BACKGROUND: For metastatic pancreatic ductal adenocarcinoma (mPDAC), there are no established third-line chemotherapy options. We examined the efficacy and safety of third-line chemotherapy in patients with mPDAC in real-world practice. METHODS: We retrospectively analyzed 257 patients with mPDAC and progressive disease after first-line treatment with gemcitabine-based regimens and second-line treatment with liposomal irinotecan plus 5-fluorouracil and leucovorin at five Taiwanese medical centers from 2018 to 2022. Treatment efficacy and toxicity were analyzed in 77 of 257 patients receiving third-line treatment subsequently. We performed univariate and multivariate analyses to identify prognostic factors for overall survival (OS) in patients receiving third-line treatment. RESULTS: Patients receiving third-line treatment had a median OS of 4.5 months (95 % confidence interval [CI], 3.6-5.4), compared to 1.6 months (95 % CI, 1.3-1.9) for those who did not. Independent poor prognostic factors for OS included the absence of previous pancreatectomy (adjusted hazard ratio [aHR] 3.03, 95 % CI, 1.30-7.14, P = 0.001), an ECOG score of ≥2 ((aHR 9.81, 95 % CI 4.34-22.1, P <
0.001), and progressive disease response during second-line treatment (aHR 1.90, 95 % CI 1.21-8.91, P = 0.020, P = 0.020). Median OS for patients with none, one, two, and three poor prognostic factors were 15.9 (95 % CI, 12.3-19.6), 7.0 (2.6-13.3), 4.4 (3.5-5.2), and 2.0 (1.7-2.2) months, respectively. 43 of 77 patients (56 %) experienced at least one grade 3 or 4 toxicity. CONCLUSION: In real-world settings, patients with mPDAC receiving third-line chemotherapy may have a moderate survival advantage, although clinicians should carefully select patients owing to high incidence of grade 3/4 toxicities.