In vivo manipulation of Vgamma9Vdelta2 T cells with zoledronate and low-dose interleukin-2 for immunotherapy of advanced breast cancer patients.

The potent anti-tumour activities of gamma delta T cells have prompted the development of protocols in which gamma delta-agonists are administered to cancer patients. Encouraging results from small Phase I trials have fuelled efforts to characterize more clearly the application of this approach to unmet clinical needs such as metastatic carcinoma. To examine this approach in breast cancer, a Phase I trial was conducted in which zoledronate, a V gamma 9V delta 2 T cell agonist, plus low-dose interleukin (IL)-2 were administered to 10 therapeutically terminal, advanced metastatic breast cancer patients. Treatment was well tolerated and promoted the effector maturation of V gamma 9V delta 2 T cells in all patients. However, a statistically significant correlation of clinical outcome with peripheral V gamma 9V delta 2 T cell numbers emerged, as seven patients who failed to sustain V gamma 9V delta 2 T cells showed progressive clinical deterioration, while three patients who sustained robust peripheral V gamma 9V delta 2 cell populations showed declining CA15-3 levels and displayed one instance of partial remission and two of stable disease, respectively. In the context of an earlier trial in prostate cancer, these data emphasize the strong linkage of V gamma 9V delta 2 T cell status to reduced carcinoma progression, and suggest that zoledronate plus low-dose IL-2 offers a novel, safe and feasible approach to enhance this in a subset of treatment-refractory patients with advanced breast cancer.