Background: The Phase II L-MIND study led to accelerated US approval and EU conditional authorization of the CD19-targeted immunotherapy, tafasitamab, + lenalidomide (LEN) followed by tafasitamab monotherapy for patients (pts) with R/R DLBCL ineligible for autologous stem cell transplant (ASCT). Long-term L-MIND data further support the regimen. Here we present exploratory analyses of final 5-year (yr) efficacy in subgroups of interest. Methods: Pts (≥18 years) with ASCT-ineligible R/R DLBCL, 1–3 prior systemic therapies (incl. ≥1 targeting CD20) and ECOG PS 0–2 received tafasitamab for ≤12 28-day cycles (+ LEN), then alone until disease progression. Primary endpoint was objective response rate (ORR). Secondary endpoints included duration of response (DoR), progression-free survival (PFS) and overall survival (OS). Exploratory subgroup analyses including by International Prognostic Index (IPI) and time to progression after 1L (in pts with only 1 prior line) used Kaplan-Meier estimates of 5-yr endpoints. Results: As of 14 Nov, 2022 in the full analysis set (FAS; n=80), ORR was 56.2% [95% CI: 44.7–67.3]. Median treatment duration was 9.0 months (mo) [0.5–73.6] and median follow-up (mFU) for OS was 65.6 mo [59.9–70.3]). Median DoR was not reached (mFU: 43.7 mo [29.9–58.4]). Of 18 patients in follow-up for ≥5 years, 9 received tafasitamab until end of study per protocol, 9 discontinued while in remission. RR and 5-yr rates for DoR, PFS and OS showed long-term clinical activity in all pt subgroups (Table). Conclusions: In this 5-yr subgroup analysis, a long-term clinical benefit with tafasitamab + LEN followed by tafasitamab monotherapy was observed in all subgroups of clinical interest, including pts with poor prognosis risk factors. These data suggest this immunotherapy may have curative potential, which is being explored in further studies. Clinical trial information: NCT02399085.

*5-yr rate estimate, % [95% CI] (5-yr n at risk). ^†Pts with 1 prior line of therapy.^‡Includes primary refractory. NE, not estimable.