An adverse tumor-protective effect of IDO1 inhibition.

By restoring tryptophan, indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors aim to reactivate anti-tumor T cells. However, a phase III trial assessing their clinical benefit failed, prompting us to revisit the role of IDO1 in tumor cells under T cell attack. We show here that IDO1 inhibition leads to an adverse protection of melanoma cells to T cell-derived interferon-gamma (IFNγ).

The Elongin BC Complex Negatively Regulates AXL and Marks a Differentiated Phenotype in Melanoma.

Unlabelled: High expression of the receptor tyrosine kinase AXL is implicated in epithelial-to-mesenchymal transition, cancer progression, and therapy resistance. For example, AXL is abundant in BRAF mutant melanomas progressing on targeted BRAF/MEK inhibition. Therefore, AXL is thought to represent an attractive therapeutic target.

is commonly amplified and high expression in cancer cells correlates with poor immune checkpoint blockade response.

Immunotherapies, in particular immune checkpoint blockade (ICB), have improved the clinical outcome of cancer patients, although many fail to mount a durable response. Several resistance mechanisms have been identified, but our understanding of the requirements for a robust ICB response is incomplete. We have engineered an MHC I/antigen: TCR-matched panel of human NSCLC cancer and T cells to identify tumor cell-intrinsic T cell resistance mechanisms.

RNF31 inhibition sensitizes tumors to bystander killing by innate and adaptive immune cells.

Tumor escape mechanisms for immunotherapy include deficiencies in antigen presentation, diminishing adaptive CD8 T cell antitumor activity. Although innate natural killer (NK) cells are triggered by loss of MHC class I, their response is often inadequate. To increase tumor susceptibility to both innate and adaptive immune elimination, we performed parallel genome-wide CRISPR-Cas9 knockout screens under NK and CD8 T cell pressure.

Predictive Immune-Checkpoint Blockade Classifiers Identify Tumors Responding to Inhibition of PD-1 and/or CTLA-4.

Purpose: Combining anti-PD-1 + anti-CTLA-4 immune-checkpoint blockade (ICB) shows improved patient benefit, but it is associated with severe immune-related adverse events and exceedingly high cost. Therefore, there is a dire need to predict which patients respond to monotherapy and which require combination ICB treatment.

Experimental Design: In patient-derived melanoma xenografts (PDX), human tumor microenvironment (TME) cells were swiftly replaced by murine cells upon transplantation.