RESUMEN
Belinostat was approved in 2014 for the treatment of relapsed or refractory peripheral T-cell lymphoma, however, there was insufficient data to recommend a dose in patients with moderate to severe hepatic impairment. The purpose of this analysis was to characterize the pharmacokinetic disposition of belinostat and its five metabolites in patients with advanced cancers and varying degrees of liver dysfunction. A population pharmacokinetic model was therefore developed to describe the parent-metabolite system. The final model was then implemented to assess the effect of liver impairment on each metabolic pathway of belinostat. It was determined that significant pharmacokinetic differences could only be demonstrated in patients with severe hepatic impairment. The final model estimated a 35%-47% reduction in metabolic clearance attributed to UGT1A1/2B7 glucuronidation, CYP2A6/3A4/2C9 metabolism, and ß-oxidation. These hepatic impairment effects reduced between-subject variability by only 5%-8% for their respective parameter, with a large amount of remaining unexplained variability. With further validation, this model can be leveraged to assess the need for dose adjustments in this patient population.
RESUMEN
BACKGROUND: The Ataxia Telangiectasia and Rad3-related (ATR) protein complex is an apical initiator of DNA damage response pathways. Several ATR inhibitors (ATRi) are in clinical development including berzosertib (formerly M6620, VX-970). Although clinical studies have examined plasma pharmacokinetics (PK) in humans, little is known regarding dose/exposure relationships and tissue distribution. To understand these concepts, we extensively characterized the PK of berzosertib in mouse plasma and tissues. METHODS: A highly sensitive LC-MS/MS method was utilized to quantitate berzosertib in plasma and tissues. Dose proportionality was assessed in female BALB/c mice following single IV doses (2, 6, 20 or 60 mg/kg). A more extensive PK study was conducted in tumor-bearing mice following a single IV dose of 20 mg/kg to evaluate distribution to tissues. PK parameters were calculated by non-compartmental analysis (NCA). A compartmental model was developed to describe the PK behavior of berzosertib. Plasma protein binding was determined in vitro. RESULTS: Increased doses of berzosertib were associated with less than proportional increases in early plasma concentrations and greater than proportional increase in tissue exposure, attributable to saturation of plasma protein binding. Berzosertib extensively distributed into bone marrow, tumor, thymus, and lymph nodes, however; brain and spinal cord exposure was less than plasma. CONCLUSION: The nonlinear PK of berzosertib displayed here can be attributed to saturation of plasma protein binding and occurred at concentrations close to those observed in clinical trials. Our results will help to understand preclinical pharmacodynamic and toxicity data and to inform optimal dosing and deployment of berzosertib.
RESUMEN
Alnuctamab, a B-cell maturation antigen (BCMA)-targeting T-cell engager, has demonstrated encouraging antitumor activity in the phase I study CC-93269-MM-001 treating patients with relapsed or refractory multiple myeloma. Identification of a recommended Phase III dose (RP3D) was a key objective, as such population pharmacokinetic (PopPK) and exposure-response analysis was critical. Intravenous (IV) alnuctamab was administered in fixed doses (0.15-10 mg) or in step-up doses to a maximum 10-mg target dose. Subcutaneous (SC) step-up doses of 3 and 6 mg were followed by a target dose range of 10-60 mg. Concentration data from IV and SC alnuctamab administration was pooled and was well described by a two-compartment PopPK model with first-order absorption and elimination. Covariate analysis determined that the inclusion of baseline soluble BCMA (sBCMA) on clearance significantly improved model fitting. Individual exposure parameters were estimated from the final model to characterize exposure-response relationships. Switching from IV to SC administration improved the safety profile of alnuctamab by limiting the frequency of grade ≥2 CRS events. A significant exposure-CRS relationship was observed after the first SC dose, but not subsequent dose administrations. Exposure-safety analysis did not find a statistically significant relationship between increasing exposure and the probability of key safety events of interest. Logistic regression analysis for patients administered SC alnuctamab identified that increased exposure significantly increased the probability of response, although the additional benefit was minimal at exposures above 30 mg target dose. Considering the totality of exposure-response data, the clinical pharmacology assessment supported a SC RP3D of 3/6/30 mg.