Brandy M. Heckman-Stoddard

We performed a phase Ib clinical trial in participants with breast carcinoma evaluating the effects of the novel rexinoid 9cUAB30 orally for 14-28 days prior to surgical resection. Twenty-seven female volunteers (mean±S.D. age 63±10 years) newly diagnosed with breast cancer awaiting surgery as their initial treatment received 9cUAB30 once daily (240 mg for first 5 participants and 160 mg for the subsequent 22 participants) for 13-25 days. Comparison of breast tissue proliferation (Ki-67) at baseline and end of study revealed no significant change with results similar to participant-matched historical control samples. Secondary analysis of tissue apoptosis (Cleaved Caspase 3) observed an increase from baseline to end of study but when compared to changes exhibited by matched to historical controls, no difference was observed. Exploratory analysis of participant tissue samples by nCounter molecular profiling observed increased cytokine and decreased proliferation marker gene expression. Assessment of circulating dendritic cells demonstrated an increase in type 1 monocytic and a decrease in type 2 plasmacytic cells. 9cUAB30 plasma concentrations day of surgery were 349 ± 204 ng/ml (range 66-873). Most participants had grade 1-2 adverse events with the most common being hypertension, headache and gastrointestinal- and skin-related symptoms. Laboratory analysis observed a small but significant increase in total and LDL serum cholesterol (p<0.001). In this phase Ib clinical trial, 9cUAB30 was well tolerated with mild rexinoid-related side effects, no measurable effect upon breast tissue proliferation but encouraging exploratory effects on gene expression and circulating immune effector cells at relatively high daily rexinoid dosing.

Supplementary Table 1: Representativeness of Study Participants

Cancer cells exhibit metabolic flexibility between anaerobic glycolysis and oxidative phosphorylation. Preclinical data showed that metformin, an oxidative phosphorylation inhibitor, combined with fasting-induced hypoglycemia led to activation of the PP2A–GSK3ß–Mcl1 axis and inhibition of tumor growth. A window-of-opportunity trial was designed to evaluate the effect of metformin and nightly fasting on proliferation in invasive breast cancer or ductal carcinoma in situ (DCIS). The primary endpoint is the pretreatment/posttreatment change of Ki67 in cancer tissue, and the co-primary endpoint is the difference in posttreatment Ki67 in cancer-adjacent DCIS or high-risk lesions. Participants with hormone receptor–positive invasive breast cancer or DCIS candidates to surgery are being accrued and randomized to either (i) fasting for ≥16 hours nightly, plus nutritional counseling and daily metformin with continuous glucose monitoring, or (ii) continuous glucose monitoring. The intervention lasts 4 to 6 weeks with gradual metformin ramp up to limit gastrointestinal disturbances. The safety of the combination was evaluated as a primary interim endpoint. The frequency of dose-limiting toxicity (≥G3 adverse events related to treatment) was assessed in the first 14 participants in the experimental arm. Most adverse events were of low grade (G1: 50; 90.9%) and unrelated to the treatment (G1: 26 unrelated; 52%). No one discontinued treatment because of toxicity, and no dose-limiting toxicities were observed, so the escalation phase of metformin was significantly shortened from 7 to 3 days. The results of this project will expand knowledge of this prevention approach and possibly provide the basis for large-scale primary prevention studies in at-risk women.Prevention Relevance:In a context of rising cancer drug costs, this research explores a low-cost treatment to optimize breast cancer preventive intervention. The approach is safe and based on repurposed drugs that could enhance prevention strategies for obesity- and insulin-related cancers, offering immediate applicability to a large-scale trial in women at risk.

A: Comparison of serum estradiol levels vs BMI at baseline (pre-treatment) (p = 0.001). B: Serum estradiol vs BMI at surgery (post-treatment) (p = 0.0004) C: Change in serum estradiol vs BMI (p = 0.86)

Change in Ki-67 compared to change in steroid receptors

Comparison of clinicopathologic factors between participants who responded to exemestane (Ki-67 decrease) and did not respond to exemestane (Ki-67 increase)

Change in Ki-67 vs baseline steroid receptors

Changes in histologic diagnosis between baseline (pre-treatment) and surgery (post-treatment)

Comparison of change in Ki-67 with baseline (pre-treatment) serum estradiol level, p = 0.11

Purpose:To evaluate exemestane, an aromatase inhibitor, as a preventive intervention for endometrial cancer.Experimental Design:This is a multicenter, single-arm, “window of opportunity” pilot study of exemestane (25 mg daily for 21–42 days) in postmenopausal individuals undergoing hysterectomy for endometrial intraepithelial neoplasia (EIN) or low-grade endometrial cancer. The primary objective is to determine the change in proliferation, measured by Ki-67 expression, in pre- and posttreatment endometrial tissue specimens. Secondary outcomes include measurement of circulating serum estradiol and progesterone levels, pathologic response, tissue biomarkers, safety, and adverse effects.Results:Forty participants were accrued to the study. The mean body mass index was 40.3 (range, 22.8–60.5, SD = 9.8). Preoperative diagnoses included EIN (n = 11, 27.5%), grade 1 endometrial cancer (n = 26, 65%), and grade 2 endometrial cancer (n = 3, 7.5%). Median Ki-67 score decreased from 40.7% [IQR (33.9, 50.3)] at baseline to 18.1% [IQR (8.8, 31.8)] at surgery, representing a median absolute change from baseline of 20.4% [IQR (−29.9, −6.7), P < 0.001]. In a matched historic control cohort, participants also had a decrease in Ki-67 score with a median absolute change from baseline of −6.7% [IQR (−12.7, −1.3), P< 0.001]. However, the decrease in Ki-67 was greater in the study participants than the historic controls, with a median difference between the groups of −13.4% [IQR (−23.3, 6.9), P ≤ 0.01]. Both tissue estrogen receptor and progesterone receptor expression declined significantly with exemestane treatment (P < 0.001). However, serum estradiol levels did not change between baseline and after treatment (P = 0.16).Conclusions:In this pilot study, exemestane demonstrated antiproliferative effects in EIN and low-grade endometrial cancer. This agent warrants further evaluation for the prevention of endometrial cancer.