Background: L-MIND (NCT02399085) is an ongoing, open-label, Phase II study of tafasitamab (MOR208), an Fc-modified, humanized, anti-CD19 monoclonal antibody, plus LEN in ASCT-ineligible patients (pts) with R/R DLBCL. Primary analyses and 2-year efficacy results were previously presented; we report an updated efficacy analysis with ≥35 months follow up (cut-off: October 30, 2020). Methods: Pts were aged ≥18 years with ASCT-ineligible R/R DLBCL, had 1–3 prior systemic therapies (Tx), including ≥1 CD20-targeting regimen, with an ECOG status of 0–2. Pts received 28-day cycles (C) of tafasitamab (12 mg/kg IV), once weekly during C1–3, with a loading dose on Day 4 of C1, then every 2 weeks (Q2W) during C4–12. LEN (25 mg PO) was administered on Days 1–21 of C1–12. After C12, progression-free pts received tafasitamab Q2W until disease progression. The primary endpoint was objective response rate (ORR), assessed by IRC. Secondary endpoints included duration of response (DoR), progression-free survival (PFS) and overall survival (OS). Results: Eighty of 81 enrolled pts received tafasitamab + LEN and were included in the full analysis set (1 prior Tx, n=40; 2+ prior Tx, n=40). At data cut-off, the overall ORR was 57.5% (n=46/80), including complete response (CR) in 40% of pts (n=32/80) and partial response (PR) in 17.5% of pts (n=14/80) (Table). Kaplan-Meier estimates: median DoR=43.9 months (95% CI: 26.1–not reached [NR]), and NR in pts who achieved a CR (95% CI: 43.9–NR); median PFS=11.6 months (95% CI: 6.3–45.7), with median follow-up 33.9 months; median OS=33.5 months (95% CI: 18.3–NR), with median follow-up 42.7 months. There were no unexpected toxicities or new safety signals. Conclusions: Combination Tx with tafasitamab + LEN followed by tafasitamab monotherapy provided durable responses in pts with R/R DLBCL not eligible for ASCT, with a manageable safety profile. These long-term data indicate the potential of tafasitamab + LEN followed by extended tafasitamab monotherapy in achieving prolonged remission and survival benefit in this patient population, especially at first relapse. Clinical trial information: NCT02399085

*No valid post-baseline response assessments. ^†Two-sided 95% Clopper-Pearson exact method based on a binomial distribution. ^‡Kaplan-Meier estimate. Data cut-off: October 30, 2020.