Real-World Effectiveness of Tafasitamab (Tafa) for the Treatment of Relapsed/Refractory Diffuse Large B-Cell Lymphoma (R/R DLBCL) in the United States

Introduction: Tafa is a CD19-targeting immunotherapy indicated in combination with lenalidomide (len) for the treatment of R/R DLBCL in adult patients (pts) ineligible for autologous stem cell transplantation. To date, few studies have examined tafa in a US real-world setting, especially from a community practice perspective. We presented results from one such real-world study (RWS), but the limited median follow-up time of 6.5 months precluded robust evaluations of the clinical benefits of tafa (Saverno K, et al. Blood. 2023;142(suppl 1):265). Herein, we examined the effectiveness of tafa among pts in this RWS after additional follow-up data were collected.

Methods: A retrospective, multisite, physician-abstracted medical chart review was conducted in US adults who initiated tafa (with or without len) on or after October 21, 2020, for R/R DLBCL outside of the clinical trial setting. Initial data collection occurred from February 22 to March 29, 2023, during which 23 physicians from Cardinal Health’s Oncology Provider Extended Network abstracted data for 181 pts. Approximately 10 months later, between December 18, 2023 and January 31, 2024, the physicians were asked to provide data on the 144 pts who were still alive at the last follow-up from the initial data collection. These data were merged with the original data and summarized using descriptive statistics; time-to-event endpoints were calculated using the Kaplan-Meier method. Univariable analyses were conducted to assess potential associations between pt demographic, clinical, and treatment characteristics, with the following endpoints of interest: real-world progression-free survival (rwPFS) and overall survival (rwOS). Variables with P≤0.2 in univariable analyses were included in initial multivariable Cox proportional hazards (PH) models. Backwards selection with P<0.05 was used to determine factors, when adjusted for others, associated with rwPFS and rwOS among pts who had initiated tafa for R/R DLBCL.

Results: After the most recent data collection, median (Q1-Q3) follow-up time from tafa initiation among the overall study population of 181 pts (male, 56%; White, 64%; median age at tafa initiation, 71 years; received tafa in second line [2L], 72%) was 14.7 (8.5-17.1) months. A total of 128/181 pts (71%) had discontinued tafa; reasons for discontinuation included progression of disease (POD, 71%; clinically defined POD, 9%; POD confirmed on imaging, 62%), toxicity (10%), pt/caregiver request (7%), complete response (rwCR, 4%), and other reasons (8%). Fifty-three of the 106 pts (50%) who were still alive were receiving tafa; 75/181 were reported deceased.

Of the 181 pts, 42 (23%) had a rwCR and 91 (50%) had a partial response (rwPR) as their best response to tafa, resulting in a real-world overall response rate (95% CI) of 73% (67%-80%). Among those who achieved a rwCR or rwPR, median (95% CI) duration of response (mDOR) was 9.6 (8.3-13.3) months. mDOR (95% CI) was 19.2 (8.8-not evaluable [NE]) months among those achieving a rwCR and 8.5 (6.8-10.0) months among those with a rwPR as best response. Median rwPFS (95% CI) was 11.3 (9.8-13.6) months and median rwOS (95% CI) was 24.8 (17.8-NE) months from tafa initiation.

In the multivariable Cox model, the factors associated (P<0.05) with increased risk of progression included tafa in 3-5L vs 2L, bulky vs nonbulky disease, Ann Arbor stage III-IV vs stage I-II, and increasing National Cancer Institute Charlson Comorbidity Index scores. To overcome violation of PH assumption caused by the variable Eastern Cooperative Oncology Group performance status (ECOG PS), coefficients were adjusted for ECOG PS ≥2 vs <2 through stratifying the model on ECOG PS. Additionally, a Cox PH model found the following factors to be associated with an increased risk of mortality: increasing age, tafa in 3-5L vs 2L, bulky vs nonbulky disease, and ECOG PS ≥2 vs <2.

Conclusions: Additional follow-up time allowed for a more robust evaluation of the real-world effectiveness of tafa in a diverse population of pts with R/R DLBCL who received tafa predominantly in a community practice setting. The outcomes observed in this RWS support the clinical benefit of tafa. Furthermore, the multivariable models of rwOS and rwPFS suggest the greatest benefit from tafa is achieved when used as 2L therapy vs later lines of therapy (3-5L).