appeared to be effective in patients with locally advanced or metastatic penile cancer, according to findings from a phase II study.

Results from the EPIC-A trial showed that treatment with the regimen after 12 weeks achieved a clinical benefit rate (CBR) of 62.1% among 29 treatment-naïve patients with the rare cancer (meeting the study’s primary endpoint), and included partial responses (PR) in 15 patients for an objective response rate (ORR) of 51.7%, “which, to my knowledge, remains one of the highest reported in the literature,” said Amit Bahl, MBBS, MD, of the Bristol Haematology and Oncology Center in Bristol, England, in a presentation at the American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium.

In addition to the 15 PRs, three patients had stable disease, accounting for the high CBR. At 21 weeks, the CBR was 48.3%, including one complete response, 12 PRs, and one stable disease, with an ORR of 44.8%.

Median progression-free survival (PFS) was 6.2 months and overall survival is currently estimated to be 15.5 months, which is “indeed very encouraging in this group of patients,” Bahl observed.

Duration of response varied, with some progressing early, Bahl said, “with the challenge remaining, how do we rescue these patients?”

Regarding adverse events (AEs), Bahl said the safety profile was in keeping with reported data on cisplatin-based chemotherapy and the PD-1 inhibitor. There were 2 grade 5 AEs (none related to cemiplimab; one related to chemotherapy) while seven patients discontinued treatment (four related to cemiplimab).

“The EPIC-A trial provides important data regarding the efficacy and safety of cemiplimab in combination with platinum-based chemotherapy as a treatment for locally advanced or metastatic penile cancer,” Bahl said. “These data support combination cisplatin-based chemotherapy plus cemiplimab as a first-line treatment option to potentially improve outcomes in this rare cancer.”

Indeed, penile cancer is rare, particularly in the U.S. and Europe, although it is diagnosed more frequently in some areas of Africa, Asia, and South America. According to the American Cancer Society, it is diagnosed in fewer than one man in 100,000 each year, and accounts for fewer than 1% of cancers in men in the U.S. The most common type of penile cancer is squamous cell penile cancer, accounting for 95% of cases.

Bahl said treatment for patients with locally advanced or metastatic penile cancer “has remained static for decades and prognosis remains poor. PD-L1 is upregulated in 40%-60% of cases, making a case for immunotherapy, and we’ve seen some recent data regarding that.”

He noted that cemiplimab is FDA approved for locally advanced or metastatic cutaneous squamous cell carcinoma.

EPIC-A included 29 patients who had not received previous chemotherapy or treatment of penile cancer. They had histologically proven squamous cell carcinoma of the penis or penile urethra; an ECOG performance status of 0-2; and adequate renal, liver, and bone marrow function.

Patients had a median age of 61. A little less than a quarter (24%) had locally advanced disease, and a little more than three-fourths (76%) had metastatic disease. They received IV cemiplimab 350 mg every 3 weeks plus cisplatin-based chemotherapy for 4 cycles, followed by cemiplimab alone every 3 weeks up to a total of 34 cycles.

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