The MDS Beacon™

Trisenox (arsenic trioxide) may have some efficacy in the treatment of myelodysplastic syndromes (MDS), according to a Phase 2 study conducted by Italian researchers.

The findings were presented at the 51^st annual American Society of Hematology (ASH) Meeting and Exposition in New Orleans on December 8.

Trisenox is an FDA-approved therapeutic agent for the treatment of certain types of leukemia. It is currently being studied for use in the treatment of high- and low-risk MDS. In vitro studies, which are those performed in controlled environments like test tubes or Petri dishes, have shown that the efficacy of Trisenox in tumor cells can be increased by combining Trisenox with vitamin C.

The Italian researchers studied the effects of Trisenox in combination with vitamin C in MDS patients. The study included 44 patients with a median age of 71. Of these patients, 23 were assessed as having low- or intermediate-1 risk MDS and 18 as high- or intermediate-1 risk MDS.

Trisenox was given intravenously at a dose of 30 mg for five days, followed by 25 mg given twice weekly for 15 weeks. Vitamin C was given intravenously at 1000 mg within 30 minutes of each Trisenox transfusion.

Response was evaluated after two and four months of treatment. Ten patients showed a clinical response, which is a rate of 23 percent.

The response rate was 35 percent for lower- risk MDS patients and 6 percent for higher-risk patients. In eight of the 10 respondents, response was evident within the first eight weeks of treatment.

Twenty-three patients discontinued treatment due to disease progression, severe adverse effects, adverse events unrelated to drug use, and withdrawal of consent.

The most common drug-related side effects were severe neutropenia (low white blood cell count) and thrombocytopenia (low platelet count), at rates of 45 percent and 23 percent respectively.

The authors concluded that Trisenox is tolerable and active in the treatment of MDS. They noted that vitamin C did not increase the response rate nor the toxicity of Trisenox.

The authors also observed that the drug regimen was least tolerated in elderly and higher-risk MDS patients.

For more information, please see abstract 943 at the ASH Meeting Web site.