Tatsuya Yoshida

Chronic fibrotic tissue disrupts various organ functions. Despite significant advances in therapies, mortality and morbidity due to heart failure remain high, resulting in poor quality of life. Beyond the cardiomyocyte-centric view of heart failure, it is now accepted that alterations in the interstitial extracellular matrix (ECM) also play a major role in the development of heart failure. Here, we show that protein kinase N (PKN) is expressed in cardiac fibroblasts. Furthermore, PKN mediates the conversion of fibroblasts into myofibroblasts, which plays a central role in secreting large amounts of ECM proteins via p38 phosphorylation signaling. Fibroblast-specific deletion of PKN led to a reduction of myocardial fibrotic changes and cardiac dysfunction in mice models of ischemia-reperfusion or heart failure with preserved ejection fraction. Our results indicate that PKN is a therapeutic target for cardiac fibrosis in heart failure.

In first-in-human (FIH) trials, sequential tumor biopsies, i.e., two consecutive tumor biopsies, the first performed at baseline (pretreatment) and the second during the early treatment period (on-treatment), provide proof of concept in investigational new drugs. We evaluated the success of sequential tumor biopsies in FIH trials, and explored approaches for improved success rates. We retrospectively reviewed the sequential tumor biopsies required in 17 of 52 FIH trials conducted from 2015 to 2020. One hundred and thirty-eight patients were identified. Success of either pretreatment or on-treatment biopsy alone, and of sequential tumor biopsies, was defined as the acquisition of viable tumor cells and as obtaining tumor cells from both biopsy specimens, respectively. The success rates of pretreatment and on-treatment biopsy were 98.6% and 94.2%, respectively, and of sequential tumor biopsies was 70.3%. Adverse events associated with the pretreatment biopsies (33.3% positive; 72.0% negative) and timing of the first imaging assessment (before on-treatment biopsy = 40.0%; after on-treatment biopsy = 82.7%) correlated with successful sequential tumor biopsies. The reasons for unsuccessful sequential tumor biopsies could be categorized into two groups: 1) patient refusal of the on-treatment biopsy (most frequently due to early disease progression); and 2) absence of tumor cells in the pretreatment or on-treatment biopsy specimen. We propose an approach to achieving greater success in sequential tumor biopsies in FIH trials; the first imaging assessment during the study should be scheduled after on-treatment biopsy. (Registration number UMIN000042487, Date of registration November 18, 2020).