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Bundle read#1: genomic correlation with immunotherapy's effectiveness

Continuing the huge trend of discovering more into the magical "immune checkpoint blockade" therapy (as the hottest field that shed hope to cancer treatment), more is to be discussed about them. As is designed to battle against body's own mechanisms that suppress immune cells, those drugs as Ipilimumab and Nivolumab potentiate patients' own immune systems so that they are able to do their jobs and to control tumor growth. Despite the exciting efficacy of these drugs in melanoma, one of the puzzles is the different reponsiveness among patients.

Two papers just came out about the topic. While Ipilimumab (CTLA-4 inhibitor) and Nivolumab (PD-1 inhibitor) were individually discussed in each paper, similar correlation of the responsiveness of immune checkpoint blockade therapy with genomic alteration in melanoma patients were found.

High mutation loads tend to correlate with a favorable clinical response of both Ipilimumab and Nivolumab. However as suggested in the Science paper (other also other papers), further characterization of neoantigens produced by the genetic alterations will probably be more meaningful to predictive clinical outcomes. Recurrent neoantigens were also observed in response group of melanoma patients, suggesting that these neoantigens could be tested to decide whether Ipilimumab should be used in the patient. On the other hand, mutation loads were able to predict survival rate but not response rate of melanoma patients treated with Nivolumab, possibly also suggesting the needs for further characterization.

Besides, characterization of gene expression provided interesting information about Nivolumab response. The non-responders seemed to express higher genes related to angiogenesis, vasculature development and epithelial-mesenchymal transition (EMT) processed, which could help tumor cells escape from immune surveillance. Moreover, MAPKi therapy, widely used in multiple cancer treatment, also seemed to be associated with the "non-responding" phenotype, suggesting that the treatment plan that a patient is receiving could cause him/her insensitive to immune therapy. Of course, most that we learn from these studies are "correlation" not "causal"- we get a lot of information but we still need more to understand "the whole story".

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