Optimizing Outcomes After PD-1 Inhibitor Failure

Managing advanced cutaneous squamous cell carcinoma (cSCC) presents significant hurdles when patients fail first-line immunotherapy. Standard treatments like cemiplimab have revolutionized care, yet many patients eventually experience disease progression. Consequently, clinicians must evaluate effective PD1-refractory cSCC treatments to improve survival. Recent institutional reports highlight the roles of CTLA-4 inhibitors, EGFR inhibitors, and surgical intervention in this salvage setting.

Researchers recently analyzed the outcomes of patients treated at high-volume academic centers. Specifically, they focused on those who progressed after receiving programmed cell death protein 1 (PD-1) monoclonal inhibitors. The study evaluated whether additional immunotherapy or targeted agents could provide durable responses when the primary treatment failed.

Exploring Options for PD1-refractory cSCC Treatments

Ipilimumab, a CTLA-4 inhibitor, emerged as a promising option for patients with refractory disease. In a retrospective case series, this agent demonstrated a 33% response rate. Remarkably, some patients achieved durable complete responses, which translated into significant survival benefits. This suggests that switching the immune checkpoint target may overcome primary resistance to PD-1 blockade in selected individuals.

Furthermore, cetuximab, an epidermal growth factor receptor (EGFR) inhibitor, provides another therapeutic avenue. Clinicians observed that cetuximab induced responses even in patients who never responded to initial cemiplimab therapy. However, the duration of these responses remains a concern. Most patients treated with cetuximab died within one to two years unless they underwent additional interventions. This highlights the need for a more comprehensive approach to management.

The Role of Salvage Surgery

While systemic therapies offer hope, surgery remains a cornerstone of the salvage strategy. Most surviving patients in the reported cohorts required salvage surgery after achieving a partial response to second-line agents. Therefore, multidisciplinary teams should prioritize surgical evaluation whenever local control becomes feasible. Combining systemic response with physical tumor removal appears to offer the best chance for long-term survival in this high-risk population.

Additionally, clinicians should consider clinical trials as a preferred route for these patients. Since no single standard second-line therapy exists, off-label use of available drugs requires careful monitoring. Understanding the sequencing of these agents is vital for improving the poor prognosis typically associated with immunotherapy failure.

FAQs

Which second-line agent showed the best durable response in PD1-refractory cSCC?

In recent clinical reports, ipilimumab demonstrated a 33% response rate, including several durable complete responses. It appears more effective than cetuximab at achieving long-term disease control in the absence of surgery.

Can cetuximab be used if a patient never responded to cemiplimab?

Yes, cetuximab has shown the ability to induce responses in patients regardless of their prior response status to PD-1 inhibitors like cemiplimab. However, the overall survival remains limited unless combined with other treatments.

What is the prognosis for patients who fail PD-1 inhibitors?

The prognosis for patients with metastatic or locally advanced cSCC who fail PD-1 therapy is generally poor. Survival often depends on the ability to perform salvage surgery following a response to second-line systemic treatments.

Disclaimer: This content is for informational and educational purposes only. It does not constitute medical advice or establish a doctor-patient relationship. Always seek the advice of a qualified healthcare provider for any medical condition. Refer to the latest local and national guidelines for clinical practice.

References

AlSharif H et al. Second-line treatments for patients with PD1-refractory cutaneous squamous cell carcinomas: a brief report. Oncologist. 2026 Feb 15. doi: undefined. PMID: 41693025.

Kasper ME et al. Cetuximab for Immunotherapy-Refractory/Ineligible Cutaneous Squamous Cell Carcinoma. Cancers (Basel). 2023 Jun 14;15(12):3180. doi: 10.3390/cancers15123180.

Zandberg DP et al. Avelumab Plus Cetuximab Versus Avelumab Monotherapy in Advanced Cutaneous Squamous Cell Carcinoma: The Alliance A091802 Phase II Randomized Trial. J Clin Oncol. 2025 Jun 1. doi: 10.1200/JCO.24.00500.