Background: Guidelines for pathological evaluation of neoadjuvant specimens and pathological response categories have been developed by the International Neoadjuvant Melanoma Consortium (INMC). As... Show moreBackground: Guidelines for pathological evaluation of neoadjuvant specimens and pathological response categories have been developed by the International Neoadjuvant Melanoma Consortium (INMC). As part of the Optimal Neo-adjuvant Combination Scheme of Ipilimumab and Nivolumab (OpACIN-neo) clinical trial of neoadjuvant combination anti-programmed cell death protein 1/anti-cytotoxic T-Iymphocyte-associated protein 4 immunotherapy for stage III melanoma, we sought to determine interobserver reproducibility of INMC histopathological assessment principles, identify specific tumour bed histopathological features of immunotherapeutic response that correlated with recurrence and relapse-free survival (RFS) and evaluate proposed INMC pathological response categories for predicting recurrence and RFS.Patients and methods: Clinicopathological characteristics of lymph node dissection specimens of 83 patients enrolled in the OpACIN-neo clinical trial were evaluated. Two methods of assessing histological features of immunotherapeutic response were evaluated: the previously described immune-related pathologic response (irPR) score and our novel immunotherapeutic response score (ITRS). For a subset of cases (n = 29), cellular composition of the tumour bed was analysed by flow cytometry.Results: There was strong interobserver reproducibility in assessment of pathological response (kappa = 0.879) and percentage residual viable melanoma (intraclass correlation coefficient = 0.965). The immunotherapeutic response subtype with high fibrosis had the strongest association with lack of recurrence (P = 0.008) and prolonged RFS (P = 0.019). Amongst patients with criteria for pathological non-response (pNR, >50% viable tumour), all who recurred had >= 70% viable melanoma. Higher ITRS and irPR scores correlated with lack of recurrence in the entire cohort (P = 0.002 and P <= 0.0001). The number of B lymphocytes was significantly increased in patients with a high fibrosis subtype of treatment response (P = 0.046).Conclusions: There is strong reproducibility for assessment of pathological response using INMC criteria. Immunotherapeutic response of fibrosis subtype correlated with improved RFS, and may represent a biomarker. Potential B-cell contribution to fibrosis development warrants further study. Reclassification of pNR to a threshold of >= 70% viable melanoma and incorporating additional criteria of <10% fibrosis subtype of response may identify those at highest risk of recurrence, but requires validation. Show less
Approximately, 50% of patients with uveal melanoma develop distant metastasis for which no standard therapy is established. In contrast to cutaneous melanoma, the anti-CTLA-4 antibody ipilimumab... Show moreApproximately, 50% of patients with uveal melanoma develop distant metastasis for which no standard therapy is established. In contrast to cutaneous melanoma, the anti-CTLA-4 antibody ipilimumab showed no clinical activity in uveal melanoma. Liver directed therapies improve local control, but fail to show overall survival (OS) benefit. Preclinical experiments demonstrated that radiofrequency ablation (RFA) induced durable responses in combination with anti-CTLA-4. The aim of this phase Ib/II study was to assess safety and efficacy of RFA plus ipilimumab in uveal melanoma. Patients underwent RFA of one liver lesion and subsequently received four courses ipilimumab 0.3, 3 or 10 mg/kg every 3 weeks in a 3 + 3 design. Primary endpoints were safety in terms of dose limiting toxicities per cohort to define the recommended phase II dose (RP2D) in the phase Ib part and confirmed the objective response rate and disease control rate (DCR) of non-RFA lesions in the phase II part. Secondary endpoints were progression-free survival (PFS) and OS. Ipilimumab 10 mg/kg + RFA was initially defined as the RP2D. However, after 19 patients, the study was amended to adjust the RP2D to ipilimumab 3 mg/kg + RFA, because 47% of patients treated with 10 mg/kg had developed grade 3 colitis. In the 3 mg/kg cohort, also 19 patients have been treated. Immunotherapy-related grade >= 3 adverse events were observed in 53% of patients in the 10 mg/kg cohort versus 32% in the 3 mg/kg cohort. No confirmed objective responses were observed; the confirmed DCR was 5% in the 10 mg/kg cohort and 11% in the 3 mg/kg cohort. Median PFS was 3 months and comparable for both cohorts, median OS was 14.2 months for the 10 mg/kg cohort versus 9.7 months for the 3 mg/kg cohort. Combining RFA with ipilimumab 3 mg/kg was well tolerated, but showed very limited clinical activity in uveal melanoma. Show less
Background The profound disparity in response to immune checkpoint blockade (ICB) by cutaneous melanoma (CM) and uveal melanoma (UM) patients is not well understood. Therefore, we characterized... Show moreBackground The profound disparity in response to immune checkpoint blockade (ICB) by cutaneous melanoma (CM) and uveal melanoma (UM) patients is not well understood. Therefore, we characterized metastases of CM and UM from the same metastatic site (liver), in order to dissect the potential underlying mechanism in differential response on ICB. Methods Tumor liver samples from CM (n=38) and UM (n=28) patients were analyzed at the genomic (whole exome sequencing), transcriptional (RNA sequencing) and protein (immunohistochemistry and GeoMx Digital Spatial Profiling) level. Results Comparison of CM and UM metastases from the same metastatic site revealed that, although originating from the same melanocyte lineage, CM and UM differed in somatic mutation profile, copy number profile, tumor mutational burden (TMB) and consequently predicted neoantigens. A higher melanin content and higher expression of the melanoma differentiation antigen MelanA was observed in liver metastases of UM patients. No difference in B2M and human leukocyte antigen-DR (HLA-DR) expression was observed. A higher expression of programmed cell death ligand 1 (PD-L1) was found in CM compared with UM liver metastases, although the majority of CM and UM liver metastases lacked PD-L1 expression. There was no difference in the extent of immune infiltration observed between CM and UM metastases, with the exception of a higher expression of CD163 (p<0.0001) in CM liver samples. While the extent of immune infiltration was similar for CM and UM metastases, the ratio of exhausted CD8 T cells to cytotoxic T cells, to total CD8 T cells and to Th1 cells, was significantly higher in UM metastases. Conclusions While TMB was different between CM and UM metastases, tumor immune infiltration was similar. The greater dependency on PD-L1 as an immune checkpoint in CM and the identification of higher exhaustion ratios in UM may both serve as explanations for the difference in response to ICB. Consequently, in order to improve current treatment for metastatic UM, reversal of T cell exhaustion beyond programmed cell death 1 blockade should be considered. Show less
