Biologics, including monoclonal antibodies (mAbs), recombinant enzymes (ERT) and peptides, have become increasingly popular over the two past decades – accounting for 13 of the 20 best selling drugs and revolutionizing the treatment of infectious disease, oncology, metabolic and autoimmune disorders. However, the need for regular IV infusions or frequent injections make them burdensome for patients and can be impractical for treating chronic conditions.

We started Nanite to expand access to life changing therapies using our internally developed polymer nanoparticle (PNP) delivery platform. Today we’re excited to share our latest advance in a new pre-print – demonstrating the first long-lasting, re-doseable DNA-encoded proteins delivered by computationally designed, polymer nanoparticles.

The Promise of DNA-Encoded Biologics

The idea of vectorizing proteins for in vivo therapies dates back to the early 1990s when researchers working on “DNA vaccines” showed that naked plasmids injected directly into muscle tissue, resulted in vivo expression in mice. Further work, using synthetic DNA, has shown durable expression and neutralizing effects of specific proteins, including antibodies, in mice and non-human primates – demonstrating versatility across diseases and translatability across species.

While promising, these early programs have been limited by challenges in delivery by relying on electroporation, which is complex and can damage tissue, or viral vectors, which are immunogenic and non-redosable. These factors have offset the value of potentially infrequent DNA dosing and limit their usefulness for chronic conditions.

More recently – RNA based therapies delivered by lipid nanoparticles (LNP) have proven a safe alternative to viral and electrostatic delivery and companies including Moderna have shown they can encode antibodies. However, RNA and LNP/RNA constructs are unstable and expression fades quickly, rendering them less effective and durable than conventional biologics. Attempts to deliver DNA with LNPs have been largely unsuccessful – showing limited transfection efficiency and significant immune recognition and toxicity.

These factors has stalled commercial development of the field of DNA therapeutics, despite clear medical need and positive readouts from the limited human trials to date.

The Advantages of Polymers

Polymer nanoparticles (PNPs) share some characteristics of LNPs but differ as these are electrostatically self-assembled – giving them a distinct method of entry into the cell’s nucleus (via chemical NLS) which allows for episomal expression of pDNA. Compared to LNPs, polymers are more chemically flexible, less immunogenic (as a result of DNA cloaking) and can be more easily tuned to meet specific pharmacokinetic (PK) profiles.

Engineering polymer nanoparticles has historically been a challenge because of their large design space, complex assembly, and lack of centralized physicochemical to biological data. We saw this as an interesting opportunity to build a platform, SAYER, to combine combinatorial chemistry, high-throughput screening and advanced machine learning to rationally design PNPs for specific delivery applications. The results of our efforts yielded applications in Targeted Lung Delivery, In Vivo CAR-T and now In Vivo Antibody production.

Muscle Targeting

While our early work focused on targeted system delivery, we believe that muscles are the ideal target for DNA-encoded biologics. Muscle cells, in particular skeletal muscle fibers, are specialized for protein synthesis, have low turn over and demonstrate highly efficient uptake of DNA plasmids. They are also highly vascularized allowing for a readily accessible route to systemic distribution of the muscle-cell produced biologic.

Muscle cells are easily accessible via intramuscular (IM) injection, allowing for local delivery and controlled expression that bypasses the liver, reducing the off-target effects and toxicity that have plagued genetic medicine. As the cells begin the production of DNA-encoded antibodies, secretion into systemic circulation, allowing for broad distribution throughout the body – making muscle cells the ideal “protein factory”.

Proof of Concept

With support from the Gates Foundation, we designed a family of bio-reducible polymers and used them to deliver DNA-Encoded PGT121, an anti-HIV neutralizing antibody. Injecting these polyplexes (pDNA+polymer) into mice, we demonstrated durability of up to 56 days with peak levels approaching >1μg/mL - well within the therapeutic window for some antibodies. We further demonstrated that our polymers are re-dosable with no observed immunogenicity and showed how modulating polymer composition and dose achieved different kinetic profiles – opening up the possibility of rationally designing PK profiles.

This work demonstrates for the first time, it is possible to induce in vivo production of antibodies through direct injection to the muscles using a chemically defined polymer nanoparticles.

Future Directions

Our work represents an early proof-of-concept for a promising new class of biologics that can improve the PK and accessibility of existing drugs, and enable new kinds of therapies. While we started with mAbs, on-going work aims to translate the same principles to enzymes (for applications like ERTs) and peptides (for applications like long lasting GLPs, FST, and others).

We are most excited about the possibility of co-expressing drugs, for instance GLP-1 and FST together in reducing side effects like muscle wasting in obesity drugs, or in the case of HIV, potentially replacing a daily cocktail with a single durable shot. We also see potential to combine complementary therapies with very different pharmacokinetic profiles.

The applications may only be limited by our imagination. While we continue to improve the platform, we’re excited to be working with partners across a range of targets and indications.

For more details read the full pre-print and get in touch if you’re interested in brainstorming with us to imagine new possibilities.