A novel in silico framework to improve MHC-I epitopes and break the tolerance to melanoma.
Authors: Capasso C, Magarkar A, Cervera-Carascon V, Fusciello M, Feola S, Muller M, Garofalo M, Kuryk L, Tähtinen S, Pastore L, Bunker A, Cerullo V
Tolerance toward tumor antigens, which are shared by normal tissues, have often limited the efficacy of cancer vaccines. However, wild type epitopes can be tweaked to activate cross-reactive T-cell clones, resulting in antitumor activity. The design of these analogs (i.e., heteroclitic peptides) can be difficult and time-consuming since no automated in silico tools are available. Hereby we describe the development of an in silico framework to improve the selection of heteroclitic peptides. The Epitope Discovery and Improvement System (EDIS) was first validated by studying the model antigen SIINFEKL. Based on artificial neural network (ANN) predictions, we selected two mutant analogs that are characterized by an increased MHC-I binding affinity (SIINFAKL) or increased TCR stimulation (SIIWFEKL). Therapeutic vaccination using optimized peptides resulted in enhanced antitumor activity and against B16.OVA melanomas in vivo. The translational potential of the EDIS platform was further demonstrated by studying the melanoma-associated antigen tyrosinase related protein 2 (TRP2). Following therapeutic immunization with the EDIS-derived epitope SVYDFFAWL, a significant reduction in the growth of established B16.F10 tumors was observed, suggesting a break in the tolerance toward the wild type epitope. Finally, we tested a multi vaccine approach, demonstrating that combination of wild type and mutant epitopes targeting both TRP2 and OVA antigens increases the antitumor response. In conclusion, by taking advantage of available prediction servers and molecular dynamics simulations, we generated an innovative platform for studying the initial sequences and selecting lead candidates with improved immunological features. Taken together, EDIS is the first automated algorithm-driven platform to speed up the design of heteroclitic peptides that can be publicly queried online.
PMID: 28932628 [PubMed]
High accuracy label-free classification of single-cell kinetic states from holographic cytometry of human melanoma cells.
Sci Rep. 2017 Sep 20;7(1):11943
Authors: Hejna M, Jorapur A, Song JS, Judson RL
Digital holographic cytometry (DHC) permits label-free visualization of adherent cells. Dozens of cellular features can be derived from segmentation of hologram-derived images. However, the accuracy of single cell classification by these features remains limited for most applications, and lack of standardization metrics has hindered independent experimental comparison and validation. Here we identify twenty-six DHC-derived features that provide biologically independent information across a variety of mammalian cell state transitions. When trained on these features, machine-learning algorithms achieve blind single cell classification with up to 95% accuracy. Using classification accuracy to guide platform optimization, we develop methods to standardize holograms for the purpose of kinetic single cell cytometry. Applying our approach to human melanoma cells treated with a panel of cancer therapeutics, we track dynamic changes in cellular behavior and cell state over time. We provide the methods and computational tools for optimizing DHC for kinetic single adherent cell classification.
PMID: 28931937 [PubMed - in process]
Melanoma Drugs Effective as Adjuvants.
Cancer Discov. 2017 Sep 20;:
BRAF-targeted strategies and PD-1-blocking immunotherapy are more effective adjuvant therapies than currently approved options for patients with high-risk resectable melanoma. However, choosing the best agent for patients with BRAF-mutated disease remains a challenge.
PMID: 28931514 [PubMed - as supplied by publisher]
Tadalafil has biologic activity in human melanoma. Results of a pilot trial with Tadalafil in patients with metastatic Melanoma (TaMe).
Authors: Hassel JC, Jiang H, Bender C, Winkler J, Sevko A, Shevchenko I, Halama N, Dimitrakopoulou-Strauss A, Haefeli WE, Jäger D, Enk A, Utikal J, Umansky V
Myeloid-derived suppressor cells (MDSCs) are known to play a critical role in the suppression of T cell antitumor responses. Our preclinical data showed that the phosphodiesterase (PDE)-5 inhibitor sildenafil impaired MDSC functions, enhanced intratumoral T cell activity and prolonged survival of melanoma-bearing mice. In this study, we evaluated biologic effects, safety and efficacy of palliative treatment with the PDE-5 inhibitor tadalafil in metastatic melanoma patients. We conducted an open-label, dose de-escalation trial with tadalafil in pretreated metastatic melanoma patients. Tumor and peripheral blood samples were taken before and 4 weeks after the start of treatment. Samples were investigated by immunohistochemistry and FACS analysis, for different immune subsets with numbers of CD8(+) tumor-infiltrating lymphocytes (TIL) as primary end point. Stable disease was achieved in 3/12 patients (25%). Median progression-free survival was 4.6 mo (range 0.7-7.1), median overall survival (OS) 8.5 mo (range 2.7-23.7). The treatment was well tolerated. Stable patients displayed significantly higher numbers of CD8(+) TIL in the center of metastases before treatment as compared with progressive patients. Upon the therapy, they showed increased expression of ζ-chain (used as a marker of T cell activation) in CD8(+) and CD4(+)TILs and CD8(+)T cells in the peripheral blood as compared with baseline. Our study suggests that the PDE-5 inhibitor tadalafil can improve clinical outcome of advanced melanoma patients by enhancing antitumor immunity and highlights its potential application in combined melanoma immunotherapy.
PMID: 28932631 [PubMed]
Primary malignant urethral melanoma resembling a urethral caruncle.
Urol Case Rep. 2017 Nov;15:28-29
Authors: Safadi A, Schwalb S, Ben-Shachar I, Katz R
PMID: 28932693 [PubMed]