FS118 First in Human Study in Patients With Advanced Malignancies

Inclusion Criteria:

All participants:

• Age ≥18 years;
• Participants with histologically confirmed, locally advanced, unresectable, or metastatic solid tumors that progressed while on or after PD-1/PD-L1 containing therapy;
• Measurable disease;
• Eastern Cooperative Oncology Group (ECOG) Performance Status ≤1;
• Life expectancy estimated to be at least 3 months;
• Highly effective contraception;
• Willing and able to provide written informed consent.

Expansion cohort only:

• Histologically and/or cytologically confirmed recurrent/metastatic (R/M) SCCHN that is not amenable to curative therapy by surgery or radiation;
• Only 1 prior anti-PD-1 or anti-PD-L1 therapy and documented PD-L1 scoring ≥1% by combined positive score or tumor proportion score as part of their treatment;
• An anti-PD-1 or anti-PD-L1 treatment regimen must be the last prior therapy before study enrollment, following no more than 2 prior systemic regimens for R/M SCCHN;
• Acquired resistance to an anti-PD-1- or anti-PD-L1-containing therapy;
• The participant agrees to undergo a pre-treatment and on-treatment core or excisional biopsy and the biopsy procedure is not judged to be high risk by the Investigator.

Exclusion Criteria:

All participants:

• Participant is deemed at high risk of fatal outcome in case of COVID-19;
• Participants with a history of COVID-19 and have not provided a negative test for SARS CoV-2 infection within 28 days of the planned first dose date with FS118;
• Prior therapy: Received systemic anti-cancer therapy within 28 days or 5 half-lives, of the first dose of study drug, or prior treatment with a LAG-3 inhibitor;
• Participants with active or documented history of autoimmune disease;
• History of uncontrolled intercurrent illness;
• Known infections;
• Uncontrolled CNS metastases, primary CNS tumors, or solid tumors with CNS metastases as only measurable disease;
• Prior history of or active interstitial lung disease or pneumonitis, encephalitis, seizures, severe immune related adverse events with prior PD-1/PD-L1 containing treatments;
• Significant cardiac abnormalities;
• Significant laboratory abnormalities;
• Intolerance to the investigational product or its excipients, or any condition that would significantly impair and/or prohibit the participants's participation in the study, as per the Investigator's judgment.

Expansion cohort only:

• Participant has nasopharynx or thyroid primary tumor site;
• History of severe immune-related toxicity during the prior treatment with checkpoint inhibitors.