A Study to Evaluate the Safety, Pharmacokinetics and Clinical Activity of RO6870810 and Atezolizumab (PD-L1 Antibody) in Participants With Advanced Ovarian Cancer or Triple Negative Breast Cancer

Inclusion Criteria:-

Groups 1 and 2: Participants with histologically confirmed advanced ovarian cancer or triple negative breast cancer who in the opinion of the Investigator are appropriate for this study
Group 3: Participants with histologically confirmed TNBC who have received either one or 2 prior systemic treatments for metastatic breast cancer, and who have documented disease progression on or after the most recent treatment
Group 4: Recurrent ovarian cancer participant who have received no more than two prior lines of platinum therapy in the recurrent setting and have progressed within 9 months from the last platinum containing regimen
Measurable disease by RECIST criteria version 1.1 prior to study drug administration
Performance status of 0 or 1 on the eastern Cooperative Oncology Group (ECOG) scale
Life expectancy, in the opinion of the Investigator, of at least 3 months
Disease-free of active second/secondary or prior malignancies for => 2 years with the exception of squamous cell carcinoma of the skin, or carcinoma in situ of the cervix or breast
Willing to provide the protocol specified tumor biopsies
Acceptable hematologic status, liver and renal function

Groups 1 and 2: Participants who have received prior treatment with CD137 agonists or immune checkpoint blockade therapies, including anti-CTLA-4, anti-PD-1, and anti-PD-L1 therapeutic antibodies, may be enrolled, provided the following requirements are met:

Minimum of 5 months from the last dose of anti-PD-1, anti-CTLA-4, anti-PD- L1 or CD137 agonist treatment
No history of severe immune-related adverse effects from CD137 agonist, anti-CTLA-4, anti-PD-1 or anti-PD-L1 (NCI CTCAE Grade 3 and 4). Any toxicity related to the therapy must have resolved completely, no residual toxicity as assessed by NCI CTCAE (v4.03)
Agree to use protocol defined methods of contraception - For all participants, the reliability of sexual abstinence must be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or post-ovulation methods) and withdrawal are not acceptable methods of contraception

Exclusion Criteria:

Participants with history of prior malignancy except solid tumor treated curatively more than 3 years ago without evidence of recurrence
Asymptomatic or symptomatic, untreated, or actively progressing central nervous system (CNS) metastases
History of leptomeningeal disease
Uncontrolled tumor-related pain
Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures. Participants with indwelling catheters are allowed.
Uncontrolled or symptomatic hypercalcemia
New York Heart Association Class III or IV cardiac disease, pericarditis, myocardial infarction within the past 6 months, unstable arrhythmia
Fredericia-corrected QT interval (QTcF) > 470 milli seconds (msec) (female) or > 450 msec (male), or history of congenital long QT syndrome. Any electrocardiogram (ECG) abnormality, including pericarditis, which in the opinion of the Investigator would preclude safe participation in the study.
Active, uncontrolled bacterial, viral, or fungal infections within 7 days of study entry requiring systemic therapy. Participants with active TB infection are excluded from the study.
Known clinically important respiratory impairment
History of major organ transplant
History of an autologous or allogeneic bone marrow transplant
Serious non-malignant disease that could compromise protocol objectives in the opinion of the Investigator and/or the Sponsor
Pregnant or nursing women
Any systemic anticancer therapy within 3 weeks prior to Cycle 1 Day 1
Any radiation treatment to metastatic site within <= 14 days of Cycle 1 Day 1
Major surgical procedure, open biopsy, or significant traumatic injury within 30 days prior to Cycle 1 Day 1 or anticipation of need for major surgical procedure during the course of the study
History of severe allergic, anaphylactic, or other hypersensitivity reactions to chimeric, human or humanized antibodies or fusion proteins
Known hypersensitivity or allergy to biopharmaceuticals produced in Chinese hamster ovary cells or any component of the atezolizumab formulation
Active or history of autoimmune disease
History of idiopathic pulmonary fibrosis (including pneumonitis), drug-induced pneumonitis, organizing pneumonia (i.e., bronchiolitis obliterans, cryptogenic organizing pneumonia), or evidence of active pneumonitis on screening chest computed tomography (CT) scan. History of radiation pneumonitis in the radiation field (fibrosis) is permitted
Positive test for Human immunodeficiency virus (HIV)
Active hepatitis B or hepatitis C
Receipt of a live, attenuated vaccine within 4 weeks prior to randomization or anticipation that such a live, attenuated vaccine will be required during the study
Treatment with investigational therapy within 28 days prior to initiation of study treatment
Treatment with therapeutic oral or IV antibiotics within 2 weeks prior to initiation of study treatment
Consumption of agents which strongly inhibit CYP3A4 enzyme, within 7 days prior to the first dose of study treatment and during the study
Consumption of agents which strongly induce CYP3A4 enzyme, within 14 days prior to the first dose of study treatment and during the study
Treatment with systemic immuno-stimulatory agents within 4 weeks or five half-lives of the drug (whichever is shorter) prior to the first dose of study treatment
Treatment with systemic corticosteroids or other systemic immunosuppressive medications within 2 weeks prior to the first dose of study treatment, or, anticipated requirement for systemic immunosuppressive medications during the trial
History of allergic reactions attributed to components of the formulated product(s)
Unwillingness or inability to comply with procedures required in this protocol