Andrzej Maćkiewicz

BACKGROUND: The BRAF inhibitors vemurafenib and dabrafenib have shown efficacy as monotherapies in patients with previously untreated metastatic melanoma with BRAF V600E or V600K mutations. Combining dabrafenib and the MEK inhibitor trametinib, as compared with dabrafenib alone, enhanced antitumor activity in this population of patients. METHODS: In this open-label, phase 3 trial, we randomly assigned 704 patients with metastatic melanoma with a BRAF V600 mutation to receive either a combination of dabrafenib (150 mg twice daily) and trametinib (2 mg once daily) or vemurafenib (960 mg twice daily) orally as first-line therapy. The primary end point was overall survival. RESULTS: At the preplanned interim overall survival analysis, which was performed after 77% of the total number of expected events occurred, the overall survival rate at 12 months was 72% (95% confidence interval [CI], 67 to 77) in the combination-therapy group and 65% (95% CI, 59 to 70) in the vemurafenib group (hazard ratio for death in the combination-therapy group, 0.69; 95% CI, 0.53 to 0.89; P=0.005). The prespecified interim stopping boundary was crossed, and the study was stopped for efficacy in July 2014. Median progression-free survival was 11.4 months in the combination-therapy group and 7.3 months in the vemurafenib group (hazard ratio, 0.56; 95% CI, 0.46 to 0.69; P<0.001). The objective response rate was 64% in the combination-therapy group and 51% in the vemurafenib group (P<0.001). Rates of severe adverse events and study-drug discontinuations were similar in the two groups. Cutaneous squamous-cell carcinoma and keratoacanthoma occurred in 1% of patients in the combination-therapy group and 18% of those in the vemurafenib group. CONCLUSIONS: Dabrafenib plus trametinib, as compared with vemurafenib monotherapy, significantly improved overall survival in previously untreated patients with metastatic melanoma with BRAF V600E or V600K mutations, without increased overall toxicity. (Funded by GlaxoSmithKline; ClinicalTrials.gov number, NCT01597908.).

BACKGROUND: V600E or V600K mutation have prolonged progression-free survival and overall survival when receiving treatment with BRAF inhibitors plus MEK inhibitors. However, long-term clinical outcomes in these patients remain undefined. To determine 5-year survival rates and clinical characteristics of the patients with durable benefit, we sought to review long-term data from randomized trials of combination therapy with BRAF and MEK inhibitors. METHODS: We analyzed pooled extended-survival data from two trials involving previously untreated patients who had received BRAF inhibitor dabrafenib (at a dose of 150 mg twice daily) plus MEK inhibitor trametinib (2 mg once daily) in the COMBI-d and COMBI-v trials. The median duration of follow-up was 22 months (range, 0 to 76). The primary end points in the COMBI-d and COMBI-v trials were progression-free survival and overall survival, respectively. RESULTS: A total of 563 patients were randomly assigned to receive dabrafenib plus trametinib (211 in the COMBI-d trial and 352 in the COMBI-v trial). The progression-free survival rates were 21% (95% confidence interval [CI], 17 to 24) at 4 years and 19% (95% CI, 15 to 22) at 5 years. The overall survival rates were 37% (95% CI, 33 to 42) at 4 years and 34% (95% CI, 30 to 38) at 5 years. In multivariate analysis, several baseline factors (e.g., performance status, age, sex, number of organ sites with metastasis, and lactate dehydrogenase level) were significantly associated with both progression-free survival and overall survival. A complete response occurred in 109 patients (19%) and was associated with an improved long-term outcome, with an overall survival rate of 71% (95% CI, 62 to 79) at 5 years. CONCLUSIONS: V600E or V600K mutation. (Funded by GlaxoSmithKline and Novartis; COMBI-d ClinicalTrials.gov number, NCT01584648; COMBI-v ClinicalTrials.gov number, NCT01597908.).

The ligand-binding subunit (gp80) of the human interleukin-6 receptor (IL-6R) was transiently expressed in COS-7 cells. The metabolically labeled protein was shown to be quantitatively released from the membrane within 20 h. We identified the protein released from the transfected COS-7 cells after purification to homogeneity and N-terminal sequencing as a soluble form of the gp80/IL-6R. Shedding of the gp80 protein was strongly induced by 4 beta-phorbol-12-myristate-13-acetate, indicating that the process was regulated by protein kinase C (PKC). This was further corroborated by the finding that co-transfection of a PKC expression plasmid led to enhanced shedding of the gp80 protein. Since shedding of gp80 could not be prevented by treatment of the cells with inhibitors of all known classes of proteases, a novel protease seems to be involved. As a control, an unrelated membrane protein (vesicular stomatitis virus glycoprotein) was transfected into COS-7 cells and analyzed for shedding. Since the turnover of this protein was not mediated by shedding, we conclude that the release of gp80 from COS-7 cells is a specific process. The shed gp80 protein specifically binds IL-6, and this complex shows biological activity on human hepatoma cells. Human peripheral blood monocytes released a soluble form of the gp80 protein into the culture medium upon PMA treatment indicating that PKC-regulated shedding is the physiological mechanism of generation of the soluble IL-6R.

The tumor microenvironment (TME) is a complex and ever-changing "rogue organ" composed of its own blood supply, lymphatic and nervous systems, stroma, immune cells and extracellular matrix (ECM). These complex components, utilizing both benign and malignant cells, nurture the harsh, immunosuppressive and nutrient-deficient environment necessary for tumor cell growth, proliferation and phenotypic flexibility and variation. An important aspect of the TME is cellular crosstalk and cell-to-ECM communication. This interaction induces the release of soluble factors responsible for immune evasion and ECM remodeling, which further contribute to therapy resistance. Other aspects are the presence of exosomes contributed by both malignant and benign cells, circulating deregulated microRNAs and TME-specific metabolic patterns which further potentiate the progression and/or resistance to therapy. In addition to biochemical signaling, specific TME characteristics such as the hypoxic environment, metabolic derangements, and abnormal mechanical forces have been implicated in the development of treatment resistance. In this review, we will provide an overview of tumor microenvironmental composition, structure, and features that influence immune suppression and contribute to treatment resistance.