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BackgroundThe randomized phase 3 COMBI-i trial did not meet its primary endpoint of improved progression-free survival (PFS) with spartalizumab plus dabrafenib and trametinib (sparta-DabTram) vs placebo plus dabrafenib and trametinib (placebo-DabTram) in the overall population of patients with unresectable/metastatic BRAF V600-mutant melanoma. This prespecified exploratory biomarker analysis was performed to identify subgroups that may derive greater treatment benefit from sparta-DabTram.MethodsIn COMBI-i (ClinicalTrials.gov, NCT02967692), 532 patients received spartalizumab 400 mg intravenously every 4 weeks plus dabrafenib 150 mg orally two times daily and trametinib 2 mg orally one time daily or placebo-DabTram. Baseline/on-treatment pharmacodynamic markers were assessed via flow cytometry-based immunophenotyping and plasma cytokine profiling. Baseline programmed death ligand 1 (PD-L1) status and T-cell phenotype were assessed via immunohistochemistry; BRAF V600 mutation type, tumor mutational burden (TMB), and circulating tumor DNA (ctDNA) via DNA sequencing; gene expression signatures via RNA sequencing; and CD4+/CD8+ T-cell ratio via immunophenotyping.ResultsExtensive biomarker analyses were possible in approximately 64% to 90% of the intention-to-treat population, depending on sample availability and assay. Subgroups based on PD-L1 status/TMB or T-cell inflammation did not show significant differences in PFS benefit with sparta-DabTram vs placebo-DabTram, although T-cell inflammation was prognostic across treatment arms. Subgroups defined by BRAF V600K mutation (HR 0.45 (95% CI 0.21 to 0.99)), detectable ctDNA shedding (HR 0.75 (95% CI 0.58 to 0.96)), or CD4+/CD8+ ratio above median (HR 0.58 (95% CI 0.40 to 0.84)) derived greater PFS benefit with sparta-DabTram vs placebo-DabTram. In a multivariate analysis, ctDNA emerged as strongly prognostic (p=0.007), while its predictive trend did not reach significance; in contrast, CD4+/CD8+ ratio was strongly predictive (interaction p=0.0131).ConclusionsThese results support the feasibility of large-scale comprehensive biomarker analyses in the context of a global phase 3 study. T-cell inflammation was prognostic but not predictive of sparta-DabTram benefit, as patients with high T-cell inflammation already benefit from targeted therapy alone. Baseline ctDNA shedding also emerged as a strong independent prognostic variable, with predictive trends consistent with established measures of disease burden such as lactate dehydrogenase levels. CD4+/CD8+ T-cell ratio was significantly predictive of PFS benefit with sparta-DabTram but requires further validation as a biomarker in melanoma. Taken together with previous observations, further study of checkpoint inhibitor plus targeted therapy combination in patients with higher disease burden may be warranted.Trial registration numberNCT02967692.

PURPOSEPreclinical data suggest the combination of an anti–programmed death receptor 1 antibody plus dabrafenib and trametinib to have superior antitumor activity compared with dabrafenib plus trametinib alone. These observations are supported by translational evidence suggesting that immune checkpoint inhibitors plus targeted therapy may improve treatment outcomes in patients with BRAF V600–mutant metastatic melanoma. COMBI-i is a phase III trial evaluating spartalizumab, an anti–programmed death receptor 1 antibody, in combination with dabrafenib and trametinib (sparta-DabTram), versus placebo plus dabrafenib and trametinib (placebo-DabTram) in patients with BRAF V600–mutant unresectable or metastatic melanoma.METHODSPatients received spartalizumab 400 mg intravenously every 4 weeks plus dabrafenib 150 mg orally twice daily and trametinib 2 mg orally once daily or placebo-DabTram. Participants were age ≥ 18 years with unresectable or metastatic BRAF V600–mutant melanoma. The primary end point was investigator-assessed progression-free survival. Overall survival was a key secondary end point (ClinicalTrials.gov identifier: NCT02967692 ).RESULTSAt data cutoff (July 1, 2020), the median progression-free survival was 16.2 months (95% CI, 12.7 to 23.9 months) in the sparta-DabTram arm versus 12.0 months (95% CI, 10.2 to 15.4 months) in the placebo-DabTram arm (hazard ratio, 0.82 [95% CI, 0.66 to 1.03]; P = .042 [one-sided; nonsignificant]). The objective response rates were 69% (183 of 267 patients) versus 64% (170 of 265 patients), respectively. Grade ≥ 3 treatment-related adverse events occurred in 55% (146 of 267) of patients in the sparta-DabTram arm and 33% (88 of 264) in the placebo-DabTram arm.CONCLUSIONThe study did not meet its primary end point; broad first-line use of sparta-DabTram is not supported by these results. Further biomarker-driven investigation may identify patient subpopulations who could benefit from checkpoint inhibitor plus targeted therapy combinations.

Sunitinib and pazopanib are antiangiogenic tyrosine kinase inhibitors (TKI) used to treat metastatic renal cell carcinoma (RCC). However, the ability of these drugs to extend progression-free and overall survival in this patient population is limited by drug resistance. It is possible that treatment outcomes in RCC patients could be improved by rationally combining TKIs with other agents. Here, we address whether inhibition of the Ras-Raf-MEK-ERK1/2 pathway is a rational means to improve the response to TKIs in RCC. Using a xenograft model of RCC, we found that tumors that are resistant to sunitinib have a significantly increased angiogenic response compared with tumors that are sensitive to sunitinib in vivo. We also observed significantly increased levels of phosphorylated ERK1/2 in the vasculature of resistant tumors, when compared with sensitive tumors. These data suggested that the Ras-Raf-MEK-ERK1/2 pathway, an important driver of angiogenesis in endothelial cells, remains active in the vasculature of TKI-resistant tumors. Using an in vitro angiogenesis assay, we identified that the MEK inhibitor (MEKI) trametinib has potent antiangiogenic activity. We then show that, when trametinib is combined with a TKI in vivo, more effective suppression of tumor growth and tumor angiogenesis is achieved than when either drug is utilized alone. In conclusion, we provide preclinical evidence that combining a TKI, such as sunitinib or pazopanib, with a MEKI, such as trametinib, is a rational and efficacious treatment regimen for RCC.

Biological therapies are claiming a place in the routine management of some solid tumours. In this review we focus on the biological treatment of melanoma and renal-cell carcinoma, identifying the background to current practice and areas of promise that may be in routine clinical use in the near future. Melanomas and renal-cell carcinomas are particularly resistant to chemotherapy and radiotherapy and are characterised by the host immune response to the tumours. For this reason there has been particular interest in the biological therapy of these diseases. Biological therapies differ from chemotherapeutic approaches in their mechanism of action, time to response, and side-effect profiles. Although biological treatment has a long history, it is only with recent advances in immunology and molecular biology that progress has been made. In the next few years investigators expect to build on their research experience with biotherapeutic agents to provide tangible benefits for patients.

Six monoclonal antibodies (McAbs) were identified as plasma cell-reactive when screened on sections of human tonsil. They were all produced following immunisation of mice with cells of a human plasmacytoid line. Three of the antibodies also stained the cytoplasm (but not the surface) of blood B cells and were unreactive with other leucocytes; one McAb showed broad lymphocyte reactivity and two were completely unreactive with blood leucocytes; on testing with a panel of cell lines specificity for the plasmacy-toid line was demonstrated by three of the McAbs. In spite of the marked restriction shown by the reactivity of these antibodies in tests on cells of haemopoietic origin, tests on other human tissues — including thyroid and pancreas — showed that a related antigen was present in the cytoplasm of secretory epithelial cells. The overall patterns of reactivity of the individual McAbs on various tissues and blood lymphocytes were different. Comparisons were made with the established McAb OKT10, which binds to plasma cells, early stem cells and activated lymphocytes; its binding to plasma cells was confirmed and it was shown that it did not stain secretory epithelia. The potent reactions obtained with the new McAbs suggest that antibodies to antigens associated with epithelial cell secretory apparatus provide potentially useful reagents for studying plasma cells.

The autocrine growth profile of human B lymphocytes transformed with Epstein-Barr virus (EBV) was found to comprise three distinct components: a B-cell growth factor (BCGF); an interleukin-1 (IL-1)-like activity; an activity requiring cell-to-cell contact for its action. Observations on the inhibition of the EBV-carrying Daudi lymphoma line by alpha-interferon indicated that loss of response to these autostimulatory factors was underlying growth cessation. Furthermore, a putative receptor for BCGF was found to be down-regulated on B cells stimulated with non-transforming mitogens but constitutively expressed following EBV-transformation. Taken together with recent evidence that normal B cells produce autostimulatory factors, these findings suggest that the special feature of autocrine growth by EBV-immortalized cells is a maintenance of what should normally be a transient phenotype, possibly through deregulation of receptor expression. This hypothesis is discussed.

Treatment of Daudi B-lymphoblastoid cells with low concentrations of either natural or recombinant human alpha-interferons inhibits cell proliferation and modulates the expression of a number of cell-surface antigens. Using a panel of monoclonal antibodies (MAbs) identifying determinants expressed at the surface of normal plasma cells, and polyclonal antibodies against surface and cytoplasmic immunoglobulin, we have found that growth inhibition is accompanied by plasmacytoid differentiation. Assays of growth stimulation of heterologous cells indicate that the culture medium from interferon-treated Daudi cells contains substantially more B-cell growth factor activity than that from control cells. However, the interferon-treated cells exhibit an impaired ability to respond to both these autocrine factors and exogenous factors produced by another Burkitt lymphoma line. These findings show that, in the case of Daudi cells, growth inhibition by interferons is closely associated with both terminal differentiation and a refractoriness to growth factors. In this system IFN-alpha may therefore be considered to be a B-cell differentiation factor, suggesting a possible basis for the anti-proliferative effects observed with certain human B-cell malignancies.