Adding Romidepsin to CHOEP in First Line Treatment of Peripheral T-Cell Lymphomas Does Not Improve the Response Rate: Final Analysis of Phase II PTCL13 Study

Introduction: Peripheral T-cell lymphomas (PTCL) have a 40-50% cure rate when treated with cyclophosphamide-doxorubicin-etoposide-vincristine-prednisone (CHOEP) and hematopoietic stem cell transplantation (HSCT). Romidepsin, a histone deacetylase inhibitor, showed promising activity in relapsed or refractory PTCLs.

Methods: On these premises, we designed a phase I/II trial (PTCL13 NCT02223208) to evaluate whether the addition of romidepsin to CHOEP improves the outcome of newly diagnosed PTCLs. In the phase Ib part of the study, we defined 14 mg/ms as the maximum tolerated dose of romidepsin when administered in combination with CHOEP (Ro-CHOEP). Thus, in the phase II part of the study we evaluated the efficacy of Ro-CHOEP followed by HSCT in young patients. The primary objective of the study was to demonstrate a 15% increase in 18-months progression-free survival (PFS) for the combination Ro-CHOEP plus HSCT (from 55% to 70%, planned sample size=110), compared to the previous Italian trial (Corradini P et al, Leukemia 2014). Patients aged 18-65 years with stage II-IV PTCL-NOS, angioimmunoblastic/T follicular helper (AITL/THF) and ALK negative anaplastic large cell lymphoma, were eligible. Treatment plan consisted of 6 courses of Ro-CHOEP every 21 days (14 mg/ms Ro day 1 and 8), followed by cisplatin-cytarabine-dexamethasone (DHAP) with stem cell harvest and HSCT. Patients in complete response (CR) after induction proceeded to autoHSCT, while those in partial response (PR), with an available HLA-matched donor, proceeded to alloHSCT upfront.

Results: From September 2017 to October 2020, 86 patients were enrolled into the phase II part of the study; median age was 55 years (IQR 49;60); 78 (91%) had stage III-IV and 31 (36%) IPI score >2. Pathological materials were collected at the time of diagnosis, and centrally reviewed by expert hemo-pathologists; subgroups were: 33 PTCL-NOS, 21 ALK negative, 31 AITL/THF, and one case not classified due to inadequate material. According to the statistical plan, an interim analysis was performed on the first 75 patients. At a median follow-up of 26 months, the 18-months PFS was 48% (95% CI: 0.36-0.58) and the OS was 75% (95% CI: 0.64-0.83). The 18-months PFS for PTCL-NOS versus ALK negative vs AITL/THF was 37% (95% CI: 0.20-0.54) vs. 51% (95% CI: 0.28-0.70) vs. 58% (95% CI: 0.36-0.74), p 0.118; the 18-months OS for PTCL-NOS vs. ALK negative vs. AITL/THF was 72% (95% CI: 0.51-0.85) vs. 76% (95% CI: 0.51-0.89) vs. 81% (95% CI: 0.60-0.92), p 0.957. All 86 patients completed the induction phase and were evaluable for response after 6 Ro-CHOEP: the overall response rate (ORR) was 71% (61 patients), with 62% (53 patients) CR. Four patients with ongoing treatment are not evaluable for response at the end of therapy, at the time of the analysis. Only 39 of 82 patients (48%) underwent HSCT and 43 did not: 28 due to progressive disease, 8 for poor mobilization, 7 for adverse events (1 sepsis, 2 cardiological events, 4 others). Among the 82 patients evaluable for response at the end of treatment, the final ORR after HSCT was 40% (33 patients), with 39% CR (32 patents). The most frequent toxicities during Ro-CHOEP treatment were hematological, with grade 3-4 neutropenia and thrombocytopenia in 33% and 34% of all the 459 cycles, respectively; severe febrile neutropenia was reported in only 4% of Ro-CHOEP courses. Severe non-hematological toxicities were observed in 35 (41%) of patients: cardiological in 5 patients (6%), gastrointestinal in 9 (10%), infections in 10 (12%), others in 11 (13%). Twenty-four deaths were recorded: 22 due to lymphoma progression, 1 due to transplant related mortality for a septic shock after alloSCT, 1 due to secondary malignancy.

Conclusions: In the PTCL13 phase I part of the study we demonstrated the feasibility of the combination Ro 14 mg/ms plus CHOEP followed by high-dose chemotherapy and HSCT; in the phase 2 part of the study, the primary objective was not achieved, with a 18-months PFS of 48%. Based on these results, the enrollment of the trial was stopped due to inefficacy of the experimental combination. The benefit of adding romidepsin to chemotherapy was not observed neither in PTCL-NOS nor in AITL/THF. In conclusion, the addition of romidepsin to CHOEP did not ameliorate prognosis in newly diagnosis PTCLs eligible to HSCT.