Selective multi-kinase inhibition sensitizes mesenchymal pancreatic cancer to immune checkpoint blockade by remodeling the tumor microenvironment.

KRAS-mutant pancreatic ductal adenocarcinoma (PDAC) is highly immunosuppressive and resistant to targeted and immunotherapies. Among the different PDAC subtypes, basal-like mesenchymal PDAC, which is driven by allelic imbalance, increased gene dosage and subsequent high expression levels of oncogenic KRAS, shows the most aggressive phenotype and strongest therapy resistance. In the present study, we performed a systematic high-throughput combination drug screen and identified a synergistic interaction between the MEK inhibitor trametinib and the multi-kinase inhibitor nintedanib, which targets KRAS-directed oncogenic signaling in mesenchymal PDAC. This combination treatment induces cell-cycle arrest and cell death, and initiates a context-dependent remodeling of the immunosuppressive cancer cell secretome. Using a combination of single-cell RNA-sequencing, CRISPR screens and immunophenotyping, we show that this combination therapy promotes intratumor infiltration of cytotoxic and effector T cells, which sensitizes mesenchymal PDAC to PD-L1 immune checkpoint inhibition. Overall, our results open new avenues to target this aggressive and therapy-refractory mesenchymal PDAC subtype.

Feasibility of electrospraying fully aqueous bovine serum albumin solutions.

Electrospraying or electrohydrodynamic atomisation, i.e. the formation of tiny droplets from a jet of conductive liquid under the influence of an electric field, has been gaining in popularity as a particle engineering technique in recent years. In addition to general benefits for particle engineering, e.g. the ability to generate nanometre sized particles with a very narrow size distribution, electrospraying also possesses a number of characteristics, like its applicability at ambient conditions, which could make it especially interesting for formulating therapeutic proteins. However, as fully aqueous solutions of proteins tend to have relatively high electrical conductivities and surface tensions, obtaining a stable Taylor cone-jet mode for these solutions is inherently challenging. This is why in the majority of studies reporting the successful electrospraying of proteins, either emulsions, aqueous suspensions or a mixture of water and one or more organic solvents were used instead of fully aqueous solutions. Therefore, an ab initio electrospraying formulation development study was conducted, using only fully aqueous feed solutions containing protein stabilising excipients commonly used in spray- and freeze-drying of therapeutic proteins. The study included bovine serum albumin (BSA) as a model protein and consisted out of two parts: (1) a one parameter at a time screening study, designed to improve the understanding of how various formulation components influence relevant physicochemical properties and the electrospraying process and (2) two subsequent mixture design of experiments (DoE) studies, designed to aid in the statistical description and prediction of the influence of different protein-excipient combinations on the electrospraying process. Additionally, the influence of physicochemical properties relevant to the electrospraying process, i.e. the volumetric mass density, electrical conductivity, kinematic viscosity and surface tension, was assessed for all feed solutions included in the study.

Formulating monoclonal antibodies as powders for reconstitution at high concentration using spray drying: Models and pitfalls.

In anticipation of non-invasive routes capable of delivering adequately high, systemic monoclonal antibody (mAb) concentrations, subcutaneous (SC) injection is arguably the most patient friendly alternative administration route available for this drug class. However, due to the limited volume that can be administered through this route and mAbs' relatively low therapeutic activity, solutions for subcutaneous injection often need to be highly concentrated, making them inherently more prone to potentially detrimental protein (self-) interaction, which is why mAb formulations for SC injection and other highly concentrated mAb solutions are often dried to increase their stability. In this work we investigated spray drying (SD) as a drying technique for formulating mAbs as powders for reconstitution, assessing the influence of SD process parameters, as well as excipients present in the feed solution on both mAb stability and relevant powder characteristics for reconstitution using a model mAb. By employing a design of experiments approach, we were able to provide statistically substantiated evidence for the reconstitution time reducing and stability improving properties of l-arginineHCl, l-histidineHCl, l-lysineHCl and polysorbate 20 when combined with a disaccharide in SD mAb powders for reconstitution. Additionally, the study yielded several statistical models describing process parameter influences on relevant powder and mAb stability characteristics.