A Study of Efficacy and Safety of LAG525 in Combination With Spartalizumab, or With Spartalizumab and Carboplatin, or With Carboplatin, in Patients With Advanced Triple-negative Breast Cancer

Inclusion Criteria:

- Patient has advanced (loco-regionally recurrent not amenable to curative therapy or
metastatic) breast cancer.

- Patient must have measurable disease, i.e., at least one measurable lesion as per
RECIST 1.1 criteria (Tumor lesions previously irradiated or subjected to other
loco-regional therapy will only be considered measurable if disease progression at the
treated site after completion of therapy is clearly documented)

- Patient progressed after adjuvant or 1 prior systemic treatment in the metastatic
setting. Patients with de novo metastatic disease are eligible if they received 1
prior line of therapy

- Patient must have received prior systemic treatment that included taxane-based
chemotherapy for adjuvant or metastatic disease

- Patient must have a site of disease amenable to biopsy, and must be willing to undergo
a new tumor biopsy at screening and during therapy on this study, the latter if
medically feasible. Patients with an available archival tumor tissue do not need to
perform a tumor biopsy at screening if patient has not received anti-cancer therapy
since the biopsy was taken.

- Patient has histologically and/or cytologically confirmed diagnosis of advanced TNBC
(based on most recently analyzed biopsy, local lab) meeting the following criteria:
HER2 negative in situ hybridization test or an IHC status of 0 or 1+, and ER and PR
expression is <1 percent as determined by immunohistochemistry (IHC)

Exclusion Criteria:

- Patient has received prior immunotherapy as anticancer treatment such as anti-LAG-3,
anti-PD-1, anti-PD-L1, or anti-PD-L2 antibody (any line of therapy).

- Patient received prior neoadjuvant or adjuvant therapy with a platinum agent or
mitomycin and experienced recurrence within 12 months after the end of the
platinum-based or mitomycin containing therapy or received Platinum or mitomycin for
metastatic disease

- Patient has had major surgery within 14 days prior to starting study treatment or has
not recovered to grade 1 or less from major side effects.

- Patient with presence of CTCAE grade 2 toxicity or higher due to prior cancer therapy.
Exception to this criterion; patients with any grade of alopecia are allowed to enter
the study..

- Patient has received radiotherapy ≤ 4 weeks prior to randomization (≤ 2 weeks for
limited field radiation for palliation), and has not recovered to grade 1 or better
from related side effects of such therapy (with the exception of alopecia).

- Patient has a known hypersensitivity to other monoclonal antibodies,
platinum-containing compounds, or to any of the excipients of LAG525, spartalizumab,
or carboplatin.

- Patient has symptomatic central nervous system (CNS) metastases or CNS metastases that
require local CNS-directed therapy (such as radiotherapy or surgery), or increasing
doses of corticosteroids within the 2 weeks prior to first dose of study treatment.
Patients with treated brain metastases should be neurologically stable and witout CNS
progression for at least 12 weeks prior to randomization and have discontinued
corticosteroid treatment (with the exception of < 10 mg/day of prednisone or
equivalent for an indication other than CNS metastases) for at least 4 weeks before
first dose of any study treatment.

Other protocol-defined inclusion/exclusion criteria may apply