LAUSR

Background: Tafasitamab, an anti-CD19 immunotherapy that enhances antibody-dependent cellular cytotoxicity and phagocytosis, received accelerated approval in the USA and conditional authorization in Europe in combination with lenalidomide (LEN) for patients (pts) with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) ineligible for autologous stem cell transplant (ASCT) based on the results of the open-label, multicenter, single-arm, Phase II L-MIND study (NCT02399085; Salles G, et al. Lancet Oncol 2020, Duell J, et al. Haematologica 2021). Here, we report the final, 5-year follow-up of L-MIND. Data cut-off was Nov 14, 2022. Methods: Pts were aged ≥18 years with ASCT-ineligible R/R DLBCL, 1-3 prior systemic therapies (including a CD20-targeting regimen), and ECOG PS 0-2. Tafasitamab (12 mg/kg) was given for up to 12 cycles in combination with LEN (25 mg), then as monotherapy until disease progression (PD) or unacceptable toxicity. The primary endpoint was best objective response rate (ORR; complete response [CR] or partial response [PR], by independent radiology committee). Secondary endpoints included duration of response (DoR), progression-free survival (PFS), overall survival (OS), and incidence and severity of adverse events (AEs). Exploratory analyses evaluated efficacy endpoints by prior lines of therapy (pLoT). Results: Of 81 pts enrolled, 80 were treated (full analysis set [FAS]). The ORR (FAS) of 57.5% [95% CI: 45.9-68.5], with CR of 41.2% [30.4-51.6] (n=33) and PR of 16.2% [8.9-26.2] (n=13), was generally consistent with the primary and 3-year analyses. Median DoR was not reached (NR) with median follow up (mFU) of 44.0 months [29.9-57.0]. Median PFS was 11.6 months [5.7-45.7] (mFU 45.6 [22.9-57.6]) and median OS was 33.5 months [18.3-NR] (mFU 65.6 [59.9-70.3]). At data cut-off, OS was >60 months in 21 pts (18 with best response of CR, 1 PR, 1 stable disease and 1 PD), including 14 with 1 pLoT and 7 with ≥2 pLoT. Pts with 1 pLoT (n=40) in the FAS had higher ORR (67.5%; 52.5% CR [n=21] and 15% PR [n=6]) compared to pts with ≥2 pLoT (n=40; 47.5%; 30% CR [n=12] and 17.5% PR [n=7]). However, median DoR was not reached for both subgroups, indicating similar long-term efficacy for responders. AEs were consistent with previous reports and manageable; incidence declined after transition from combination to tafasitamab monotherapy and again with monotherapy >2 years. Conclusion: The final, 5-year analysis of L-MIND showed prolonged durable responses with tafasitamab + LEN combination therapy, followed by long-term tafasitamab monotherapy, in pts with R/R DLBCL ineligible for ASCT, with median DoR not reached after 44 months mFU. No new safety signals were identified, confirming the tolerability profile observed with earlier data cuts. These long-term data suggest that this immunotherapy may have curative potential that is being explored in further studies. Citation Format: Johannes Duell, Pau Abrisqueta, Marc Andre, Marinela Augustin, Gianluca Gaidano, Eva González Barca, Wojciech Jurczak, Nagesh Kalakonda, Anna Marina Liberati, Kami J. Maddocks, Tobias Menne, Zsolt Nagy, Olivier Tournilhac, Abhishek Bakuli, Aasim Amin, Konstantin Gurbanov, Gilles Salles. Five-year efficacy and safety of tafasitamab in patients with relapsed or refractory DLBCL: Final results from the phase II L-MIND study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT022.