Treatment Of Newly Diagnosed


Table 6.1 presents the results of treatment of over 3000 APL patients from four continents and eight major leukemia cooperative groups since the advent of ATRA-based therapy in approximately 1990. In virtually all of these patients, the diagnosis of APL was confirmed by modern molecular or cytogenetic techniques, and all received ATRA during induction therapy, either alone or in combination with chemotherapy. While it is beyond the scope of this chapter to discuss each trial in detail, careful analysis of the aggregate results illuminates many of the successes (and some of the failures) of treatment of APL over the last 15 years. The most obvious success is the long-term survival rate of approximately 80%, which compares to a rate of 30-40% in the pre-ATRA era.33 Although 80% is a spectacular number, 5-10% of APL patients die early during induction, another 10% die of refractory disease, and 10% are successfully treated for relapsed APL (but are subjected to the side effects and long-term toxici-ties of salvage therapies). Furthermore, with the exception of one study,20 the event-free survival (EFS) of patients with high-risk disease is relatively poor, generally around 50-60%. Thus, as we enter the era of

"third-generation" ATRA-based protocols, exemplified by the APL200020 and AIDA200026 studies, our challenge is to better manage patients during the initial induction period (particularly those who present with high WBC counts), and to choose appropriate therapies based on accurate risk-group assessment. Questions remain, and newer approaches are under study,34 but curative, safe treatments for virtually all patients with APL are now available, and it is fair to say that survival free of disease should be attainable for up to 95% of APL patients who survive induction therapy. Assuming a 5% rate of early death, and a small number of relapses and deaths in CR, the EFS target for all future trials of APL should be 85-90%, and anything below this number should be considered unacceptable.

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