A Study of DSP107 Alone and in Combination with Atezolizumab for Patients with Advanced Solid Tumors

This study will be the first time that DSP107 is administered to human subjects. The aim of the study is to evaluate the safety, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary efficacy of DSP107 monotherapy and combination therapy in a two-part design.

Part 1 will involve DSP107 monotherapy dose escalation in subjects with advanced solid tumors that are not amenable to surgical resection or other approved therapeutic options that have demonstrated clinical benefit. Additional dose finding cohorts will be enrolled to establish a safe dose of DSP107 when given in combination with atezolizumab.

Part 2 will comprise two expansion cohorts:

A) Expansion cohort A consisting of one treatment arm in which subjects will be treated with DSP107 in combination with atezolizumab. This expansion cohort will enroll subjects with non small cell lung cancer who have progressed following no more than 2 lines of prior systemic treatment including treatment with PD-1 or PD-L1 targeting agents.

B) Expansion cohort B consisting of two treatment arms in which subjects will be treated either with DSP107 monotherapy or DSP107 in combination with atezolizumab. This expansion cohort will enroll subjects with colorectal cancer who have progressed following two previous lines of therapy.

Inclusion criteria

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
• Subject must have measurable disease per RECIST version 1.1
• Part 1:

o Histologically confirmed advanced solid tumor that is not amenable to surgical resection or other approved therapeutic options that have demonstrated clinical benefit or subject is intolerant or has refused available therapies

• Part 2, Expansion Cohort A:

• Histologically confirmed, inoperable non-small cell lung cancer (Stage 3b or Stage 4). Squamous and non-squamous histologies are both acceptable
• Wildtype for actionable oncogenic driver mutations (e.g., ALK, EGFR, ROS1, RET, NTRK). Driver mutations for KRAS, BRAF and c-METex14skip will be allowed.
• Received no more than 2 lines of prior systemic treatment, including anti PD-1 or anti PD-L1 therapeutic agent ± chemotherapy. Targeted therapies for KRAS, BRAF and c-METex14skip will not be counted towards the previous lines of therapy.
• Part 2, Expansion Cohort B:

• Histologically confirmed, inoperable microsatellite stable colorectal carcinoma (Stage 3b or Stage 4)
• Received two previous lines of therapy including standard chemotherapy and/or targeted antibodies

Exclusion criteria

• Life expectancy of ≤ 3 months
• Central nervous system (CNS) metastases
• Life-threatening (grade 4) immune-mediated adverse event related to prior immunotherapy
• Immune-mediated adverse reaction that required discontinuation of prior immunotherapy
• Past or current history of autoimmune disease or immune deficiency
• History of autoimmune hemolytic anemia or autoimmune thrombocytopenia
• History of hematological malignancy
• History of organ or stem cell transplantation
• Clinically significant liver disease, including alcoholic hepatitis, cirrhosis, fatty liver disease and inherited liver disease
• Previously treatment with CAR-T cells
• Treatment with systemic immunosuppressive medication within 2 weeks prior to first dose of study treatment
• Received live, attenuated vaccine within 4 weeks prior to first dose of study treatment
• Treatment with systemic immunostimulatory agents within 4 weeks prior to first dose of study treatment
• Treatment with atezolizumab, any CD47/SIRPα targeting agent or immune agonists (e.g., anti-CD137, anti-CD40, anti-OX40)
• Known allergy or hypersensitivity to any of the test compounds, materials or contraindication to test product
• Clinically significant abnormal laboratory safety tests
• Detection of anti DSP107 antibodies at screening
• History of HIV infection or active Hepatitis B or C infection
• Pregnant or breast feeding or planning to become pregnant while enrolled in the study
• History or evidence of any other clinically unstable/uncontrolled disorder, condition, or disease