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 anthracyclines havecytotoxic 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 cardiac arrhythmia
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 small moleculekinase 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
10. Patients with unresectable soft tissue sarcomas of the extremity AJCC Stage III ORselect IV (=>5 cm injectable tumors) locally advanced and or metastatic, not amendableto primary surgical intervention according to the consensus of a multidisciplinarytreatment team, determined prior to screening.
11. High grade STS, Grade 2/3, with an assessable/injectable lesion of at least diameter ≥5 cm by RECIST 1.1 criteria
12. No prior chemotherapy for STS, or radiation to affected limb Phase 2a Expansion Group 1 (Extremity STS): Exclusion
13. Uncontrolled pain related to tumor
14. Open wounds or tissue necrosis related to tumor mass
15. Compartment syndrome or impending compartment syndrome Phase 2a Expansion Group 2 (Unresectable STS): Inclusion
16. Locally advanced or metastatic, unresectable, soft-tissue sarcoma of intermediate orhigh grade with measurable disease.
17. Life expectancy >12 weeks (about 3 month) Phase 2a Expansion Group 2 (Unresectable STS): Exclusion
18. Prior exposure to anthracyclines
19. Treatment naive extremity tumors Phase 2a Expansion Group 3a (Head and Neck): Inclusion
20. Patients with histologically or cytologically confirmed squamous-cell carcinoma of thehead and neck (HNSCC) who meet any of the following a) confirmed relapsed HNSCC or b)metastatic at initial presentation HNSCC
21. Patients who may have received two or less systemic regimens (therapies includechemotherapy and/or immunotherapy) Phase 2a Expansion Group 3a (Head and Neck): Exclusion
22. Airway obstruction by tumor mass that requires clinical intervention
23. Prior treatment with anthracyclines