• Response [ Time Frame: Approximately 2 years ] [ Designated as safety issue: No ]
  

• Safety [ Time Frame: 30 days post last dose of study drug ] [ Designated as safety issue: Yes ]
  

Conventional therapy for MDS has been poor at best. Supportive care with transfusion therapy and antibiotics have remained an option for all patients with MDS.

The only known curative therapy is an allogeneic bone marrow transplant. However due to its high morbidity in this elderly population and the lack of available donors, it is estimated that less than 5% of patients with MDS are candidates for this type of aggressive therapy. Investigational therapies are thus warranted in MDS.

Decitabine shows significant clinical activity in patients with MDS, with moderate toxicity. The major toxicity is myelosuppression with subsequent infection occurring in 20-25% of patients.

Arsenic trioxide is an FDA approved drug for the treatment of patients with acute promyelocytic leukemia (APL) who are refractory to, or have relapsed from, retinoid and anthracycline chemotherapy. Two pivotal studies of arsenic trioxide in the setting of relapsed APL showed a complete remission rate of 87% with a 36 month survival estimate of 50%. As of May 2004, over 800 patients had received arsenic trioxide in clinical studies or through a compassionate use program, and an additional 3600 patients had received the drug in clinical practice.

Arsenic trioxide shows clinical activity in MDS. Side effects have been noted and are manageable.

Adult patients with an established diagnosis of MDS will receive decitabine 20 mg/m2 IV over one hour for days1-5 of each cycle, and arsenic trioxide 0.25 mg/kg IV for days 1-5 of cycle 1 followed by 0.25 mg/kg twice weekly (Mon-Thurs or Tues-Fri) for all remaining cycles. The dose of ascorbic acid will be 1000 mg in 100 mL D5W (protected from light and air) administered as an IV infusion over 15 to 30 minutes and administered within 30 minutes after arsenic trioxide administration.

Each cycle will consist of 4 weeks of treatment, and patients will be assessed each cycle for toxicity, and after 4 cycles for response as defined by the IWSG (see section 8.0). Patients will have transfusion and supportive care therapy administered per the treating physician's discretion.

Patients with a response (CR, PR, or hematologic improvement) after 4 cycles of therapy may choose to continue on two more cycles of decitabine with arsenic and ascorbic acid given only during the first week of those two additional cycles.