Executive Highlights
The POD1UM-304 phase 3 trial marks a significant milestone in the management of metastatic non-small-cell lung cancer (NSCLC). The study successfully met its primary endpoint, demonstrating that the addition of retifanlimab, a PD-1 inhibitor, to standard-of-care platinum-based chemotherapy significantly prolongs overall survival (OS) compared to chemotherapy alone.
Key findings include a median OS of 18.1 months in the retifanlimab-chemotherapy group versus 13.4 months in the placebo-chemotherapy group (Hazard Ratio [HR] 0.75; p=0.0042).
The safety profile observed was consistent with the established class effects of PD-1 inhibitors, with no new safety signals identified. This study reinforces the role of combined chemo-immunotherapy as the standard of care for first-line treatment of advanced NSCLC regardless of histological subtype.
The Evolving Landscape of First-Line NSCLC Therapy
Non-small-cell lung cancer remains the leading cause of cancer-related mortality worldwide. For patients presenting with metastatic or stage IV disease, the therapeutic paradigm has shifted dramatically over the last decade from cytotoxic chemotherapy alone to the integration of immune checkpoint inhibitors (ICIs). Specifically, the combination of programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) inhibitors with platinum-based chemotherapy has established itself as a cornerstone of first-line treatment.
Despite the clinical success of several approved ICIs, global access to these life-extending therapies remains uneven due to economic and logistical barriers. There is a persistent clinical need for additional high-quality, evidence-based immunotherapy options that can be integrated into standard treatment protocols. Retifanlimab, a humanized IgG4 monoclonal antibody designed to block the interaction between PD-1 and its ligands (PD-L1 and PD-L2), represents a critical addition to the oncological arsenal. The POD1UM-304 trial was designed to rigorously evaluate the efficacy and safety of retifanlimab in a multiregional, diverse patient population.
POD1UM-304: Study Design and Methodology
Patient Population and Randomization
The POD1UM-304 study (NCT04205812) was a multiregional, placebo-controlled, double-blind, randomized phase 3 trial conducted across 124 hospitals and clinical centers in 16 countries. The study enrolled 583 adult patients with histologically confirmed squamous or non-squamous stage IV NSCLC. Eligible participants were required to have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 and no prior systemic therapy for metastatic disease.
Patients were randomized in a 2:1 ratio to receive either retifanlimab plus chemotherapy (n=391) or placebo plus chemotherapy (n=192). Randomization was stratified by PD-L1 expression (Tumor Proportion Score [TPS] <1% vs 1–49% vs ≥50%), geographical region, and predominant tumor histology (squamous vs non-squamous).
Intervention Regimen
Patients in the experimental arm received intravenous retifanlimab 375 mg every 21 days for up to 35 cycles (approximately 2 years). The chemotherapy component was tailored to tumor histology:
Non-squamous NSCLC: Pemetrexed (500 mg/m2) plus either cisplatin (75 mg/m2) or carboplatin (AUC 5) for four cycles, followed by pemetrexed maintenance.\n2. Squamous NSCLC: Carboplatin (AUC 6) plus either paclitaxel (200 mg/m2) every 21 days or nab-paclitaxel (100 mg/m2) on days 1, 8, and 15 for four cycles.
Treatment continued until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoint of the study was overall survival (OS) in the full analysis set.
Key Findings: Survival and Efficacy
Overall Survival Advantage
The results of the POD1UM-304 trial provide robust evidence for the efficacy of retifanlimab. In the full analysis set, the median overall survival was significantly longer in the retifanlimab plus chemotherapy group compared to the placebo plus chemotherapy group. Specifically, patients receiving retifanlimab reached a median OS of 18.1 months (95% CI 16.2–21.0), while those in the control group reached 13.4 months (95% CI 11.0–16.7). This represents a 25% reduction in the risk of death (Hazard Ratio 0.75; 95% CI 0.60–0.93; p=0.0042).
Subgroup Consistency
The survival benefit was observed across various pre-specified subgroups. Notably, the benefit of retifanlimab was consistent regardless of the histological subtype—both squamous and non-squamous patients derived a clinical advantage. Furthermore, the efficacy was maintained across different levels of PD-L1 expression, including patients with TPS <1%, suggesting that retifanlimab combined with chemotherapy remains a viable option for patients who might otherwise have a lower likelihood of responding to ICI monotherapy.
Safety and Tolerability Profile
Safety was evaluated in all randomized patients who received at least one dose of the study drug. The addition of retifanlimab to platinum-based chemotherapy increased the incidence of certain adverse events, but the overall safety profile was manageable and consistent with previous reports for other PD-1/L1 inhibitors.
Treatment-emergent adverse events (TEAEs) of grade 3 or higher were reported in 61% of the retifanlimab group compared to 54% in the placebo group. Serious TEAEs occurred in 41% of the retifanlimab group versus 30% of the placebo group. Dose delays due to TEAEs were more frequent in the retifanlimab arm (43% vs 35%), and the rate of treatment discontinuation due to adverse events was 8% for retifanlimab versus 5% for placebo.
Given the timing of the study during the global pandemic, the trial also monitored COVID-19-related events. Fatal COVID-19-related TEAEs were rare and balanced between the groups (1% in the retifanlimab arm vs 3% in the placebo arm), suggesting that the immunotherapy did not disproportionately exacerbate the risks associated with the virus in this vulnerable population.
Clinical Interpretation and Expert Commentary
Mechanistic Insights and Global Access
The success of the POD1UM-304 trial validates the biological plausibility of retifanlimab as a potent PD-1 antagonist. By preventing the PD-1 receptor from engaging its ligands, retifanlimab restores the ability of T-cells to recognize and eliminate tumor cells. When combined with chemotherapy, which can induce immunogenic cell death and increase tumor antigen presentation, the synergy between the two modalities provides a powerful dual-action approach to controlling metastatic disease.
From a health policy and clinical practice perspective, the availability of retifanlimab is a positive development. While the field already has several established ICIs, having multiple high-quality options ensures a more resilient supply chain and potentially improves access for patients in various healthcare systems. The multiregional nature of POD1UM-304, which included participants from 16 different countries, enhances the generalizability of these findings to a broad global population.
Study Limitations
While the results are statistically significant and clinically meaningful, certain limitations should be noted. The study did not include a head-to-head comparison with other established PD-1 inhibitors like pembrolizumab or nivolumab. Furthermore, while the OS benefit is clear, long-term follow-up will be necessary to determine the 5-year survival rates and the durability of response in different molecular subgroups, such as those with rare mutations.
Conclusion: A New Standardized Option for Advanced NSCLC
In summary, the POD1UM-304 trial demonstrates that retifanlimab in combination with platinum-based chemotherapy significantly improves overall survival in patients with first-line metastatic NSCLC. With a 4.7-month improvement in median OS and a safety profile that aligns with established standards, retifanlimab represents a validated and effective treatment option. These findings support the inclusion of retifanlimab-chemotherapy combinations in clinical guidelines for the management of both squamous and non-squamous advanced NSCLC, offering renewed hope for improved outcomes in this challenging disease setting.
Funding and ClinicalTrials.gov
This study was funded by Incyte. The trial is registered with ClinicalTrials.gov, number NCT04205812.
References
1. Lu S, et al. Retifanlimab versus placebo in combination with platinum-based chemotherapy in patients with first-line non-squamous or squamous metastatic non-small-cell lung cancer (POD1UM-304): a phase 3, multiregional, placebo-controlled, double-blind, randomised study. Lancet Respir Med. 2025;13(12):1096-1107.
2. Gandhi L, et al. Pembrolizumab plus Chemotherapy in Metastatic Non-Small-Cell Lung Cancer. N Engl J Med. 2018;378:2078-2092.
3. Paz-Ares L, et al. Pembrolizumab plus Chemotherapy for Squamous Non-Small-Cell Lung Cancer. N Engl J Med. 2018;379:2040-2051.
4. Sezer A, et al. Cemiplimab plus chemotherapy versus chemotherapy alone in non-small-cell lung cancer: a randomised, multicentre, double-blind, phase 3 trial. Lancet Oncol. 2022;23(8):1023-1033.