Vladimir Kirkin

DARPins (Designed Ankyrin Repeat Proteins) are a non-antibody based protein scaffold which has undergone extensive clinical characterization. DARPins are small, stable proteins derived from naturally occurring ankyrin repeat proteins and are characterized by high binding affinity and specificity, and a flexible architecture enabling multispecific approaches beyond bi-specific molecules. A total of seven clinical DARPin drug candidates across therapeutic areas spanning ophthalmology (abicipar), virology (ensovibep), and oncology – including solid tumors (MP0250, MP0274, MP0310, MP0317) and hematologic neoplasms (MP0250, MP0533) – have been tested in patients, with the two most advanced reaching the registrational phase of development. Here, we systematically review the published clinical experience with DARPin therapeutics and imaging agents generated over the past decade. The DARPin drug candidates have evolved from relatively simple binders/neutralizers, with impact on specific disease hallmarks, to more sophisticated effector function-enabled molecules that modulate complex tumor-host interactions with therapeutic intent. The accumulated clinical safety, pharmacokinetics, and activity data described herein illustrate the versatility of DARPins to influence complex biological processes and thus help patients with medical conditions that are in some cases difficult to treat with other therapeutic modalities. Following recent breakthroughs in protein structure prediction and de novo protein design, DARPins are poised to deliver an array of unprecedented and exquisitely targeted novel drug candidates eagerly awaited by patients with high unmet medical needs.

Supplementary Fig. S3. TAA quantification on healthy blood cells.

Supplementary Fig. S15. TCE-induced CD70 upregulation on activated CD4 and CD8 T cells. Expression of CD70 on T cells in cocultures with MOLM-13 cells and 1 nmol/L MP0533 or CD123-CD3 DART.

Supplementary Fig. S17. TAA expression analysis on AML PDX cells.

Supplementary Fig. S6. Characterization of MOLM-13 clones.

Supplementary Fig. S2. MP0533 affinity traces and simultaneous binding to its targets.

Supplementary Fig. S10. Competition/inhibition with soluble ligands/TAAs.