Nearly 40% of children treated within the AML BFM studies experience recurrence of their disease after having achieved remission. In our retrospective analysis we tried to estimate prognosis after relapse in children treated with intensive relapse regimens and studied the impact of prognostic factors for second remission and survival.
Patients: 102 patients suffering from first relapse were treated intensively according to the relapse protocols BFM REZ91 and REZ93 or intensive salvage therapy consisting of double induction with high dose Ara-C, mitoxantrone and VP-16. Once in CR, patients continued to receive a 6-week consolidation and either allogeneic or autologous bone marrow transplantation (BMT).
Results: Time to relapse was in median 1.1 years, range 0-8 years. Fifty-two of 102 pts. (51%) achieved 2nd remission (CR), 10 (10%) partial remission, 37 (36%) were nonresponders, and 3(3%) died early during salvage therapy. Twenty-seven were still in CR, median 2.5 years, range 0.4-7.0 years, with an overall survival of 21%, SE 5% after 5 years. The response and survival rate was similar in all treatment groups. Fifty patients were transplanted, 43 being in 2nd CR, and 7 with residual blasts. Twenty-seven patients received an allograft: Twenty-one from a matched sibling (MSD), 1 from a haploid and 5 from a matched unrelated donor (MUD); 23 received an autograft. None of the patients transplanted in partial remission survived. Whereas 7 of 16 patients were alive after MSD in 2nd CR, 1 after haploid BMT. Four of 5 patients died after MUD BMT. Multivariate risk factor analysis revealed duration until relapse to be the most important factor for survival after relapse. The maximum risk-ratio was obtained at a threshold value of 1.5 years after diagnosis resulting in a 5-year survival of 10%, SE 5% for early relapse, and 40%, SE 10% for late relapse, p logrank 0.0001.
Conclusion: Intensive relapse regimens can induce a 2nd CR in half of the patients. Children with late relapse (> 1.5 years after diagnosis) have a realistic chance for longtime survival.