<scp><i>CYP3A</i></scp> Genotype Is Associated With Variability in the Exposure and Clearance of the Novel Oncogenic Transcription Inhibitor Lurbinectedin

Lurbinectedin is an oncogenic transcription inhibitor indicated for the treatment of small cell lung cancer (SCLC), which has also shown activity against other malignancies. In this work, two independent cohorts of 180 (discovery cohort) and 719 (validation cohort) cancer patients receiving lurbinectedin in Phases I, II, or III clinical trials were enrolled. Using a population pharmacokinetic (popPK) model of the discovery cohort, patients with extremely high (n = 10, cohort 1) and low (n = 10, cohort 2) etaCL values (i.e., a variable used as a surrogate of unexplained CL interindividual variability) were identified. They were sequenced for 42 candidate genes involved in lurbinectedin pharmacokinetics. A total of 34 variants located in 20 genes were significantly associated with lurbinectedin etaCL; the best nine hits (located in CYP3A5, CYP3A4, ABCB1, ARNT, NR5A2, NR1H4, and FOXA3) were subsequently genotyped in the validation cohort. A strong additive association between CYP3A4 and CYP3A5 genotypes (informed as a CYP3A activity score [AS] variable) and lurbinectedin clearance (CL) and exposure was confirmed, for example, patients with an AS of 3, 2, or 1 showed a 2.3-, 1.6-, and 1.5-fold higher total lurbinectedin CL compared to those with an AS of 0 and 2.3-, 1.8-, and 1.6-fold higher unbound lurbinectedin CL. In conclusion, preemptive CYP3A genotyping may offer a valuable approach for personalizing treatment with lurbinectedin in cancer patients.