Intraoperative drug delivery to hindbrain tumours via an injectable hydrogel is well tolerated and confers survival benefit against atypical teratoid/rhabdoid xenografts

Intraoperatively applied local drug delivery systems (LDDS) offer a means of overcoming blood-brain barrier (BBB) impermeability. However, there is a paucity of LDDS development for paediatric tumours arising in the posterior fossa. Here we demonstrate applicability of an LDDS against medulloblastoma group 3 (G3 MB) and atypical teratoid/rhabdoid tumours (AT/RT), neoplasms associated with poor prognoses. A poly(ethyleneglycol)-poly(caprolactone)-poly(ethyleneglycol) (PECE) hydrogel loaded with chemotherapeutics identified as effective against primary G3 MB and AT/RT in vitro, was prepared as an injectable, biodegradable formulation. CHIR99021 (glycogen synthase kinase-3 inhibitor), ribavirin (guanosine analogue) and PG545 (heparanase inhibitor) were chosen based upon an inability to traverse the BBB. The hydrogel alone was well-tolerated, and drug-loaded hydrogel achieved > 1-month therapeutic release. Orthotopic xenograft studies against G3 MB and AT/RT indicated good tolerability to combined CHIR99021 and PG545 or combined CHIR99021 and ribavirin loaded loaded LDDS respectively. Median survival of AT/RT arms receiving XRT alone was comparable to CHIR99021- and ribavirin-loaded LDDS, with long-term survivors observed only in the latter arm, demonstrating a significant survival benefit. LDDS against cerebellar tumours using PECE offers a promising therapeutic alternative and the possibility of circumventing radiation-induced adverse effects for children impacted by these diseases.