Phase 1/2a Study of SQ3370 in Patients With Advanced Solid Tumors

Phase 1: Inclusion Criteria:

1. Diagnosis of advanced soft tissue sarcoma or other solid tumors

2. Adequate hematologic, hepatic, renal, and coagulation function

3. ECOG performance status score 0-1

4. Tumor is the type where published clinical data would suggest that anthracyclineshave cytotoxic activity

5. Injectable tumor present

Phase 1: Exclusion Criteria:

1. Prior exposure to 300 mg/m^2 of Dox HCl or DOXIL / CAELYX ® or 600 mg/m^2 ofEpirubicin HCl

2. Congestive heart failure (CHF), severe myocardial insufficiency, or cardiacarrhythmia

3. Any of the following within 28 days prior to Cycle 1 Day 1:

• Major surgery, as defined by the Investigator

• Radiotherapy

• Chemotherapy, immunotherapy and/or anticancer therapy (except for smallmolecule kinase inhibitors, which are 6 elimination half-lives)

4. Trastuzumab or trastuzumab emtansine dosed within 7 months prior to Cycle 1 Day 1.

5. Any transfusion within 14 days prior to Cycle 1 Day 1.

6. Pregnant or breast-feeding women.

7. Known active CNS metastases and/or carcinomatous meningitis or symptomatic brainmetastasis. Participants with previously treated brain metastases may participateprovided they are radiologically stable

8. History of allergic reactions attributed to Dox or other anthracyclines, NaHA,hyaluronic acid, or gram-positive bacterial proteins

9. History or evidence of clinically unstable/uncontrolled disorder, condition, ordisease

Phase 2a Expansion Group 1 (Extremity STS): Inclusion

1. Patients with unresectable soft tissue sarcomas of the extremity AJCC Stage III ORselect IV (=>5 cm injectable tumors) locally advanced and or metastatic, notamendable to primary surgical intervention according to the consensus of amultidisciplinary treatment team, determined prior to screening.

2. High grade STS, Grade 2/3, with an assessable/injectable lesion of at least diameter ≥5 cm by RECIST 1.1 criteria

3. No prior chemotherapy for STS, or radiation to affected limb

Phase 2a Expansion Group 1 (Extremity STS): Exclusion

1. Uncontrolled pain related to tumor

2. Open wounds or tissue necrosis related to tumor mass

3. Compartment syndrome or impending compartment syndrome

Phase 2a Expansion Group 2 (Unresectable STS): Inclusion

1. Locally advanced or metastatic, unresectable, soft-tissue sarcoma of intermediate orhigh grade with measurable disease.

2. Life expectancy >12 weeks (about 3 month)

Phase 2a Expansion Group 2 (Unresectable STS): Exclusion

1. Prior exposure to anthracyclines

2. Treatment naive extremity tumors

Phase 2a Expansion Group 3a (Head and Neck): Inclusion

1. Patients with histologically or cytologically confirmed squamous-cell carcinoma ofthe head and neck (HNSCC) who meet any of the following a) confirmed relapsed HNSCCor b) metastatic at initial presentation HNSCC

2. Patients who may have received two or less systemic regimens (therapies includechemotherapy and/or immunotherapy)

Phase 2a Expansion Group 3a (Head and Neck): Exclusion

1. Airway obstruction by tumor mass that requires clinical intervention

2. Prior treatment with anthracyclines