Vinblastine shows promise against pediatric low-grade glioma

NEW YORK (Reuters Health) - Phase II trial results suggest vinblastine might be an option for children with refractory low-grade glioma (LGG).

With weekly vinblastine, the estimated five-year event-free survival (42.3%) was comparable to the 30% to 40% seen with the most common first-line chemotherapy regimens using carboplatin and vincristine.

The new international study, published online March 5 by the Journal of Clinical Oncology, "is encouraging, because vinblastine provides another effective therapy for some pediatric patients with low-grade glioma who have already been treated with other chemotherapy," Dr. Mary Lovely, clinical science officer for the National Brain Tumor Society, told Reuters Health by e-mail.

"It may delay having radiation therapy in younger patients, thus decreasing its side effects," added Dr. Lovely, who was not involved in the trial. "In the long run, we will see some of these brain tumors treated as chronic illnesses. We need to have as many treatments as possible to manage them."

Pediatric LGG is "the most common brain tumor in children," Dr. Eric Bouffet of the Hospital for Sick Children, Toronto, who led the study, told Reuters Health by e-mail. "In the United States, more than 1,000 children are diagnosed each year."

A follow-up study of vinblastine in chemotherapy-naïve patients is underway, Dr. Bouffet said, with the first results due early next year. He expects vinblastine to be equivalent to other current treatments.

That would be good news, because vinblastine has several advantages, he said: It is cheap, it has a low toxicity profile, and it can be easily administered over prolonged periods.

The study reported this month involved 51 patients under age 21 (median age at enrollment, 7.2 years) with measurable disease on contrast-enhanced magnetic resonance imaging.

The most common histology was pilocytic astrocytoma. Most patients (34) had hypothalamic/chiasmatic tumors.

All but one had received at least one line of chemotherapy, and 10 had been treated with radiotherapy.

Vinblastine was given as an IV push at a dose of 6 mg/m2 (10 mg maximum) once a week for 52 weeks.

Response was assessable in 50 of 51 patients, and central review was performed in 48 patients.

There was one complete response, 10 partial responses, and seven minor responses. Nineteen patients had stable disease, and 13 had progressive disease.

Vinblastine was well tolerated. The main toxicity was hematologic, with 18 patients experiencing grade 4 neutropenia requiring dose reduction.

"The role of single-agent vinblastine and other vinca alkaloids in the management of pediatric low-grade gliomas deserves further investigation," the authors conclude.

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