Model-Informed Dose Justifications of Posaconazole in Japanese Patients for Prophylaxis and Treatment Against Fungal Infection

Posaconazole is a globally approved broad-spectrum triazole antifungal compound. In Japanese patients, posaconazole has identical dosing regimens as those approved globally for both tablet and intravenous formulations. This article aims to describe a model-informed approach for dose justification of posaconazole in the Japanese population as either high-risk patients with fungal infections (prophylaxis patients) or patients with fungal infections (treatment patients). A simultaneous population pharmacokinetic (PK) model for tablet and intravenous formulation was developed on the basis of a data set including Japanese data from healthy participants and treatment patients. The PK profiles and exposure distributions in Japanese patients were predicted and compared against foreign patients, that is, patients outside of Japan. Relationships between the post hoc posaconazole exposures and frequently observed clinical adverse events were evaluated. Although clinical trials for Japanese prophylaxis patients were not conducted, PK profiles in Japanese prophylaxis patients were predicted using the population PK model and demographic covariate information obtained from the published literature. Based upon the globally approved dosing regimen, posaconazole exposure distribution was predicted to be the highest in Japanese treatment patients, and generally similar between Japanese and foreign prophylaxis patients. Exposures in Japanese patients exceeded the efficacy target level (500 ng/mL). Safety profiles in Japanese treatment patients with the highest exposures were clinically acceptable without specific concerns to Japanese patients and appeared to have no relationship with posaconazole exposures. From PK, safety, and efficacy perspectives, the use of the same dosing regimen as in foreign patients was justified in Japanese prophylaxis and treatment patients.

Exposure-safety and exposure-efficacy analyses of polatuzumab vedotin in patients with relapsed or refractory diffuse large B-cell lymphoma

Exposure-response relationships were investigated to assess the risk/benefit of polatuzumab vedotin (pola) + bendamustine-rituximab (pola + BR) in relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL). Analyses were conducted in pivotal study GO29365 (NCT02257567; BR/pola + BR/pola + BG [BG: bendamustine-obinutuzumab]; 1.8 mg/kg pola, every 3 weeks [Q3W], six cycles), and supportive studies DCS4968g (NCT01290549) and GO27834 (NCT01691898) (pola/pola + R/pola + G; 0.1-2.4 mg/kg pola Q3W; eight-cycle landmark), separately. Exposure was characterized as simulated cycle-6 AUC and C _max for antibody-conjugated mono-methyl auristatin E (acMMAE) and unconjugated MMAE. Supportive studies showed response rate and safety risk (grade ≥2 peripheral neuropathy; grade ≥3 anemia) increased with exposure, suggesting not to dose below 1.8 mg/kg (up to eight-cycle) for balancing safety and efficacy. Pivotal study with limited exposure range showed no exposure-safety relationship and slightly positive exposure (acMMAE)-efficacy relationship for overall survival. The exposure-response analyses and the observed risk/benefit characteristics in pivotal study supported pola (1.8 mg/kg) +BR Q3W for six cycles in R/R DLBCL patients.

Ceftolozane/tazobactam pharmacokinetic/pharmacodynamic-derived dose justification for phase 3 studies in patients with nosocomial pneumonia

Ceftolozane/tazobactam is an antipseudomonal antibacterial approved for the treatment of complicated urinary tract infections (cUTIs) and complicated intra‐abdominal infections (cIAIs) and in phase 3 clinical development for treatment of nosocomial pneumonia. A population pharmacokinetic (PK) model with the plasma‐to‐epithelial lining fluid (ELF) kinetics of ceftolozane/tazobactam was used to justify dosing regimens for patients with nosocomial pneumonia in phase 3 studies. Monte Carlo simulations were performed to determine ceftolozane/tazobactam dosing regimens with a >90% probability of target attainment (PTA) for a range of pharmacokinetic/pharmacodynamic targets at relevant minimum inhibitory concentrations (MICs) for key pathogens in nosocomial pneumonia. With a plasma‐to‐ELF penetration ratio of approximately 50%, as observed from an ELF PK study, a doubling of the current dose regimens for different renal functions that are approved for cUTIs and cIAIs is needed to achieve >90% PTA for nosocomial pneumonia. For example, a 3‐g dose of ceftolozane/tazobactam for nosocomial pneumonia patients with normal renal function is needed to achieve a >90% PTA (actual 98%) for the 1‐log kill target against pathogens with an MIC of ≤8 mg/L in ELF, compared with the 1.5‐g dose approved for cIAIs and cUTIs.