A 2-Week Ketogenic Diet in Combination With Letrozole to Modulate PI3K Signaling in ER+ Breast Cancer

Inclusion Criteria:

All participants must provide written informed consent.

Patients must have histologically confirmed primary invasive mammary carcinoma

The tumor must be estrogen receptor positive
The tumor must be HER2 negative (negative IHC or FISH)
The primary tumor size must be at least 2 mm in size.

Patients must be post-menopausal defined by any of the following:

Subjects at least 55 years of age.
Subjects younger than 55 years of age and amenorrheic for at least 12 months or serum follicle-stimulating hormone (FSH) levels and estradiol levels in the post-menopausal range by local lab criteria
Subjects with history of bilateral oophorectomy or prior radiation castration with amenorrhea for at least 6 months.
Patients must have clinical stage I, II, or III invasive mammary carcinoma planning to undergo surgical treatment with either segmental resection or total mastectomy.
Patients must have BMI >= 30.
A core biopsy from the time of diagnosis must be available.
Mammogram or ultrasound required prior to screening

Patients must have adequate organ function based on the following laboratory parameters:

Serum creatinine <= 1.5x ULN
SGOT, SGPT <= 4x ULN (unless known steatohepatitis)
Serum albumin >= 2.0 g/dL
Total serum bilirubin <= 1.5x ULN (or <= 3x ULN if known Gilbert's syndrome)

Exclusion Criteria:

Patients with locally advanced disease who are candidates for other preoperative (chemo)therapy at the time of initial evaluation. This includes patients with inflammatory breast cancer.

Evidence of distant metastatic disease (stage IV).
Serious medical illness that in the judgment of the treating physician places the patient at high risk of operative mortality.
Serious medical illness that in the judgment of the treating physician would preclude the use of a ketogenic diet.
Severe uncontrolled malabsorption condition or disease (e.g. grade II/III diarrhea, severe malnutrition, short gut syndrome).
Diabetes mellitus requiring insulin therapy.
Dementia, altered mental status, or any psychiatric condition that would prohibit the understanding or rendering of informed consent.
Participation in any other neoadjuvant therapeutic clinical trial.
Concurrent anti-cancer therapy other than endocrine therapy (e.g. chemotherapy, radiotherapy, immunotherapy, or any other biologic therapy).
Concurrent treatment with an investigational agent.
Use of an investigational drug within 30 days or 5 half-lives, whichever is longer, preceding the first day of dietary intervention.