Pedret‐Dunn, Anna

AbstractLiposomal irinotecan is a liposomal formulation of irinotecan, which prolongs circulation of irinotecan and its active metabolite SN‐38. A population pharmacokinetic (PK) model was developed based on data from seven studies (N = 440). Adequacy of the model was assessed using multiple methods, including visual predictive check. Associations between PK exposure and the incidence of diarrhea (grade ≥3) and neutropenia adverse events (AEs) (grade ≥3) at first event in patients with metastatic pancreatic ductal adenocarcinoma (mPDAC) were investigated using logistic regression based on data from two studies (the phase III NAPOLI‐1 [N = 260] and phase I/II NCT02551991 [N = 56] trials). The PKs of total irinotecan was described by a two‐compartment model with first‐order elimination, with SN‐38 formed directly by a first‐order constant from the central compartment of irinotecan or after using a transit compartment. Clearance was 17.9 L/week (0.107 L/h) and 19,800 L/week (118 L/h) for total irinotecan and SN‐38, respectively. The UGT1A1*28 7/7 homozygous genotype had no significant impact on SN‐38 clearance. Model evaluation was satisfactory for both irinotecan and SN‐38. The incidence of diarrhea (grade ≥3) at first event was significantly higher with increasing average concentrations of total irinotecan and SN‐38; there was no significant association between an increased risk of neutropenia AEs (grade ≥3) at first event and average SN‐38 concentrations. In summary, the PKs of total irinotecan and SN‐38 after administration of liposomal irinotecan were well‐described by the model. The UGT1A1*28 status had no significant impact on the PKs of liposomal irinotecan.

e12003 Background: Irinotecan liposome injection (nal-IRI) uses intraliposomal stabilisation technology to enable high drug load and in-vivo stability. This analysis characterizes the PK profile of nal-IRI in pts with mBC. Methods: The expansion of NCT01770353 enrolled 30 pts with mBC over three cohorts (Cohort 1: ER+ and/or PR+ BC [C-1]; Cohort 2: Triple Negative BC [C-2]; and Cohort 3: BC with active Brain Metastasis [C-3]). Key inclusion criteria: ECOG ≤1; adequate organ function; and >1 and ≤5 prior lines of cytotoxic therapy in metastatic setting. Most pts received nal-IRI 60 mg/m2 salt-based equivalent (50 mg/m2 free base equivalent [FBE]) or 80 mg/m2 (70 mg/m2 FBE) q2w by iv infusion, based on tolerance; 2 pts were treated at 40 mg/m2 (35 mg/m2 FBE). Plasma samples were collected over 360h across cycles 1, 2 &3, and analysed using LC-MS/MS for total irinotecan. Data were analysed by a non-compartmental approach using Phoenix Winnonlin, and were compared with values from studies in other tumor types. Results: 21 patients were evaluable for PK analysis (C-1, n=6; C-2, n=7; and C-3, n=8). No trend for accumulation was observed in cycle 2 or 3, when comparing total irinotecan Cmax & exposure (area under the curve at 168 h [AUC168]) versus cycle 1. At 40-80 mg/m2 (35-70 mg/m2 FBE), Cmax of irinotecan tended to increase proportionally with total dose, and was comparable to studies in other tumour types (see Table). Among 29 pts who received nal-IRI, partial response (per RECIST) was observed in 10 pts. The most related TEAEs (≥ 25%) were diarrhea, nausea, vomiting, hypokalaemia, decreased appetite and fatigue. Stable disease was observed in 5 pts. Conclusions: PK parameters in patients with mBC were comparable to historical studies in patients with other tumour types. The safety profile of nal-IRI monotherapy appeared consistent with gastrointestinal and blood disorders. [Table: see text]