Phase 2 Study of Penpulimab Plus Rituximab, HD-MTX, and Cytarabine in Newly Diagnosed PCNSL

Overview

This phase 2 study evaluated the efficacy and safety of penpulimab combined with rituximab, high-dose methotrexate, and cytarabine (Pen-RMA) in patients with newly diagnosed primary central nervous system lymphoma (PCNSL). The regimen demonstrated promising response rates with manageable toxicity, suggesting a potential new therapeutic option for this challenging disease.

Background

Primary central nervous system lymphoma (PCNSL) is a rare, aggressive large B-cell lymphoma confined to the CNS with poor prognosis and median survival of 1-2 years. Standard induction therapy includes high-dose methotrexate combined with agents like cytarabine and rituximab, but relapse rates remain high. Immune checkpoint inhibitors targeting PD-1 have shown efficacy in relapsed/refractory PCNSL, but most are IgG4 antibodies associated with immune-related adverse events. Penpulimab, a humanized IgG1 anti-PD-1 antibody with reduced Fc-mediated toxicity, may improve outcomes when combined with chemotherapy in newly diagnosed PCNSL.

Data Highlights

Key Findings

• Penpulimab combined with rituximab, HD-MTX, and cytarabine (Pen-RMA) was feasible and well tolerated in newly diagnosed PCNSL patients.
• The regimen achieved high overall response rates, consistent with or exceeding historical controls of standard chemotherapy regimens.
• Penpulimab’s IgG1 Fc modification potentially reduced immune-related adverse events compared to traditional IgG4 PD-1 inhibitors.
• Patients older than 60 or with ECOG >2 received reduced cytarabine dosing to maintain safety without compromising efficacy.
• Follow-up is ongoing to assess progression-free and overall survival outcomes.

Clinical Implications

The Pen-RMA regimen incorporating penpulimab offers a promising frontline treatment option for PCNSL, potentially improving response rates while minimizing immune-related toxicity. Dose adjustments based on patient age and performance status allow for tailored therapy. Further follow-up will clarify long-term benefits and inform consolidation strategies.

Conclusion

Penpulimab combined with rituximab, high-dose methotrexate, and cytarabine demonstrates encouraging efficacy and safety in newly diagnosed PCNSL, warranting further investigation as a frontline therapeutic approach.

References

1. WHO-HAEM5 Classification, 2022 -- Large B-cell lymphomas of immune-privileged sites
2. IELSG 32 Study, 2016 -- MATRix regimen in PCNSL
3. Zhiyong Zeng et al., 2023 -- Sintilimab plus chemotherapy in PCNSL
4. Graber et al., 2019 -- Pembrolizumab in relapsed/refractory PCNSL
5. Nayak et al., 2017 -- Nivolumab in relapsed/refractory PCNSL
6. Penpulimab approval in China, 2021 -- Treatment of relapsed/refractory Hodgkin lymphoma