ABSTRACT
PURPOSE: Adverse events after the use of the CDK4/6 inhibitor abemaciclib are dose-dependent. However, its pharmacokinetics varies among individuals. Abemaciclib is reportedly transported by P-glycoprotein and breast cancer resistance protein. Therefore, we evaluated whether ABCB1 and ABCG2 polymorphisms are pharmacokinetic predictive factors of abemaciclib. METHODS: A total of 45 patients with breast cancer taking abemaciclib (150 mg twice per day) for 2 weeks were evaluated to determine the associations among abemaciclib concentration; adverse events; and ABCB1 1236 T > C, 2677G > T/A, 3435C > T, and ABCG2 421C > A gene polymorphisms. RESULTS: The trough concentration of abemaciclib was significantly higher in the group with grade 2 or greater neutropenia and thrombocytopenia than in those with grades 0 or 1. For ABCB1 2677G > T/A polymorphisms, the concentration of abemaciclib tended to be higher in the homozygous group (TT + AT) than in the wild-type + heterozygous group (GG + GA + GT) (median [range], 222.8 [80.5-295.8] ng/mL vs. 113.5 [23.6-355.2] ng/mL, P = 0.09), Moreover, the ABCB1 2677G > T/A homozygous group had a higher tendency of abemaciclib withdrawal or dose reduction within 4 weeks than the wild-type + heterozygous group (odds ratio, 4.22; 95% confidence interval, 0.86-20.7; P = 0.08). No significant association was observed among abemaciclib concentration; adverse reactions; and ABCB1 1236 T > C, 3435C > T, and ABCG2 421C > A polymorphisms. CONCLUSION: ABCB1 2677G > T/A polymorphism might be a predictor of the pharmacokinetics and tolerability of abemaciclib.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B , ATP Binding Cassette Transporter, Subfamily G, Member 2 , Aminopyridines , Benzimidazoles , Breast Neoplasms , ATP Binding Cassette Transporter, Subfamily B/genetics , ATP Binding Cassette Transporter, Subfamily G, Member 2/genetics , Aminopyridines/pharmacokinetics , Aminopyridines/therapeutic use , Benzimidazoles/pharmacokinetics , Benzimidazoles/therapeutic use , Breast Neoplasms/drug therapy , Female , Genotype , Humans , Polymorphism, Single NucleotideABSTRACT
OBJECTIVE: Due to the occurrence of severe adverse drug reactions to regorafenib, a drug used in cancer therapy, the identification of a predictive marker(s) is needed to increase the therapeutic applicability of this compound. We therefore investigated whether polymorphisms in the ABCG2 and SLCO1B genes are associated with adverse drug reactions to regorafenib. METHODS: For these analyses, 37 Japanese cancer patients were treated with regorafenib, genotyped for polymorphisms in ABCG2 and SLCO1B, and evaluated for drug-related adverse drug reactions. RESULTS: There was no association between the ABCG2 421C>A variant and adverse drug reactions to regorafenib. After treatment, the incidences of increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as increased total bilirubin (grade ≥ 2) were 8%, 4%, and 12%, and 42%, 25%, and 25% among SLCO1B1*1b carriers and non-carriers, respectively. There were no significant associations between elevated ALT and bilirubin and the SLCO1B1*1b allele. However, there were significantly lower incidences of increased AST (8% vs. 42%) and anemia (16% vs. 50%) in SLCO1B1*1b carriers than in non-carriers. CONCLUSIONS: The absence of SLCO1B1*1b allele appears to be associated with the development of adverse drug reactions to regorafenib; however, further studies involving larger test groups and other populations are needed to confirm these findings.â©.