Evaluating the Base Excision Repair Inhibitor TRC102 and Temozolomide for patients with Recurrent Glioblastoma in the Phase 2 Adult Brain Tumor Consortium Trial BERT.

PURPOSE: Patients with glioblastoma (GBM) have a dismal prognosis. While DNA alkylating agent temozolomide (TMZ) is mainstay of chemotherapy, therapeutic resistance develops rapidly in patients. Base excision repair inhibitor TRC102 (methoxyamine) reverses TMZ resistance in preclinical glioma models. We sought to investigate efficacy and safety of oral TRC102+TMZ for recurrent GBM (rGBM). PATIENTS AND METHODS: A pre-registered (NCT02395692), non-randomized, multicenter, phase 2 clinical trial (BERT) was planned and conducted through the Adult Brain Tumor Consortium (ABTC-1402). Arm 1 included bevacizumab-naïve GBM patients at first recurrence, with primary endpoint of response rates. If sufficient activity was identified, a second arm was planned in bevacizumab-refractory patients. Secondary endpoints were overall survival (OS), progression-free survival (PFS), PFS at six months (PFS-6), and toxicity. RESULTS: Arm 1 enrolled 19 patients with median of two treatment cycles. Objective responses were not observed, hence, arm 2 did not open. Median OS was 11.1 months (95%CI 8.2-17.9). Median PFS was 1.9 months (95%CI 1.8-3.7). PFS-6 was 10.5% (95%CI 1.3-33.1%). Most toxicities were Grade 1-2, with two Grade 3 lymphopenias and one Grade 4 thrombocytopenia. Two patients with PFS ≥17 months and OS >32 months were deemed 'extended survivors'. RNA sequencing of tumor tissue, obtained at diagnosis, demonstrated significantly enriched signatures of DNA damage response (DDR), chromosomal instability (CIN70, CIN25), and cellular proliferation (PCNA25) in 'extended survivors'. CONCLUSIONS: These findings confirm safety and feasibility of TRC102+TMZ for rGBM patients. They also warrant further evaluation of combination therapy in biomarker-enriched trials enrolling GBM patients with baseline hyperactivated DDR pathways.

Pharmacokinetics and pharmacogenetics of 13-cis retinoic acid in Indian high-risk neuroblastoma patients.

PURPOSE: To compare the pharmacokinetics of 13-cis retinoic acid (13-cisRA) between Indian and UK neuroblastoma patients receiving comparable treatment, alongside measures of toxicity and response. METHODS: 13-cisRA (160 mg/m(2)/day) was administered to 36 patients ≤16 years in two divided doses. Plasma 13-cisRA concentrations were determined on days 1 and 14 of cycles 1 and 4 of treatment. Area under the plasma concentration-time curve (AUC0-6h) was estimated using non-compartment modelling. Patients were genotyped for UGT2B7, CYP3A5*3, CYP3A7*2 and *2, *3 and *4 variants of CYP2C8. RESULTS: Marked inter-patient variability in 13-cisRA pharmacokinetics was observed. There was a trend towards a higher AUC0-6h on day 1 versus day 14 for both treatment cycles studied. Children who swallowed 13-cisRA capsules (n = 18) achieved higher AUC0-6h values compared to those who could not (n = 16) (Mean AUC 21.53 vs. 9.35 µM h, P < 0.05). Patients who were event free at 1 year tended to have higher AUC0-6h on C1D1 compared to those patients who progressed, although this did not reach significance with the number of patients studied (P = 0.08). Similarly, patients who achieved a 13-cisRA C max of ≥2 µM on C1D1 tended to have higher median EFS compared to those who did not (17.0 vs. 8.1 months). UGT2B7, CYP2C8*2/*3/*4 or CYP3A5*3 genotype did not have any effect on 13-cisRA pharmacokinetics. CONCLUSIONS: Method of administration markedly affects 13-cisRA pharmacokinetics in Indian neuroblastoma patients, supporting similar findings in UK patients. An appropriate oral liquid formulation of 13-cisRA that can be administered to all children with neuroblastoma is urgently needed on an international level.

Population pharmacokinetics of Reditux™, a biosimilar Rituximab, in diffuse large B-cell lymphoma.

PURPOSE: Rituximab (MabThera™, Roche) is a chimeric IgG1 monoclonal antibody targeting the CD20 surface antigen on normal and neoplastic B cells. It revolutionized the treatment of non-Hodgkin's lymphoma with superior progression-free and overall survival. However, its prohibitively high cost makes it inaccessible to majority of patients in developing countries. Reditux™ (Dr. Reddy's Laboratories, India), a biosimilar, was introduced in India in 2007 at nearly half the price of the innovator. However, there is a dearth of data regarding the pharmacokinetics and efficacy of Reditux™. METHODS: Twenty-one patients of diffuse large B-cell lymphoma on R-CHOP regimen were enrolled for the study. Reditux™ was administered as a slow intravenous infusion at a dose of 375 mg/m(2) on day 1 of a 21-day cycle. Pharmacokinetic sampling was performed at pre-dose, post-infusion, 24, 48 h, 7 and 21 days. Rituximab levels were estimated by ELISA. Population pharmacokinetics was performed using NONMEM. In addition, B-cell count was determined at baseline and days 3 and 21 of the first cycle. Survival analysis was performed using Kaplan-Meier plots. RESULTS: The volume of distribution of central compartment and clearance of Reditux™ were estimated at 0.95 L and 5.98 mL/h, respectively. No covariate effects were seen. B-cell count was completely depleted by day 3 and remained so on day 21. Overall survival was 84.6 % at a median follow-up of 36 months. CONCLUSION: The pharmacokinetic profile and B-cell response to Reditux™ are comparable with those reported for MabThera™. Thus, MabThera™ can be substituted with Reditux™ for the treatment of B-cell lymphomas.