Recurrent Tumor Cell-Intrinsic and -Extrinsic Alterations during MAPKi-Induced Melanoma Regression and Early Adaptation

• Published in: Cancer discovery 2017-11, Vol.7 (11), p.1248-1265
• Main Authors: Song, Chunying, Piva, Marco, Sun, Lu, Hong, Aayoung, Moriceau, Gatien, Kong, Xiangju, Zhang, Hong, Lomeli, Shirley, Qian, Jin, Yu, Clarissa C, Damoiseaux, Robert, Kelley, Mark C, Dahlman, Kimberley B, Scumpia, Philip O, Sosman, Jeffrey A, Johnson, Douglas B, Ribas, Antoni, Hugo, Willy, Lo, Roger S
• Format: Article
• Language: English
• Subjects: Animals; Cell Line, Tumor; Drug Resistance, Neoplasm - genetics; Humans; Indoles - administration & dosage; Leukocyte Common Antigens - genetics; MAP Kinase Kinase 1 - antagonists & inhibitors; MAP Kinase Kinase 1 - genetics; Melanoma - drug therapy; Melanoma - genetics; Melanoma - pathology; Melanoma, Experimental - drug therapy; Melanoma, Experimental - genetics; Melanoma, Experimental - pathology; Mice; Mutation; Protein Kinase Inhibitors - administration & dosage; Proto-Oncogene Proteins B-raf - genetics; Sulfonamides - administration & dosage; Transcriptome - drug effects; Transcriptome - genetics
• ISSN: 2159-8274; 2159-8290; 2159-8290
• DOI: 10.1158/2159-8290.CD-17-0401

Treatment of advanced -mutant melanoma using a BRAF inhibitor or its combination with a MEK inhibitor typically elicits partial responses. We compared the transcriptomes of patient-derived tumors regressing on MAPK inhibitor (MAPKi) therapy against MAPKi-induced temporal transcriptomic states in human melanoma cell lines or murine melanoma in immune-competent mice. Despite heterogeneous dynamics of clinical tumor regression, residual tumors displayed highly recurrent transcriptomic alterations and enriched processes, which were also observed in MAPKi-selected cell lines (implying tumor cell-intrinsic reprogramming) or in bulk mouse tumors (and the CD45-negative or CD45-positive fractions, implying tumor cell-intrinsic or stromal/immune alterations, respectively). Tumor cell-intrinsic reprogramming attenuated MAPK dependency, while enhancing mesenchymal, angiogenic, and IFN-inflammatory features and growth/survival dependence on multi-RTKs and PD-L2. In the immune compartment, PD-L2 upregulation in CD11c immunocytes drove the loss of T-cell inflammation and promoted BRAFi resistance. Thus, residual melanoma early on MAPKi therapy already displays potentially exploitable adaptive transcriptomic, epigenomic, immune-regulomic alterations. Incomplete MAPKi-induced melanoma regression results in transcriptome/methylome-wide reprogramming and MAPK-redundant escape. Although regressing/residual melanoma is highly T cell-inflamed, stromal adaptations, many of which are tumor cell-driven, could suppress/eliminate intratumoral T cells, reversing tumor regression. This catalog of recurrent alterations helps identify adaptations such as PD-L2 operative tumor cell intrinsically and/or extrinsically early on therapy. .