Lymphoid neogenesis, or the development of lymphoid structures in nonlymphoid organs, is frequently observed in chronically inflamed tissues, during the course of autoimmune, infectious, and chronic graft rejection diseases, in which a sustained lymphocyte activation occurs in the presence of persistent antigenic stimuli. The presence of such ectopic lymphoid structures has also been reported in primary lung, breast, and germline cancers, but not yet in melanoma. In this study, we observed ectopic lymphoid structures, defined as lymphoid follicles comprising clusters of B lymphocytes and follicular dendritic cells (DC), associated with high endothelial venules (HEV) and clusters of T cells and mature DCs, in 7 of 29 cutaneous metastases from melanoma patients. Some follicles contained germinal centers. In contrast to metastatic lesions, primary melanomas did not host follicles, but many contained HEVs, suggesting an incomplete lymphoid neogenesis. Analysis of the repertoire of rearranged immunoglobulin genes in the B cells of microdissected follicles revealed clonal amplification, somatic mutation and isotype switching, indicating a local antigen-driven B-cell response. Surprisingly, IgA responses were observed despite the nonmucosal location of the follicles. Taken together, our findings show the existence of lymphoid neogenesis in melanoma and suggest that the presence of functional ectopic lymphoid structures in direct contact with the tumor makes the local development of antimelanoma B- and T-cell responses possible. Cancer Res; 72(16); 3997–4007. ©2012 AACR.

BRAF V600 mutant circulating cell-free tumor DNA (BRAF V600mut ctDNA) could serve as a specific biomarker in patients with BRAF V600 mutant melanoma. We analyzed the value of BRAF V600mut ctDNA from plasma as a monitoring tool for advanced melanoma patients treated with BRAF/MEK inhibitors. Allele-specific quantitative PCR analysis for BRAF V600 E/E2/D/K/R/M mutations was performed on DNA extracted from plasma of patients with known BRAF V600 mutant melanoma who were treated with dabrafenib and trametinib. 245 plasma samples from 36 patients were analyzed. In 16 patients the first plasma sample was obtained before the first dosing of dabrafenib/trametinib. At baseline, BRAF V600mut ctDNA was detected in 75 % of patients (n = 12/16). BRAF V600mut ctDNA decreased rapidly upon initiation of targeted therapy (p < 0.001) and became undetectable in 60 % of patients (n = 7/12) after 6 weeks of treatment. During treatment, disease progression (PD) was diagnosed in 27 of 36 patients. An increase of the BRAF V600mut ctDNA copy number and fraction, identified PD with a sensitivity of 70 % (n = 19/27) and a specificity of 100 %. An increase in the BRAF V600mut ctDNA fraction was detected prior to clinical PD in 44 % of cases (n = 12/27) and simultaneously with PD in 26 % of patients (n = 7/27). Quantitative analysis of BRAF V600mut ctDNA in plasma has unique features as a monitoring tool during treatment with BRAF/MEK inhibitors. Its potential as an early predictor of acquired resistance deserves further evaluation.

Treatment with anti-PD1 monoclonal antibodies improves the survival of metastatic melanoma patients but only a subgroup of patients benefits from durable disease control. Predictive biomarkers for durable benefit could improve the clinical management of patients. Plasma samples were collected from patients receiving anti-PD1 therapy for ctDNA quantitative assessment of BRAFV600 and NRASQ61/G12/G13 mutations. After a median follow-up of 84 weeks 457 samples from 85 patients were analyzed. Patients with undetectable ctDNA at baseline had a better PFS (Hazard ratio (HR) = 0.47, median 26 weeks versus 9 weeks, p = 0.01) and OS (HR = 0.37, median not reached versus 21.3 weeks, p = 0.005) than patients with detectable ctDNA. Additionally, the HR for death was lower after the ctDNA level became undetectable during follow-up (adjusted HR: 0.16 (95% CI 0.07–0.36), p-value < 0.001). ctDNA levels > 500 copies/ml at baseline or week 3 were associated with poor clinical outcome. Patients progressive exclusively in the central nervous system (CNS) had undetectable ctDNA at baseline and at subsequent assessments. In multivariate analysis adjusted for LDH, CRP, ECOG and number of metastatic sites, the ctDNA remained significant for PFS and OS. A positive correlation was observed between ctDNA levels and total metabolic tumor volume (TMTV), number of metastatic sites and total tumor burden. Assessment of ctDNA baseline and during therapy was predictive for tumor response and clinical outcome in metastatic melanoma patients and reflected the tumor burden. ctDNA evaluation provided reliable complementary information during anti-PD1 antibody therapy.

Previous advances have identified immune pathways associated with inflammatory skin diseases, leading to the development of targeted therapies. However, there is a lack of molecular approaches that delineate these pathways at the individual patient level for personalized diagnostic and therapeutic guidance. Here, we conduct a cross-comparison of expression profiles from multiple inflammatory skin diseases to identify gene modules defining relevant immune pathways. Seven modules are identified, representing key immune pathways: Th17, Th2, Th1, Type I IFNs, neutrophilic, macrophagic, and eosinophilic. These modules allow the development of a molecular map with high diagnostic efficacy for inflammatory skin diseases and clinico-pathologically undetermined cases. Aligning dominant modules with treatment targets offers a rational framework for treatment selection, improving response rates in both treatment-naïve patients and non-responders to targeted therapies. Overall, our approach offers precision medicine for inflammatory skin diseases, utilizing transcriptional modules to support diagnosis and guide personalized treatment selection.

A 61-year-old man was diagnosed with stage IIIB BRAF V600E mutant melanoma in October 2012. He was treated with a combination therapy of dabrafenib and trametinib. He remained in complete remission for 18 months and the treatment was well tolerated after dose reduction because of pyrexia. In March 2013, he developed bilateral pitting edema of the legs with an erythematous, slightly infiltrated rash on his back and upper arms. His face was edematous, with a heliotrope rash-like aspect. Eye examination showed bilateral blepharitis. Additional blood test showed inflammation and acute kidney injury Rifle category failure. A skin and kidney biopsy indicated a granulomatous inflammation. A complete workup for other causes of granulomatous inflammation was negative. Treatment with dabrafenib and trametinib was stopped and corticosteroids were initiated, with a rapid beneficial effect on both the kidney function and skin rash. When corticosteroids were halted after 1 month, a rapid decline in the kidney function was observed. After reintroduction of corticosteroids, kidney function normalized and steroids could be tapered gradually over 6 months. To our knowledge, interstitial nephritis has not been described in patients on BRAF-targeted nor MEK-targeted therapy for melanoma, although it has been described in a melanoma patient treated with the immune checkpoint inhibitor, ipilimumab. Currently, the patient has no sign of local or distal recurrence of melanoma, notwithstanding that treatment with dabrafenib and trametinib has been stopped for 10 months and no other antimelanoma therapy was initiated.