Safety and efficacy of intratumoral injections of chimeric antigen receptor (CAR) T cells in metastatic breast cancer
Mené sur 6 patientes atteintes d'un cancer du sein avec métastases cutanées ou ganglionnaires, cet essai de phase 0 évalue la tolérabilité et l'efficacité, du point de vue de la réponse immunitaire, d'une injection intratumorale de lymphocytes présentant un récepteur chimérique d'antigène spécifique de la protéine c-Met
Résumé en anglais
Chimeric antigen receptors (CARs) are synthetic molecules that provide new specificities to T cells. Although successful in treatment of hematologic malignancies, CAR T cells are ineffective for solid tumors to date. We found that the cell-surface molecule c-Met was expressed in ~50% of breast tumors, prompting the construction of a CAR T cell specific for c-Met, which halted tumor growth in immune-incompetent mice with tumor xenografts. We then evaluated the safety and feasibility of treating metastatic breast cancer with intratumoral administration of mRNA-transfected c-Met-CAR T cells in a phase 0 clinical trial (NCT01837602). Introducing the CAR construct via mRNA ensured safety by limiting the non-tumor cell effects (on-target/off-tumor) of targeting c-Met. Patients with metastatic breast cancer with accessible cutaneous or lymph node metastases received a single intratumoral injection of 3 x 107 or 3 x 108 cells. CAR T mRNA was detectable in peripheral blood and in the injected tumor tissues after intratumoral injection in two and four patients, respectively. mRNA c-Met-CAR T cells cell injections were well tolerated, as none of the patients had study drug-related adverse effects greater than grade 1. Tumors treated with intratumoral injected mRNA c-Met-CAR T cells were excised and analyzed by immunohistochemistry, revealing extensive tumor necrosis at the injection site, cellular debris, loss of c-Met immunoreactivity, all surrounded by macrophages at the leading edges and within necrotic zones. We conclude that intratumoral injections of mRNA c-Met-CAR T cells are well tolerated and evoke an inflammatory response within tumors.
