Intratumoral oncolytic herpes virus G47 increment for residual or recurrent glioblastoma: a phase 2 trial

Results from a pivotal single-arm phase 2 trial show that the repeated intratumoral administration of the oncolytic herpes virus G47 increment in residual or recurrent glioblastoma exhibits survival benefit and a safe profile. This investigator-initiated, phase 2, single-arm trial primarily assessed the efficacy of G47 increment , a triple-mutated, third-generation oncolytic herpes simplex virus type 1, in 19 adult patients with residual or recurrent, supratentorial glioblastoma after radiation therapy and temozolomide (UMIN-CTR Clinical Trial Registry UMIN000015995). G47 Delta was administered intratumorally and repeatedly for up to six doses. The primary endpoint of 1-yr survival rate after G47 increment initiation was 84.2% (95% confidence interval, 60.4-96.6; 16 of 19). The prespecified endpoint was met and the trial was terminated early. Regarding secondary endpoints, the median overall survival was 20.2 (16.8-23.6) months after G47 increment initiation and 28.8 (20.1-37.5) months from the initial surgery. The most common G47 increment -related adverse event was fever (17 of 19) followed by vomiting, nausea, lymphocytopenia and leukopenia. On magnetic resonance imaging, enlargement of and contrast-enhancement clearing within the target lesion repeatedly occurred after each G47 increment administration, which was characteristic to this therapy. Thus, the best overall response in 2 yr was partial response in one patient and stable disease in 18 patients. Biopsies revealed increasing numbers of tumor-infiltrating CD4(+)/CD8(+) lymphocytes and persistent low numbers of Foxp3(+) cells. This study showed a survival benefit and good safety profile, which led to the approval of G47 increment as the first oncolytic virus product in Japan.