Comparison of High-Throughput Sequencing for Phage Display Peptide Screening on Two Commercially Available Platforms

A novel anti-B7-H3 chimeric antigen receptor from a single-chain antibody library for immunotherapy of solid cancers

B7-H3 (CD276) has emerged as a target for cancer immunotherapy by virtue of consistent expression in many malignancies, relative absence from healthy tissues, and an emerging role as a driver of tumor immune inhibition. Recent studies have reported B7-H3 to be a suitable target for chimeric antigen receptor-modified T cell (CAR-T) therapy using CARs constructed from established anti-B7-H3 antibodies converted into single-chain Fv format (scFv). We constructed and screened binders in an scFv library to generate a new anti-B7-H3 CAR-T with favorable properties. This allowed access to numerous specificities ready formatted for CAR evaluation. Selected anti-human B7-H3 scFvs were readily cloned into CAR-T and evaluated for anti-tumor reactivity in cytotoxicity, cytokine, and proliferation assays. Two binders with divergent complementarity determining regions were found to show optimal antigen-specific cytotoxicity and cytokine secretion. One binder in second-generation CD28-CD3ζ CAR format induced sustained in vitro proliferation on repeat antigen challenge. The lead candidate CAR-T also demonstrated in vivo activity in a resistant neuroblastoma model. An empirical approach to B7-H3 CAR-T discovery through screening of novel scFv sequences in CAR-T format has led to the identification of a new construct with sustained proliferative capacity warranting further evaluation.

Phage Display Screening for Alba Superfamily Proteins from the Human Malaria Parasite, Plasmodium falciparum Reveals a High Level of Association with Protein Modification Pathways and Hints at New Drug Targets

PURPOSE

A 2016 study estimated that over 3 billion people are currently at risk of contracting malaria. Although a wide variety of medications are available to treat malaria, the parasites have started to exhibit resistance to many commonly used therapeutics necessitating a push for new investigations to identify novel drug targets.

METHODS

In this study, nucleic acid-binding Alba superfamily proteins of the human malaria parasite, Plasmodium falciparum were investigated to identify interacting protein motifs. A high-throughput molecular screening technique, phage display, coupled with next-generation sequencing was applied to assess large data sets.

RESULTS

Four P. falciparum Alba proteins were used for screening which appear to have distinct roles in parasite biology based on the results of this work. The majority of the peptide motifs identified from phage display were involved in post-translational modification pathways, thus suggesting that parasite-specific gene regulatory mechanisms are involved which could serve as drug targets for novel therapeutics.

CONCLUSION

This study found 18 peptide motifs which potentially have strong interactions with one or more of the Alba superfamily proteins from P. falciparum. Considering the large fraction of post-translational modification-related peptide motifs identified from this work, one or more of the protein modification pathways could serve as a good target for malaria treatment.