Advancing First-Line Treatment in Metastatic NSCLC: The Promise of Retifanlimab Combined with Chemotherapy

Introduction

Lung cancer remains the leading cause of cancer-related mortality worldwide, with non-small-cell lung cancer (NSCLC) constituting approximately 85% of cases. Despite advances in targeted therapies and immunotherapy, the prognosis for metastatic NSCLC continues to be poor, with median survival historically limited to less than one year. The advent of immune checkpoint inhibitors targeting PD-1 and PD-L1 has significantly improved outcomes, especially when combined with chemotherapy. Nevertheless, access and efficacy vary across populations, underscoring the need for ongoing clinical evaluation of new immunotherapeutic agents.

This article critically examines the findings from the phase 3 POD1UM-304 trial, which investigated the efficacy and safety of retifanlimab, a PD-1 inhibitor, in combination with standard platinum-based chemotherapy as first-line treatment for metastatic NSCLC.

Study Rationale and Design

The rationale for the POD1UM-304 study stems from the established benefit of PD-1 blockade with agents such as pembrolizumab and nivolumab in first-line NSCLC. Retifanlimab, a novel PD-1 inhibitor, was evaluated for its potential to enhance treatment efficacy in a broad, multiregional population, including both squamous and non-squamous histologies.

This randomized, double-blind, placebo-controlled phase 3 trial involved approximately 124 centers across 16 countries. Eligible participants were adults with stage IV NSCLC, both squamous and non-squamous, with ECOG performance status 0 or 1, and no prior systemic therapy. Patients were randomly assigned in a 2:1 ratio to receive either retifanlimab plus chemotherapy or placebo plus chemotherapy.

Standard chemotherapy protocols varied based on histology, with non-squamous patients receiving pemetrexed with either cisplatin or carboplatin, and squamous patients receiving paclitaxel or nab-paclitaxel combined with carboplatin. The treatment continued for up to 2 years or until disease progression or unacceptable toxicity.

Primary and secondary endpoints included overall survival (OS), progression-free survival (PFS), objective response rate, and safety profiles. Stratification factors encompassed PD-L1 expression, geography, and tumor histology.

Key Findings

Between September 2020 and March 2023, a total of 1388 patients were evaluated, with 583 randomized to the intervention arm (retifanlimab plus chemotherapy) and 192 to the control arm (placebo plus chemotherapy). The median age was 64 years, with a majority being male (80%), consistent with epidemiological data.

The primary outcome revealed a statistically significant improvement in OS for patients receiving retifanlimab. Median OS was 18.1 months in the retifanlimab group compared to 13.4 months in the placebo group (hazard ratio [HR] 0.75; 95% CI 0.60-0.93; p=0.0042). This suggests a meaningful survival benefit attributable to the addition of retifanlimab.

Secondary analyses demonstrated an improvement in progression-free survival and response rates, aligning with the primary survival benefit. Notably, the safety profile of retifanlimab was consistent with other PD-1 inhibitors, with higher incidences of adverse events (AEs), serious AEs, and treatment discontinuations. Grade 3 or higher AEs occurred in 61% of the retifanlimab group versus 54% in the control, with immune-related AEs being manageable.

Infections, including COVID-19-related deaths, occurred at similar rates between groups, underscoring that the addition of retifanlimab did not significantly increase fatal infectious complications.

Clinical Implications

The POD1UM-304 trial adds to the growing evidence that immunotherapy combined with chemotherapy enhances survival in first-line metastatic NSCLC, potentially expanding treatment options. Retifanlimab’s efficacy and safety profile warrant consideration for integration into clinical practice, especially in contexts where access to other PD-1/PD-L1 inhibitors may be limited.

However, further research is required to determine long-term outcomes, optimal patient selection based on biomarkers like PD-L1, and comparisons with existing standard-of-care agents.

Limitations and Future Directions

While promising, the study’s limitations include the predominantly male population and regional heterogeneity that may influence generalizability. Additional studies are needed to evaluate retifanlimab in combination with other therapeutic modalities and in distinct patient populations.

Looking ahead, incorporation of biomarker-driven strategies and real-world evidence will facilitate personalized treatment approaches, ensuring maximal benefit for patients with metastatic NSCLC.

Conclusion

The POD1UM-304 trial demonstrates that adding retifanlimab to platinum-based chemotherapy improves overall survival for first-line treatment of metastatic NSCLC. Its safety profile aligns with existing PD-1 inhibitors, offering a potentially new therapeutic option that could complement current standards and improve patient outcomes.

Funding for this study was provided by Incyte, with clinical trial registration under NCT04205812. Continued research will determine retifanlimab’s precise role within the evolving landscape of NSCLC management.