Quantitative evaluation of trastuzumab deruxtecan pharmacokinetics and pharmacodynamics in mouse models of varying degrees of HER2 expression.

Trastuzumab deruxtecan (T-DXd; DS-8201; ENHERTU®) is a human epithelial growth factor receptor 2 (HER2)-directed antibody drug conjugate (ADC) with demonstrated antitumor activity against a range of tumor types. Aiming to understand the relationship between antigen expression and downstream efficacy outcomes, T-DXd was administered in tumor-bearing mice carrying NCI-N87, Capan-1, JIMT-1, and MDA-MB-468 xenografts, characterized by varying HER2 levels. Plasma pharmacokinetics (PK) of total antibody, T-DXd, and released DXd and tumor concentrations of released DXd were evaluated, in addition to monitoring γΗ2AX and pRAD50 pharmacodynamic (PD) response.

Macrophage Activation Status Rather than Repolarization Is Associated with Enhanced Checkpoint Activity in Combination with PI3Kγ Inhibition.

Suppressive myeloid cells mediate resistance to immune checkpoint blockade. PI3Kγ inhibition can target suppressive macrophages, and enhance efficacy of immune checkpoint inhibitors. However, how PI3Kγ inhibitors function in different tumor microenvironments (TME) to activate specific immune cells is underexplored.

Antisense Oligonucleotide Remodels the Suppressive Tumor Microenvironment to Enhance Immune Activation in Combination with Anti-PD-L1.

Purpose: Danvatirsen is a therapeutic antisense oligonucleotide (ASO) that selectively targets and has shown clinical activity in two phase I clinical studies. We interrogated the clinical mechanism of action using danvatirsen-treated patient samples and conducted back-translational studies to further elucidate its immunomodulatory mechanism of action.

Experimental Design: Paired biopsies and blood samples from danvatirsen-treated patients were evaluated using immunohistochemistry and gene-expression analysis.

Epithelial-to-mesenchymal transition activates PERK-eIF2α and sensitizes cells to endoplasmic reticulum stress.

Unlabelled: Epithelial-to-mesenchymal transition (EMT) promotes both tumor progression and drug resistance, yet few vulnerabilities of this state have been identified. Using selective small molecules as cellular probes, we show that induction of EMT greatly sensitizes cells to agents that perturb endoplasmic reticulum (ER) function. This sensitivity to ER perturbations is caused by the synthesis and secretion of large quantities of extracellular matrix (ECM) proteins by EMT cells.

Genetic predisposition directs breast cancer phenotype by dictating progenitor cell fate.

Women with inherited mutations in the BRCA1 gene have increased risk of developing breast cancer but also exhibit a predisposition for the development of aggressive basal-like breast tumors. We report here that breast epithelial cells derived from patients harboring deleterious mutations in BRCA1 (BRCA1(mut /+) give rise to tumors with increased basal differentiation relative to cells from BRCA1+/+ patients. Molecular analysis of disease-free breast tissues from BRCA1(mut /+) patients revealed defects in progenitor cell lineage commitment even before cancer incidence.