GM-CSF can cause T cell activation; results of sequential chemo-immunotherapy

Clinical uses of GM-CSF, a critical appraisal and update

The role of granulocyte-macrophage-colony-stimulating factor (GM-CSF) in the supportive care of cancer patients has been evaluated with promising results. More recently, GM-CSF has been added to regimens for the mobilization of hematopoietic progenitor cells. An expanding role for GM-CSF in regulating immune responses has been recognized based upon its activity on the development and maturation of antigen presenting cells and its capability for skewing the immune system toward Th1-type responses. GM-CSF has been shown to preferentially enhance both the numbers and activity of type 1 dendritic cells (DC1), the subsets of dendritic cells responsible for initiating cytotoxic immune responses. The increase in DC1 content and activity following local and systemic GM-CSF administration support a role for GM-CSF as an immune stimulant and vaccine adjuvant in cancer patients. GM-CSF has shown clinical activity as an immune stimulant in tumor cell and dendritic cell vaccines, and may increase antibody-dependent cellular cytotoxicity. The successful use of myeloid acting cytokines to enhance anti-tumor responses will likely require the utilization of GM-CSF in combination with cytotoxic or other targeted therapies.

Infiltration of activated dendritic cells and T cells in renal cell carcinoma following combined cytokine immunotherapy

OBJECTIVES

In a phase I study the feasibility, toxicity and immunological effects of peri-operative cytokine immunotherapy of renal cell carcinoma were studied. Main goals were to determine the maximal tolerable dose and detailed in situ analysis of tumor infiltrates.

METHODS

Fifteen patients with renal cell carcinoma, undergoing nephrectomy, received subcutaneous immunotherapy, consisting of low-dose IL-2, IFNalpha and GM-CSF, from day -3 prior, until day +5 following surgery in a dose escalation study. Infiltrates from resected tumor tissues from patients undergoing immunotherapy or control patients that underwent nephrectomy only, were examined using quantitative immunohistological analysis and 3-color immunofluorescence staining and confocal laser scanning microscope analysis.

RESULTS

Toxicity was limited and the maximal tolerable dose was established. In peripheral blood an increase was found in total lymphocytes, (activated) T cells, NK cells and monocytes. Quantitative immunohistological analysis of tumor infiltrates showed enhanced numbers of CD3+ T cells, S100+ DC, CD83+ DC and IL-2 receptor positive cells (4-fold, 2-fold, 10-fold and 20-fold, respectively, compared to controls). In treated patients preferential invasion was observed of TNFalpha positive CD8+ T cells and DC, positive for DC-SIGN (CD209), CD83, CD80, IL-12 and the DC specific chemokine, DC-CK1 (CCL18).

CONCLUSIONS

These findings show increased infiltration of activated, mature DC and functionally active CD8+ T cells in renal tumors, which may suggest clinical potential of cytokine immunotherapy.

Reinfusion of autologous lymphocytes with granulocyte-macrophage colony-stimulating factor induces rapid recovery of CD4+ and CD8+ T cells after high-dose chemotherapy for metastatic breast cancer

PURPOSE

Repeated high-dose chemotherapy (HDCT) followed by peripheral-blood progenitor cell (PBPC) transplantation can induce a complete remission in patients with metastatic breast cancer sensitive to standard chemotherapy (CT), but the majority of patients relapse within 1 to 2 years. The immune system is seriously compromised after HDCT, which precludes the development of effective immunotherapy. We investigated whether autologous lymphocytes, reinfused after HDCT, could induce a rapid recovery of T cells.

PATIENTS AND METHODS

Three patients were monitored for immune recovery without reinfusion of lymphocytes. In the next 11 patients, stem cells were harvested after CT + granulocyte colony-stimulating factor (G-CSF) and lymphocytes were harvested after CT + granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2. These patients received stem cells and G-CSF after the first HDCT; stem cells, G-CSF, and lymphocytes after the second; and stem cells, GM-CSF, and lymphocytes after the third HDCT.

RESULTS

Patients not receiving lymphocyte reinfusion had a very slow recovery of lymphocytes. In particular, CD4 counts remained low (< 200/microL for 9 months). Lymphocyte reinfusion had a significant effect on the recovery of lymphocytes, T cells, and CD8+ T cells (normalized on day 25). Recovery of CD4+ T cells was significantly accelerated by lymphocyte reinfusion and GM-CSF, leading to counts of 500/microL at 25 days.

CONCLUSION

Lymphocyte reinfusion with G-CSF had a significant effect on the recovery of CD8+ T cells, whereas rapid recovery of CD4+ T cells required lymphocyte reinfusion and GM-CSF, which possibly acts as a survival factor through activation of antigen presenting cells. Whether the rapid recovery of CD4+ and CD8+ T cells prevents or delays relapse of the disease should be further investigated.