CTNI-45. PHASE 2 STUDY OF SORAFENIB, VALPROIC ACID, AND SILDENAFIL IN THE TREATMENT OF RECURRENT HIGH-GRADE GLIOMA

Abstract PURPOSE Here we report the results of a single-center phase 2 clinical trial combining sorafenib tosylate, valproic acid, and sildenafil for the treatment of patients with recurrent high-grade glioma. PATIENTS AND METHODS Eligible patients were 18 years of age and older with an Eastern Cooperative Oncology Group performance status of 0-2 and pathologically confirmed high-grade glioma (WHO grade 3 or 4), with documented CT or MRI progression or recurrence and measurable or evaluable disease. The treatment schedule was a combination of sorafenib, valproic acid, and sildenafil, each agent administered orally, twice daily continuously. A cycle consisted of 4 weeks. RESULTS Clinical toxicities were grade 1 and grade 2, with one grade 3 toxicity for maculopapular rash (6.4%). For all evaluable patients, the median progression-free survival was 3.65 months and overall survival (OS) 10.0 months. There was promising evidence showing clinical activity and benefit. In the 33 evaluable patients, low protein levels of the chaperone GRP78 (HSPA5) was significantly associated with a better OS (p < 0.0026). A correlation between the expression of PDGFRa and OS approached significance (p < 0.0728). Five patients presently have a mean OS of 73.6 months and remain alive. CONCLUSIONS This is the first therapeutic intervention glioblastoma trial to significantly associate GRP78 expression to OS. Our data suggest that the combination of sorafenib tosylate, valproic acid, and sildenafil requires additional clinical development in the recurrent glioma population.