Intratumoral administration of unconjugated Accum™ impairs the growth of pre‐established solid lymphoma tumors

Abstract

The Accum™ technology was initially designed to enhance the bioaccumulation of a given molecule in target cells. It does so by triggering endosomal membrane damages allowing endocytosed products to enter the cytosol, escaping the harsh environmental cues of the endosomal lumen. In an attempt to minimize manufacturing hurdles associated with Accum™ conjugation, we tested whether free Accum™ admixed with antigens could lead to outcomes similar to those obtained with conjugated products. Surprisingly, unconjugated Accum™ was found to promote cell death in vitro, an observation further confirmed on various murine tumor cell lines (EL4, CT‐26, B16, and 4 T1). At the molecular level, unconjugated Accum™ triggers the production of reactive oxygen species and elicits immunogenic cell death while retaining its innate ability to cause endosomal damages. When administered as a monotherapy to animals with pre‐established EL4 T‐cell lymphoma, Accum™ controlled tumor growth in a dose‐dependent manner, and its therapeutic effect relies on CD4 and CD8 T cells. Although unconjugated Accum™ synergizes with various immune checkpoint inhibitors (anti‐CTLA4, anti‐PD‐1, or anti‐CD47) at controlling tumor growth, its therapeutic potency could not be further enhanced when combined with all three tested immune checkpoint inhibitors at once due to its dependency on a specific dosing regimen. In sum, we report in this study an unprecedented new function for unconjugated Accum™ as a novel anticancer molecule. These results could pave the path for a new line of investigation aimed at exploring the pro‐killing properties of additional Accum™ variants as a mean to develop second‐generation anticancer therapeutics.

Local delivery of accutox® synergises with immune-checkpoint inhibitors at disrupting tumor growth

“…We have recently reported that unconjugated Accum ® exerts anti-tumoral activities both in vitro and in vivo [ 14 ]. However, the pro-apoptotic ability of the parental Accum ® molecule was inconsistent as it triggered cell death with different efficiencies on cancer cells, with B16 melanoma being the most resistant [ 14 ].…”

“…Apoptosis analysis was conducted by flow-cytometry as previously reported [ 14 ]. Briefly, target cells (EL4, B16, E0771, MBA-MD-468, A549, and H460) were first treated with 33 µM of AccuTOX ® (unless otherwise stated) overnight then washed twice with PBS containing 2% FBS.…”

“…For Accum ® -related studies, animals received the Accum ® compound (16 mg/kg—to maintain equimolar concentrations with AccuTOX ® ) following the same dosing schedule used for AccuTOX ® . All used ICIs were administered at 200 μg per injection and delivered via the intraperitoneal (IP) route 3 times per week for two consecutive weeks (total of 6 injections) [ 14 ]. All vaccinated animals were monitored for up to 6 weeks.…”

“…While investigating the use of Accum ® in vaccine engineering, a novel function was uncovered for the unconjugated molecule. More specifically, Accum ® triggered immunogenic cell death in various murine tumor cell lines with marked endosomal damage and increased production of reactive oxygen species (ROS) [ 14 ]. When tested in vivo, intra-tumoral (IT) injection of unconjugated Accum ® successfully inhibited tumor growth in mice with pre-established EL4 T cell lymphoma, an effect that was dose dependent and reliant on T-cell activity as well as immune-check point inhibitors (ICI) [ 14 ].…”

“…More specifically, Accum ® triggered immunogenic cell death in various murine tumor cell lines with marked endosomal damage and increased production of reactive oxygen species (ROS) [ 14 ]. When tested in vivo, intra-tumoral (IT) injection of unconjugated Accum ® successfully inhibited tumor growth in mice with pre-established EL4 T cell lymphoma, an effect that was dose dependent and reliant on T-cell activity as well as immune-check point inhibitors (ICI) [ 14 ]. Along this line of thought, the original Accum ® molecule was further modified to create a second-generation entity, named AccuTOX ® .…”