Preclinical exploration of combining plasmacytoid and myeloid dendritic cell vaccination with BRAF inhibition

Abstract

BackgroundMelanoma is the most lethal type of skin cancer and its incidence is progressively increasing. The introductions of immunotherapy and targeted therapies have tremendously improved the treatment of melanoma. Selective inhibition of BRAF by vemurafenib results in objective clinical responses in around 50 % of patients suffering from BRAFV600 mutated melanoma. However, drug resistance often results in hampering long-term tumor control. Alternatively, immunotherapy by vaccination with natural dendritic cells (nDCs) demonstrated long-term tumor control in a proportion of patients. We postulate that the rapid tumor debulking by vemurafenib can synergize the long-term tumor control of nDC vaccination to result in an effective treatment modality in a large proportion of patients. Here, we investigated the feasibility of this combination by analyzing the effect of vemurafenib on the functionality of nDCs.MethodsPlasmacytoid DCs (pDCs) and myeloid DCs (mDCs) were isolated from PBMCs obtained from buffy coats from healthy volunteers or vemurafenib-treated melanoma patients. Maturation of pDCs, mDCs and immature monocyte-derived DCs was induced by R848 in the presence or absence of vemurafenib and analyzed by FACS. Cytokine production and T cell proliferation induced by mature DCs were analyzed.ResultsVemurafenib inhibited maturation and cytokine production of highly purified nDCs of healthy volunteers resulting in diminished allogeneic T cell proliferation. This deleterious effect of vemurafenib on nDC functionality was absent when total PBMCs were exposed to vemurafenib. In patients receiving vemurafenib, nDC functionality and T cell allostimulatory capacity were unaffected.ConclusionAlthough vemurafenib inhibited the functionality of purified nDC of healthy volunteers, this effect was not observed when nDCs were matured in the complete PBMC fraction. This might have been caused by increased vemurafenib uptake in absence of other cell types. In accordance, nDCs isolated from patients on active vemurafenib treatment showed no negative effects. In conclusion, our results pave the way for a combinatorial treatment strategy and, we propose that combining vemurafenib with nDC vaccination represent a powerful opportunity that deserves more investigation in the clinic.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0844-6) contains supplementary material, which is available to authorized users.

Mechanisms of Acquired BRAF Inhibitor Resistance in Melanoma: A Systematic Review

“…As described earlier, the use of immune checkpoint inhibitors in combination with a BRAF inhibitor + MEK inhibitor appears to be effective but is associated with a high rate of toxicity [ 194 ]. Other potential immune-targeted therapies undergoing preclinical investigation include adoptive T-cell therapy [ 171 , 248 , 249 ], dendritic cell vaccination [ 250 ], and combining BRAF inhibitor treatment with a toll-like receptor 7 agonist (e.g., imiquimod) [ 160 ].…”

Harnessing RNA sequencing for global, unbiased evaluation of two new adjuvants for dendritic-cell immunotherapy

“…Here we chose the markers CD80, PDL-1, and CD40 (Figure 1A–1C ) as representatives for the maturation state of these DC subsets. CD80 is a co-stimulatory maturation marker also used in our clinical set up to determine the maturation state of the DCs [ 8 , 39 ]. PD-L1 as a co-inhibitory and CD40 as an additional co-stimulatory marker were considered suitable candidates to complete the set, because both maturation markers are known to be expressed on both cell subsets [ 40 ].…”

BRAF inhibitors stimulate inflammasome activation and interleukin 1 beta production in dendritic cells

“…In previous studies VEM [ 20 ] and DAB [ 21 ] were reported to yield no immuno-modulatory effects on human MODC. Interestingly, Tel and coworkers [ 22 ] showed that VEM, but not DAB interfered with R848-induced upregulation of surface activation markers and cytokines by human primary DC. However, the inhibitiory effect of VEM on DC activation was largely prevented when applying VEM to total PBMC.…”