Abstract PO4-20-04: A Randomized Window of Opportunity Study of Preoperative Letrozole and Simvastatin Versus Letrozole Alone in Stage I-III Hormone Receptor Positive, HER2 Negative Breast Cancer
Authors: Sacks Ruth , Haas Elizabeth , Jones Jade , Bhave Manali , Gogineni Keerthi , Meisel Jane , Smith-Graziani Demetria , Pakkala Suchi , Friend Sarah , Arciero Cletus , Postlewait Lauren , Farley Clara , Graham Cathy , Styblo Toncred , Rizzo Monica , Pickett Rhonda , Crasta Nicholas , Brown Lori , Li Xiaoxian , Badve Sunil , Dhodapkar Madhav , Kalinsky Kevin 
Published: May 2024

Hormone receptor positive (HR+), HER2 negative (HER2-) breast cancers are poor responders to immunotherapy. There is a need for innovative approaches to improve immune responses in these tumors. The combination of statins and aromatase inhibitors have demonstrated antiproliferative and immunomodulatory properties. However, this combination has never been studied in the preoperative setting; thus, our ongoing study represents an opportunity to investigate this approach.

We designed a randomized two-arm presurgical “window of opportunity” trial to evaluate the effects of letrozole and simvastatin versus letrozole alone 14 days prior to surgery. Tissue and blood will be obtained at baseline and 14 days after completion of therapy at the time of surgery. Inflammatory markers in the blood and multiplex immunohistochemistry (IHC) in tissue will be assessed. To be eligible for the trial, participants must be postmenopausal women with histologically confirmed stage I-III HR+, HER2- invasive breast cancer with baseline ki-67 ≥10% that have not received prior chemotherapy, endocrine therapy, and/or immunotherapy within 3 months prior to trial enrollment. They should also not have received any cholesterol lowering medication within 3 months prior to trial enrollment.

The primary objective is to determine if the addition of simvastatin to letrozole compared to letrozole alone will result in a decrease in geometric mean % change in ki-67 from pre-surgical baseline to 14 days following preoperative therapy. Ki-67 is a validated surrogate marker for disease-free survival in HR+, HER2- breast cancer. The main secondary objective is to determine if the addition of simvastatin to letrozole compared to letrozole alone will result in increased immune activation from pre- to post-treatment based on the evaluation of the immune subtype composition in tissue via multiplex immunofluorescence.

We aim to enroll 16 patients in each arm to achieve 90% power and detect a minimum difference of 7.5% in ki-67 using a two-sided Mann-Whitney U or Wilcoxon Rank-Sum test. After accounting for a possible drop off rate of 20%, the study’s target accrual will be 40 participants. Statistical analyses will be performed using SAS 9.4. the significance level will be set at alpha = 0.1. Descriptive statistics will be applied to tissue and blood biomarkers of interest at 2 designated time points, prior to preoperative therapy and following completion of preoperative therapy. The absolute change or percentage change of those biomarkers will also be calculated and compared between the 2 arms using the nonparametric Mann-Whitney U test. The correlation among biomarkers will be described by Pearson correlation coefficient with 95% confidence interval. The p-value will be adjusted by Benjamini-Hochberg procedure to control the false discovery rate. All adverse events experienced data will be described by summary statistics and will be assessed according to CTCAE version 5.0.

Currently, the study has accrued 2 participants. After completing accrual, we will assess whether the tumor-immune milieu has undergone modulation, resulting in a more immunogenic environment. If an immunogenic effect is demonstrated, this will provide rationale for a future multi-center trial assessing the combination of letrozole, simvastatin, and immunotherapy.

Citation Format: Ruth Sacks, Elizabeth Haas, Jade Jones, Manali Bhave, Keerthi Gogineni, Jane Meisel, Demetria Smith-Graziani, Suchi Pakkala, Sarah Friend, Cletus Arciero, Lauren Postlewait, Clara Farley, Cathy Graham, Toncred Styblo, Monica Rizzo, Rhonda Pickett, Nicholas Crasta, Lori Brown, Xiaoxian Li, Sunil Badve, Madhav Dhodapkar, Kevin Kalinsky. A Randomized Window of Opportunity Study of Preoperative Letrozole and Simvastatin Versus Letrozole Alone in Stage I-III Hormone Receptor Positive, HER2 Negative Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-20-04.