An area of cancer immunotherapy that is undergoing rapid development is the use of agents that function as checkpoint blockaders. These agents work by interfering with receptors on T cells that normally induce inhibitory signals that suppress T cell responses. For example, one clinical trial tested the effects of a drug known as ipilimumab, which is a human monoclonal antibody that binds to and inhibits CTLA-4, on patients with metastatic melanoma, a deadly form of skin cancer. A simplified version of these data are shown in Figure Q20). In this case, one group of patients received a peptide vaccine, comprised of a mixture of HLA class I-binding peptides derived from the melanoma antigen, gp100. A second group of patients received ipilimumab, and a third group received the gp100 peptide vaccine + ipilimumab. survival of ~20% of the patients receiving ipilimumab. However, based on the similarity in the data for the group of patients receiving ipilimumab plus the gp100 peptide vaccine versus those receiving ipilimumab alone, the most likely affect of the ipilimumab is:
A) That it promotes the development of effector T cells from tumor-specific naive T cells
B) That it allows T cells already present in the patient to kill tumor cells more effectively
C) That it promotes the activation of CD4 instead of CD8 T cells specific for the tumor
D) To prevent the immunosuppressive environment of the tumor from killing T cells
E) To act directly on the tumor cells, similar to a cytotoxic chemotherapeutic drug

Question

An area of cancer immunotherapy that is undergoing rapid development is the use of agents that function as checkpoint blockaders. These agents work by interfering with receptors on T cells that normally induce inhibitory signals that suppress T cell responses. For example, one clinical trial tested the effects of a drug known as ipilimumab, which is a human monoclonal antibody that binds to and inhibits CTLA-4, on patients with metastatic melanoma, a deadly form of skin cancer. A simplified version of these data are shown in Figure Q20). In this case, one group of patients received a peptide vaccine, comprised of a mixture of HLA class I-binding peptides derived from the melanoma antigen, gp100. A second group of patients received ipilimumab, and a third group received the gp100 peptide vaccine + ipilimumab.  survival of ~20% of the patients receiving ipilimumab. However, based on the similarity in the data for the group of patients receiving ipilimumab plus the gp100 peptide vaccine versus those receiving ipilimumab alone, the most likely affect of the ipilimumab is:
A) That it promotes the development of effector T cells from tumor-specific naive T cells 
B) That it allows T cells already present in the patient to kill tumor cells more effectively 
C) That it promotes the activation of CD4 instead of CD8 T cells specific for the tumor 
D) To prevent the immunosuppressive environment of the tumor from killing T cells 
E) To act directly on the tumor cells, similar to a cytotoxic chemotherapeutic drug

Quizplus · Accepted Answer

The data suggest that ipilimumab allows T cells already present in the patient to kill tumor cells more effectively, as evidenced by the improved survival rates in patients receiving ipilimumab alone or in combination with the peptide vaccine compared to those receiving the vaccine alone. Ipilimumab does not promote the development of effector T cells from tumor-specific naive T cells (A), promote the activation of CD4 instead of CD8 T cells specific for the tumor (C), or prevent the immunosuppressive environment of the tumor from killing T cells (D). It also does not act directly on the tumor cells like a cytotoxic chemotherapeutic drug (E).

An Area of Cancer Immunotherapy That Is Undergoing Rapid Development