A 63-year-old man comes to the physician after noticing a reddish tinge to his urine for the last couple of days. During evaluation of his hematuria, an abdominal CT scan reveals a left-sided renal mass. Further workup also shows multiple pulmonary and bone nodules. CT-guided biopsy of a peripherally located lung nodule demonstrates renal cell carcinoma. High-dose interleukin-2 (IL-2) is started, and 4 weeks later there is a significant reduction in his tumor burden. Which of the following mechanisms was most likely responsible for regression of his malignancy?

Question

A 63-year-old man comes to the physician after noticing a reddish tinge to his urine for the last couple of days.  During evaluation of his hematuria, an abdominal CT scan reveals a left-sided renal mass.  Further workup also shows multiple pulmonary and bone nodules.  CT-guided biopsy of a peripherally located lung nodule demonstrates renal cell carcinoma.  High-dose interleukin-2 (IL-2) is started, and 4 weeks later there is a significant reduction in his tumor burden.  Which of the following mechanisms was most likely responsible for regression of his malignancy?

Quizplus · Accepted Answer

11ec160b_37a8_4aa6_9249_b5aa27a0b7b4_MD0001_00 Interleukin-2 (IL-2) is produced primarily by helper T cells and is the major growth factor for T lymphocytes. Antigen binding to the T cell receptor stimulates the secretion of IL-2 and the expression of IL-2 receptors (IL-2R). The IL-2/IL-2R (autocrine) interaction then stimulates the growth, differentiation, and survival of antigen-specific CD4+ T cells and CD8+ T cells. IL-2 also promotes the growth of B cells and activates natural killer (NK) cells and monocytes. Increased activity of T cells and NK cells is thought to be responsible for IL-2's anti-tumor effects. IL-2 (aldesleukin) is currently used as immunotherapy for metastatic melanoma and renal cell carcinoma. The IL-2-induced immune response against renal cell carcinoma results in tumor regression in approximately 10% of patients. These responses can persist for many years, and the majority of complete responders remain free of long-term relapses. (Choice A) A marked increase in vascular endothelial growth factor (VEGF) expression is thought to play a role in tumor angiogenesis. Bevacizumab, a humanized monoclonal antibody, interferes with VEGF receptor activation, thereby inhibiting angiogenesis. (Choice B) Alemtuzumab, an anti-CD52 humanized monoclonal antibody, is used for treatment of chronic lymphocytic leukemia. On binding to CD52, alemtuzumab initiates a direct cytotoxic effect through complement fixation and antibody-dependent, cell-mediated cytotoxicity. (Choice D) Chemotherapeutic agents (eg, etoposide, vincristine, and cyclophosphamide) are able to kill cancer cells by inducing apoptosis. (Choice E) Interferon-gamma increases expression of MHC class I & II, improving antigen presentation in all cells. Educational objective: Interleukin-2 (IL-2) is produced by helper T cells and stimulates the growth of CD4+ and CD8+ T cells and B cells. IL-2 also activates natural killer cells and monocytes. The increased activity of T cells and natural killer cells is thought to be responsible for IL-2's anti-cancer effect on metastatic melanoma and renal cell carcinoma. __________ References: Role of immunotherapy for renal cell cancer in 2011. (http://www.ncbi.nlm.nih.gov/pubmed/21917625)

A 63-Year-Old Man Comes to the Physician After Noticing a Reddish