This drug was approved in 2000 through the FDA’s expedited release program. For what it’s worth, it was not approved for use in Europe because of several studies showing “only a small proportion” of patient’s achieving complete remission while on the drug and the lack of comparisons with other treatments.”
In the non randomized studies of 277 patients that led to U.S. approval in 2000:
The overall response (OR) rate for the three pooled monotherapy studies was 26% (71/277) consisting of 13% (35/277) of patients with CR and 13% (36/277) of patients with CRp (remission but platelets remain low). The median time to blast clearance in both CR and CRp patients was 28 days from the first dose of Mylotarg. The median time to remission was 60 days for both CR and CRp. Remission rates are shown in Table 1. Of the 157 patients who were ≥ 60 years old, the overall remission rate (OR = CR + CRp) was 24%. For the patients < 60 years old and all 277 patients the OR rates were 28% and 26%, respectively.
IN SMALL Print it is noted:
The median overall survival was 3.3 months for NR (not responding) patients; in all 277 patients it was 4.9 months. (Medicynical emphasis: a 1.6 month benefit)
The approval in 2000 was conditional on further studies being done. These studies have now been analyzed and the results show:
The five-year Mylotarg study released in December didn’t show benefit in response rate, disease free survival or overall survival in 627 previously untreated patients ages 18 to 60. Deaths possibly related to treatment were reported in 1.4 percent of patients taking standard therapy and 5.7 percent of patients with Mylotarg added to therapy, according to an analysis by the Southwest Oncology Group, one of the largest clinical trials cooperative groups supported by the National Cancer Institute.
Medicynical Note: This is bad news for elderly acute myelogenous leukemia. Trials of new drugs often show better results in initial studies than in later ones. The reason for this is not fully understood. Some drugs that on reevaluation were not as useful as previously thought include the various types of erytropoietin and estrogen hormone replacement therapy.
Sadly with the industry aggressively marketing new marginally effective drugs this type expensive result, both in terms of patient outcomes and cost, will be repeated in the future.