Cyclophosphamide maintenance to extend combination chemotherapy-free interval in metastatic pancreatic ductal adenocarcinoma

Background: Administering chemotherapy until progression to metastatic pancreatic ductal adenocarcinoma (PDAC) patients lacks of supporting evidence and causes cumulative toxicity. We explored the role of cyclophosphamide as maintenance therapy. Methods: PDAC germline BRCA1-2 wild-type patients who were progression-free after ≥6 months of any regimen and line of chemotherapy and received maintenance cyclophosphamide (mCTX) (50 mg/day), were included in the analysis. Results: 42 patients were included in the analysis. Thirty-nine patients had progression of disease. Median PFS was 3.5 (range 1.0-31+) months. PFS rates at 6 and 12 months were 26.2% and 11.9%. At a median follow-up of 20.0 months (range 12.1-31.0 months), 20 patients died and 22 are alive. Median OS was 20.0 months (range 2.2-31.0+). OS at 6 and 12 months was 97.6% (95%CI: 93.4-100), and 73.8% (95% CI: 61.1-86.5), respectively. Only 2 patients receiving mCTX had Grade 3 toxicity. Conclusions: mCTX therapy yielded promising PFS and OS outcome in PDAC patients who were progression-free after induction chemotherapy, with unremarkable toxicity. Accordingly, this approach warrants further investigation.