Decreased tolerance to interleukin-2 with repeated courses of therapy in patients with metastatic melanoma or renal cell cancer

New Developments in T Cell Immunometabolism and Implications for Cancer Immunotherapy

Despite rapid advances in the field of immunotherapy, the elimination of established tumors has not been achieved. Many promising new treatments such as adoptive cell therapy (ACT) fall short, primarily due to the loss of T cell effector function or the failure of long-term T cell persistence. With the availability of new tools and advancements in technology, our understanding of metabolic processes has increased enormously in the last decade. Redundancy in metabolic pathways and overlapping targets that could address the plasticity and heterogenous phenotypes of various T cell subsets have illuminated the need for understanding immunometabolism in the context of multiple disease states, including cancer immunology. Herein, we discuss the developing field of T cell immunometabolism and its crucial relevance to improving immunotherapeutic approaches. This in-depth review details the metabolic pathways and preferences of the antitumor immune system and the state of various metabolism-targeting therapeutic approaches.

IL-2-mediated apoptosis of kidney tubular epithelial cells is regulated by the caspase-8 inhibitor c-FLIP

BACKGROUND

Tubular epithelial cells (TECs) are essential in the maintenance of kidney function. Apoptosis of TECs occur during acute and chronic renal allograft rejection as well as other forms of renal injury, including autoimmune nephritis. The regulation of TEC apoptosis by proinflammatory cytokines associated with renal inflammation [e.g., interleukin (IL)-2 and interferon-gamma (IFN-gamma)] has not been extensively investigated.

METHODS

Apoptosis in murine TECs was determined by FACS with annexin-V or ligation-mediated-polymerase chain reaction (LM-PCR) and mRNA levels by reverse transcription (RT)-PCR or Northern blot. Protein expression was observed using Western blot.

RESULTS

IL-2R (CD25) was expressed by murine TECs and up-regulated by IL-2. Both IL-2 and IFN-gamma induced TEC apoptosis and activated caspase-8. Apoptosis with IL-2 was concentration-dependent and blocked by z-IETD-fmk, a specific caspase-8 inhibitor. Apoptosis with IFN-gamma was associated with increased surface expression of Fas, while IL-2 had no effect on Fas. IL-2 did not induce apoptosis in Fas-deficient TECs (M3.1-lpr) suggesting IL-2 regulation of caspase-8 activity requires Fas. Consistent with this, IL-2 but not IFN-gamma was found to decrease mRNA and protein expression of c-FLIP, an endogenous caspase-8 inhibitor in murine TECs. Overexpression of c-FLIP in TECs (CS3.7-FLIP) blocked apoptosis and caspase-8 activation with both IFN-gamma and IL-2. c-FLIP expression was found in kidney cortex, primary and cloned TECs, suggesting c-FLIP is likely a key regulator of caspase-8-mediated apoptosis in vivo.

CONCLUSION

This is the first report of c-FLIP regulation by IL-2 in renal TECs. Augmentation of c-FLIP in TECs may enhance an endogenous mechanism by which TECs normally resist injury to caspase-8-mediated apoptosis and thus may be a useful and novel strategy to prevent tubular injury in transplant rejection and autoimmune nephritis.

Cell transfer therapy for cancer: lessons from sequential treatments of a patient with metastatic melanoma

The development of effective autologous cell transfer therapies for the treatment of patients with cancer has been difficult, in part because the cells used to treat each patient are different, as are the patient's tumor and immune status. Much can thus be learned by sequential treatments of the same patient with the same cells, making single modifications in the treatments to determine which factors are critical. The authors have treated a single patient with five sequential administrations of the same cells with minor modifications in the mode of administration and the immune status of the patient. The treatment of this patient strongly suggested that 1) the highly avid recognition of tumor antigens in vitro by a transferred lymphocyte population does not necessarily predict in vivo antitumor activity; 2) the administration of highly avid antitumor autologous lymphocyte populations can be far more active in mediating tumor regression in vivo when administered after nonmyeloablative chemotherapy than when administered without this prior chemotherapy; 3) intra-arterial administration of highly avid antitumor autologous lymphocytes into the blood supply of the tumor can be more effective in mediating tumor regression than the intravenous administration of these same tumor infiltrating lymphocytes; 4) one mechanism of tumor escape from immunotherapy is loss of class I MHC antigen expression by the tumor due to mutation of the beta-2 microglobulin gene.