BTX-A51 in Patients With Liposarcoma

Inclusion Criteria:

• Study participants must have histologically-confirmed metastatic and/or recurrentliposarcoma (limited to the subtypes of well-differentiated and/or dedifferentiatedliposarcoma, which are associated with MDM2 amplifications).

• ECOG performance status ≤2

• Adequate organ and marrow function as defined by the following metrics resultedwithin 7 days of study enrollment:

• WBC >3000/mm3

• Platelets >75,000μl

• ANC >1500μl

• Hgb >9g/dl

• Creatinine <1.5 x ULN or measured CrCl of >60ml/m2/1.73 m2

• Total bilirubin <2 x ULN

• AST/ALT <3 x ULN

• Participants must have measurable disease, defined as at least one lesion that canbe accurately measured in at least one dimension (longest diameter to be recordedfor non- nodal lesions and short axis for nodal lesions) as ≥20 mm (≥2 cm) by chestx-ray or as

≥10 mm (≥1 cm) with CT scan, MRI, or calipers by clinical exam. See Section 11 (Measurement of Effect) for the evaluation of measurable disease.

• Patients must have recovered from toxicity related to prior therapy to grade <=1 (defined by CTCAE v5.0) (except alopecia and neuropathy, or immunotherapy relatedhypothyroidism)

• As the effect of this study drug on the developing human fetus is not known, womenof child-bearing potential and men must agree to use at least 2 methods ofcontraception (abstinence; hormonal or barrier method of birth control) for thestudy and at least 2 months after completion.

• Female patient of childbearing potential has a negative serum pregnancy test within 7 days of study enrollment.

• Ability to understand and the willingness to sign a written informed consentdocument.

• Age ≥18 years

• Patients must have completed all prior anti-cancer treatment for liposarcoma,including radiation, ≥ 14 days prior to registration.

Exclusion Criteria:

• Patient with current evidence of active and uncontrolled infection, NYHA ClassIII-IV CHF, documented Child's class B-C cirrhosis, or uncontrolled medical diseasewhich in the opinion of the investigator or the sponsor could compromise safetyand/or assessment of efficacy.

• Active infection with hepatitis C virus (HCV) or hepatitis B virus (HBV); subjectswho are positive for hepatitis B core antibody, hepatitis B surface antigen, orhepatitis C antibody must have a negative PCR result before enrollment; those whoare PCR positive will be excluded.

• Major surgical procedure or open surgical biopsy within 28 days of first dose ofstudy drug

• Active central nervous system (CNS) disease involvement, or prior history of NCICTCAE Grade ≥3 drug-related CNS toxicity. Subject with known CNS metastases that aretreated and stable (without evidence of CNS toxicity) and are not requiring systemicsteroids are allowed to be enrolled.

• Patient has known psychiatric or substance abuse disorders that would interfere withcooperation with the requirements of the trial

• Myocardial infarction within 12 months of screening

• Use of any other concurrent investigational agents or anticancer agents, excludinghormonal therapy for breast or prostate cancer

• Pregnant women are excluded from this study because there is an unknown butpotential risk for adverse events in nursing infants secondary to treatment of themother with BTX- A51, breastfeeding should be discontinued if the mother is treatedwith BTX-A51.

• Inability to swallow pills or inadequate GI absorption in the opinion of thetreating investigator.