Poster IV-16 Population pharmacokinetic-based targeted exome sequencing (PopPK- TES) approach to assess the impact of genetic variants on pharmacokinetics of lurbinectedin in patients with advanced cancer

Rubin Lubomirov, Carlos Fernández-Teruel, Ignacio González García, Salvador Fudio

Phama Mar S.A., Colmenar Viejo, Madrid, Spain.

BACKGROUND RESULTS Lurbinectedin (Zepsyre®) also known as PM01183, is a new RNA A three-compartment mammillary model with linear distribution and polymerase II inhibitor, currently being tested in a Phase III study in elimination from central compartment was suitable to describe the patients with small cell lung cancer (SCLC). Lurbinectedin is highly data. The model estimated a volume of distribution at steady state of -bound, and a preferential affinity for α-1-acid glycoprotein 438 L caused by the distribution to deep tissues, and a low central (AAG) has been suggested. Metabolism by CYP3A is expected to be volume of 11.6 L while CL was 11.2 L/h. The model detected several the major clearance mechanism. However, up to now the impact of covariates that affected CL: serum albumin, AAG, C-reactive protein genetic factors on lurbinectedin pharmacokinetic variability have not and the presence of CYP3A4 inhibitors. Histogram plots and the been investigated. The objective of this work is to develop a “probit” distribution of etaCL values of the subset of 180 patients who population pharmacokinetic-based targeted exome sequencing gave signed written informed consent for genetic testing, allowed the (PopPK-TES) strategy aiming to assess the impact of genetic variants identification of subpopulations of low (n=10) and high (n=10) CL on pharmacokinetics of lurbinectedin. outliers (Fig. 1). gDNA of these 20 patients was used to perform NGS at the exons of 42 . The detected genetic variants were MATERIALS and METHODS analyzed comparing their allelic frequencies between cases and The plasma concentrations of lurbinectedin from advanced cancer controls. Genetic variants (n=34) located in relevant genes (n=20) patients participating in phase I and II clinical trials were pooled and were identified (Fig. 2). fitted to a population pharmacokinetic (PopPK) model using non-liner Figure 1. Subpopulations identification mixed-effects modelling implemented in NONMEM v7.3 [1]. On the basis of PopPK analysis, restricted to the subset of patients who gave written informed consent for genetic testing, lurbinectedin interpatient variability on clearance (etaCL) was used as a phenotype, considering that this parameter would best reflect the remaining Controls unexplained variance in lurbinectedin elimination that could be (n=10) accounted for by genetic variations. Histogram plots and the “probit” distribution of etaCL values were used to identify the subpopulations of low and high CL outliers (i.e. patients with high and low Cases (n=10) lurbinectedin plasma exposure, respectively) as cases and controls, respectively. The germinal DNA (gDNA) was extracted from peripheral blood mononuclear cells. Targeted exome sequencing of 42 genes (Table 1) involved in lurbinectedin metabolism and transport was performed in an Ion PGM™ System for Next-Generation etaCL Sequencing (NGS) using an Ion 318™ chip v2 for every ten samples. Figure 2. TES Manhattan plot The analysis of the identified variants in PGM v5.0.2 was done with Ion Reporter v5.2 software and Annotate Variants Single v5.2 workflow, specific for GRCh38_human_5.0. The associations in the case and control population were assessed by comparing allelic frequencies between cases and controls using PLINK 2.0 [2].

Table 1. Selected genes (n=42) for targeted exome sequencing. Gene symbol subgroup (HGNC) Drug metabolizing CYP3A4, CYP3A5, CYP3A7, CYP3A43, CYP2D6 enzymes (DMEs)

DME electron donors POR, CYB5A, PGRMC1, PGRMC2

Regulators of DME Ligand-dependent nuclear receptors: expression NR1I2, NR1I3, VDR, NR1H4, PPARA, RARA, RXRA, NR1H3, NR1H2, NR3C1, ARNT, AHR, NR5A2, NR0B2 Constitutive transcription factors: CONCLUSIONS HNF4A, NR2F2, CEBPB, CEBPA, USF1, HNF1A, The applied PopPK-TES approach may allow to discover genetic FOXA3, FOXA2, PPARGC1A, NCOA1 Transcription factors signaling regulators: variants associated with the variability in pharmacokinetics of NFKB1, NFKB2, NFKBIA, IL6R, IL6ST lurbinectedin in patients with advanced cancer. These results need Drug transporters ABCB1 further confirmation in an independent population of advanced cancer Plasma binding ALB, ORM1, ORM2 patients treated with lurbinectedin. (PBP)

[1] Beal SL, Sheiner LB, Boeckmann AJ & Bauer RJ (Eds.) NONMEM Users Guides. 1989-2017. Icon Development Solutions, Ellicott City, Maryland, USA. [2] Purcell S, et al. PLINK: a tool set for whole-genome association and population-based linkage analyses. Am J Hum Genet 2007; 81:559–575.