Combined effects of exercise and immuno-chemotherapy treatments on tumor growth in MC38 colorectal cancer-bearing mice.

Acute exercise induces transient modifications in the tumor microenvironment and has been linked to reduced tumor growth along with increased infiltration of immune cells within the tumor in mouse models. In this study, we aimed to evaluate the impact of acute exercise before treatment administration on tumor growth in a mice model of MC38 colorectal cancer receiving an immune checkpoint inhibitor (ICI) and chemotherapy. Six-week-old mice injected with colorectal cancer cells (MC38) were randomized in 4 groups: control (CTRL), immuno-chemotherapy (TRT), exercise (EXE) and combined intervention (TRT/EXE). Both TRT and TRT-EXE received ICI: anti-PD1-1 (1 injection/week) and capecitabine + oxaliplatin (5 times a week) for 1 week (experimentation 1), 3 weeks (experimentation 2). TRT-EXE and EXE groups were submitted to 50 minutes of treadmill exercise before each treatment administration. Over the protocol duration, tumor size has been monitored daily. Tumor growth and microenvironment parameters were measured after the intervention on Day 7 (D7) and Day 16 (D16). From day 4 to day 7, tumor volumes decreased in the EXE/TRT group while remaining stable in the TRT group (p=0.0213). From day 7 until day 16 tumor volume decreased with no significant difference between TRT and TRT/EXE. At D7 the TRT/EXE group exhibited a higher total infiltrate T cell (p=0.0118) and CD8+ cytotoxic T cell (p=0.0031). At D16, tumor marker of apoptosis, vascular integrity and inflammation were not significantly different between TRT and TRT/EXE. Our main result was that acute exercise before immuno-chemotherapy administration significantly decreased early-phase tumor growth (D0 to D4). Additionally, exercise led to immune cell infiltration changes during the first week after exercise, while no significant molecular alterations in the tumor were observed 3 weeks after exercise.

A systemically administered detoxified TLR4 agonist displays potent antitumor activity and an acceptable tolerance profile in preclinical models.

Bacterial lipopolysaccharides (LPS) are potent innate immunostimulants targeting the Toll-like receptor 4 (TLR4), an attractive and validated target for immunostimulation in cancer therapy. Although LPS possess anti-tumor activity, toxicity issues prevent their systemic administration at effective doses in humans. We first demonstrated that LPS formulated in liposomes preserved a potent antitumor activity per se upon systemic administration in syngeneic models, and significantly enhance the antitumor activity of the anti-CD20 antibody rituximab in mice xenografted with the human RL lymphoma model. Liposomal encapsulation also allowed a 2-fold reduction in the induction of pro-inflammatory cytokines by LPS. Mice receiving an intravenous administration demonstrated a significant increase of neutrophils, monocytes and macrophages at the tumor site as well as an increase of macrophages in spleen. Further, we chemically detoxified LPS to obtain MP-LPS that was associated with a 200-fold decrease in the induction of proinflammatory cytokines. When encapsulated in a clinically approved liposomal formulation, toxicity, notably pyrogenicity (10-fold), was limited while the antitumor activity and immunoadjuvant effect were maintained. This improved tolerance profile of liposomal MP-LPS was associated with the preferential activation of the TLR4-TRIF pathway. Finally, in vitro studies demonstrated that stimulation with encapsulated MP-LPS reversed the polarization of M2 macrophages towards an M1 phenotype, and a phase 1 trial in healthy dogs validated its tolerance upon systemic administration up to very high doses (10µg/kg). Altogether, our results demonstrate the strong therapeutic potential of MPLPS formulated in liposomes as a systemically active anticancer agent, supporting its evaluation in patients with cancer.

Characterization of T-DM1-resistant breast cancer cells.

The development of targeted therapies has drastically improved the outcome of patients with different types of cancer. T-DM1 (trastuzumab-emtansine) is an antibody-drug conjugate used for the treatment of HER2-positive breast cancer combining the FDA approved mAb (monoclonal antibody) trastuzumab and the microtubule cytotoxic agent DM1 (emtansine). Despite clinical successes achieved by targeted therapies, a large number of patients develop resistance during treatment. To explore mechanisms of resistance to T-DM1, the MDA-MB-361 HER2-positive breast cancer cell line was exposed in vitro to T-DM1 in the absence or presence of ciclosporin A. Previously reported mechanisms of resistance such as trastuzumab-binding alterations, MDR1 upregulation, and SLC46A3 downregulation were not observed in these models. Despite a decrease in HER2 expression at the cell surface, both resistant cell lines remained sensitive to HER2 targeted therapies such as mAbs and tyrosine kinase inhibitors. In addition, sensitivity to DNA damaging agents and topoisomerase inhibitors were unchanged. Conversely resistance to anti-tubulin agents increased. Resistant cells displayed a decreased content of polymerized tubulin and a decreased content of ßIII tubulin although the downregulation of ßIII tubulin by siRNA in the parental cell line did not modified the sensitivity to T-DM1. Both cell lines resistant to T-DM1 also presented giant aneuploid cells. Several SLC (solute carrier) transporters were found to be differentially expressed in the resistant cells in comparison to parental cells. These results suggest that some characteristics such as increased baseline aneuploidy and altered intracellular drug trafficking might be involved in resistance to T-DM1.

Monodisperse polysarcosine-based highly-loaded antibody-drug conjugates.

Antibody-drug conjugates (ADCs) convey highly potent anticancer drugs to antigen-expressing tumor cells, thereby sparing healthy tissues throughout the body. Pharmacokinetics and tolerability of ADCs are predominantly influenced by the drug-antibody ratio (DAR) of the conjugates, which is to-date limited to a value of 3-4 drugs per antibody in ADCs under clinical investigations. Here, we report the synthesis of monodisperse (i.e. discrete) polysarcosine compounds and their use as a hydrophobicity masking entity for the construction of highly-loaded homogeneous ß-glucuronidase-responsive antibody-drug conjugates (ADCs). The highly hydrophilic drug-linker platform described herein improves drug-loading, physicochemical properties, pharmacokinetics and in vivo antitumor efficacy of the resulting conjugates.