Results of therapy with interferon alpha and cyclic combination chemotherapy in patients with philadelphia chromosome positive chronic myelogenous leukemia in early chronic phase

The objective of the study was to investigate the toxicity and efficacy of cyclic combination therapy offered to patients with Ph-positive CML having a sub-optimal response to IFN-α. Patients in early chronic phase CML were treated with IFN-α at 5MU/m² daily. Patients who did not achieve cytogenetic response after 6 months of IFN-α therapy, or Ph-suppression to less than 35% Ph-positive cells (partial cytogenetic response) after 12 months of therapy were offered cyclic intensive chemotherapy every 6 months, with IFN-α maintenance between cycles. The initial 3 cycles included daunorubicin, vincristine, cytosine arabinoside (ara-C) and prednisone (DOAP). Later cycles were given with cyclophosphamide replacing daunorubicin (COAP). Of 74 patients treated, 61 (82%) achieved complete hematologic response (CHR): 51 (69%) had a cytogenetic response, which was major (Ph < 35%) in 31 (42%), and complete in 23 (31%). Fifty-five patients (74%) achieved CHR by 6 months of therapy, 38 (69%; 51% of total) with a cytogenetic response - 13 (24%) had a major cytogenetic response. Seventeen patients received at least 1 course of DOAP therapy. Median survival of the overall cohort of patients was 120 months. With a median follow-up of 145 months (103+ to 155+ months), 40 patients (54%) have died. The median duration of cytogenetic response was 35 months (range 3 to 149+ months) and the estimated 10-year cytogenetic response rate was 37%. A durable complete cytogenetic response was observed in 16 patients (20%) with a median duration of 139+ months (range 12+ to 149+ months), 11 of them (15%) are now off IFN-α therapy for a median of 57+ months (range 12+ to 128+ months). The projected 10-year survival was 50% for the study group versus 35% for 208 patients who received other IFN-α based regimens at the MD Anderson Cancer Center (p<.01). In conclusion, the addition of intensive chemotherapy may improve survival in patients with CML who have not obtained an adequate cytogenetic response on an IFN-α-based regimen.