Study of Autologous CAR-T Cells Targeting B7-H3 in TNBC iC9-CAR.B7-H3 T Cells

Toxicity will be graded as the Number of participants with adverse events (AE)s

AEs will be classified and graded according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 5.0.

CRS will be graded according to the American Society for Transplantation and Cellular Therapy (ASTCT) CRS Consensus Grading. Grade 1 - Mild: Fever ≥38^ o C, No hypotension, No hypoxia, Grade 2 - Moderate: Fever ≥38^ o C, Hypotension not requiring vasopressors, Hypoxia requiring low-flow nasal cannula (≤6 L/minute) or blow-by, Grade 3 - Severe: Fever ≥ 38^ o C, Hypotension requiring a vasopressor with or without vasopressin, Hypoxia requiring high-flow nasal cannula (>6 L/minute), facemask, nonrebreather mask, or Venturi mask, Grade 4 - Life-threatening: Fever ≥38^oC, Hypotension requiring multiple vasopressors (excluding vasopressin), Hypoxia requiring positive pressure (e.g. Continuous positive airway pressure, BiPAP, intubation, mechanical ventilation), Grade 5 - Death

Neurotoxicity will be graded according to the Immune effector cell-associated neurotoxicity syndrome (ICANS) criteria.

Immune effector cell-associated neurotoxicity syndrome (ICANS) symptoms will be graded according to the criteria outlined in the protocol on a scale from 1 (mild) to 4 (critical). Cytokine release syndrome (CRS) will be graded according to criteria outlined in the protocol on a scale from 1 (mild) to grade 5 (death).

The RP2D of iC9-CAR.B7-H3 T cells will be determined based on modified 3+3 dose finding rules and the tolerability of iC9-CAR.B7-H3 T cells will be assessed by NCI-CTCAE v5 criteria.

The RP2D of iC9-CAR.B7-H3 T cells will be determined based on modified 3+3 dose finding rules and the tolerability of iC9-CAR.B7-H3 T cells will be assessed byASTCT Consensus CRS Grading Criteria.

The RP2D of iC9-CAR.B7-H3 T cells will be determined based on modified 3+3 dose finding rules and the tolerability of iC9-CAR.B7-H3 T cells will be assessed by ASTCT Consensus ICANS Grading Criteria.

Objective response rate is defined as the percentage of subjects achieving a confirmed partial response (PR) or better (≥ PR) based on RECIST 1.1 criteria.

Complete response - Disappearance of all target lesions. Any pathological lymph node (LN) must be <10mm. Partial response: At least a 30% decrease in the sum of the largest distance (LD) of the target lesions. Progressive Disease (PD): At least a 20% increase in the sum of the LD of the target lesions taking as reference the smallest sum LD recorded since the treatment started including baseline if that is the smallest in the study. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5mm. The appearance of one or more new lesions also constitutes PD. Stable disease (SD): Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD taking as references the smallest sum LD since the treatment started.

PFS will be measured from the first day of lymphodepletion chemotherapy prior to iC9-CAR.B7-H3 T cell infusion to progression per RECIST 1.1 or death.

OS will be measured from the first day of lymphodepleting chemotherapy prior to iC9-CAR.B7-H3 T cell infusion to the date of death for any cause.

DOR is time from the first immune Complete Response (iCR) or immune Partial Response (iPR) until progressive disease (iCPD) per immune Response Evaluation Criteria in Solid Tumors (iRECIST), criteria or death, whichever occurs first. Per iRECIST) responses are assessed by imaging as follows: iCR: Disappearance of all lesions, with pathological lymph nodes <10 mm. iPR: ≥30% decrease in target lesions from baseline. Immune Stable Disease (iSD): Neither sufficient shrinkage for iPR nor sufficient increase. Immune Unconfirmed Progressive Disease (iUPD): Initial evidence of progression based on RECIST 1.1, including growth of existing lesions and/or new lesions; requires confirmation. Immune Confirmed Progressive Disease (iCPD): Progression confirmed at a subsequent assessment following iUPD per iRECIST. New lesions are recorded separately and do not automatically constitute treatment failure. Progression must be confirmed after iUPD to establish iCPD.