Adolescent and young adult patients with high-risk ALL have poorer survival than younger patients

CHICAGO — Adolescents and young adults with high-risk acute lymphoblastic leukemia had lower rates of event-free survival and OS compared with younger patients, according to results of a phase 3 Children’s Oncology Group study.

Adolescent and young adult (AYA) patients — defined as those aged 16 to 30 years — also had higher rates of relapse than patients aged 1 to 15 years, researchers said.

Historical data suggest AYA patients with high-risk ALL have inferior outcomes compared with younger patients. AYA patients have higher rates of relapse and higher rates of toxicity, possibly because of differences in disease biology, treatment, host factors and complex socioeconomic factors, the researchers said.

Most previous analyses were comparisons between different clinical trials. However, the scope of this trial allowed for a direct comparison of outcome between the two age groups.

Most pediatric ALL trials had upper age limits of 18 or 21 years. For this trial, researchers included patients up to age 30 years so they could make that direct comparison.

Eric Larsen, MD, medical director of the Maine Children’s Cancer Program, and colleagues enrolled 2,574 patients aged 1 to 30 years with newly diagnosed B-precursor high-risk ALL. The study included 501 AYA patients. Of them, 466 were aged 16 to 21 years and 35 were aged 22 to 30 years.

Five-year event-free survival was 80.9% in the younger patient group, compared with 68% among AYA patients (P<.0001), study results showed. OS was 88.4% in the younger patient group, compared with 79.8% among AYA patients (P<.0001). Both results were highly statistically significant, the researchers said.

Although 5-year event-free survival among AYA patients was inferior to that seen in younger patients, it was an improvement over outcomes of many previous trials, which typically show 5-year event-free survival among AYA patients in the 50% to 60% range, Larsen said during a press conference.

In the Children’s Oncology Group study, AYA patients also had higher rates of relapse (21.3% vs. 13.4%; P=.0018), as well as higher rates of remission deaths (5.5% vs. 2.1%). Both differences were statistically significant.

“This study tells us that the inferior outcome for AYA patients is the result of more resistant disease, resulting in higher rates of relapse and higher rates of toxicity from treatment,” Larsen said. “We have to find novel agents to better eradicate the leukemia, but while we want to intensify therapy, we also have to reduce toxicity.”

For more information:

Larsen E. Abstract #CRA9508. Presented at: the 2012 American Society of Clinical Oncology Annual Meeting; June 1-5, 2012; Chicago.

Disclosure: The researchers report no relevant financial disclosures.