Phase I/II Study of the WEE1 Inhibitor Adavosertib (AZD1775) in Combination with Carboplatin in Children with Advanced Malignancies: Arm C of the AcSé-ESMART Trial.

PURPOSE: AcSé-ESMART Arm C aimed to define the recommended dose and activity of the WEE1 inhibitor adavosertib in combination with carboplatin in children and young adults with molecularly enriched recurrent/refractory malignancies. PATIENTS AND METHODS: Adavosertib was administered orally, twice every day on Days 1 to 3 and carboplatin intravenously on Day 1 of a 21-day cycle, starting at 100 mg/m2/dose and AUC 5, respectively. Patients were enriched for molecular alterations in cell cycle and/or homologous recombination (HR). RESULTS: Twenty patients (median age: 14.0 years; range: 3.4-23.5) were included; 18 received 69 treatment cycles. Dose-limiting toxicities were prolonged grade 4 neutropenia and grade 3/4 thrombocytopenia requiring transfusions, leading to two de-escalations to adavosertib 75 mg/m2/dose and carboplatin AUC 4; no recommended phase II dose was defined. Main treatment-related toxicities were hematologic and gastrointestinal. Adavosertib exposure in children was equivalent to that in adults; both doses achieved the cell kill target. Overall response rate was 11% (95% confidence interval, 0.0-25.6) with partial responses in 2 patients with neuroblastoma. One patient with medulloblastoma experienced unconfirmed partial response and 5 patients had stable disease beyond four cycles. Seven of these eight patients with clinical benefit had alterations in HR, replication stress, and/or RAS pathway genes with or without TP53 alterations, whereas TP53 pathway alterations alone (8/10) or no relevant alterations (2/10) were present in the 10 patients without benefit. CONCLUSIONS: Adavosertib-carboplatin combination exhibited significant hematologic toxicity. Activity signals and identified potential biomarkers suggest further studies with less hematotoxic DNA-damaging therapy in molecularly enriched pediatric cancers.

A Phase 1 Study to Evaluate Absolute Bioavailability and Absorption, Distribution, Metabolism, and Excretion of Savolitinib in Healthy Male Volunteers.

Savolitinib is an oral MET (hepatocyte growth factor receptor) tyrosine kinase inhibitor, with demonstrated preliminary efficacy in several cancer types. Previous pharmacokinetics assessments showed that savolitinib is rapidly absorbed but there are limited data on the absolute bioavailability and absorption, distribution, metabolism, and excretion (ADME) of savolitinib. This open-label, two-part, phase 1 clinical study (NCT04675021) used a radiolabeled micro-tracer approach to evaluate absolute bioavailability and a traditional approach to determine the ADME of savolitinib in healthy male adult volunteers (N = 8). Pharmacokinetics, safety, and metabolic profiling and structural identification from plasma, urine, and fecal samples were also assessed. Volunteers received a single oral savolitinib 600 mg dose followed by intravenous 100 µg of [14 C]savolitinib in Part 1 and a single oral 300 mg [14 C]savolitinib dose (≤4.1 MBq [megabecquerel] [14 C]) in Part 2. Following Part 1, absolute oral bioavailability was 69%, the median time of maximum observed concentration was 3.5 hours, and the mean terminal half-life was 6.1 hours. Following Part 2, 94% of the radioactivity administered was recovered, with 56% and 38% in urine and feces, respectively. Exposure to savolitinib and metabolites M8, M44, M2, and M3 accounted for 22%, 36%, 13%, 7%, and 2%, respectively, of plasma total radioactivity. Approximately 3% of the dose was excreted as unchanged savolitinib in urine. Most savolitinib elimination occurred via metabolism by several different pathways. No new safety signals were observed. Our data show that the oral bioavailability of savolitinib is high and the majority of savolitinib elimination occurs via metabolism and is excreted in the urine.

A Phase 1b Study to Evaluate the Safety and Efficacy of Durvalumab in Combination With Tremelimumab or Danvatirsen in Patients With Relapsed or Refractory Diffuse Large B-Cell Lymphoma.

BACKGROUND: Despite recent advances, outcomes in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) remain poor. Immune checkpoint inhibitors have shown limited efficacy in this setting, but combinations with novel agents may enhance benefit. Combination therapy with durvalumab, an anti-programmed death ligand 1 (PD-L1) antibody, and danvatirsen (AZD9150; an antisense oligonucleotide inhibiting signal transducer and activator of transcription 3 [STAT3]) or tremelimumab (an anti-cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] antibody) may augment endogenous antitumor activity. PATIENTS AND METHODS: In this phase 1b dose escalation and dose expansion study, we evaluated durvalumab 20 mg/kg every 4 weeks plus either tremelimumab 1 mg/kg every 4 weeks or danvatirsen 2 or 3 mg/kg (administered on days 1, 3, 5, 8, 15, and 22, then every week). Treatment continued until disease progression. The primary endpoint was safety; secondary endpoints included efficacy, pharmacokinetics, and immunogenicity. RESULTS: As of April 4, 2019, 32 patients were enrolled and treated, receiving a median of 2 prior lines of systemic therapy. Treatment-related adverse events occurred in 21 patients (65.6%), most commonly alanine aminotransferase/aspartate aminotransferase increased (grade 1-3), anemia (grade 1-3), and fatigue (grade 1). The overall objective response rate was 6.3%, with 2 partial responses. Median time to response was 11.0 weeks (range, 7.7-14.3 weeks). Median progression-free survival was 7.4 weeks (range, 0.1-31.4 weeks), and median overall survival was 28.0 weeks (range, 1.9-115.4 weeks). CONCLUSION: The primary endpoint was met, with durvalumab plus tremelimumab/danvatirsen generally well tolerated in patients with relapsed/refractory DLBCL; however, antitumor activity was limited.