Statins inhibit onco-dimerization of the 4Ig isoform of B7-H3.

B7-H3 (CD276), a member of the B7-family of immune checkpoint proteins, has been shown to have immunological and non-immunological effects promoting tumorigenesis [1, 2] and expression correlates with poor prognosis for many solid tumors, including cervical, ovarian and breast cancers [3-6]. We recently identified a tumor-cell autochthonous tumorigenic role for dimerization of the 4Ig isoform of B7-H3 (4Ig-B7-H3) [7], where 4Ig-B7-H3 dimerization activated tumor-intrinsic cellular proliferation and tumorigenesis pathways, providing a novel opportunity for therapeutic intervention. Herein, a live cell split-luciferase complementation strategy was used to visualize 4Ig-B7-H3 homodimerization in a high-throughput small molecule screen (HTS) to identify modulators of this protein-protein interaction (PPI).

Illuminating immunotherapy response via precision T cell-targeted PET imaging.

Traditionally, immunotherapy agent selection and treatment strategies are guided by biopsy-based histological information. However, biopsies are limited in that they are invasive, provide static information regarding the tumor immune microenvironment, and only sample a small part of one tumor site. The tumor microenvironment is dynamic and heterogenous.

Dimerization of the 4Ig isoform of B7-H3 in tumor cells mediates enhanced proliferation and tumorigenic signaling.

B7-H3 (CD276) has two isoforms (2Ig and 4Ig), no confirmed cognate receptor, and physiological functions that remain elusive. While differentially expressed on many solid tumors correlating with poor survival, mechanisms of how B7-H3 signals in cis (tumor cell) versus in trans (immune cell co-regulator) to elicit pro-tumorigenic phenotypes remain poorly defined. Herein, we characterized a tumorigenic and signaling role for tumor cell-expressed 4Ig-B7-H3, the dominant human isoform, in gynecological cancers that could be abrogated upon CRISPR/Cas9 knockout of B7-H3; tumorigenesis was rescued upon re-expression of 4Ig-B7-H3.

Evaluation of Zr-Labeled Anti-PD-L1 Monoclonal Antibodies Using DFO and Novel HOPO Analogues as Chelating Agents for Immuno-PET.

Programmed death ligand 1 (PD-L1) is a type 1 transmembrane immunosuppressive protein that is expressed on a wide range of cell types, including cancer cells. Anti-PD-L1 antibodies have revolutionized cancer therapy and have led to improved outcomes for subsets of cancer patients, including triple-negative breast cancer (TNBC) patients. As a result, PET imaging of PD-L1 protein expression in cancer patients has been explored for noninvasive detection of PD-L1 expressing tumors as well as monitoring response to anti-PD-L1 immune checkpoint therapy.

TLR5 agonists enhance anti-tumor immunity and overcome resistance to immune checkpoint therapy.

Primary and adaptive resistance to immune checkpoint therapies (ICT) represent a considerable obstacle to achieving enhanced overall survival. Innate immune activators have been actively pursued for their antitumor potential. Herein we report that a syngeneic 4T1 mammary carcinoma murine model for established highly-refractory triple negative breast cancer showed enhanced survival when treated intra-tumorally with either the TLR5 agonist flagellin or CBLB502, a flagellin derivative, in combination with antibodies targeting CTLA-4 and PD-1.