A PD Study of Oral eFT508 in Subjects With Advanced TNBC and HCC

Inclusion Criteria (TNBC Cohort Only):

- Women ≥18 years of age

- Pathologically documented diagnosis of TNBC that is metastatic or locally advanced and
unresectable

- Adequate hepatic function and coagulation profile

- Negative HIV, HBV and HCV

Inclusion Criteria (HCC Cohort Only):

- Men or Women ≥18 years of age

- Histological or cytological confirmed diagnosis of HCC with Barcelona Clinic Liver
Cancer Stage B or C who cannot benefit from resection, local ablation, or
chemoembolization

- ECOG performance status of 0 or 1

- Has at least 1 measurable lesion based on irRECIST 1.1.

- Negative HIV tests

Inclusion Criteria (Either Cohort):

- subject agrees to undergo a pre-treatment and an on-treatment biopsy of the tumor

- Completion of all previous therapy for the treatment of cancer ≥3 weeks before the
start of study drug

- All acute toxic effects of any prior antitumor therapy resolved to Grade ≤1 before the
start of study drug

- Adequate bone marrow and renal function

- Life expectancy of ≥3 months

Exclusion Criteria (Either Cohort):

- Pregnant or breastfeeding

- History of another malignancy except for the following: adequately treated local basal
cell or squamous cell carcinoma of the skin; in situ cervical carcinoma; adequately
treated, papillary, noninvasive bladder cancer; other adequately treated Stage 1 or 2
cancers currently in complete remission; or any other cancer that has been in complete
remission for ≥2 years.

- Gastrointestinal disease that may interfere with drug absorption or with
interpretation of GI AEs.

- Known symptomatic brain metastases requiring ≥10 mg/day of prednisolone (or its
equivalent).

- Significant cardiovascular disease within 6 months prior to start of study drug

- Ongoing risk for bleeding due to active peptic ulcer disease or bleeding diathesis or
requirement for systemic anticoagulation with unfractionated heparin,
low-molecular-weight heparin or heparin fractions, or oral anticoagulants.

- Evidence of an ongoing systemic bacterial, fungal, or viral infection

- Has received a live vaccine within 30 days of planned start of study drug

- Major surgery within 4 weeks before the start of study drug

- Prior solid organ or bone marrow progenitor cell transplantation

- Prior therapy with any known inhibitor of MNK1 or MNK2

- Prior high dose chemotherapy requiring stem cell rescue

- History of or active autoimmune disorders or other conditions that might impair or
compromise the immune system

- Ongoing immunosuppressive therapy, including systemic or enteric corticosteroids

- Use of a strong inhibitor or inducer of cytochrome P450 (CYP)3A4 within 7 days prior
to the start of study drug or expected requirement for use of a strong CYP3A4
inhibitor or inducer during study participation

- Need for proton pump inhibitors and histamine H2 blockers

- Previously received investigational product in a clinical trial within 30 days or
within 5 elimination half lives (whichever is longer) prior to the start of study
drug, or is planning to take part in another clinical trial while participating in
this study

- HCC Cohort Only: Portal vein invasion at the main portal (Vp4), inferior vena cava, or
cardiac involvement of HCC based on imaging.