A Multicenter Phase II Study Using a Dose Intensified Pediatric Regimen in Adults with Untreated Acute Lymphoblastic Leukemia.

Background: In children with ALL, current chemotherapy regimens produce an event-free survival (EFS) of greater than 80%. Adults with ALL have a much poorer prognosis, with EFS rates of 30–40%. Recent retrospective studies suggest that young adult patients may have superior outcomes when treated on more intensive pediatric regimens, but prospective studies are lacking. A phase II trial was performed in an effort to determine if an intensive pediatric regimen can be administered to adults with ALL.

Methods: The therapeutic backbone of this protocol is based upon the high-risk arm of the DFCI Childhood ALL Consortium Protocol 00–01. Patients with newly diagnosed ALL were enrolled and received intensive multiagent remission induction chemotherapy, which included doxorubicin, prednisone, vincristine, high-dose methotrexate, high-dose asparaginase, and triple intrathecal therapy. CNS prophylaxis included triple intrathecal therapy and cranial radiation. Intensification therapy consisted of 3 week courses of doxorubicin, vincristine, dexamethasone, 6-mercaptopurine and 30 weeks of high-dose asparaginase that was individually dosed in order to maintain asparagine depletion. Continuation therapy consisted of 3 week courses of vincristine, dexamethasone, methotrexate and 6-mercaptopurine for a total of 2 years from an established complete remission (CR).

Results: 71 patients have been enrolled to date. Although there was no initial upper age restriction, the protocol was amended to include only patients between the ages of 18–50 with de novo ALL; this amendment excluded 4 patients from the analysis. Two patients were enrolled but never received therapy. Demographic data are available for 61 evaluable patients. The median age was 28 years, (range, 18–50), 65% were male, 75% had B-lineage phenotype, and 13% were Philadelphia chromosome positive. In the 54 patients for whom response data was available, the 4 week CR rate was 82%. Among the patients who had the opportunity to complete Intensification therapy, asparaginase data was available for 23 patients, 18 (78%) of whom completed all 30 weeks. One death occurred during induction therapy from sepsis. Four patients developed grade 3 pancreatitis and one patient died of grade 5 pancreatitis. The latter case represented the only remission death on study. There were two cases of osteonecrosis, 10 cases of thrombosis/embolism and 12 cases of neutropenic infection that occurred during the post-remission period. At the median follow-up time of 18.4 months, the estimated EFS is 75% (95%CI: 61–89%) and the overall survival is 79% (95%CI: 65–93%).

Conclusions: These results suggest that administration of a dose intensified pediatric-like strategy is feasible. Although the high EFS rate requires longer follow up and larger confirmatory studies, such intensive treatment of young adults with ALL could represent a major therapeutic advance.