Can the CD4+/CD8+ ratio predict the outcome of interferon-alpha therapy for renal cell carcinoma?

In a randomised trial, patients with renal cell carcinoma (RCC) treated with vinblastine alone or in combination with interferon-alpha (IFN) were monitored for peripheral blood lymphocyte subsets (CD4+ and CD8+) prior to and during treatment to elucidate the influence of IFN on these cells, and the association of the change in the CD4+/CD8+ ratio with treatment outcome.

Blood samples were systematically obtained from 30 patients receiving either vinblastine or vinblastine + IFN-alpha-2a. Flow cytometry was used to detect CD4+ (T-helper) and CD8+ cells (T-suppressor) with monoclonal antibodies.

Increasing CD4+/CD8+ ratios were seen in 10 of 17 patients in the vinblastine-IFN group and in 7 of 13 patients in the vinblastine group. Two of three patients achieving a complete response with the vinblastine-IFN treatment showed a dramatic increase in CD4+/CD8+ ratio concomitantly with regression of all metastases. Those treated with vinblastine-IFN who showed an increasing ratio had a better median survival (not reached at 28 months of follow-up) compared to those with a decreasing ratio (6.3-month survival) (P = 0.0037, log-rank). No such difference occurred in patients treated with vinblastine alone. In the multivariate analysis, the increase in CD4+/CD8+ ratio was the most important prognostic factor.

In a proportion of patients receiving an interferon-based therapy, IFN seems to influence the host's immune system, resulting in an increased CD4+/CD8+ ratio concomitantly with tumour regression. Changes in the CD4+/CD8+ ratio of patients with metastatic RCC receiving such therapy, may provide valuable prognostic information and a basis for future improvements of immunotherapy.