A Trial Evaluating the Efficacy of Ivonescimab in Metastatic Endocrine Refractory HR-positive HER2-negative or Triple Negative Invasive Lobular Carcinoma

Inclusion Criteria: * 18 years of age or older. * Historically confirmed invasive lobular cancer with negative E-cadherin staining by IHC. * Estrogen receptor (ER) positive (\>1%) or negative, progesterone receptor (PgR) positive or negative, and HER2-negative according to HER2 testing guidelines from the American Society of Clinical Oncology/College of American Pathologists. * Participants must be willing to undergo biopsy as required by the study if the tumor is safely accessible. * If ER+, participant must be endocrine refractory as per the treating oncologist assessment and has been exposed to at least one line of endocrine therapy prior to enrollment. * Participants who received prior chemotherapy, antibody-drug conjugates (ADCs), mTOR inhibitor and/or PI3K are eligible. o Participants should not have received more than 2 chemotherapeutic agents and/or ADCs in the metastatic setting. * Eastern Cooperative Oncology Group Performance status ≤ 1. * Participant has either measurable disease per response evaluation criteria in solid tumors (RECIST) v1.1 criteria OR at least one predominantly lytic bone lesion must be present. * Adequate Organ Function: * Hematology (no blood transfusions or growth factor therapy used within 7 days of the screening CBC): i. Absolute neutrophil count (ANC) ≥ 1.0 × 109/L ii. Platelet count ≥ 100 × 109/L iii. Hemoglobin ≥ 9.0 g/dL * Kidneys: * Creatinine clearance (CrCL) ≥ 60 mL/min using the Cockcroft-Gault formula or estimated glomerul…