716 Background: Metastatic Pancreatic Ductal Adenocarcinoma (mPDAC) has a grim prognosis, with limited therapeutic options. In this context, treating patients (pts) with chemotherapy (CT) till progression is not supported by scientific evidence and must be weighed against quality of life impairment and cumulative toxicity. Therefore, we explored the role of metronomic oral cyclophosphamide (mCTX) as maintenance therapy (MT) in mPDAC pts. Methods: Any age mPDAC pts, with Karnofsky performance status >60 and wild-type germline BRCA1-2, who were progression-free after at least 6 months of any regimen and line CT and received mCTX (50 mg/die) MT between August 2020 and July 2022, were included in the analysis. An historical cohort (HC) of mPDAC pts, who were progression-free after 6 months of 1st-line platinum-based combination CT and did not receive MT between 2000 and 2016, was considered for exploratory comparison. Progression-free and Overall Survival (PFS and OS) were calculated from last CT administration for both cohorts. Results: 41 and 122 pts were included in mCTX and HC, respectively. Median PFS was 4.1 (range 1.5-18.4) and 3.1 (1-141) months for mCTX and HC, respectively (p= 0.003). PFS rates at 6 and 12 months were 34.7% and 11.1% in the mCTX cohort, 18.9% and 6.6% in the HC. Median OS was not reached (range 1.5-25) and 10.2 (1.3-142) months for mCTX and HC, respectively (p= 0.002). OS rates at 6 and 12 months were 96.9% and 74.6% in the mCTX cohort, 74.5% and 46.9% in the HC. Factors associated with longer PFS in the mCTX cohort were normal CA19.9 at CT start (p= 0.006), female gender (p= 0.036), no liver metastases (p= 0.01), normalized CA19.9 after CT (p= 0.01). Only 2 pts receiving mCTX had Grade 3 toxicity. Conclusions: mCTX MT extends PFS and OS of mPDAC pts not progressing after at least 6 months of CT with unremarkable toxicity in our exploratory non-randomized analysis.[Table: see text]
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