Abstract Proteasome inhibition sensitizes glioma cells to TMZ and RT, providing a novel therapeutic strategy for ndGBM. MRZ, an irreversible, brain-penetrant, pan-proteasome inhibitor with anti-glioma activity was combined with standard-of-care (SOC) concomitant TMZ/RT followed by adjuvant TMZ in ndGBM (NCT02903069), to determine the recommended dose (RD). Patients were enrolled in separate concomitant (TMZ/RT+MRZ, N=15) and adjuvant (TMZ+MRZ, N=18) cohorts in dose-escalation (3 + 3 design), followed by dose-expansion (N=20) at RD (0.8 mg/m2) in concomitant followed by adjuvant treatment. MRZ infused IV (10 min) at increasing dose levels (0.55, 0.7, 0.8, and 1.0 mg/m2): Concomitant days 1, 8, 15, 29, 36; Adjuvant days 1, 8, 15 (28-day cycle). RESULTS (as of 02May2018): Mean age 55 years, 68% male. Most common treatment-emergent adverse events (TEAEs, 20% patients, all grades): fatigue, nausea, vomiting, hallucination, ataxia, headache. Dose-limiting toxicities (DLTs): 1 (fatigue) at 0.7 mg/m2 adjuvant cohort, 3 (ataxia/diarrhea; ataxia/confusion; myocardial infarction) in concomitant and 2 (delirium/ataxia; ataxia/fatigue) in adjuvant cohorts at 1.0 mg/m2. Grade 3 TEAEs in 11 of 12 patients at 1.0 mg/m2 including one Grade 4 and one Grade 5 TEAE; at 0.8 mg/m2 MRZ, Grade 3 TEAEs in 9 of 21 patients. MRZ demonstrated a steep dose-response with TEAEs/DLTs predominately CNS AEs (ataxia, hallucinations) which were dose-related, short-lasting, reversible and ameliorated by early dose reductions, allowing patients to remain on treatment. Currently 8 dose-escalation patients remain active in Cycle 10–23. Median OS for dose-expansion not yet estimated; 7 patients remain active, 1 death, median follow-up 4.1 months. MRZ at the RD with adjuvant TMZ+Tumor Treating Fields (Optune) is currently enrolling. An international Phase 3 trial (EORTC #1709-BTG, NCT03345095) has been launched in 2018 to assess the overall survival benefit of MRZ added to SOC in ndGBM.

Desmoplasia describes the deposition of extensive extracellular matrix and defines primary pancreatic ductal adenocarcinoma (PDA). The acellular component of this stroma has been implicated in PDA pathogenesis and is being targeted therapeutically in clinical trials. By analyzing the stromal content of PDA samples from numerous annotated PDA data sets and correlating stromal content with both anatomic site and clinical outcome, we found PDA metastases in the liver, the primary cause of mortality to have less stroma, have higher tumor cellularity than primary tumors. Experimentally manipulating stromal matrix with an anti-lysyl oxidase like-2 (anti-LOXL2) antibody in syngeneic orthotopic PDA mouse models significantly decreased matrix content, led to lower tissue stiffness, lower contrast retention on computed tomography, and accelerated tumor growth, resulting in diminished overall survival. These studies suggest an important protective role of stroma in PDA and urge caution in clinically deploying stromal depletion strategies.