Zorzi, Jane

10509 Background: PST allows for improved surgical outcomes and response assessment without compromising long term outcomes. PST is an attractive model for assessing surrogate markers of response to therapy. We hypothesized that changes in tumor standardized uptake values corrected for lean body mass (SUL) max on FDG- PET by cycle 1 day 15 (C1D15) of therapy would predict pathological complete response (pCR) to PST in women with stage 2-3, grade 2-3, HER2-negative breast cancer. Methods: TBCRC008 is a multicenter placebo-controlled trial that investigates pCR following 12 weeks of preoperative carboplatin and albumin-bound paclitaxel with or without vorinostat. FDG-PET followed by tumor biopsies were performed at baseline and C1D15. We correlated % reduction in SULmax on FDG-PET (PERCIST 1.0; Wahl RL, J Nuc Med 2009) with pCR (no invasive cancer in breast/axilla). We compared % reduction in SULmax between responders (pCR) and non responders (no pCR) using nonparametric Wilcoxon rank sum test. We explored association of % reduction in SULmax at pre-specified cutoff with response using Fisher’s exact test and logistic regression. We correlated baseline, C1D15, and % change in Ki67 at C1D15 with pCR. Results: Accrual is complete. Of 62 women enrolled (10/2009-11/2011), 40 have completed study PST and surgery (median age 47.5 [range 30-68], ER-positive 67%). Overall pCR was 26%. In an intent to treat analysis (n=39), we observed a significant difference in median % reduction in SULmax between responders vs not (66.6% vs 32.4%, p <0.001). We observed a higher proportion of reduction in SULmax ≥ 60% in responders vs not (80% vs 3.5%, p <0.001). The differences in baseline, C1D15 and % change in Ki67 were not significant between responders and non-responders. Conclusions: Change in SULmax on FDG-PET 15 days after initiating PST was significantly greater in patients with pCR versus no pCR. Future studies will determine whether altering therapy based on early changes in SULmax will improve pCR. Unblinded data from all participants will be presented at the meeting.

Abstract Background: Epigenetic alterations in the genome, including abnormal DNA methylation and histone hypoacetylation, initiate and promote cancerous changes via several mechanisms, including inactivation of tumor suppressor genes. Preclinical investigations in breast cancer suggest that use of epigenetic modifiers results in re-expression of aberrantly silenced genes and proteins that represent important therapeutic targets (e.g. estrogen receptor alpha, ER). Combination therapy with a DNA methyltransferase inhibitor (DNMTI) and a histone deacetylase inhibitor (HDACI) has yielded superior ER reexpression and greater restoration of tamoxifen responsiveness than with HDACI alone. We hypothesize that clinically tolerable doses of the DNMTI 5-azacitidine (5-AZA) and the HDACI entinostat may not only effect changes in DNA methylation and gene expression, but also yield objective disease responses in women with advanced breast cancer. Trial design: This multicenter phase II study (NCT01349959) is enrolling patients with advanced human epidermal growth factor receptor 2 (HER2)-negative breast cancer with triple negative (ER/progesterone receptor [PR]/HER2−negative, Cohort A) or hormone-resistant (Cohort B) disease. Patients will receive 5-AZA 40 mg/m2 subcutaneously days 1–5 and 8–10 and entinostat 7 mg orally days 3 and 10 every 28 days. Because of the potential for re-expression of the ER with epigenetic agents, patients will be offered continuation of 5-AZA and entinostat at progression with the addition of hormonal therapy (investigator discretion). Mandatory tumor biopsies will be performed at baseline and after 8 weeks of therapy to evaluate correlative biomarkers. Eligibility Criteria: Eligible patients must be ≥ 18 years, have measurable locally advanced/metastatic triple-negative (at least one prior chemotherapy received adjuvant/metastatic setting) or hormone-resistant (must have received two prior hormonal agents and one prior chemotherapy) disease, adequate organ function and ECOG PS ≤ 2. Specific Aims: 1. Objective response rate (ORR) by RECIST 1.1 criteria. 2. Safety and tolerability 3. Progression-free survival, overall survival and clinical benefit rate. 4. Safety and toxicity data, feasibility and response rate where hormonal therapy is added to the combination under investigation at the time of progressive disease. 5. Pharmacokinetics, cytidine deaminase, changes from baseline of candidate gene methylation and expression in circulating deoxyribonucleic acid (DNA) and malignant tissue. Statistical Methods: Using a two-stage three-outcome design to assess the efficacy of the combination, a maximum of 30 patients (requiring 27 evaluable) will be accrued to each cohort unless undue toxicity is encountered for a maximum sample size of 60 patients. The study design tests the null hypothesis that the ORR is at most 5% against the alternative hypothesis that it is at least 20% with a type I error of 4% and power of 90%. Present and Targeted Accrual: This study has just opened to patient enrollment. We anticipate a rapid accrual of 60 patients within 1 year.br](Funding from Stand Up to Cancer and CTEP). Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-01-06.