Glioblastoma: Prognosis is poor, but new therapies are emerging
Standard treatment approaches
The first step in the treatment of glioblastomas is maximal safe therapy, Dr. Lee said.
“You want to achieve as much of a resection as possible without leaving the patient with some sort of permanent neurologic deficit that could severely compromise the quality of their life,” she explained.
Sen. McCain’s tumor was “completely resected by imaging criteria,” according to the Mayo Clinic statement, which also noted that treatment options might include a combination of chemotherapy and radiation.
Indeed, the standard of care for glioblastomas after surgery is combined chemotherapy and radiation – typically given as approximately 6 weeks of radiation combined with oral temozolomide chemotherapy – followed by 6 monthly cycles of temozolomide, she explained.
Radiation is sometimes given for only 3 weeks, but this option is mainly reserved for elderly patients, she said, adding that trials in patients aged 65-70 years have shown that this shorter course of radiation can be equally effective but potentially less toxic.
Emerging treatment approaches
Another treatment that has shown promise involves the use of tumor-treating fields (TTFields) – a locoregionally delivered antimitotic treatment that disrupts cell division and organelle assembly.
A 2015 phase 3 trial showed that adding TTFields to maintenance temozolomide significantly prolonged progression-free and overall survival, Dr. Ahluwalia said.
Other studies, including two presented during poster sessions at the ASCO annual meeting, have shown a progression-free survival benefit with the addition of bevacizumab to the treatment regimen. One open-label phase 2 study showed that hypofractionated radiotherapy in combination with IV bevacizumab every 2 weeks vs. radiotherapy alone in newly diagnosed patients over age 65 years improved progression-free survival (median, 7.6 vs. 4.8 months), but not overall survival (median, 12.1 vs. 12.2 months).
Another phase 2 study presented by Phioanh (Leia) Nghiemphu, MD, of the University of California, Los Angeles, showed that in newly diagnosed patients aged 70 years and older, upfront treatment with bevacizumab and temozolomide was associated with promising survival benefits (overall survival, 12.3 months; progression-free survival, 5.1 months) and tolerable side effects. The best survival in multivariate analysis was in patients who received radiotherapy at progression; it was unclear whether the addition of bevacizumab led to a survival advantage, but it may have allowed delay of radiotherapy treatment, she noted.
“Although we have no cure for glioblastoma, treatments can control tumor growth for a period of time, and there are additional promising therapies emerging every day to treat this deadly cancer, she said in an interview. “There has been increasing interest in developing better therapies for the older patients with glioblastoma with less toxicity and still-robust survival, such as the addition of bevacizumab or a short course of radiotherapy with temozolomide chemotherapy.”
Dr. Ahluwalia encourages clinical trial participation for patients diagnosed with glioblastoma and noted that he is particularly excited about immunotherapy and targeted therapy trials.
Dr. Lee has served as consultant to Eli Lilly. Dr. Ahluwalia disclosed a financial relationship with multiple companies, including Novocure, which markets a TTFields device. Dr. Weller disclosed a financial relationships with multiple companies, including Novocure; Merck Sharp & Dohme, which markets temozolomide; and Roche, which markets bevacizumab. Dr. Nghiemphu has received research funding from Genentech/Roche and Novartis. Dr. Mohapatra reporting having no disclosures.
