INTRODUCING A NOVEL THERAPEUTIC MODALITY UNLOCKED FROM ANCIENT RIBONUCLEASE

• resistance to pathogens • cancer protection • longevity

Ribonucleases (RNases) emerged over a billion years ago on the evolutionary landscape, tasked with a vital mission – rapidly degrading foreign RNA threats to confer an edge against invading pathogens. Higher organisms expanded upon primordial RNase functionalities to manage broader homeostatic roles related to growth, development, and defense. We are now poised to reactivate this ancient apparatus for next-generation precision medicine.

Bats have leveraged RNase A diversification to acquire unmatched longevity with natural resilience against RNA viruses and cancer – an incremental evolutionary experiment millions of years in the making

WE DISCOVERED UNIQUE PROPERTIES OF RNASE ENZYMES IN ANIMALS

The human enzyme RNase-1 shares striking similarity to the RNase-1 found in bats, including an identical catalytic site, structure, and enzymatic preference for cleaving RNA after pyrimidine nucleotides. This evolutionary conservation also confers cell penetration and internalization capacities. The conserved anti-pathogen functions between the bat and human versions set the stage for harnessing RNase-1’s enhanced microbial defenses for therapeutic development. 

In human cancers, RNase-1 interacts specifically with anionic cell surface glycoproteins such as the tumor‐associated antigen Globo H on tumor cells. This stimulates internalization of RNase-1 via endosomes, translocation into the cytosol, and cleavage of cancer cell RNA, leading to apoptosis. We propose RNase-1 may have evolved to defend host organisms against malignancies.

 

Human RNase-1
RNASE INHIBITOR
MABS-139
EVASION OF INHIBITOR

PIONEERING RNA DEGRADER PLATFORM VIA PRECISION ENGINEERING OF RNASES

Our first-in-field RNAD platform integrates interspecies RNase learnings to design biologics with tailored properties. By optimizing catalytic activity, cell penetration, and resistance to physiological inhibitors, we engineer RNA-degrading enzymes to harness intrinsic anti-viral and anti-cancer defenses. The resulting biologics achieve catalytic RNA knockdown akin to gene silencing, but through protein-based guided missiles rather than oligonucleotides. Our RNase engineering fine-tunes innate host properties for precision treatment of previously undruggable transcripts across cancers and diseases.

RNase-1 enzymatic activity is normally suppressed due to high affinity interactions with the ribonuclease inhibitor (RI). However, our engineered variants carry mutations at the protein-protein interface between RNase-1 and RI. These amino acid substitutions selectively disrupt binding between RNase-1 and RI, liberating active RNase-1 that can freely degrade RNA substrates.

ONE OF MANY APPLICATIONS: A UNIFYING THERAPEUTIC APPROACH FOR CANCER VULNERABILITIES

Components of the RNA life cycle, including RNA transcription, ribosomal biogenesis or mRNA translation are frequently upregulated in tumors to sustain their abnormal growth and proliferation. Accordingly, a number of cancers, both common and rare, exhibit enhanced dependence on unchecked RNA production and protein synthesis to enable their uncontrolled proliferation. By targeting broad RNA classes that drive growth signaling, re-engineered RNase enzymes can exploit this shared vulnerability – halting runaway cascades across many malignancies. 

Our team has designed highly optimized RNA-degrading biologics that penetrate cells and degrade cytoplasmic and nuclear RNAs. Our degraders have demonstrated broad anti-tumor efficacy by eliminating previously undruggable disease drivers in hard-to-treat liquid and solid tumors. With this platform, we have an unprecedented opportunity to develop RNA-cleaving enzymes as a single therapeutic modality that can treat a breadth of aggressive and drug-resistant cancers sharing key molecular addictions. Our pioneering approach has undergone rigorous validation in multiple preclinical tumor models, demonstrating both safety and efficacy. 

HOW RNA IS MADE: FROM RNA TO PROTEIN

MAJOR TYPES OF RNA IN HUMAN CELLS

OUR PUBLICATIONS IN RNA DEGRADATION & RIBONUCLEASES FIELD

Selected publications by Dr Ronald T. Raines  display the citations in PubMed

1: Garnett ER, Raines RT. Emerging biological functions of ribonuclease 1 and angiogenin. Crit Rev Biochem Mol Biol. 2022 Jun;57(3):244-260. doi: 10.1080/10409238.2021.2004577. Epub 2021 Dec 9. PMID: 34886717; PMCID: PMC9156540.

2: Windsor IW, Dudley DM, O’Connor DH, Raines RT. Ribonuclease zymogen induces cytotoxicity upon HIV-1 infection. AIDS Res Ther. 2021 Oct 26;18(1):77. doi: 10.1186/s12981-021-00399-z. PMID: 34702287; PMCID: PMC8549155.

3: Sayers J, Wralstad EC, Raines RT. Semisynthesis of Human Ribonuclease-S. Bioconjug Chem. 2021 Jan 20;32(1):82-87. doi: 10.1021/acs.bioconjchem.0c00557. Epub 2020 Dec 9. PMID: 33296182; PMCID: PMC7856262.

4: Eller CH, Raines RT. Antimicrobial Synergy of a Ribonuclease and a Peptide Secreted by Human Cells. ACS Infect Dis. 2020 Nov 13;6(11):3083-3088. doi: 10.1021/acsinfecdis.0c00594. Epub 2020 Oct 15. PMID: 33054163; PMCID: PMC7669604.

5: Kilgore HR, Latham AP, Ressler VT, Zhang B, Raines RT. Structure and Dynamics of N-Glycosylated Human Ribonuclease 1. Biochemistry. 2020 Sep 1;59(34):3148-3156. doi: 10.1021/acs.biochem.0c00191. Epub 2020 Jun 30. PMID: 32544330; PMCID: PMC7483697.

6: Shepard SM, Windsor IW, Raines RT, Cummins CC. Nucleoside Tetra- and Pentaphosphates Prepared Using a Tetraphosphorylation Reagent Are Potent Inhibitors of Ribonuclease A. J Am Chem Soc. 2019 Nov 20;141(46):18400-18404. doi: 10.1021/jacs.9b09760. Epub 2019 Nov 11. PMID: 31651164; PMCID: PMC7015663.

7: Hoang TT, Johnson DA, Raines RT, Johnson JA. Angiogenin activates the astrocytic Nrf2/antioxidant-response element pathway and thereby protects murine neurons from oxidative stress. J Biol Chem. 2019 Oct 11;294(41):15095-15103. doi: 10.1074/jbc.RA119.008491. Epub 2019 Aug 20. PMID: 31431502; PMCID: PMC6791309.

8: Windsor IW, Graff CJ, Raines RT. Circular zymogens of human ribonuclease 1. Protein Sci. 2019 Sep;28(9):1713-1719. doi: 10.1002/pro.3686. Epub 2019 Aug 6. PMID: 31306518; PMCID: PMC6699097.

9: Garnett ER, Lomax JE, Mohammed BM, Gailani D, Sheehan JP, Raines RT. Phenotype of ribonuclease 1 deficiency in mice. RNA. 2019 Aug;25(8):921-934. doi: 10.1261/rna.070433.119. Epub 2019 May 3. PMID: 31053653; PMCID: PMC6633200.

10: Ressler VT, Mix KA, Raines RT. Esterification Delivers a Functional Enzyme into a Human Cell. ACS Chem Biol. 2019 Apr 19;14(4):599-602. doi: 10.1021/acschembio.9b00033. Epub 2019 Mar 11. PMID: 30830748; PMCID: PMC6474803.

11: Ressler VT, Raines RT. Consequences of the Endogenous N-Glycosylation of Human Ribonuclease 1. Biochemistry. 2019 Feb 19;58(7):987-996. doi: 10.1021/acs.biochem.8b01246. Epub 2019 Jan 29. PMID: 30633504; PMCID: PMC6380942.

12: Hoang TT, Tanrikulu IC, Vatland QA, Hoang TM, Raines RT. A Human Ribonuclease Variant and ERK-Pathway Inhibitors Exhibit Highly Synergistic Toxicity for Cancer Cells. Mol Cancer Ther. 2018 Dec;17(12):2622-2632. doi: 10.1158/1535-7163.MCT-18-0724. Epub 2018 Oct 3. PMID: 30282811; PMCID: PMC6279581.

13: Thomas SP, Hoang TT, Ressler VT, Raines RT. Human angiogenin is a potent cytotoxin in the absence of ribonuclease inhibitor. RNA. 2018 Aug;24(8):1018-1027. doi: 10.1261/rna.065516.117. Epub 2018 May 10. PMID: 29748193; PMCID: PMC6049508.

14: Lomax JE, Eller CH, Raines RT. Comparative functional analysis of ribonuclease 1 homologs: molecular insights into evolving vertebrate physiology. Biochem J. 2017 Jun 21;474(13):2219-2233. doi: 10.1042/BCJ20170173. PMID: 28495858; PMCID: PMC5660862.

15: Hoang TT, Smith TP, Raines RT. A Boronic Acid Conjugate of Angiogenin that Shows ROS-Responsive Neuroprotective Activity. Angew Chem Int Ed Engl. 2017 Mar 1;56(10):2619-2622. doi: 10.1002/anie.201611446. Epub 2017 Jan 25. PMID: 28120377; PMCID: PMC5418131.

16: Hoang TT, Raines RT. Molecular basis for the autonomous promotion of cell proliferation by angiogenin. Nucleic Acids Res. 2017 Jan 25;45(2):818-831. doi: 10.1093/nar/gkw1192. Epub 2016 Dec 2. PMID: 27915233; PMCID: PMC5314776.

17: Thomas SP, Kim E, Kim JS, Raines RT. Knockout of the Ribonuclease Inhibitor Gene Leaves Human Cells Vulnerable to Secretory Ribonucleases. Biochemistry. 2016 Nov 22;55(46):6359-6362. doi: 10.1021/acs.biochem.6b01003. Epub 2016 Nov 8. PMID: 27806571; PMCID: PMC5148631.

18: Arnold U, Raines RT. Replacing a single atom accelerates the folding of a protein and increases its thermostability. Org Biomol Chem. 2016 Jul 12;14(28):6780-5. doi: 10.1039/c6ob00980h. PMID: 27336677; PMCID: PMC5070668.

19: Andersen KA, Smith TP, Lomax JE, Raines RT. Boronic Acid for the Traceless Delivery of Proteins into Cells. ACS Chem Biol. 2016 Feb 19;11(2):319-23. doi: 10.1021/acschembio.5b00966. Epub 2015 Dec 15. PMID: 26629587; PMCID: PMC4900815.

20: Eller CH, Chao TY, Singarapu KK, Ouerfelli O, Yang G, Markley JL, Danishefsky SJ, Raines RT. Human Cancer Antigen Globo H Is a Cell-Surface Ligand for Human Ribonuclease 1. ACS Cent Sci. 2015 Jul 22;1(4):181-190. doi: 10.1021/acscentsci.5b00164. Epub 2015 Jul 13. PMID: 26405690; PMCID: PMC4571170.