WEDNESDAY, March 18, 2015 (HealthDay News) -- An FDA-approved drug doubled the amount of time that patients with Hodgkins lymphoma survived without any progression in their disease, a new study shows.

All of the patients also received stem cell therapy along with the drug, called brentuximab vedotin.

While the results are encouraging, doctors may never know if the drug is actually lengthening patients' lives, said Dr. Owen O'Connor, director of the Center for Lymphoid Malignancies at Columbia University Medical Center in New York City.

That's because brentuximab is fast becoming standard care for all patients with Hodgkin lymphoma who've relapsed after stem cell transplant, he said. So, a trial comparing the survival of patients who got the drug against those who did not might never be feasible, due to ethical concerns.

O'Connor was not involved in the trial, which was led by Dr. Craig Moskowitz, professor of medicine at Memorial Sloan Kettering Cancer Center in New York City. His team published the findings March 18 in The Lancet. The study was funded by Seattle Genetics Inc. and drug maker Takeda.

According to the American Cancer Society, about 9,000 new cases of Hodgkin lymphoma are diagnosed each year, and more than 1,100 people die from the illness annually. The cancer most often strikes young adults.

The phase 3 trial of brentuximab vedotin included 329 patients, aged 18 and older, who were at high risk of cancer relapse or progression after undergoing stem cell transplant, in which healthy stem cells from the patient are used to replace those lost to cancer or chemotherapy.

The patients were randomly assigned to receive 16 cycles of brentuximab vedotin infusions once every three weeks, or an inactive placebo.

After two years, there was no cancer progression in 65 percent of the patients who received the drug, compared with 45 percent of those in the placebo group, the researchers found. Progression-free survival was 43 months for those who received the drug, compared with 24 months for those in the placebo group.

"Nearly all of these patients who are progression-free at two years are likely to be cured since relapse two years after a transplant is unlikely," Moskowitz said in a journal news release. "No medication available today has had such dramatic results in patients with hard-to-treat Hodgkin lymphoma," he said.

Read more:
New Drug May Help Keep Hodgkin Lymphoma at Bay