Allogeneic stem cell transplantation for advanced acute promyelocytic leukemia: results in patients treated in second molecular remission or with molecularly persistent disease.

In all, 17 consecutive patients in hematological complete remission (HCR) of acute promyelocytic leukemia (APL) received allogeneic stem cell transplantation (SCT) from an HLA-identical sibling and were monitored by reverse transcriptase polymerase chain reaction of PML/RARalpha prior and after transplant. Median age was 31 years (range 3-50 years). At 10 years, the actuarial probabilities of nonrelapse mortality, relapse and disease-free survival were 32% (95% CI: 8-56%), 33% (95% CI: 6-60%) and 46% (95% CI: 22-70%). Six patients tested PCR +ve (1st HCR n=2; 2nd HCR n=3; 3rd HCR n=1) and 11 PCR -ve (2nd HCR n=11) pre-SCT. Of the six patients PCR +ve, two showed early persistence of PCR positivity and converted to sustained PCR negativity after CSA withdrawal (one died of secondary tumor in molecular remission and one is alive in relapse), while four converted to PCR -ve rapidly (one died of the underlying disease and three are in molecular remission). Of the 11 patients PCR -ve pre-SCT, six died (four of transplant-related mortality, one of relapse and one after heart transplantation) and five are alive, four in molecular remission and one is in relapse. Allogeneic SCT seems a valid option for advanced APL, particularly for the poor prognostic group of patients with pre-SCT molecularly persistent disease.