Allogeneic transplantation in T‐cell lymphoma: Lessons from the AATT study

Treatment of non-cutaneous mature T-cell lymphoma (PTCL) remains difficult. Results of the AATT study (Schmitz et al. Blood 2021) demonstrated that standard 1st line chemotherapy followed by alloSCT did not improve outcome of PTCL patients (pts) when compared to autoSCT. We sought to investigate long-term outcomes of AATT patients focusing on the role of alloSCT in pts transplanted on and off study. AATT was a randomized trial comparing alloSCT and autoSCT in younger pts (18–60 yrs) with newly diagnosed PTCL who achieved CR, PR, or SD after 4 xCHOEP and 1xDHAP. These pts were to receive autoSCT or alloSCT from matched related or unrelated donors for consolidation. Detailed reports on all therapy given until last follow up or death were retrieved to calculate long-term event-free (EFS) and overall survival (OS) focusing on patients receiving alloSCT on study as well as off study for primary refractory disease or after failing autoSCT. 103 pts (median age 50 years) randomized to autoSCT (n = 54) or alloSCT (n = 49) formed the full analysis set (FAS), 67 pts (65%) received autoSCT (n = 41) or alloSCT (n = 26) (per protocol set, PPS) on study. 36 pts went off study mainly for early progression (n = 29) or change of diagnosis (n = 4). With a median observation time of 7 years EFS and OS were 36% [95% CI: 27%–46%] and 58% [48–68] for all 103 pts with no significant differences between treatment arms. For patients transplanted 7-year-EFS and -OS were 50% [34–66] versus 61% [42–80] and 72% [58–86] versus 61% [42–80] after autoSCT versus alloSCT. After autoSCT, 20 of 41 pts progressed (n = 5) or relapsed (n = 15) and 10 could be allografted off study. In the alloSCT arm (n = 26) only 1 pt each progressed or relapsed after alloSCT, these pts were not allografted again. Among 29 pts with early progression before transplantation 15 were allografted off study. Thus, 25 of 49 pts (51%) who had early progression before transplantation or had failed autoSCT received alloSCT. Five-year OS rate for these 25 pts was 64% [45–83] with no significant differences between pts allografted for early progression or relapse after autoSCT. Surprisingly, OS after alloSCT for 26 pts transplanted on study and 25 pts transplanted off study was superimposable with a 5-year OS-rate of 65% [47–84] for on study patients (Figure 1). Pts with progression or relapse not proceeding to alloSCT had a dismal. The research was funded by: rants: Norbert Schmitz and Lorenz Truemper: Bundesministerium für Bildung und Forschung (BMBF, FKZ 01KG0705), Olivier Tournilhac: Ministère de la Santé et des Solidarités (PHRC09_05-004-TOURNILHAC). In France, Keywords: Aggressive T-cell non-Hodgkin lymphoma, Cellular therapies Conflicts of interests pertinent to the abstract. O. Tournilhac Consultant or advisory role: Takeda Honoraria: Takeda Educational grants: Takeda