The Rational Development of CD133-Targeting Immunotherapies for Glioblastoma.

CD133 marks self-renewing cancer stem cells (CSCs) in a variety of solid tumors, and CD133+ tumor-initiating cells are known markers of chemo- and radio-resistance in multiple aggressive cancers, including glioblastoma (GBM), that may drive intra-tumoral heterogeneity. Here, we report three immunotherapeutic modalities based on a human anti-CD133 antibody fragment that targets a unique epitope present in glycosylated and non-glycosylated CD133 and studied their effects on targeting CD133+ cells in patient-derived models of GBM. We generated an immunoglobulin G (IgG) (RW03-IgG), a dual-antigen T cell engager (DATE), and a CD133-specific chimeric antigen receptor T cell (CAR-T): CART133. All three showed activity against patient-derived CD133+ GBM cells, and CART133 cells demonstrated superior efficacy in patient-derived GBM xenograft models without causing adverse effects on normal CD133+ hematopoietic stem cells in humanized CD34+ mice. Thus, CART133 cells may be a therapeutically tractable strategy to target CD133+ CSCs in human GBM or other treatment-resistant primary cancers.

Displacement Affinity Release of Antibodies from Injectable Hydrogels.

Current methods to tune release rates of therapeutic antibodies (Abs) for local delivery are complex and routinely require bioconjugations that may reduce Ab bioactivity. To rapidly tune release profiles of bioactive Abs, we developed a biophysical interaction system within a neutravidin modified poly(carboxybetaine) hydrogel (pCB-NT) that tunes release rates of desthiobiotinylated Abs (D-Abs) using a constant hydrogel and D-Ab combination. Herein, we delivered desthiobiotinylated bevacizumab (D-Bv), a recombinant humanized monoclonal IgG1 Ab for antiangiogenic cancer therapies. D-Bv's high affinity for pCB-NT (KD 7.8 × 10-10 M; t1/2 ∼ 2 h) produces a slow D-Bv release rate (∼5 ng day-1) that is increased by the dissolution of hydrogel encapsulated biotin derivative pellets, which displaces D-Bv from pCB-NT binding sites. In contrast to traditional affinity systems, displacement affinity release of Abs (DARA) does not require Ab or hydrogel modifications for each unique release rate. D-Bv release rates were tuned by simply altering the total biotin derivative concentration; the effective first-order (keff) and mass per day release rates were tuned 25- and 8-fold, respectively. Local surface plasmon resonance (LSPR) and biolayer interferometry (BLI) confirmed the D-Bv binding affinity for the corresponding ligand and Fc receptor, demonstrating that the biophysical interaction system is amenable to anticancer Abs for receptor or cytokine blockade and immune cell recruitment to cancer cells.