This study explored the safety and pathological response of neoadjuvant modified FOLFIRINOX (mFFX) combined with nivolumab in patients with borderline-resectable pancreatic cancer. The regimen was well tolerated and induced a high rate of pathological response. Multi-omics analyses further revealed dynamic changes in immune cells within the tumor microenvironment.
Literature Overview
The article titled 'Neoadjuvant modified FOLFIRINOX plus nivolumab in borderline-resectable pancreatic ductal adenocarcinoma: a pilot phase 1 trial,' published in Nature Communications, reviews and summarizes a single-arm, prospective phase Ib/II trial evaluating the safety, efficacy, and immune mechanisms of neoadjuvant modified FOLFIRINOX (mFFX) combined with nivolumab in patients with borderline-resectable pancreatic ductal adenocarcinoma (BRPC). A total of 28 patients were enrolled. The results demonstrated that the combination regimen was safe and feasible, with 79% of patients undergoing surgery successfully and no grade ≥3 immune-related adverse events observed. Pathological assessment revealed a 9% complete pathological response rate and a 72% partial response rate. Exploratory analyses showed significant increases in CD8+ T cells and plasma cells within the tumor microenvironment post-treatment. Moreover, lymphoid aggregates with high plasma cell-to-B cell ratios were associated with terminally exhausted T cells, suggesting a potential mechanism of immune dysregulation. This study provides new clinical evidence and mechanistic insights for immunotherapy in pancreatic cancer.Background Knowledge
Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a 5-year survival rate of less than 10%, primarily due to late-stage diagnosis and poor response to systemic therapies. The current standard of care for borderline-resectable PDAC involves neoadjuvant chemotherapy, typically using modified FOLFIRINOX (mFFX), which improves R0 resection rates and controls micrometastases. Although mFFX significantly extends survival, most patients eventually relapse. Immune checkpoint inhibitors (ICIs), such as PD-1/PD-L1 monoclonal antibodies, have achieved breakthroughs in various solid tumors but show limited efficacy in PDAC, benefiting only patients with high microsatellite instability (MSI-H). This is largely attributed to the immunologically 'cold' tumor microenvironment (TME) of PDAC, characterized by sparse T-cell infiltration, abundant immunosuppressive cells, and a dense stromal barrier. Thus, converting 'cold' tumors into 'hot' ones has become a research focus. Combining chemotherapy with ICIs is a potential strategy, as chemotherapy can release tumor antigens and modulate the immune microenvironment. However, previous attempts to combine ICIs with chemoradiation in locally advanced PDAC failed to significantly improve outcomes. This study innovatively investigates mFFX combined with the PD-1 inhibitor nivolumab in BRPC patients, aiming to leverage the neoadjuvant window to assess pathological responses and immune changes, thereby providing mechanistic insights and clinical data for PDAC immunotherapy. It fills a critical gap in combining mFFX with ICIs in resectable PDAC and holds significant translational implications.
Research Methods and Experiments
This was a single-center, single-arm, prospective phase Ib/II trial (NCT03970252) that enrolled 28 adult patients with histologically confirmed borderline-resectable PDAC. All patients received neoadjuvant mFFX (oxaliplatin, leucovorin, irinotecan, 5-FU) combined with nivolumab (480 mg IV every 28 days) for up to six cycles. The primary endpoints were safety (CTCAE v5.0) and pathological response rate (CAP scoring). Surgery was performed 4–6 weeks after the last treatment cycle. Pre-treatment biopsies and post-surgical resection specimens were collected for RNA-seq, immunohistochemistry (IHC), and spatial transcriptomic analysis. Immune cell deconvolution was performed using CIBERSORT-ABS. Plasma cells and lymphoid aggregates (LA) were quantified via IHC. Spatial transcriptomics was conducted using 10x Genomics Xenium. Historical mFFX monotherapy cohort data were used as a comparator to assess the incremental benefit of nivolumab.Key Conclusions and Perspectives
Research Significance and Prospects
This study provides the first clinical and translational data on combining mFFX with a PD-1 inhibitor in borderline-resectable PDAC, confirming the regimen’s favorable safety profile and high pathological response rate. Adding nivolumab to mFFX did not significantly increase toxicity and may enhance antitumor immune responses. However, spatial transcriptomic analyses revealed an unexpected finding: although CD8+ T cells and plasma cells increased, high-PBR LAs were associated with T-cell exhaustion, suggesting that PD-1 blockade may promote effector T cells while simultaneously disrupting lymphoid architecture, leading to non-functional immune responses. This challenges the simplified model of 'ICI activates T cells' and underscores the need for a more nuanced understanding of dynamic changes in the immune microenvironment. Future studies should explore strategies to preserve or remodel LA function—such as combining ICOS agonists or targeting regulatory B cells—to optimize immunotherapy efficacy. Additionally, identifying biomarkers predictive of response to this combination (e.g., MSI, TMB, specific immune gene signatures) will be critical.
Conclusion
This study systematically evaluated the safety and efficacy of neoadjuvant mFFX combined with nivolumab in patients with borderline-resectable pancreatic cancer. The regimen demonstrated good tolerability, a high surgical conversion rate, significant pathological responses, and a median overall survival of 38 months—superior to historical controls. Multi-omics analyses revealed a coordinated increase in CD8+ T cells and plasma cells within the tumor microenvironment post-treatment. However, a key finding was that lymphoid aggregates with high plasma cell-to-B cell ratios were associated with terminally exhausted T cells, suggesting that PD-1 blockade may induce suboptimal immune remodeling, leading to T-cell dysfunction. This discovery offers a novel mechanistic perspective on PDAC immunotherapy, indicating that simply enhancing T-cell infiltration is insufficient for durable responses; maintaining the integrity of lymphoid structures may be crucial. Future efforts should focus on developing combination strategies that target LA functionality to overcome immune resistance. This study lays an important foundation for neoadjuvant immunotherapy in PDAC, supports larger randomized controlled trials to confirm survival benefits, and promotes the development of precision immunotherapy strategies based on microenvironmental features.
