Comprehensive genomic profiling of penile squamous cell carcinoma and the impact of human papillomavirus status on immune-checkpoint inhibitor-related biomarkers

BACKGROUND

Advanced penile squamous cell carcinoma (pSCC) is a rare and aggressive malignancy with limited success of immune-checkpoint inhibitors (ICIs). Approximately half of pSCC cases are associated with human papillomavirus (HPV) infection.

METHODS

Evaluation was done retrospectively of the landscape of somatic alterations and ICI-related biomarkers in pSCC by using the Caris Life Sciences data set with the aim to establish signatures for HPV-dependent oncogenesis. The pSCC tumors were analyzed by using next-generation sequencing (NGS) of DNA and RNA. Programmed death ligand 1 (PD-L1) expression was evaluated by immunohistochemistry (IHC). Microsatellite instability (MSI) was tested by fragment analysis, IHC (SP142; ≥1%), and NGS. Tumor mutational burden (TMB)-high was defined as ≥10 mutations/Mb. HPV16/18 status was determined by using whole-exome sequencing (WES) when available. Significance was adjusted for multiple comparisons (q value < .05).

RESULTS

NGS of the overall cohort (N = 108) revealed TP53 (46%), CDKN2A (26%), and PIK3CA (25%) to be the most common mutations. Overall, 51% of tumors were PD-L1+, 10.7% had high TMB, and 1.1% had mismatch repair-deficient (dMMR)/MSI-high status. Twenty-nine patients had their HPV status made available by WES (HPV16/18+, n = 13; HPV16/18-, n = 16). KMT2C mutations (33% vs. 0%) and FGF3 amplifications (30.8% vs. 0%) were specific to HPV16/18+ tumors, whereas CDKN2A mutations (0% vs. 37.5%) were exclusive to HPV16/18- tumors. TMB-high was exclusively found in the HPV16/18+ group (30.8%). The two groups had comparable PD-L1 and dMMR/MSI-H status.

CONCLUSIONS

In a large and comprehensive NGS-based evaluation of somatic alterations in pSCC, HPV16/18+ versus HPV16/18- pSCCs were molecularly distinct tumors. Our finding that TMB-high is exclusive to HPV16/18+ tumors requires confirmation in larger data sets.

PLAIN LANGUAGE SUMMARY

Penile squamous cell carcinoma (pSCC) is a rare and aggressive malignancy in the advanced setting, with poor prognosis and little success with immune-checkpoint inhibitors (ICIs) in an unselected patient approach. Human papillomavirus (HPV) infection is a known risk factor for pSCC; its impact on genomic tumor profiling is less defined. Using next-generation sequencing, we explored the genetic landscape and ICI-related biomarkers of pSCC and HPV-driven oncogenic molecular signatures. Our results indicate that HPV-positive and HPV-negative pSCCs are molecularly distinct tumors. Increased tumor mutational burden is associated with HPV-positive tumors, and could serve as a biomarker for predicting therapeutic response to ICI-based therapies. Our results support the growing literature indicating that HPV status in pSCC can be used to guide patient stratification in ICI-based clinical trials.

A Prospective Study of Chemoradiotherapy as Primary Treatment in Patients With Locoregionally Advanced Penile Carcinoma

PURPOSE

Neoadjuvant chemotherapy followed by surgery for locoregionally advanced penile carcinoma (LAPSCC) is associated with severe toxicity and a 1-year survival probability of ∼50%. We aimed to evaluate the safety and efficacy of chemoradiotherapy (CRT) as the primary treatment for LAPSCC and the association of high-risk human papillomavirus (hrHPV) with the outcome.

METHODS AND MATERIALS

This was a prospective, single-center, single-arm study of CRT in LAPSCC, defined as a large/inoperable primary tumor, large palpable nodes, suspicion of extranodal extension or pelvic nodal involvement, and no distant metastases. CRT consisted of 49.5 Gy (33 × 1.5 Gy) on affected inguinal and pelvic areas combined with intravenous mitomycin C on day 1 and capecitabine on radiation days. Primary tumors and positron emission tomography/computed tomography-positive deposits received a boost of 59.4 Gy (33 × 1.8 Gy). The response was evaluated by 18F-fluorodeoxyglucose positron emission tomography/computed tomography. If feasible, patients with residual/recurrent disease underwent salvage surgery. The primary endpoint was 1-year progression-free survival (PFS), reached when 1-year PFS was ≥50%. Other endpoints were 2-year PFS, overall survival, and toxicity rates. Kaplan-Meier survival curves were compared using the log-rank test.

RESULTS

Thirty-three patients were included: 29 (88%) with stage IV disease (T4 any-N M0 and/or any-T N3 M0) and 8 (24%) with hrHPV-positive disease. Median follow-up was 41 months. Thirty-two completed CRT. Eleven (33%) experienced ≥1 grade 3 treatment-related adverse event. There were no grade 4 or 5 treatment-related events. Twenty-four patients (73%) responded, including 13 (39%) complete responses. Nine patients (27%) underwent salvage surgery, and an additional 8 patients underwent later surgery (together 52%). One- and 2-year PFS were 34% and 31%, respectively. One- and 2-year overall survival were 73% and 46%, respectively. No significant difference between patients with hrHPV-positive and -negative tumors was observed.

CONCLUSIONS

CRT is a viable treatment option for LAPSCC with acceptable toxicity. CRT can result in an enduring response. If patients have residual tumor, salvage surgery is feasible. HrHPV status was not associated with outcomes.

Therapeutic Approaches to Penile Cancer: Standards of Care and Recent Developments

Penile cancer is a rare malignancy, most commonly diagnosed in older men, associated with poor outcomes, dramatic decline in quality of life and sexual function. Squamous cell carcinoma is the most common histopathology of penile cancer, accounting for 95% of all cases. Localized, early-stage penile cancer can be effectively managed through penile-sparing techniques in many cases, though advanced stages of penile cancer carry a poor prognosis. Current innovative treatments are exploring the role of targeted therapy, HPV-directed therapy, immune checkpoint inhibitors and adoptive T-cell therapies in treatment and prevention of relapse of penile cancer. Clinical trials are investigating the potential of targeted therapies and immune checkpoint inhibitors in advanced penile cancer. This review examines the current management of penile cancer and highlights future directions in research and treatment.

An update on treatment of penile cancer

Penile cancer is a rare malignancy, particularly in industrialized nations. In the United States, rates are approximately less than 1 per 100,000 men per year with just over 2000 new cases per year. However, there is significantly increased prevalence in developing nations, with limited treatment expertise and reduced access to care, further driving an unmet clinical need. The most noteworthy risk factor for penile cancer is the association with human papillomavirus infection, which may be present in up to 50% of all penile carcinomas. In addition to local primary tumor approaches, multimodality treatment strategies are vital to patients with clinical regional nodal disease, locally advanced disease. Presence and degree of lymph node involvement remains the most important prognostic factor and patients may benefit from multiple treatment strategies. Interim analysis data from the first randomized clinical trial is expected to yield results in mid/late 2024–early 2025. These treatment approaches include neoadjuvant chemotherapy, adjuvant therapy, including chemotherapy and radiation. Systemic therapy for distant recurrent or metastatic disease is primarily a platinum-based chemotherapy, however with poor overall response. As poor outcomes remain high, particularly in indigent populations, there remains an unmet need for these patients, particularly for high level randomized trials and novel therapeutics. In this review, we will highlight treatment updates for penile cancer. In addition to standard of care, we will review novel lines of therapies including immunotherapies and targeted therapies as well as sequencing approaches.