RESUMEN
Despite activity as single agent cancer therapies, Rapamycin (rapa) and its rapalogs may have their greatest effects when combined with other therapeutic modalities. In addition to direct antitumor activity, rapalogs reverse multiple tumor-intrinsic immune evasion mechanisms. These should facilitate tumor-specific T cell activity, but since rapa directly inhibits effector T cells, this potential immune enhancement is lost. We hypothesized that if T cells were rendered resistant to rapa they could capitalize on its downregulation of tumor immune evasion. We therefore modified T cells with a rapa-resistant mutant of mTor, mTorRR, and directed them to B lymphomas by coexpressing a chimeric antigen receptor (CAR) for CD19 (CAR.CD19-28ζ). T cells expressing transgenic mTorRR from a piggyBac transposon maintain mTor signaling, proliferate in the presence of rapa and retain their cytotoxic function and ability to secrete interferon-γ (IFNγ) after stimulation, effector functions that were inhibited by rapa in control T cells. In combination, rapa and rapa-resistant-CAR.CD19-28ζ-expressing T cells produced greater antitumor activity against Burkitt's lymphoma and pre-B ALL cell lines in vitro than CAR.CD19-28ζ T cells or rapa alone. In conclusion, the combination of rapa and rapa-resistant, CAR.CD19-28ζ-expressing T cells may provide a novel therapy for the treatment of B cell malignancies and other cancers.
Asunto(s)
Linfoma de Burkitt/prevención & control , Resistencia a Antineoplásicos , Inmunosupresores/farmacología , Leucemia-Linfoma Linfoblástico de Células Precursoras B/prevención & control , Sirolimus/farmacología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Animales , Antígenos CD19/genética , Antígenos CD19/metabolismo , Apoptosis/efectos de los fármacos , Linfocitos B/efectos de los fármacos , Linfocitos B/metabolismo , Western Blotting , Linfoma de Burkitt/genética , Linfoma de Burkitt/inmunología , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Terapia Combinada , Femenino , Citometría de Flujo , Humanos , Interferón gamma/metabolismo , Activación de Linfocitos/efectos de los fármacos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/inmunología , Receptores de Antígenos/genética , Receptores de Antígenos/metabolismo , Linfocitos T/efectos de los fármacos , Linfocitos T/metabolismo , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
Rat limb allograft recipients represent surgically induced, immediately vascularized bone marrow transplant (VBMT) chimeras. The majority of these chimeras undergo tolerance while a minority develop graft versus host disease (GVHD). T-cell chimerism and associated mechanisms of cellular immune nonresponsiveness were investigated in tolerant VBMT chimeras. A strong correlation (p < 0.01) was observed between the clinical onset of GVHD and levels of donor T-cell chimerism approximating or greater than 50%. However, stable mixed chimerism was associated with tolerance. In conclusion, three major sequential mechanisms of immune nonresponsiveness were elucidated in tolerant VBMT chimeras over time and included development of nonspecific suppressor cells (which potentially represent natural suppressor cells), maturation of antigen-specific suppressor cell circuits, and eventually putative clonal inactivation.