Second Chance for Mylotarg

Acute myeloid leukemia treatment with gemtuzumab ozogamicin successful

(RxWiki News) Drug development is a tricky process, and it's common for pharmaceuticals to flounder initially before their best use is discovered.

The issue is further complicated when you consider that drugs made to fight cancer are usually designed to kill cells, so it is not surprising that many pharmaceutical therapies struggle with the balance between effective treatment and toxic effects.

So although FDA approval was withdrawn for the cancer drug Mylotarg (gemtuzumab ozogamicin) recent research on tweaking the dose may prove to be a second chance for using Mylotarg as an effective cancer treatment.

"Ask your doctor about combination therapy."

Researchers from the Centre Hospitalier de Versailles in France experimenting with lower doses of Mylotarg given on top of normal chemotherapy doubled the amount of patients who had no symptoms of cancer after two years.

The study was a phase III clinical trial, showing that standard chemotherapy with the addition of fractionated Mylotarg was a better alternative than chemotherapy alone.

Like many drugs used to treat cancer, Mylotarg had side effects in some patients, most importantly blood abnormalities, due to high levels of the drug in the body affecting healthy cells. Fractionated dosing is a method of delivering the same amount of drug over time while reducing the highest amount at any given point.

FDA approval of Mylotarg was withdrawn in 2010 after ten years, when a clinical trial showed that use of the drug raised overall mortality in patients.

Lead author and professor Sylvie Castaigne, MD, wrote that after with the lower dose, "We believe that our results support the reevaluation of the place of gemtuzumab ozogamicin in available front-line therapy for acute myeloid leukaemia."

The study compared 140 patients given chemotherapy as a control with 140 patients given the same chemotherapy as well as fractionated Mylotarg. The patients were between 50 and 70 years old, newly diagnosed acute myeloid leukemia. Two year survival improved from 17 percent to 41 percent when Mylotarg was added to the cancer therapy.

Some prominent researchers feel that each case of cancer should be evaluated genetically for an individualized therapy, but traditionally cancers have been treated depending on where in the body they began. Debate on this topic has increased as more advanced cancer drugs target increasingly specific molecular characteristics, which patients may or may not have.

Published with the study were the comments of Elihu Estey, MD reflecting on the history of Mylotarg in the context of the need to pick the right drug for each patient, rather than treating all cancers the same.

"Indeed, experience with gemtuzumab ozogamicin suggests a need to move beyond focusing on an average result. Instead, emphasis needs to be placed on outcome in various subsets of this highly heterogeneous disease."

The study and accompanying editorial were published in The Lancet on April 21, 2012.

Funding for the study was provided by the pharmaceutical corporation Pfizer.

Review Date: 
May 3, 2012