Metabolic Pathway Analysis and Effectiveness of Tamoxifen in Danish Breast Cancer Patients

The impact of single nucleotide polymorphisms on return-to-work after taxane-based chemotherapy in breast cancer

PURPOSE

Breast cancer treatment is associated with adverse effects, which may delay return-to-work. Single nucleotide polymorphisms (SNPs) may influence the risk and severity of treatment toxicities, which in turn could delay return-to-work. We examined the association of 26 SNPs with return-to-work in premenopausal women with breast cancer.

METHODS

Using Danish registries, we identified premenopausal women diagnosed with non-distant metastatic breast cancer during 2007‒2011, assigned adjuvant combination chemotherapy including cyclophosphamide and docetaxel. We genotyped 26 SNPs in 20 genes (ABCB1, ABCC2, ABCG2, CYP1A1, CYP1B1, CYP3A, CYP3A4, CYP3A5, GSTP1, SLCO1B1, SLCO1B3, ARHGEF10, EPHA4, EPHA5, EPHA6, EPHA8, ERCC1, ERCC2, FGD4 and TRPV1) using TaqMan assays. We computed the cumulative incidence of return-to-work (defined as 4 consecutive weeks of work) up to 10 years after surgery, treating death and retirement as competing events and fitted cause-specific Cox regression models to estimate crude hazard ratios (HRs) and 95% confidence intervals (CIs) of return-to-work. We also examined stable labor market attachment (defined as 12 consecutive weeks of work).

RESULTS

We included 1,964 women. No associations were found for 25 SNPs. The cumulative incidence of return-to-work varied by CYP3A5 rs776746 genotype. From 6 months to 10 years after surgery, return-to-work increased from 25 to 94% in wildtypes (n = 1600), from 17 to 94% in heterozygotes (n = 249), and from 7 to 82% in homozygotes (n = 15). The HR showed delayed return-to-work in CYP3A5 rs776746 homozygotes throughout follow-up (0.48, 95% CI 0.26, 0.86), compared with wildtypes. Estimates were similar for stable labor market attachment.

CONCLUSION

Overall, the SNPs examined in the study did not influence return-to-work or stable labor market attachment after breast cancer in premenopausal women. Our findings did suggest that the outcomes were delayed in homozygote carriers of CYP3A5 rs776746, though the number of homozygotes was low.

Analysis of the complications of endocrine therapy with tamoxifen in breast cancer: clinical and pharmacogenetic aspects. Prospective pharmacogenetic cohort study

Background. Tamoxifen is the drug of choice in ER-positive breast cancer (BC) therapy for perimenopausal women and one of the endocrine therapy options for menopausal patients. The pharmacological effect of tamoxifen can be influenced by the activity of cytochrome P450 (CYP) enzymes and P-glycoprotein transporters (Pg), and the genes encoding them have broad polymorphism, affecting serum concentrations of active metabolites. This article presents the overall results of a prospective population-based study of the clinical significance of genetic polymorphism of tamoxifen metabolic enzymes and transporters in breast cancer patients after radical treatment receiving adjuvant endocrine therapy with tamoxifen in outpatient settings during 2018-2019. The study was approved by the Research Ethics Committee of the Russian Medical Academy of Continuing Professional Education. Aim. To analyze the clinical presentation of endocrine therapy with tamoxifen in the adjuvant regimen and to assess the association of polymorphisms of genes encoding cytochrome P450 enzymes and drug transporter proteins with adverse events in BC patients. Materials and methods. One hundred and four women with stage I-III luminal breast cancer receiving adjuvant tamoxifen were examined for the presence of CYP2D6, CYP2C, and the following CYP3A gene polymorphisms: CYP2D6*4, CYP3A5*3, CYP2C9*2, CYP2C9*3, CYP2C19*2, CYP2C19*3, as well as the ABCB1 gene polymorphic marker (C3435T) encoding the P-glycoprotein. The allelic variants were identified using the real-time polymerase chain reaction; the test was performed in the Research Center of the Russian Medical Academy of Continuing Professional Education. The study material was buccal epithelium (double sampling) taken after informed consent signing. Results. Association analysis showed the association of different genetic polymorphisms of CYP2D6, CYP3A5, CYP2C9, and ABCB1 with tamoxifen adverse drug reactions, indicating the clinical significance of these polymorphisms. Conclusion. With the implementation of genetic testing of the studied polymorphisms into the routine clinical practice of oncologists prescribing tamoxifen and gynecologists involved in the follow-up of breast cancer patients receiving endocrine therapy in the adjuvant mode, there will be an opportunity for more effective and safer pharmacotherapy.

Single-nucleotide polymorphisms and the effectiveness of taxane-based chemotherapy in premenopausal breast cancer: a population-based cohort study in Denmark

Purpose

Taxane-based chemotherapy is the primary treatment for premenopausal breast cancer. Although being inconsistent, research suggests that variant alleles alter pharmacokinetics through reduced function of OATP transporters (limiting hepatic uptake), CYP-450 enzymes (hampering drug metabolism), and ABC transporters (decreasing clearance). Reduced function of DNA repair enzymes may hamper effectiveness through dose-limiting toxicities. We investigated whether single-nucleotide polymorphisms (SNPs) were associated with breast cancer recurrence or mortality in premenopausal women diagnosed with breast cancer.

Methods

We conducted a population-based cohort study of premenopausal women diagnosed with non-distant metastatic breast cancer in Denmark during 2007‒2011, when guidelines recommended adjuvant combination chemotherapy (taxanes, anthracyclines, and cyclophosphamide). Using archived formalin-fixed paraffin-embedded primary tumor tissue, we genotyped 26 SNPs using TaqMan assays. Danish health registries provided data on breast cancer recurrence (through September 25, 2017) and death (through December 31, 2019). We fit Cox regression models to calculate crude hazard ratios (HRs) and 95% confidence intervals (CIs) for recurrence and mortality across genotypes.

Results

Among 2,262 women, 249 experienced recurrence (cumulative incidence: 13%) and 259 died (cumulative incidence: 16%) during follow-up (median 7.0 and 10.1 years, respectively). Mortality was increased in variant carriers of GSTP1 rs1138272 (HR: 1.30, 95% CI 0.95–1.78) and CYP3A rs10273424 (HR: 1.33, 95% CI 0.98–1.81). SLCO1B1 rs2306283 (encoding OATP1B1) variant carriers had decreased recurrence (HR: 0.82, 95% CI 0.64–1.07) and mortality (HR: 0.77, 95% CI 0.60–0.98).

Conclusion

Docetaxel effectiveness was influenced by SNPs in GSTP1, CYP3A, and SLCO1B1 in premenopausal women with non-distant metastatic breast cancer, likely related to altered docetaxel pharmacokinetics. These SNPs may help determine individual benefit from taxane-based chemotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-022-06596-2.

Bayesian Pathway Analysis for Complex Interactions

Modern epidemiologic studies permit investigation of the complex pathways that mediate effects of social, behavioral, and molecular factors on health outcomes. Conventional analytical approaches struggle with high-dimensional data, leading to high likelihoods of both false-positive and false-negative inferences. Herein, we describe a novel Bayesian pathway analysis approach, the algorithm for learning pathway structure (ALPS), which addresses key limitations in existing approaches to complex data analysis. ALPS uses prior information about pathways in concert with empirical data to identify and quantify complex interactions within networks of factors that mediate an association between an exposure and an outcome. We illustrate ALPS through application to a complex gene-drug interaction analysis in the Predictors of Breast Cancer Recurrence (ProBe CaRe) Study, a Danish cohort study of premenopausal breast cancer patients (2002-2011), for which conventional analyses severely limit the quality of inference.