Case 36

Published on 18/02/2015 by admin

Filed under Allergy and Immunology

Last modified 22/04/2025

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CASE 36

You are looking after a 60-year-old male patient with renal carcinoma. The patient is due for surgery in 2 days, and you are investigating follow-up immunotherapies you might offer this patient, besides conventional chemotherapy. Discuss some of the options.

QUESTIONS FOR GROUP DISCUSSION

1. Explain the differences between sporadic and inherited renal cell carcinoma.
2. Describe the clinical presentation of renal cell cancer and general approach leading to diagnosis.
3. Describe the general procedure for tumor-infiltrating lymphocyte (TIL) therapy. What is the rationale for this approach?
4. TIL therapy has met with limited success. List at least two reasons why this approach may not work.
5. Attempts to enhance the efficacy of TIL therapy have led to changes in the protocol to include exogenous cytokines. Discuss the negative side effects associated with this modification. Describe an alternative approach to overcome this side effect and yet still benefit from intervention of cytokines.
6. Provide a rationale for introduction of each of the following cytokines in the TIL protocol: interleukin (IL)-2, interferon gamma (IFNγ), and granulocyte-macrophage colony-stimulating factor (GM-CSF).
7. Discuss the pros and cons (regarding tumor killing) of enhanced class I MHC on the tumor cells.
8. Discuss the general approach for treatment of tumors using antigen-pulsed dendritic cells.
9. What is the advantage of this approach compared with the tumor-infiltrating cell approach? What is the potential problem to this approach? How might this be addressed?
10. Describe, in general terms, the tetramer biology approach. Explain why this approach holds out more hope for treatment than the other two approaches (TILs, or pulsed dendritic cells).

RECOMMENDED APPROACH

Implications/Analysis of Family History

Renal cell carcinoma may be sporadic or inherited. Sporadic renal cancer typically develops in the elderly and is much more frequent in males. In contrast, hereditary renal cancers may develop much earlier in life, even in teenagers, and occur in equal frequency in females and males. There are a number of different hereditary renal cell cancers, the most common being von Hippel-Lindau (VHL) disease, a familial multiple cancer syndrome that includes renal cell cancer. The von Hippel-Lindau gene is now known to be a tumor suppressor gene.

Given that our patient is a 60-year-old man, it is likely that this patient has sporadic renal cell cancer.

Implications/Analysis of Clinical History

Clinical presentations generally include hematuria (blood in urine), abdominal pain, and mass in the abdomen. Some patients will also experience weight loss, night sweats, and a general listless feeling. However, incidental detection often occurs before these clinical symptoms appear when patients receive ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI) for other reasons.

Implications/Analysis of Laboratory Investigation

Diagnosis may involve urography (radiography of the urinary tract that is preceded by intravenous injection of a dye that is excreted by the kidney) and renal angiography (imaging of arteries that bring in blood to the kidneys) in the presence of the clinical symptoms described.

Additional Laboratory Tests

To characterize the mass, however, ultrasonography, CT, and MRI are more accurate than urography or renal angiography. Sporadic renal cell cancers are generally unilateral with (frequently) only one tumor mass, whereas inherited renal cell cancers are most likely to be bilateral with several tumors.

DIAGNOSIS

To confirm a diagnosis of renal cell carcinoma, it is essential to examine tissue, which is generally obtained during surgery. Surgery is the mainstay of treatment of renal cell carcinoma. In the United States, two different staging systems are used for prognosis: the modified Robson system and the American Joint Committee on Cancer.

THERAPY

For the most part, first-line therapy for renal cell carcinoma is surgery. However, adjunctive therapies are under investigation.

Tumor-Infiltrating Lymphocytes

One alternative therapy includes isolation of natural killer (NK) cells from the patient’s peripheral blood lymphocytes or isolation of TILs from within the resected tumor mass and expanding these ex vivo (with IL-2 or other growth factors for NK cells). When these NK cells are cultured under these conditions, so-called lymphokine-activated killer (LAK) cells are produced. LAK cells are re-infused into the patient. This therapy has been used in renal carcinoma patients but with very limited success.

Potential Problem: Homing

A potential problem might be that the cells re-infused to the patient never “home” to the right locale in vivo to eradicate the tumor. In addition, there is no a priori evidence to document that TILs are necessarily the important cells (in vivo) for eliminating tumor. They may locate to the tumor as a means of regulating immune responses directed against the tumor in vivo!

Potential Problem: Cytokine Toxicity

Both cell infusions (LAK cells or TILs) have also been used in the presence of additional exogenous cytokine infusion, although this has been often accompanied by toxicity from high-dose cytokine use (in particular, inflammation of the vascular bed, and a “capillary leak” syndrome). In other cases it has been suggested that we attempt further gene transfection into TILs, to circumvent the problem of infusion of cytokines separately. IL-2, IFNγ, and even GM-CSF (to attract dendritic cells for antigen presentation) have all been suggested as auxiliary reagents for gene transfection.

Role of MHC in CD8+ T cell and NK cell in Tumor Cell Killing

Some tumors can evade host CTL (CD8) immunity by downregulating class I MHC. However, because NK cells have killer inhibitory receptors (KIRs, recognizing class I MHC), which are thought to play a role in regulating killing activity by NK cells, one would predict that loss of class I MHC, while rendering a tumor less susceptible to killing by CD8+ CTL, would leave it more susceptible to NK cell lysis.

Pulsed Dendritic Cells Using Crude Extracts

Another current experimental therapy for treatment of some tumors consists of pulsing cultured dendritic cells with tumor cell antigens, and/or genes encoding the antigens, before re-infusing these dendritic cells into patients as a means of boosting host tumor cell antigen recognition.

Technique

Peripheral blood lymphocytes are obtained from the patient, and CD34+ cells (dendritic cell precursors) can be isolated using antibodies specific for CD34 antigen. These CD34+ cells are grown in bulk in vitro in the presence of GM-CSF and IL-4, which are potent dendritic cell growth factors. After 9 to 10 days, the dendritic cell population is “pulsed” in vitro with a crude extract of tumor antigen (e.g., a tumor cell lysate) and the mixture is re-infused in vivo alone, or again in the presence of additional cytokines. In some variants of this therapy, dendritic cells are first transfected with genes for additional cytokines.

Advantage

The clear advantage of this approach is that it makes no assumptions about what the relevant tumor antigen (for immunization) is, only that it is present in the tumor lysate. This may also be the problem with such an approach! Perhaps the lysate contains a more abundant source of tumor tolerogens, rather than immunogens.

Pulsed Dendritic Cells with Tumor-Specific Antigens

A variant of this theme attempts to use more defined tumor antigens to pulse the dendritic cells. These are preselected by screening (e.g., with antibodies or cultured T cells from patients with homologous tumors) for purified proteins/molecules that bind antibodies and/or induce proliferation in T cells. Such purified antigens can then be used for pulsing the tumor. Alternatively, the gene(s) encoding the tumor antigen may be cloned and used for transfection of enriched dendritic cells (again with/without genes encoding cytokines).

Tetramer Biology Approach

Finally, there is growing interest in an approach that is essentially a variant of both of the above. This uses a so-called tetramer biology approach to first enrich for T cells specific for the antigen under consideration (which must therefore be known). Artificial (tetramer) complexes of MHC proteins and antigen are made using fluorescence-marked MHC proteins. This combination is mixed with patient peripheral blood lymphocytes to allow binding of antigen-specific T cells (class I restricted CD8+) to the tetramers, which can be purified (>80% pure) by flow cytometry cell sorting. These are then cultured in vitro, with purified dendritic cells (obtained from CD34+ precursors) pulsed with tumor antigen. (Note: although the dendritic cells can endocytose antigen into vacuoles for subsequent presentation to MHC class II restricted T cells, dendritic cells can also pinocytose soluble antigens. Pinocytosed antigens enter the cytosol, not the endosome, and so the antigen can be processed for subsequent presentation to class I restricted CD8+ T cells).

This experimental approach has been used to generate large numbers (>1010) purified antigen-specific CD8+ cytotoxic T cells, which can be infused for patient therapy. Although still in its experimental phase, this newer technology holds out hope of providing an important means of treating at least some human cancers in the future.

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