SAN FRANCISCO– The study was small but encouraging: Among 47 older patients with newly diagnosed acute lymphoblastic leukemia positive for the Philadelphia chromosome, 41 had a complete hematologic response to a combination of chemotherapy and the targeted agent nilotinib (Tasigna), report investigators from a European consortium.
“The data I have presented show that the combination of nilotinib with this age-adapted chemotherapy is highly effective. We do have quite a reasonable overall survival estimate at 2 years of just more than 70%,” said Dr. Oliver Ottmann of Goethe University in Frankfurt, on behalf of colleagues in the European Working Group for Adult ALL (EWALL).
The study also shows that although some centers are reluctant to offer allogeneic stem cell transplantation (SCT) to older patients, it is still a viable treatment option in this population, Dr. Ottmann said at a briefing at the annual meeting of the American Society of Hematology.
Although older patients with newly diagnosed Philadelphia-positive (Ph+) ALL have a high complete hematologic response rate (CHR) with imatinib (Gleevec), they generally have a poor prognosis because of a high rate of relapse.
Because nilotinib, a potent inhibitor of the ABL kinase, has good efficacy in the chronic and accelerated phase of Ph+ chronic myeloid leukemia, the EWALL investigators initiated a study to evaluate it in combination with chemotherapy in the front-line setting.
Adults aged 55 years and older with ALL positive for the Philadelphia chromosome and/or BCR-ABL1 fusion who were treatment naive or had not received therapy other than corticosteroids, single-dose vincristine, or three doses of cyclophosphamide were eligible.
Details of the combination regimen are available online.
Briefly, following a prephase with dexamethasone and optional cyclophosphamide, patients receive nilotinib 400 mg twice daily starting with induction and continuously thereafter. During induction, nilotinib is given with intravenous injections of vincristine and dexamethasone for 4 weeks, followed by consolidation with nilotinib, methotrexate, asparaginase and cytarabine. Maintenance consists of nilotinib, 6-mercaptopurine, and methotrexate once weekly for 1 month then every other month, and dexamethasone and vincristine in 2 month intervals up to 24 months.
The data Dr. Ottmann reported come from an interim analysis of the ongoing study. As of August 2014, data on 47 of 56 patients was available for an efficacy analysis, As noted before, the rate of CHR was 87%, occurring in 41 of 47 patients. The treatment evoked a partial response or no response in 2 patients, and there was one death during the induction phase. Additionally, three patients discontinued therapy early and were not included in the assessment, but at least one had a complete response later on, Dr. Ottmann noted.
The median time to a complete response (CR) was 41 days, but CRs occurred as early as 25 days and as late as 62 days after the start of therapy. The remissions at the time of data cutoff appeared to be durable, but follow-up is still early, he said.
Overall survival at a median follow-up for all patients of 8.6 months was 72.7% at 30 months for patients who did not undergo SCT (allowed under the protocol), and 67.1% at 30 months for patients who underwent SCT. This difference was not significant, but only nine patients at the time of data cutoff had undergone transplantation.
“It will be interesting to see how this will proceed if the transplant-free patients will do as well as the others,” Dr. Ottmann said.
An analysis of molecular response by minimal residual disease (MRD) time point showed a significant further increase with the consolidation chemotherapy and kinase inhibitor, emphasizing that “continuing the treatment in this form emphasizes the depth of response. If we then look at the rate of MRD negativity using high quality assays, then a quarter of the patients have undetectable polymerase chain reaction during the consolidation cycles, and approximately 80% achieves something that we call a major molecular response,” he said.
Dr. Ottmann did not provide updated safety data, but at the time of the data cutoff, there had been 34 serious adverse events reported, 11 of which occurred during induction, 16 during consolidation, 6 during maintenance, and 1 following discontinuation. The most-common adverse events were infections and neutropenic fevers. Single serious adverse events included metabolic, cardiovascular, neurologic, renal, and hepatic events.
The trial is expected to be completed in the next few months.