Arsenic Trioxide Effective as Single Agent in Newly Diagnosed APL

Arsenic Trioxide Effective as Single Agent in Newly Diagnosed APL

According to an article recently published in the journal Blood, the agent arsenic trioxide, when used as a single agent, provides impressive outcomes among patients with newly diagnosed acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is a subset of acute myeloid leukemia (AML), a fast-growing cancer of the blood cells. APL is not common; it affects just approximately 1,500 individuals annually in the U.S.

APL is a cancer of the white blood cells (immune cells) that causes these cells to remain in an immature state and continue to replicate uncontrollably. The immature blood cells are not able to perform their intended function of fighting infection and also suppress the maturation of other blood cells.

Standard initial treatment for APL consists of chemotherapy, including an anthracycline (doxorubicin, epirubicin, mitoxantrone, idarubicin) and the agent all trans-retinoic acid (ATRA).

Arsenic trioxide (ATO) is an agent that provides impressive anticancer activity in patients with APL who experience a relapse following prior therapy. Studies have indicated that the combination of ATRA and ATO is also very effective in the treatment of APL.

Researchers from India recently conducted a clinical trial to evaluate ATO as a single agent in the treatment of newly diagnosed APL. This trial included 72 patients who received treatment with ATO. As well, 74% of patients received the chemotherapy agent hydroxyurea to help normalize blood cell levels, and eight patients received treatment with a chemotherapy agent classified as an anthracycline.

ATO produced impressive outcomes in these patients. The median follow-up was 2 years:

  • A complete disappearance of detectable cancer was achieved in 86% of patients.
  • Only 12% of patients experienced a cancer relapse.
  • Overall survival was 86%.
  • Side effects were reported to be minimal.
  • Most therapy following initial disease control was administered in an outpatient setting.

The researchers concluded that treatment with single-agent ATO provides impressive long-term outcomes and appears extremely well tolerated in patients with newly diagnosed APL. Furthermore, the authors note that treatment with ATO is relatively inexpensive compared to standard treatment for APL with combination chemotherapy or ATRA. Larger clinical trials further evaluating ATO as a single agent for treatment of newly diagnosed APL are necessary to determine the true effectiveness of this approach.

Reference: Mathews V, George B, Lakshmi KM, et al. Single-agent arsenic trioxide in the treatment of newly diagnosed acute promyelocytic leukemia: durable remissions with minimal toxicity. Blood. 2006;107:2627-2632.

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