CB-839 + Capecitabine in Solid Tumors and Fluoropyrimidine Resistant PIK3CA Mutant Colorectal Cancer

Phase I Primary Objective:

To determine the safety, tolerability and recommended phase II dose (RP2D) of combination
CB-839 and capecitabine chemotherapy in patients with advanced solid tumors for whom there
are no remaining treatment options or for whom single agent capecitabine is an acceptable
therapy.

Phase II Primary Objective:

To determine the disease control rate of combination CB-839 and capecitabine chemotherapy in
patients with metastatic PIK3CA mutant colorectal cancers who are refractory to
fluoropyrimidine based therapy.

Phase I Secondary Objectives:

To determine the dose-limiting toxicities and maximum tolerated dose of combination therapy
with CB-839 and capecitabine in patients with advanced solid tumors for whom there are no
remaining treatment options or for whom single agent capecitabine is an acceptable therapy.

To determine the disease control rate as assessed by RECIST criteria of combination therapy
with CB-839 and capecitabine in patients with advanced solid tumors for whom there are no
remaining treatment options or for whom single agent capecitabine is an acceptable therapy.

Phase II Secondary Objectives:

To determine the progression free survival following treatment with CB-839 and capecitabine
chemotherapy in patients with metastatic PIK3CA mutant colorectal cancer and are refractory
to fluoropyrimidine therapy.

To determine the overall survival following treatment with CB-839 and capecitabine
chemotherapy in patients who have metastatic PIK3CA mutant colorectal cancer and are
refractory to fluoropyrimidine therapy.

Inclusion Criteria:

- Phase I

- Patients must have an advanced solid tumors for whom there are no remaining
treatment options or colorectal patients who have progressed on front-line
fluoropyrimidine containing therapy. Patients with colorectal cancer must have
progressed on at least one line of fluoropyrimidine containing therapy. Receipt
of either oxaliplatin or irinotecan in combination with a fluoropyrimidine is
required in the front line setting for all colorectal cancer patients unless
either of these agents are otherwise contraindicated in the opinion of the
treating physician. Prior regorafenib or TAS-102 therapy is not required.

- Patients must have an Eastern Cooperative Oncology Group (ECOG) performance
status of 0-1

- Patients must have normal organ and marrow function as defined below:

- Hemoglobin ≥ 9.0 g/dl

- Leukocytes ≥ 3,000/mcL

- Absolute neutrophil count ≥ 1,500/mcL

- Platelet count ≥ 100,000/mcL

- Serum creatinine ≤ 1.5 X institutional upper limit of normal

- Total bilirubin ≤ 1.5mg/dL

- Aspartate Aminotransferase (AST) serum glutamic oxaloacetic transaminase
(SGOT) ≤ 2.5 X institutional upper limit of normal

- Alanine Aminotransferase (ALT) serum glutamic pyruvic transaminase (SGPT) ≤
2.5 x institutional upper limit of normal

- Patients must be able to swallow pills.

- Patients must have the ability to understand and the willingness to sign a
written informed consent document.

- Female patients of childbearing potential must have a negative serum or urine
pregnancy test within 3 days prior to the first dose of study drug and agree to
use dual methods of contraception during the study and for a minimum of 3 months
following the last dose of study drug. Post-menopausal females (>45 years old and
without menses for >1 year) and surgically sterilized females are exempt from
these requirements. Male patients must use an effective barrier method of
contraception during the study and for a minimum of 3 months following the last
dose of study drug if sexually active with a female of childbearing potential.

- Phase II

- Patients must have histologically or cytologically confirmed,
phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)
mutant metastatic colorectal cancer. PIK3CA status must be confirmed by tumor
sequencing in a CLIA certified lab.

- Patients must have measurable disease according to Response Evaluation Criteria
In Solid Tumors (RECIST) 1.1 criteria that is amenable to biopsy and be willing
to undergo pre- and post-treatment tumor biopsies. Lesions to be biopsied do not
have to be those used for measurement.

- Patients must have received and progressed on fluoropyrimidine or
fluoropyrimidine based therapy. Receipt of either oxaliplatin or irinotecan in
combination with a fluoropyrimidine is required in the front line setting unless
either of these agents are otherwise contraindicated in the opinion of the
treating physician in which case a fluoropyrimidine only may be used. Prior
regorafenib or TAS-102 therapy is not required.

- Patients must have an Eastern Cooperative Oncology Group (ECOG) performance
status of 0-1.

- Patients must have normal organ and marrow function as defined below:

- Hemoglobin ≥ 9.0 g/dl

- Leukocytes ≥ 3,000/mcL

- Absolute neutrophil count ≥ 1,500/mcL

- Platelet count ≥ 100,000/mcL

- Serum creatinine within normal institutional limits

- Total bilirubin ≤ 1.5 mg/dL

- AST (SGOT) ≤ 2.5 X institutional upper limit of normal

- ALT (SGPT) ≤ 2.5 x institutional upper limit of normal

- Patients must be able to swallow pills.

- Patients must have the ability to understand and the willingness to sign a
written informed consent document.

- Female patients of childbearing potential must have a negative serum or urine
pregnancy test within 3 days prior to the first dose of study drug and agree to
use dual methods of contraception during the study and for a minimum of 3 months
following the last dose of study drug. Post-menopausal females (>45 years old and
without menses for >1 year) and surgically sterilized females are exempt from
these requirements. Male patients must use an effective barrier method of
contraception during the study and for a minimum of 3 months following the last
dose of study drug if sexually active with a female of childbearing potential.

Exclusion Criteria:

- Both Phase I and Phase II

- Patients with ongoing toxicities > grade 1 according to National Cancer Institute
(NCI) Common Terminology Criteria For Adverse Events (CTCAE) Version 4.0
(excluding alopecia) due to prior anti-cancer therapy.

- Patients receiving any other investigational agents or whom have received recent
treatment for colorectal cancer (radiation within the previous two weeks,
chemotherapy or investigational therapy within the previous four weeks).

- Patients with untreated brain metastases/central nervous system disease will be
excluded due to their poor prognosis and because they often develop progressive
neurologic dysfunction that would confound the evaluation of neurologic and other
adverse events.

- Patients with a history of allergic reactions attributed to or intolerance to
compounds of similar chemical or biologic composition to either CB-839 or
capecitabine. If capecitabine has been received previously, must have tolerated
at least an equivalent dose to the dose to be administered at their assigned dose
level.

- Patients who are unable to swallow pills or who have undergone surgery that
prohibits the absorption of pills in the stomach.

- Patients with uncontrolled intercurrent illness including, but not limited to
ongoing or active infection, symptomatic congestive heart failure, unstable
angina pectoris or myocardial infarction within prior 6 months, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance
with study requirements.

- Patients who are pregnant or breastfeeding will be excluded from the study.

- Patients known to be HIV positive who are not receiving anti-retroviral therapy
will be excluded due to the marrow suppressive therapy involved in administration
of the study treatment.