Prospective validation of genetic predictors of aromatase inhibitor-associated musculoskeletal symptoms (AIMSS) in a racially diverse cohort: Results from ECOG-ACRIN E1Z11.

Abstract

12003 Background: AIMSS are common and frequently lead to early discontinuation of adjuvant AI therapy. Single nucleotide polymorphisms (SNPs) in candidate genes have been associated with AIMSS and AI discontinuation. The primary objective of E1Z11 was to validate previously identified associations between 10 specific SNPs in candidate genes and AI discontinuation due to AIMSS in a community-based, racially diverse cohort. Methods: Postmenopausal women with hormone receptor-positive stage I-III breast cancer enrolled onto a prospective multi-site cohort study, the majority through the NCI Community Oncology Research Program (NCORP). Participants received anastrozole 1 mg oral daily, and completed patient-reported outcomes (PROs) at baseline, 3, 6, 9, and 12 months. AIMSS was defined as >20% increase in Stanford Health Assessment Questionnaire (HAQ) score over baseline occurring within 1 year of AI therapy. We projected 40% would develop AIMSS and 25% would discontinue AI treatment within 1 year, informing a planned enrollment of 1000 women with a fixed number per strata (600 Caucasian, 200 African-American [AA] & 200 Asian) to provide 80% power to detect an effect size of 1.5-4. SNPs include ESR1 (rs2234693, rs2347868, rs9340835), CYP19A1 (rs1062033, rs4646), TCL1A (rs11849538, rs2369049, rs7158782, rs7159713), and HTR2A (rs2296972). Hardy-Weinberg equilibrium (HWE) was evaluated within each racial subset. SNP genotypes were coded as additive effects on the log odds ratio by coding as 0, 1 or 2 for the count of the minor allele. A Cochran-Armitage trend test was used with a 1-sided alpha of 0.0025 (Bonferroni correction for 10 tests). Results: We enrolled 999 evaluable women (616 Caucasian, 184 AA, 199 Asian). Genotyping was successful in 974 (98%). AIMSS developed in 43%, and AI therapy was discontinued in 12% within 1 year. While more AA and Asians developed AIMSS compared to Caucasians (48% vs 38%, p=0.017; 50% vs 38%, p=0.004), AI discontinuation rates were similar across racial groups. HWE was satisfied for all SNPs at the 5% alpha level, except for TCL1A/rs11849538 (p=0.002) in the AA cohort. None of the 10 SNPs were significantly associated with AI discontinuation or development of AIMSS in the overall population, or in any of the 3 cohorts. Conclusions: Although AIMSS were more common in AA and Asians, AI discontinuation rates were similar in the 3 cohorts. We were unable to prospectively validate 10 SNPs in 4 genes previously associated with AI discontinuation due to AIMSS. Future analyses will include other predictors of AIMSS, PROs, and additional genetic markers for the entire cohort and by race. Support: NCI UG1CA189828, UG1CA233196, UG1CA233277, UG1CA233320, UG1CA233178, UG1CA233160, UG1CA232760, UG1CA233341, UG1CA233329, U10CA180821, UG1CA189821, UG1CA189830, U10CA180888, UG1CA189859, UG1CA189863, UG1CA189971. Clinical trial information: NCT01824836.