© ASCO/Max Gersh
CHICAGO—Allogeneic and autologous transplants produce similar survival rates when used as first-line therapy in younger patients with peripheral
T-cell lymphoma (PTCL), according to interim results of the AATT trial.
The study also showed that deaths among patients who received autologous stem cell transplants (auto-SCTs) were a result of relapse and salvage treatment, while deaths among allogeneic SCT (allo-SCT) recipients were transplant-related.
Norbert Schmitz, MD, PhD, of Asklepios Hospital St. Georg in Hamburg, Germany, presented these findings at the 2015 ASCO Annual Meeting (abstract 8507*).
Dr Schmitz noted that only previous study comparing auto-SCT with allo-SCT as first-line therapy in PTCL was not designed or powered to evaluate the differences between the transplant types.
So he and his colleagues conducted the AATT trial to determine the differences. The team hypothesized that allo-SCT would improve 3-year event-free survival from 35% to 60%, given an α of 5% and a power of 80%. They needed 140 patients to prove or disprove this theory.
Ultimately, the investigators enrolled 104 patients and performed an interim analysis when 58 patients were evaluable for response.
Of the 58 patients, 30 were randomized to the auto-SCT arm and 28 to the allo-SCT arm. Baseline characteristics were similar between the arms, including patients’ median ages (49 and 50, respectively), the proportion of patients with stage III/IV disease (87% and 93%), and the proportion with ECOG status greater than 1 (23% and 18%).
Most patients in both arms had PTCL not otherwise specified (36% in the auto-SCT arm and 50% in the allo-SCT arm). Other subtypes included angioimmunoblastic T-cell lymphoma (23% and 32%, respectively), ALK-negative anaplastic large-cell lymphoma (20% and 4%), and “other” PTCLs (20% and 8%). The other PTCLs were NK/T-cell lymphoma, intestinal T/NK-cell lymphoma, hepatosplenic γδ lymphoma, and subcutaneous panniculitis-like PTCL.
Treatment characteristics
Before undergoing transplant, patients in both arms received treatment with CHOEP (cyclophosphamide, doxorubicin, etoposide, vincristine, and prednisone) on days 1, 15, 29, and 43. If they experienced a complete response (CR), partial response, or no change, patients received DHAP (dexamethasone, cytarabine, and cisplatin) on day 64.
Patients in the auto-SCT arm received BEAM (carmustine, etoposide, cytarabine, and melphalan) prior to transplant. And patients in the allo-SCT arm received FBC (fludarabine, busulfan, and cyclophosphamide).
Overall, 36 patients (62%) completed treatment per protocol, 19 in the auto-SCT arm and 17 in the allo-SCT arm. Thirty-eight percent of all patients could not proceed to transplant per protocol, mostly because of early lymphoma progression.
Response and survival
The researchers observed CRs/unconfirmed CRs (CRus) in 33% (n=10) of patients in the auto-SCT arm and 39% (n=11) in the allo-SCT arm. CR/CRus and progressive disease within 2 months occurred in 3% (n=1) and 4% (n=1) of patients, respectively.
Partial responses were seen in 17% (n=5) of patients in the auto-SCT arm and 7% (n=2) in the allo-SCT arm. There was no change in 7% (n=2) and 0% of patients, respectively. And responses were unknown in 7% (n=2) of patients in the auto-SCT arm.
Progressive disease occurred in 33% (n=10) of patients in the auto-SCT arm and 36% (n=10) in the allo-SCT arm. And treatment-related death occurred in 0% (n=0) and 14% (n=4), respectively.
At the interim analysis, there was no significant difference between the treatment arms with regard to event-free survival (P=0.963) or overall survival (P=0.174).
“At that time, the decision was made to stop the study,” Dr Schmitz said.
He explained that a conditional power analysis showed a low probability that the primary endpoint—a 25% improvement in event-free survival with allo-SCT—could still be met. So the data safety monitoring board decided to stop enrollment.
An updated analysis, performed at a median observation time of 26 months, showed there was still no significant difference in overall survival between the treatment arms (P=0.362).
Cause of death
In the intent-to-treat population—30 patients in the auto-SCT arm and 28 in the allo-SCT arm—there were 16 lymphoma-related deaths, 10 in the auto-SCT arm and 6 in the allo-SCT arm.
There were 6 deaths related to study treatment (4 early and 2 late), all in the allo-SCT arm. One patient in the allo-SCT arm died of post-transplant lymphoproliferative disorder, and 1 patient in the same arm died of hemorrhage after salvage. One patient in each arm died as a result of salvage treatment.
Dr Schmitz and his colleagues also looked at the cause of death among patients who received a transplant—19 in the auto-SCT arm and 17 in the allo-SCT arm.
After SCT, there were 7 deaths in each arm. In the auto-SCT arm, there were 6 lymphoma-related deaths and 1 death related to salvage treatment. In the allo-SCT arm, there were 7 cases of non-relapse-related mortality, including 1 patient with post-transplant lymphoproliferative disorder.
“There certainly seems to be a [graft-vs-lymphoma] effect of allo-transplant in T-cell lymphoma that is, unfortunately, in some way, counterbalanced by high transplant-related mortality,” Dr Schmitz said.
He added that results of a final analysis of the 104 patients enrolled on this study should be available in 2017.
*Information in the abstract differs from that presented at the meeting.