Background The recent clinical success of LNP-mRNA based COVID vaccine has accelerated the development of lipid nanoparticles (LNP) as safe and effective deliver approach for next wave of genomic medicine. Bispecific T cell engager (BiTE) therapy is an approved immunotherapy to treat hematological malignancies, such as ALL, by redirecting cytotoxic T-cells to eliminate cancer cells. However, the relatively short serum half-life of recombinant BiTE, and reported CRS and neurotoxicity have limited its applications. Here, we describe tissue targeted LNP-mRNA encoding BiTE that expressed long-lasting and therapeutic levels of BiTE protein at the targeted tumor sites. The results from the preclinical studies have demonstrated activation of T-cells to eliminate tumor cells in hematological malignancy and solid tumor mouse models and deplete circulating B-cell in a NHP model.
Methods The LNP formulated with Hopewell’s proprietary ionizable lipid HTX-L01 was selected through in vitro biophysiochemical characterization and in vivo screening. HTX-L01–003 and HTX-L01–008 encapsulated with mRNA encoding optimized single chain sequence of CD19-CD3 and GPC3-CD3 respectively, were evaluated for their PK/PD profile, biodistribution and bio-tolerability in WT mice and NHP (dose escalating at 0.014, 0.07 and 0.1 mg/kg). The tumor control activities were assessed in the Raji-xenograft non-Hodgkin lymphoma (NHL) model for HTX-L01-003 at the dose of 0.08 mg/kg and Hep3B-orthotopic hepatocellular carcinoma (HCC) model for HTX-L01-008 at the dose of 0.5 mg/kg.
Results LNP-mRNA formulated with HTX-L01 primarily targets liver, spleen, and less extent BM via intravenous injection. Specifically high level of transfection in hepatocytes, Kupffer cells and immune cells were achieved. In a hPBMC-reconstituted Raji-luc xenograft model, a much lower dosage and less frequent injection of HTX-L01–003 achieve the equivalent tumor regression/elimination efficacy as recombinant BiTEs (figure 1) in NHP studies, dose-dependent protein expression was observed in 3-week repeat dosing and resulted in transient T-cell activated and complete and sustained B-cell depletion (figure 2). HTX-L01–008 maintained the extended GPC3-CD3 BiTE protein expression, and successfully eliminates orthotopic HCC tumors in mice (figure 3).
Conclusions Systemic administration of HTX-L01-003 demonstrated in-body and ‘local’ production of CD19/CD3 BiTE protein which resulted in highly potent and long-lasting depletion of target cells in both mouse and NHP studies. HTX-L01–008 demonstrates the ability to regress solid tumors in situ via i.v. injection. The LNP-mRNAs were well-tolerated. Overall, the studies showed the tissue targeting LNP-mRNA encoding BiTE provides a unique platform with enhanced efficacy and reduced toxicity for the treatment of both liquid and solid tumors.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See http://creativecommons.org/licenses/by-nc/4.0/.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.