Nirogacestat in Premenopausal Females With Desmoid Tumor/Aggressive Fibromatosis (DT/AF)

Inclusion Criteria: * Participant is female, postpubertal aged ≥18 and ≤40 years of age at the time of signing the informed consent and premenopausal at baseline. Premenopausal is defined as meeting all of the following: Estradiol \>30 pg/mL. Follicle-stimulating hormone (FSH) \<40 IU/L. Regular menses (e.g., menstrual cycle length of 21 to 35 days) for at least 3 menstrual cycles prior to signing informed consent * Participant uses 1 highly effective non-hormonal contraceptive method, has a negative pregnancy test prior to first dose of study treatment), is not breastfeeding, agrees to not harvest or donate eggs for at least 90 days prior to and during the study * Participant has histologically confirmed DT/AF with symptomatic or progressive disease requiring systemic treatment * Participant has an Eastern Cooperative Oncology Group (ECOG) performance status ≤2 at screening * Participant has adequate organ and bone marrow function. Exclusion Criteria: * Participant has known malabsorption syndrome or preexisting gastrointestinal conditions that may impair absorption of nirogacestat * Participant has experienced any of the following within 6 months of signing informed consent: clinically significant cardiac disease (New York Heart Association Class III or IV), myocardial infarction, severe/unstable angina, coronary/peripheral artery bypass graft, symptomatic congestive heart failure, cerebrovascular accident, transient ischemic attack, or symptomatic pulmonary embolism. * …