Chemo-immunotherapy Using Ibrutinib Plus Indoximod for Patients With Pediatric Brain Cancer

Recent lab-based discoveries suggest that IDO (indoleamine 2,3-dioxygenase) and BTK (Bruton's tyrosine Kinase) form a closely linked metabolic checkpoint in tumor-associated antigen-presenting cells. The central clinical hypothesis for the GCC2020 study is that combining ibrutinib (BTK-inhibitor) with indoximod (IDO-inhibitor) during chemotherapy will synergistically enhance anti-tumor immune responses, leading to improvement in clinical response with manageable overlapping toxicity. The GCC2020 trial is a prospective open-label phase 1 trial to determine the best safe dose of the BTK-inhibitor ibrutinib to use in combination with previously studied chemo-immunotherapy regimens comprised of the investigational IDO-inhibitor indoximod plus oral palliative chemotherapy for participants, age 6 to 25 years, with relapsed or refractory primary brain cancer. Those previously treated with indoximod-based therapy may be eligible, including prior treatment via the phase 2 indoximod study (GCC1949, NCT04049669), the now closed phase 1 study (NLG2105, NCT02502708), or any expanded access (compassionate use) protocols. Ibrutinib will be combined with either indoximod plus oral cyclophosphamide and etoposide (Regimen A) or indoximod plus oral temozolomide (Regimen B). No cross-over between these two regimens will be allowed. Dose-escalation cohorts will determine the best safe dose of ibrutinib for each of these regimens. This will be followed by expansion cohorts, using ibrutinib at the best safe dose for each regimen, to allow assessment of preliminary evidence of efficacy.