Background: Maintenance treatments in m-PDAC patients (pts) after FFX induction is discussed. We assessed the efficacy of genetic-driven maintenance in pts with controlled disease. Methods: In this multicenter, open-label, phase II study, PS 0-1 pts with histologically confirmed m-PDAC controlled after 4 months (mo) of mFFX received a genetically-driven maintenance therapy (centralized analysis): BRCAness - olaparib 300 mgx2/d (Arm A); no BRCAness, but KRAS mutation - randomization (2:1) to S+D (1500 mg IV q4w + 75 mg PO BID; Arm B) or FOLFIRI q2w (Arm C), until confirmed progression or toxicity. Statistical hypotheses: Arm A, PFS4mo rate after inclusion - H0: PFS4mo ≤40%, H1: PFS4mo ≥70%; Arm B and C, H0: PFS_c=PFS_b, H1: PFS_c<PFS_b (one-sided 2.5% α-type I-error and 10% β-type 2). A prespecified single interim analysis for futility using a-spending function with O’Brien-Fleming boundaries was planned after 33.1% of events (~93 pts). The Kaplan-Meier method and a swimmer plot were applied. Results: 124 pts were included in the study; Arm A: 16 pts (male: 9, median age: 67 years, PS 0: 9 pts) received olaparib; PFS 4mo: 50%; median PFS: 3.7 mo (1.7-9.4), ORR: 13%, median OS: 18 mo (5.5-21.5). Arm B/Arm C: at interim analysis (12/5/2022): 104 pts were randomized (Arm B/Arm C: 70/34); median PFS in Arms B and C: 3.5 mo (95% CI 2.1-3.9) vs 5.7 mo (95% CI 2.2-10.7), respectively. Due to futility, inclusions were stopped. At final analysis (data cutoff: 06/15/2023) with median follow up of 11.2 mo (95% Cl 9.4-13.1): 108 pts (male: 53%, age: 63.5 years, PS 0: 44%) were treated (Arm B/Arm C: 72/36). 123/124 pts (ITT population) had ≥1 cycle treatment (median: 4.0 [IQR, 2.0-6.0]). Primary endpoint was not met: median PFS 3.7 mo (95% Cl 2.1-5.0) in Arm B vs 6.6 mo in Arm C (95% Cl 2.6-8.7); HR=1.6 (0.99-2.58), P=0.0523. Median OS (entire population): 12.7 mo (95% CI 8.7-18.2); 10.1 mo (95% CI 8.3-20.6) in Arm B and 17.3 mo (95% CI 8.4-20.9) in Arm C. The toxicity profile: ≥1 grade 3-4 treatment-related arms (A/B/C) was as expected: 18.8%, 23.6%, 28.6% of pts. Conclusions: MAZEPPA study did not meet its primary endpoint of improving PFS4mo in m-PDAC pts treated with S+D maintenance vs those receiving FOLFIRI. Data on genomic alterations analyses will be presented at the congress. Clinical trial information: NCT04348045.