This critically important question was debated at the annual meeting of the Society of Hematologic Oncology, held in Houston and online.
Johannes Schetelig, MD, argued in favor of proceeding to transplant, even without a complete remission.
“In the past, I’ve told many patients with relapsed or refractory AML that we do need to induce a [complete remission] prior to transplantation,” said Dr. Schetelig, from the Clinical Trials Unit at DKMS in Dresden, Germany. “But is it true?”
According to findings from a recent randomized trial, it may not be. The trial, led by Dr. Schetelig, found that patients with AML who received immediate allogeneic transplant without first having achieved a complete response following induction therapy did just as well as those who received intensive salvage induction therapy to establish remission before transplant.
If this finding holds, it “completely upends” how experts have traditionally approached patients with AML, Mikkael A. Sekeres, MD, of the University of Miami said at a conference press briefing last year.
The phase 3 ASAP trial, presented at last year’s American Society of Hematology meeting, included patients with AML who had had a poor response or who had experienced a relapse after first induction therapy. Patients were randomly assigned to a remission-induction strategy prior to allogeneic stem cell transplant (alloHCT) or a disease-control approach of watchful waiting followed by sequential conditioning and alloHCT. The primary endpoint was treatment success, defined as a complete response at day 56 following alloHCT.
In an intention-to-treat analysis, 83.5% of patients in the disease-control group and 81% in the remission-induction group achieved treatment success. Similarly, in the per-protocol analysis, 84.1% and 81.3%, respectively, achieved a complete response at day 56 after alloHCT. After a median follow-up of 4 years, there were no differences in leukemia-free survival or overall survival between the two groups.
Another advantage to forgoing an intensive salvage induction regimen: Patients in the disease-control arm experienced significantly fewer severe adverse events (23% vs. 64% in the remission induction arm) and spent a mean of 27 fewer days in the hospital prior to transplantation.
At last year’s press briefing, Dr. Schetelig said his team did not expect that a complete response on day 56 after transplantation would translate into “equal long-term benefit” for these groups. “This is what I was really astonished about,” he said.
Delving further into the findings, Dr. Schetelig explained that in the remission-induction arm patients who had had a complete response prior to transplantation demonstrated significantly better overall survival at 4 years than those who had not had a complete response at that point: 60% vs. 40%.
The study also revealed that in the disease-control arm, for patients under watchful waiting who did not need low-dose cytarabine and mitoxantrone for disease control, overall survival outcomes were similar to those of patients in the remission-induction arm who achieved a complete response.
These findings suggest that patients who can be bridged with watchful waiting may have a more favorable disease biology, and chemosensitivity could just be a biomarker for disease biology. In other words, “AML biology matters for transplant outcome and not tumor load,” Dr. Schetelig explained.
A recent study that found that having minimal residual disease (MRD) prior to transplant “had no independent effect on leukemia-free survival” supports this idea, he added.
Overall, Dr. Schetelig concluded that data from the ASAP trial suggest that watchful waiting prior to alloHCT represents “an alternative” for some patients.