Who Benefits and How Long to Treat? Practical Considerations in Immunotherapy Use

This segment addresses 2 key clinical questions following the adoption of chemo-immunotherapy in advanced SCAC: which patients benefit most and how long treatment should be continued. Based on the POD1UM-303 data, there are currently no clinical, phenotypic, or biomarker-defined subgroups that clearly identify “super responders.” Exploratory analyses, including forest plots for PFS, demonstrated consistent benefit across patient populations, regardless of disease extent, metastatic pattern, or organ involvement, including liver metastases. As a result, the current approach is to offer carboplatin, paclitaxel, and retifanlimab broadly to eligible patients, with exclusions based primarily on contraindications to immunotherapy rather than predictive factors.

The discussion also highlights ongoing research efforts to identify more precise tools for patient selection and response monitoring. Investigational approaches include circulating tumor DNA and HPV-related viral markers, although these strategies are not yet part of routine clinical practice.

Treatment duration remains an evolving area. In practice, chemotherapy is typically administered for approximately 6 months, after which patients continue on maintenance immunotherapy. Although the trial specified a defined treatment duration, many clinicians individualize therapy based on response and tolerability. For patients with ongoing measurable but stable disease, immunotherapy is often continued until disease progression. In cases of complete response and sustained disease control for approximately 2 years, treatment discontinuation may be considered.

Experts also describe the importance of safety monitoring. Although generally well-tolerated, immune checkpoint inhibitors carry risks of immune-related adverse events, including dermatologic, endocrine, hepatic, and gastrointestinal toxicities, leading to discontinuation in a minority of patients. Careful monitoring for both chemotherapy-related and immune-mediated toxicities is essential to optimize outcomes in routine practice.