Project description:<p>Blockade of T cell coinhibitory molecules such as CTLA-4 and PD-1, can activate T cell antitumor response. Although these immune checkpoint blockades (CTLA-4 blockade and PD-1 blockade) have shown durable response, response rate is modest. Therefore, there is a need to find stable biomarkers predictive of response to immune checkpoint blockades and to understand underlying resistance mechanisms. We collected longitudinal tumor biopsies from a cohort of metastatic melanoma patients treated with sequential immune checkpoint blockades and performed whole exome sequencing of this cohort. The comprehensive genomic characterization of tumors enabled identification of higher copy number loss burden as a resistance mechanism and clonal T cell repertoire as a predictive biomarker.</p>
Project description:Tumor cell-containing Regions of Interest from 17 patients with melanoma after progression to Immune Checkpoint Blockade were profiled at the transcriptomic level.
Project description:Immune checkpoint blockade (ICB) has demonstrated efficacy in patients with melanoma, but many exhibit poor responses. Using single cell RNA sequencing of melanoma patient-derived circulating tumor cells (CTCs) and functional characterization using mouse melanoma models, we show that the KEAP1/NRF2 pathway modulates sensitivity to ICB, independently of tumorigenesis. The NRF2 negative regulator, KEAP1, shows intrinsic variation in expression, leading to tumor heterogeneity and subclonal resistance.
Project description:Immune checkpoint blockade (ICB) has demonstrated efficacy in patients with melanoma, but many exhibit poor responses. Using single cell RNA sequencing of melanoma patient-derived circulating tumor cells (CTCs) and functional characterization using mouse melanoma models, we show that the KEAP1/NRF2 pathway modulates sensitivity to ICB, independently of tumorigenesis. The NRF2 negative regulator, KEAP1, shows intrinsic variation in expression, leading to tumor heterogeneity and subclonal resistance.
Project description:Immune checkpoint blockade (ICB) therapy provides remarkable clinical gains, where melanoma is at the forefront of its success. However, only a subset of patients with advanced tumors currently benefit from these therapies, which at times incur considerable side-effects and costs. Constructing such predictors of patient’s response has remained a serious challenge due to the complexity of the immune response and the shortage of large ICB-treated patient cohorts including both omics and response data. Here we build IMPRES, a predictor of ICB-response in melanoma which encompasses 15 pairwise transcriptomics relations between immune checkpoint genes. It is based on two key conjectures: (a) immune mechanisms underlining spontaneous regression in neuroblastoma can predict ICB response in melanoma, and (b) key immune interactions can be captured via specific pairwise relations of immune checkpoint genes’ expression. IMPRES is validated on 9 published datasets1–6 and on a newly generated dataset of 31 tumor samples treated with anti-PD-1 and 10 tumor samples treated with anti-CTLA-4 (some of these are treated with both antibodies), spanning 297 samples in total. It achieves an overall accuracy of AUC=0.83, outperforming existing predictors, capturing almost all true responders while misclassifying less than half of the non-responders. Future studies are warranted to determine the value of the approach presented here in other cancer types.
Project description:Immune checkpoint blockade (ICB) has improved outcome for patients with metastatic melanoma but not all benefit from treatment. Several immune- and tumor intrinsic features are associated with clinical response at baseline. However, we need to further understand the molecular changes occurring during development of ICB resistance. Here, we collected biopsies from a cohort of 44 melanoma patients after progression to anti-CTLA4 or anti-PD1 monotherapy. Genetic alterations of antigen presentation and interferon gamma signaling pathways were observed in approximately 25% of ICB resistant cases. Anti-CTLA4 resistant lesions had a sustained immune response, including immune-regulatory features, as suggested by multiplex spatial and TCR clonality analyses. One anti-PD1 resistant lesion harbored a distinct immune cell niche, however, anti-PD1 resistant tumors were generally immune poor with non-expanded TCR clones. Such immune poor microenvironments were associated with melanoma cells having a de-differentiated phenotype lacking expression of MHC-I molecules. In addition, anti-PD1 resistant tumors had reduced fractions of PD1+ CD8+ T cells as compared to ICB naïve metastases. Collectively, these data show the complexity of ICB resistance and highlight differences between anti-CTLA4 and anti-PD1 resistance that may underlie differential clinical outcomes of therapy sequence and combination.
Project description:Immune checkpoint blockade (ICB) has demonstrated significant promise for the treatment of advanced malignancies. Anti-CTLA4 and ant-PD1 therapy can activate the immune system and result in durable control in diseases such as melanoma and non-small cell lung cancer.