1. Differential influence of vemurafenib and dabrafenib on patients’ lymphocytes despite similar clinical efficacy in melanoma.
- Author
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Schilling, B., Sondermann, W., Zhao, F., Griewank, K. G., Livingstone, E., Sucker, A., Zelba, H., Weide, B., Trefzer, U., Wilhelm, T., Loquai, C., Berking, C., Hassel, J., Kähler, K. C., Utikal, J., Al Ghazal, P., Gutzmer, R., Goldinger, S. M., Zimmer, L., and Paschen, A.
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MELANOMA , *CD4 lymphocyte count , *CLINICAL trials , *CANCER immunotherapy , *IMMUNOREGULATION , *IMMUNE system , *PATIENTS - Abstract
In this study, we demonstrate that vemurafenib but not dabrafenib reduces peripheral lymphocyte counts in melanoma patients while both agents show similar clinical efficacy. Within the lymphocyte compartment, vemurafenib selectively decreases circulating CD4+ T cells and changes their phenotype and function. This indicates that selective BRAFi need to be assessed individually for immunomodulatory effects, especially, when planning combinations with immunotherapies.Background Since the majority of melanomas eventually become resistant and progress, combining selective BRAF inhibitors (BRAFi) with immunotherapies has been proposed to achieve more durable treatment responses. Here, we explored the impact of selective BRAFi on the hosts' immune system. Patients and methods Clinical data, whole blood counts (WBC) and serum lactate dehydrogenase (LDH) of 277 vemurafenib- and 65 dabrafenib-treated melanoma patients were evaluated. The frequency and phenotype of lymphocyte subpopulations were determined by flow cytometry while T cell cytokine secretion was measured by multiplex assays. Results Progression-free survival (PFS) as well as overall survival (OS) were similar in patients treated with either BRAFi. High pretreatment LDH was associated with shorter PFS and OS in both groups. During therapy, peripheral lymphocytes decreased by 24.3% (median, P < 0.0001) in vemurafenib-treated patients but remained unchanged in dabrafenib-treated patients (+1.2%, P = 0.717). Differentiation of peripheral lymphocytes of vemurafenib-treated patients showed a significant decrease in CD4+ T cells (P < 0.05). Within CD4+ T cells obtained during treatment, an increase in CCR7+CD45RA+ (naïve) and a decrease in CCR7+CD45RA− (central memory) populations were found (P < 0.01 for both). Furthermore, secretion of interferon-γ and interleukin-9 by CD4+ T cells was significantly lower in samples obtained during vemurafenib treatment compared with baseline samples. Conclusion While both compounds have comparable clinical efficacy, vemurafenib but not dabrafenib decreases patients peripheral lymphocyte counts and alters CD4+ T cell phenotype and function. Thus, selective BRAFi can significantly affect patients' peripheral lymphocyte populations. Fully understanding these effects could be critical for successfully implementing combinatorial therapies of BRAFi with immunomodulatory agents. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
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