Oblimersen Shows Promising Results in Older Patients with Acute Myeloid Leukemia
May 6, 2005 - 10:19:38 AM

Researchers from Ohio University, University of Chicago, the National Cancer Institute and Genta, Inc. have reported a promising phase I study of Genasense™ (oblimersen) in untreated older patients with acute myeloid leukemia (AML). The details of this study appeared as an advanced on-line publication in the Journal of Clinical Oncology on April 11, 2005.[1]

Bcl-2 is a potent inhibitor of apoptosis which is a cause of cell death. Over-expression of this protein in patients with leukemia is associated with resistance to chemotherapy.

The Bcl-2 antisense oligonucleotide, Genasense™ down-regulates Bcl-2 and has been investigated in several hematological malignances where Bcl-2 has been implicated in disease resistance. In vitro studies have suggested that Genasense™ can down-regulate Bcl-2 activity and inhibit cell viability. Thus, the targeting of Bcl-2 was a potential strategy for treatment of leukemia. These same researchers previously reported the results of treatment of patients with refractory AML with the combination of Fludara®, cytarabine, Genasense™ and Neupogen®.[2]

Seventeen patients in this study had relapsed or refractory AML and 3 had acute ALL, including 2 patients who had failed stem cell transplantation. Five patients with AML and one patient with ALL achieved a complete response. Three other patients had disappearance of blasts but did not achieve full hematological recovery. In two patients, the response persisted for over one year before recurrence. Responses were also seen in older patients. The researchers also reported that Bcl-2 mRNA levels were down-regulated in 75% of evaluable patients.

The current study included 29 patients who were 60 years of age or older with newly diagnosed AML. All received treatment with cytarabine, daunomycin and Genasense™. Complete remissions occurred in 14 patients (48%). Seven of these 14 patients have relapsed. They suggested that the degree of down regulation of Bcl-2 correlated with response. These authors stated that CALGB would be performing a randomized trial in older patients with newly diagnosed AML to determine the contribution of Genasense™.

Comments: It’s impossible to tell from this study whether or not Genasense™ contributed to outcome and the randomized trial will be of great interest.

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