Miao, Y. R. | Search bioRxiv

bioRxiv2021

Aberrant BCMA Signaling Promotes Tumor Growth by Altering Protein Translation Machinery, a Therapeutic Target for the Treatment of Relapse/Refractory Multiple Myeloma

Recent T Cell therapies have been effective in the treatment of hematological cancers. However, immunotoxicity and treatment relapse pose significant clinical challenges. Here, we revealed distinctive requirement for neutralizing TNF receptor ligands APRIL and BAFF in MM and DLBCL. Furthermore, we investigated the use of BCMA decoy receptor (sBCMA-Fc) as a therapeutic inhibitor of ARPIL and BAFF. While wild-type sBCMA-Fc successfully blocked APRIL signaling with picomolar binding affinity, inhibiting tumor growth in MM models, it lacked efficacy in inhibiting DLBCL progression due to its weak binding for BAFF. To expand the therapeutic utility of sBCMA-Fc, using a protein engineering approach, we generated an affinity enhanced mutant sBCMA-Fc fusion molecule (sBCMA-Fc V3) with 4-folds and 500-folds enhancement in binding to APRIL and BAFF respectively. The sBCMA-Fc V3 clone significantly enhanced antitumor activity against both MM and DLBCL. Importantly, sBCMA-Fc V3 was proven to be a viable clinical candidate by showing adequate toxicity profile and on-target mechanism of action in nonhuman primates. SUMMARYThis study demonstrates the dichotomous function of APRIL and BAFF in MM and DLBCL, that can be safely targeted by an engineered fusion protein designed to trap APRIL and BAFF with ultra-high binding affinity.

cancer biology↗

bioRxiv2020

Neutralizing PD-L1 and PD-L2 Enhances the Efficacy of Immune Checkpoint Inhibitors in Ovarian Cancer.

Immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway have improved for a number of solid tumors. Unfortunately, ovarian cancer represents a major clinical hurdle for immune checkpoint blockade (ICB) with reported low patient response rates. Using IHC staining, we find that PD-L2 is highly expressed in ovarian cancers and other malignancies with sub-optimal response to ICB, and is expressed at low levels in cancers responsive to ICB. Based on this observation, we hypothesized that the elevated expression of PD-L2 produced by both tumor and surrounding stromal cells contributes to immune-suppression. Since PD-L2 has been reported to have a 6- to10-fold higher native binding affinity to PD-1 compared with PD-L1, we hypothesized that high levels of PD-L2 can lead to insufficient blockade of the PD-1 signaling pathway. To overcome the immune repressive activity of PD-L2, we engineered a soluble PD-1 decoy molecule (sPD-1 mutant) that binds and neutralizes both PD-L1 and PD-L2 with a 10,000- and 200- fold improvement in binding affinity, respectively, when compared to wild-type binding to these same molecules. Such enhancement in binding affinity is facilitated by amino acid mutations both within and outside of the binding interface. Furthermore, this high affinity sPD-1 mutant molecule demonstrates superior in vivo efficacy in multiple cancer models including ovarian cancer where PD-L2 is highly expressed on the cell surface. One Sentence SummaryDual Inhibition of PD-L1 and PD-L2 using an affinity enhanced sPD-1 decoy molecule delivers superior antitumor activity when compared with PD-1 and PD-L1 antibodies in ovarian cancer.

cancer biology↗