Design of two immunotoxins based rovalpituzumab antibody against DLL3 receptor; a promising potential opportunity

The lack of a new effective treatment for small cell lung cancer (SCLC) is an unresolved problem. Due to the new identification of delta-like ligand 3 (DLL3) and its high expression in SCLC patients, the use of DLL3 in target therapy can be effective. The use of bacterial toxins belonging to the ADP-ribosyl transferase toxins family and human enzymes to remove cancerous cells has been effective in the structure of immunotoxins. In this study, single-chain fragment variable of rovalpituzumab antibody fused to granzyme B (Rova-GrB) and PltA of typhoid toxin (Rova-Typh) as immunotoxins were designed, and bioinformatics analysis was done.

In silico analysis including the physicochemical properties, evaluation of the secondary and tertiary structure, refinement and validation of 3D models, and docking were performed. Immunotoxin genes were cloned and expressed in the Escherichia coli BL21 (DE3) host, purified, subsequently confirmed by western blotting and their secondary structure was evaluated by the circular dichroism method.

The bioinformatics analysis showed that Rova-GrB and Rova-Typh had hydrophilic properties, their codon optimization parameters were standard, validation parameters were improved after immunotoxin refinement, and docking analysis showed that the binding domain of immunotoxins could bind the N-terminal region of DLL3. immunotoxins had high expression and after purification under denaturing condition by Ni-NTA column, the immunotoxins were dialyzed against PBS buffer.

The immunotoxins had the right structure and can be produced in a prokaryotic host. The recombinant immunotoxins against DLL3 can be promising therapeutic agents for SCLC cancer.