FOLFIRINOX Induction Therapy for Stage 3 Pancreatic Adenocarcinoma

ABSTRACT Background. Reports show that FOLFIRINOX therapy for pancreatic ductal adenocarcinoma (PDAC) results in objective response rates two to threefold higher than those of other regimens. This study aimed to assess response and resection rates for locally unresectable (stage 3) patients initially treated with induction FOLFIRINOX. Methods. The institutional cancer database was queried for patients treated with induction FOLFIRINOX therapy between 2010 and 2013. Patients were included in the study if they were treated at the authors' institution for stage 3 PDAC (locally unresectable) that had been adjudicated at a weekly multidisciplinary tumor board. Results. The study identified 101 patients. The median age was 64 years (range 37-81 years), and the median followup period was 12 months (range 3-37 months). The patients received a median of six cycles (range 1-20 cycles) of induction FOLFIRINOX. No grade 4 or 5 toxicity was recorded. At the initial restaging (median of 3 months after diagnosis), 23 patients (23 %) had developed distant metastases, 15 patients (15 %) had undergone resection, and 63 patients (63 %) had proceeded to chemoradiation. In the group of 63 patients who had proceeded to chemoradiation (median of 9 months after diagnosis), an additional 16 patients (16 %) had undergone resection, and 5 patients (5 %) had developed metastases. A partial radiographic response was observed in 29 % of all the patients, which was associated with ability to perform resection (p = 0.004). The median overall survival time was 11 months for the group that progressed with FOLFIRINOX and 26 months for the group that did not progress. Conclusion. Nearly one third of the patients who had been initially identified as having stage 3 pancreatic carcinoma and had been treated with FOLFIRINOX responded radiographically and underwent tumor resection. A recently completed phase 3 randomized trial for stage 4 pancreatic ductal adenocarcinoma (PDAC) identified FOL-FIRINOX as superior to gemcitabine in terms of radiographic response together with improved progression-free and overall survival. 1 Patients who received FOLFIRINOX experienced a 32 % objective response rate (ORR) compared with 9 % in the gemcitabine arm of the study, which correlated with survival benefit (median overall and progression-free survival, 11 and 6 versus 7 and 3 months, respectively). Retrospective studies of patients with both borderline resectable PDAC (stages 1 and 2) and stage 3 disease (locally unresectable) also have suggested an ORR of approximately 30 % with FOLFIRINOX. 2,3 The reported ORR from non-FOLFIRINOX regimens has generally been in the range of 10 %, including the results of a phase

Identification of unique neoantigen qualities in long-term survivors of pancreatic cancer

Pancreatic ductal adenocarcinoma is a lethal cancer with fewer than 7% of patients surviving past 5 years. T-cell immunity has been linked to the exceptional outcome of the few long-term survivors, yet the relevant antigens remain unknown. Here we use genetic, immunohistochemical and transcriptional immunoprofiling, computational biophysics, and functional assays to identify T-cell antigens in long-term survivors of pancreatic cancer. Using whole-exome sequencing and in silico neoantigen prediction, we found that tumours with both the highest neoantigen number and the most abundant CD8(+) T-cell infiltrates, but neither alone, stratified patients with the longest survival. Investigating the specific neoantigen qualities promoting T-cell activation in long-term survivors, we discovered that these individuals were enriched in neoantigen qualities defined by a fitness model, and neoantigens in the tumour antigen MUC16 (also known as CA125). A neoantigen quality fitness model conferring greater immunogenicity to neoantigens with differential presentation and homology to infectious disease-derived peptides identified long-term survivors in two independent datasets, whereas a neoantigen quantity model ascribing greater immunogenicity to increasing neoantigen number alone did not. We detected intratumoural and lasting circulating T-cell reactivity to both high-quality and MUC16 neoantigens in long-term survivors of pancreatic cancer, including clones with specificity to both high-quality neoantigens and predicted cross-reactive microbial epitopes, consistent with neoantigen molecular mimicry. Notably, we observed selective loss of high-quality and MUC16 neoantigenic clones on metastatic progression, suggesting neoantigen immunoediting. Our results identify neoantigens with unique qualities as T-cell targets in pancreatic ductal adenocarcinoma. More broadly, we identify neoantigen quality as a biomarker for immunogenic tumours that may guide the application of immunotherapies