Dr. Porter noted that since 2005, the treatment standard for GBM has been concomitant TMZ with radiotherapy followed by adjuvant TMZ. This resulted in a 2-year survival rate of 26.5%, which was higher than any prior treatment regimen had shown. The time to progression on this regimen is about 6 months, she said, which points to the refractory and aggressive nature of this tumor.
Thus far, she added, bevacizumab has been the only agent approved by the Food and Drug Administration for use in the setting of recurrent GBM. Given the dismal prognosis for this patient population, novel agents are needed not only to augment up-front therapy to prevent recurrence but also to provide further treatment options in the recurrent setting. Dr. Porter described the study of Ms. Gilbert and colleagues as “eloquent,” and noted “the remarkable in vitro and in vivo data” suggesting that GSI and TMZ act together to halt neurosphere replication, and the finding that administering a GSI after TMZ may have the maximum impact in affecting neurosphere repopulation. “These data suggest that GSIs may indeed have an impact on glioblastoma recurrence and time to progression.”
Dr. Porter agreed with the authors’ observation that future studies to assess the total impact of the GSI in the GBM population will need to incorporate irradiation in addition to TMZ to reflect a more accurate sense of the full effect and toxicity of the GSI.
The National Institutes of Health and the CVIP Technology Development Fund funded the research. The investigators had no conflicts of interest to disclose.