Nab-paclitaxel plus S-1 followed by gemcitabine-oxaliplatin as first-line alternating sequential treatment of pancreatic ductal adenocarcinoma

Background: Alternating sequential administration of drugs may be a promising approach to overcome chemotherapy resistance in advanced pancreatic ductal adenocarcinoma (PDAC). Methods: This study was an open-label, single-arm, and prospective trial included patients with untreated advanced PDAC. They received 2 cycles of NS regimen (nab-paclitaxel:125 mg/m(2), intravenously injected on days 1 and 8, plus S-1:40-60 mg, orally twice per day for 1-14 days) followed by 2 cycles of GemOx regimen (gemcitabine, intravenously injected on days 1 and 8, and oxaliplatin: 130 mg/m(2), intravenously injected on day 1). The primary efficacy endpoint was a progression-free survival rate at 6 months (PFSR-6m). The secondary efficacy endpoints included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and adverse events (AEs). Specific mRNA transcripts were used to explore survival associated genes. Results: Forty-two patients received a minimum of one treatment cycle, and of these, 30 patients completed one alternating treatment consisting of 4 cycles. The PFSR-6m was 71% (95% CI = 58%-87%). The median PFS and OS were 6.53 months (95% CI = 6.03-8.43) and 11.4 months (95% CI = 9.8-14.4), respectively. Common grades 3-4 hematological AEs included neutropenia 30.9%, leukopenia 26.2%, anemia 2.4%, and thrombocytopenia in 11.9%. Patients with OS > 10 months showed high expression of HLA-DQA2 while melanoma-associated antigen genes (MAGE) were notably upregulated in patients with OS < 10 months. Conclusion: The alternating sequential administration of the NS and GemOx regimens may be a novel approach for first-line chemotherapy in patients with advanced PDAC requiring further study (ClinicalTrials.gov Identifier: ChiCTR1900024867).