High CMR, CR rates
As noted before, the CMR rate, the primary endpoint among patients with newly diagnosed Ph+ALL, was 85%, with a CR/CRp rate of 100%. Six of the patients in the frontline group and one in the salvage therapy group had CRs but were positive for minimal residual disease (MRD) at study outset.
The CR/CRp rate for the entire cohort of 28 patients (excluding those with a CR at start) was 96%, with only 1 patient who had relapsed/refractory disease not having a CR. This patient had received ponatinib in a prior salvage regimen.
The CMR rate among the entire cohort was 79%, with 85% of patients in the frontline ALL cohort having a CMR, 88% in the relapsed/refractory cohort, and 40% in the CML cohort. There were no early deaths among any patients.
“After one cycle of ponatinib plus blinatumomab, 84% of frontline patients had achieved at least a major molecular response, and 58% had achieved a CMR. Among those with relapsed/refractory Ph+ALL, 75% achieved CMR after one cycle of therapy,” Dr. Short said.
Of the 20 frontline patients in CR, one patient experienced visual changes and possible stroke that were considered possibly related to the study medication. This patient was taken off study. During a later maintenance regimen this patient developed a non-ST elevation myocardial infarction and died from postprocedural bleeding and hypovolemic shock following a cardiac catheterization procedure.
The remainder of patients in the frontline cohort had ongoing responses without the need for HSCT at last follow-up. There were no relapses, with a median duration of CR of 6 months,
Among the 10 with relapsed/refractory Ph+ALL, one did not have a response, and the remaining 9 had CR/CRps.
Of the latter groups, four went on to allogeneic HSCT and three were still alive; one patient who underwent a transplant experienced a relapse and died. One additional patient was alive with relapsed disease with T315I and E255V mutations at the time of relapse, one patient in CR who went off study due to insurance issues died from an unknown cause, and the three remaining patients had ongoing responses without transplant.
Among the five patients with CML in lymphoid blast phase, two had relapses, but both are still alive and currently in remission, and three have ongoing responses without transplant.
After a median follow-up of 12 months the 1-year event-free survival (EFS) rate for the entire 35-patient group was 76%, and the 2-year EFS was 70%.
The 1-year overall survival rate was 93%, and the 2-year OS rate was 80%.
Among patients in the frontline group, the 1-year and 2-year EFS and OS rates were all 93%.
For the relapsed/refractory cohort, the estimated 2-year EFS was 41% and OS was 53%. For the CML cohort, the 2-year EFS was 60%, with all patients still alive at last follow-up.
There were no grade 4 adverse events on study. Grade 3 adverse events considered at least possibly related to study treatment were elevated lipase, fever/febrile neutropenia, increased alanine aminotransferase, cerebrovascular ischemia, hypertension, pancreatitis, deep vein thrombosis, and encephalopathy. There were no cases of grade 3 cytokine release syndrome or tremor.
The study was sponsored by MD Anderson Cancer Center with collaboration from the National Cancer Institute, Amgen, and Takeda. Dr. Short has disclosed relationships with Amgen and Takeda. Dr. Nichols reported having no conflicts of interest.