Citations

Abstract Background: The third-generation aromatase inhibitors (AIs) are established adjuvant therapy for postmenopausal women with early stage breast cancer. Musculoskeletal adverse events (MS AE) have become increasingly recognized as an issue for many women receiving AIs resulting in decreased quality of life and, in some instances, discontinuation of the AI. MA.27 is an ongoing randomized clinical trial comparing anastrozole with exemestane that accrued 7576 patients (pts), including 6827 from North America, about 79% of whom provided DNA and consent for genetic testing. A review of withdrawals related to adverse events revealed that the most common cause was MS AE. The hypothesis for our study was that a genome-wide association (GWA) case control study would identify single nucleotide polymorphisms (SNPs) associated with MS AE.Methods: Cases were defined as pts with grade 3 or 4 MS AE (NCI CTCAE v3.0) or who went off treatment for any grade MS AE within the first 2 years and were matched to 2 controls based on treatment arm, length of follow-up, prior chemotherapy, age and prior celecoxib (at least 3 months prior to MS AE). The study was restricted to the 94% of pts self-identified as Caucasian. Genotyping was performed with the Illumina Human610-Quad. Genotype quality control prior to analysis required call rates ≥98%. Eigenstrat analyses were performed to control for population stratification.Results: The GWA study included 293 cases and 586 controls with 6 pts (0.7%) (4 cases, 2 controls) excluded for call rates <98%. 551,358 SNPs were used in the analyses after removing 29,439 for a minor allele frequency <1% and 82 with Hardy Weinberg Equilibrium p-values <10-6. Eigenvectors did not impact the results when used as covariates. Four SNPs with the lowest p-values (3.3-8.2 x 10-6, Armitage test), 3 in high LD (r2>.8) on chromosome (ch) 14 (rs7158782, rs7159713, rs2369049) and 1 on the X ch (rs6637820) were identified. The gene closest (4000-7000 bp) to the 3 SNPs on ch 14 was T-Cell Leukemia 1A (TCL1A), encoding a protein known to augment AKT kinase activity. Expression array data from lymphoblastoid cell lines from 300 subjects of 3 ethnicities revealed that all 3 SNPs were associated with decreased TCL1A expression after adjusting for ethnicity using 2 probe sets (p=0.006 to 0.03). Electromobility shift assay (EMSA) showed that 2 of these SNPs (rs7158782, rs7159713) displayed a shift and the former SNP showed substantially less binding for variant than wild type. The gene closest to the X ch SNP was Immunoglobulin Superfamily 1 (IGSF1), but EMSA did not show a shift for this SNP.Conclusions: MS AEs represent a major impediment to optimal use of AIs in women with breast cancer and this GWA study identified SNPs on ch 14 that provide a focus for further research to identify pts at risk for, and means to ameliorate, this adverse event.(Supported in part by NIH grants U01GM61388, U01GM63173, P50CA116201 and U10CA77202) Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 15.

Abstract Background: Analyses of adjuvant endocrine therapy suggest that the appearance of new vasomotor or joint symptoms within 3 months of initiating either tamoxifen or aromatase inhibitor therapy predict for lower subsequent recurrence. We hypothesized that new vasomotor or joint symptoms may predict outcomes with anastrozole or exemestane in participants in the ongoing NCIC CTG Trial MA.27. We performed a pooled analysis across treatment arms of the MA.27 trial, to examine the effects of early onset new or worsening symptoms on relapse-free survival (RFS).Methods: 7576 postmenopausal women with early breast cancer were accrued to MA.27, a randomized adjuvant trial of exemestane and anastrozole. The second interim analysis data with a 3 year median follow-up was used for this analysis. The trial's primary endpoint is event-free survival, but for this investigational analysis is RFS, which excludes non-breast cancer deaths. All 7118 participants known to be hormone receptor-positive who received trial therapy, and had no relapse in the first 3 months, were included. The association of vasomotor and joint symptoms with patient characteristics was examined with chi-square tests. Stratified log-rank and stratified univariate and multivariate Cox modeling were used to examine the association of early vasomotor and joint symptoms on disease outcomes.Results: Of 4749 women who were asymptomatic at baseline, 230 (5%) experienced vasomotor or joint symptoms at 3 months. The RFS stratified univariate Cox hazard ratio (HR) for vasomotor or joint-related symptoms was 1.184 (95% CI, 0.675-2.079). When all 7118 women were included, 361 (5%) developed new or worsening symptoms at 3 months. RFS was not statistically significant between the women with or without new symptoms (HR 1.129, 95% CI, 0.708-1.800). Higher T stage was the only factor included in the multivariate Cox RFS model that was associated with new or worsening symptoms (p<0.001).Conclusions: In contrast to prior findings, we did not observe a correlation between early emergence of symptoms and improved RFS. Longer follow-up and analysis by treatment arm and at different time points are required. Additional symptoms and time points will be added to the analysis prior to the meeting. Until further data are available, clinicians should not use treatment-emergent symptoms to counsel their patient whether to continue or change their prescribed medication. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 14.

Abstract Abstract #57 Background: ABCSG 8 is the only prospective trial examining the value of switching patients (pts) to an aromatase inhibitor after tamoxifen (Tam) in which randomization occurred prior to therapy. This trial demonstrated that 2 years (yrs) of Tam followed by 3 yrs of anastrozole (TAM to A) was superior to 5 yrs of Tam (Jakesz SABC 2005). Tam is metabolically activated by CYP2D6 to endoxifen and pts with impaired CYP2D6 metabolism have a higher risk of recurrence (Goetz JCO 2005). The HOXB13/IL17BR (H/I) index (Ma Cancer Cell 2004) is associated with Tam resistance while a 5-gene molecular grade index (MGI) distinguishes outcome in grade II tumors. H/I and MGI are complementary prognostic factors that define low (low MGI), intermediate (low H/I, high MGI) and high risk groups (high H/I and MGI) (Ma Clin Cancer Res 2008). We sought to validate these biomarkers in ABCSG Trial 8, and hypothesized that they may predict the benefit of sequencing TAM to A versus Tam alone.
 Methods: From 1996-2004, ABCSG 8 randomized 3,901 pts with ER positive breast cancer. The primary endpoint was event-free survival. Assuming 40% of pts had reduced CYP2D6 metabolism, we designed a nested case control study in which 110 Tam treated cases matched to 2 controls would yield 80% power to detect a relative risk of 2.3 for pts with reduced CYP2D6 metabolism. Additionally, we sought to perform an exploratory analysis of the benefit of switching from Tam to A in pts with impaired vs non-impaired CYP2D6 metabolism. DNA and RNA derived from paraffin embedded sections were used to genotype for CYP2D6 and to obtain H/I and MGI RT-PCR profiles.
 Findings: Thus far, CYP2D6 genotyping is complete in 345 pts corresponding to 53 cases/106 controls (Tam) and 62 cases/124 controls (Tam to A). DNA and RNA yields were excellent with a CYP2D6 genotype call rate of >95%. CYP2D6 allele frequencies were as expected: *3 (.01), *4, (.23), *6 (.01), *10 (.02), *17 (.00), and *41 (.10). 44% of pts had reduced CYP2D6 metabolism (at least one CYP2D6 null allele or intermediate metabolizer) and 8% were CYP2D6 poor metabolizers. For H/I and MGI, 340 pts were profiled with 64%, 20% and 16% in the low, intermediate, and high risk groups, respectively. Tissue sectioning/genotyping for additional cases/controls is ongoing.
 Discussion: This is the first retrospective analysis of a large Tam versus Tam to A trial to evaluate the association between 1) CYP2D6, HOXB13/IL17BR, and MGI with TAM treatment outcome and 2) the predictive benefit of these biomarkers in pts randomized to switch from Tam to AI versus Tam alone. Final results will be presented at the meeting. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 57.

Abstract Abstract #404 Background: The oral HDACi vorinostat (V) sensitizes breast cancer cells to tubulin polymerizing agents and anti-VEGF directed therapies in vitro. We sought to determine the safety and efficacy of V plus paclitaxel (P) and bevacizumab (B) as first-line therapy for MBC.
 Methods: Eligible patients (pts) with measurable disease, ECOG PS 0 or 1, and no prior chemotherapy for MBC, received P (90mg/m2) on days 1, 8, 15 and B (10mg/kg) on days 1,15 every 28 days, plus V 200 mg (N=3) or 300 mg (N=28) BID orally for 3 days given the day before, day of, and day after each P dose. Response was assessed after every 3 cycles (RECIST). The trial was designed to distinguish between a response rate of < 40% vs. > 60% (alpha=0.10, beta=0.10) using Simon's optimal 2-stage design. At least 12 responses were required in the first 28 evaluable pts in the 1st stage and 21 of 41 in the 2nd stage.
 Results: There were no dose-limiting toxicities among the first 6 pts treated at the 1st (200 mg BID; N=3) and 2nd (300 mg BID; N=3) dose levels. Among the 26 evaluable pts treated at the recommended phase II dose of 300mg bid in the 1st stage, 14 patients had a partial response (PR-54%; 90% confidence interval [C.I.] 36%-71%), 6 had stable disease (SD) at 3 months and remain on treatment, 2 had SD as the best response with progressive disease (PD) at 11.8 and 15 months, and 4 had PD as their best response. Additionally, 2 of 3 pts treated at the first V dose level had a PR, indicating PR in 16 of 29 overall (55%, 90% C.I 38%-71%). Only 11 of 29 evaluable pts (38%) have progressed after a median followup of 10.5 months (R-2.3-14.9). Two pts had tumor biopsies and peripheral blood mononuclear cells (PBMC) collected before and 4 hours after the 3rd V dose (300 mg BID) which showed increased acetylation of K69 lysine residue of the chaperone protein Hsp 90, upregulation of Hsp70, and downregulation of AKT by Western Blot, providing evidence of Hsp90 inhibition in tumor and PBMC.
 
 Gr 3-4 toxicities included neutropenia (26%), neuropathy (23%), fatigue (16%), thrombosis (10%), vomiting (6%), hypertension (3%), and diarrhea (3%).
 Conclusions: Our preliminary findings indicate that the HDACi V inhibits Hsp90 and downregulates AKT in breast cancer in vivo, and enhances the effectiveness of P plus B in MBC. Accrual is nearly complete and the final efficacy analysis will be presented. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 404.