A Phase 1-2 Study of ST101 in Patients With Advanced Solid Tumors

Dose escalation / regimen exploration phase During the dose escalation/regimen exploration phase, only patients diagnosed with locally advanced or metastatic melanoma, carcinoma or sarcoma of any tumor type who are refractory or intolerant to all available therapies that would impact survival will be enrolled. ST101 will be administered intravenously (IV), initially once per week. The dose escalation cohorts will be recruited using a standard 3+3 design. At each new dosing cohort, there will be a 1-week observation period after dosing the first patient in order to assess safety prior to dosing the remainder of the patients in that cohort. The dose cohorts will be 0.5, 1, 2, 4, 8 and 16 mg/kg with once weekly (QW) dosing in all cohorts except for the highest dose level which will be dosed every other week (Q2W). The expansion phase consists of 4 specific tumor-type cohorts, which each follow the same Simon 2-stage design. Fifteen (15) patients will be enrolled in each cohort and treated with the ST101 RP2D. If one or more responses is observed that cohort will be expanded to a total of 30 patients to further assess efficacy. Responses will be graded using response evaluation criteria in solid tumors (RECIST) 1.1 (Eisenhauer 2009) for hormonal receptor positive (HRpos) locally advanced/metastatic breast cancer (LA/MBC) and melanoma, modified response assessment in neuro-oncology (RANO) (Ellingson 2017) for GBM and prostate cancer clinical trials working group 3 (PCWG3) (Scher 2016) for castration-resistant prostate cancer (CRPC).During the expansion phase, only patients diagnosed with the following tumor types will be allowed into this phase of the study: * HRpos LA/MBC that has progressed after prior 1-2 hormone-based therapies. Previous treatment with cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, mammalian target of rapamycin (mTOR) inhibitor or chemotherapy is allowed as monotherapy or in combination. * Melanoma that has progressed after/or on treatment with an immune checkpoint inhibitor (CPI) and have received 1-2 prior lines of therapy for their advanced/metastatic disease. Patients that have BRAF mutated disease should also have received one line of appropriate targeted therapy. * Primary (de novo) GBM that has recurred or progressed (per modified RANO criteria) after 1 standard treatment regimen. Standard therapy is defined as maximal surgical resection, radiotherapy, and concomitant temozolomide with radiotherapy or adjuvant chemotherapy with temozolomide. Patients that undergo tumor treating fields as an adjuvant to first line therapy are allowed. * CRPC that has progressed after previous treatment with taxanes, abiraterone and enzalutamide/apalutamide. The tumor types in the expansion phase may change based on emerging data from the dose escalation phase of this study. Additional mini cohorts of 10 patients may be added to the expansion phase based on efficacy signals during the dose escalation phase.