A Study of a New Drug, Nirogacestat, for Treating Desmoid Tumors That Cannot be Removed by Surgery

Inclusion Criteria:

   - Patients must be > 12 months and < 18 years of age at the time of enrollment

   - Patients must have a body surface area of > 0.3 m^2 at the time of enrollment

   - Existing or recurrent desmoid tumor that is deemed not amenable to surgery without
   significant morbidity and progressed by >= 10% as assessed by RECIST version (v)1.1
   within the 6-month period prior to study enrollment

      - Patients must have had histologic verification of the desmoid tumor

      - Patients must have measurable disease by RECIST v1.1 criteria

      - Patient must have received at least one prior course of systemic therapy for
      desmoid tumor

   - Patients must have a Lansky (for patients =< 16 years of age) or Karnofsky (for
   patients > 16 years of age) performance status score of >= 50. Patients who are unable
   to walk because of paralysis, but who are up in a wheelchair, will be considered
   ambulatory for the purpose of assessing performance score

   - Patients must have fully recovered from the acute toxic effects of all prior
   chemotherapy, immunotherapy, surgery or radiotherapy prior to entering this study.
   Patients may not be using or anticipate using these treatments after the observed
   progression or within the time period stated below

      - Cytotoxic chemotherapy: must not have received within 2 weeks of entry onto this
      study (4 weeks if prior nitrosourea)

      - Small molecule tyrosine kinase inhibitors (e.g., sorafenib, pazopanib, imatinib),
      rapalogs (e.g., temsirolimus, everolimus, sirolimus) or anti estrogen therapy
      (e.g., tamoxifen): may not have received within 28 days prior to the first dose
      of study treatment

      - Antibodies: >= 21 days must have elapsed from infusion of last dose of antibody,
      and toxicity related to prior antibody therapy must be recovered to grade =< 1

      - Biologic (anti-neoplastic agent): at least 7 days since the completion of therapy
      with a biologic agent

      - Local regional tumor directed therapy, including, but not limited to small port
      radiation therapy (RT), radiofrequency ablation, cryotherapy, surgery: at least 2
      weeks since these therapies and all toxicity must have resolved to grade =< 1. If
      prior craniospinal RT or if >= 50% radiation of pelvis then >= 6 months must have
      elapsed. If other substantial bone marrow (BM) radiation, then >= 6 weeks must
      have elapsed

      - Stem cell transplant (SCT): No evidence of active graft versus (vs.) host
      disease. For allogeneic SCT, >= 6 months must have elapsed

      - No prior gamma-secretase, Notch or beta-catenin inhibitor

      - Investigational drugs: must not have received investigational drug within 4 weeks
      of study entry, and all toxicities related to prior therapy must be resolved to
      grade =< 1 or baseline

   - Concomitant Medication Restrictions

      - Growth factor(s): must not have received within 1 week of entry onto this study

      - Patients who are currently receiving drugs that are strong inducers or moderate
      or strong inhibitors of CYP3A4 are not eligible. Strong inducers or moderate or
      strong inhibitors of CYP3A4 are not allowed from 14 days prior to enrollment to
      the end of protocol therapy. Note: CYP3A4 inducing anti-epileptic drugs on a
      stable dose, are allowed

      - Must not be receiving non-steroidal anti-inflammatory drugs (NSAIDs) as treatment
      for desmoid tumor after the observed progression and patient agrees to not use
      NSAIDs while on study. Occasional use (defined as =< 3 times per week) for
      treatment of pain is permitted

   - Peripheral absolute neutrophil count (ANC) >= 1000/uL (within 7 days prior to
   enrollment)

   - Platelet count >= 100,000/uL (transfusion independent) (within 7 days prior to
   enrollment)

   - Hemoglobin >= 9.0 g/dL (may receive red blood cell [RBC] transfusions) (within 7 days
   prior to enrollment)

   - Creatinine clearance or radioisotope glomerular filtration rate (GFR) >= 70
   mL/min/1.73 m^2 or a serum creatinine based on age/gender as follows (within 7 days
   prior to enrollment):

      - Age: Maximum serum creatinine (mg/dL)

      - Age: 1 to < 2 years; Maximum serum creatinine (mg/dL): 0.6 (male and female)

      - Age: 2 to < 6 years; Maximum serum creatinine (mg/dL): 0.8 (male and female)

      - Age: 6 to < 10 years; Maximum serum creatinine (mg/dL): 1 (male and female)

      - Age: 10 to < 13 years; Maximum serum creatinine (mg/dL): 1.2 (male and female)

      - Age: 13 to < 16 years; Maximum serum creatinine (mg/dL): 1.5 (male); 1.4 (female)

      - Age: >= 16 years; Maximum serum creatinine (mg/dL): 1.7 (male); 1.4 (female)

   - Adequate liver function defined as:

   - Total bilirubin =< 1.5 x upper limit of normal (ULN) for age (unless secondary to
   previously diagnosed Gilbert's syndrome) (within 7 days prior to enrollment)

   - Serum glutamate pyruvate transaminase (SGPT) (alanine aminotransferase [ALT]) =< 135
   U/L

      - Note: For the purpose of this study, the ULN for SGPT (ALT) has been set to the
      value of 45 U/L (within 7 days prior to enrollment)

   - Adequate cardiac function defined as:

      - Corrected QT (QTc) interval < 470 ms

      - No history of congenital or acquired prolonged QTc syndrome

      - No history of clinically significant cardiac arrhythmias, congestive heart
      failure, stroke or myocardial infarction within 6 months prior to study entry

   - All patients and/or their parents or legal guardians must sign a written informed
   consent

   - All institutional, Food and Drug Administration (FDA), and National Cancer Institute
   (NCI) requirements for human studies must be met

Exclusion Criteria:

   - Active or chronic infection within 7 days prior to study entry

   - Presence of non-healing fracture

      - Note: patients with pathologic fracture related to tumor are eligible

   - Use of corticosteroids within 21 days of enrollment, except in the following
   situations:

      - Physiologic steroid replacement for adrenal insufficiency

      - Topical, ocular, intra-articular, intranasal, or inhaled corticosteroid with
      minimal systemic absorption

      - Short course (=< 7 days) of corticosteroid prescribed prophylactically (eg, for
      contrast dye allergy) or for the treatment of a non-autoimmune condition (eg,
      delayed-type hypersensitivity reaction caused by contact allergen), or
      exacerbation of asthma

   - Patients with gastrointestinal conditions that might predispose for drug
   intolerability or poor drug absorption (e.g., inability to take oral medication, prior
   surgical procedures affecting absorption (e.g., gastric bypass), malabsorption
   syndrome, and active peptic ulcer disease)

   - Patients with ulcerative colitis, inflammatory bowel disease, or a partial or complete
   small bowel obstruction

   - Known active infection with hepatitis B, hepatitis C or human immunodeficiency virus
   (HIV)

   - Patients with a prior history of malignancy, with the exceptions of desmoid tumor(s)
   and non-melanoma skin cancer, who are not in remission for more than 3 years

   - Patients who are unable to swallow tablets. Tablets must not be crushed or chewed.
   Administration of nirogacestat via gastrostomy tube or nasogastric tube is not allowed

   - Patients who in the opinion of the investigator may not be able to comply with the
   safety monitoring requirements of the study

   - Sexually active female patients of reproductive potential who have not agreed to use 1
   method of highly effective contraceptive (including copper-containing intrauterine
   device, condom with spermicidal foam/gel/film/cream/suppository, bilateral tubal
   ligation, established use of inserted, injected or implanted hormonal method of
   contraception, abstinence, or male sterilization) for the duration of their study
   participation and for at least 6 months after last dose of nirogacestat. A second form
   of contraception (i.e. barrier method) is required for patients who are using hormonal
   contraception as nirogacestat may reduce the efficacy of hormonal contraceptives

   - Sexually active male patients of reproductive potential who have not agreed to use a
   condom and their female partner who have not agreed to use one of the highly effective
   methods of contraception mentioned above during treatment and for at least 90 days
   after the last dose of nirogacestat

   - Female patients who are breastfeeding

   - Female patients who are pregnant. These patients are excluded because there is no
   available information regarding the effects of nirogacestat on the developing human
   fetus and inhibition of gamma-secretase is known to be teratogenic

   - Female patients of childbearing potential unless a negative pregnancy test result has
   been obtained