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The use of biologics in therapeutics and drug development has burgeoned over the last twenty years, with antibody-based therapeutics showing particularly rapid growth. Since the development of monoclonal antibody production by hybridoma cell culture over forty years ago, scores of therapeutic antibodies have been successfully marketed for various indications. In addition to antibodies that bind and act extracellularly to exert their effect, antibodies have been conjugated to drug molecules to deliver toxic payloads to diseased cells where they are internalized to exert their apoptotic function.
Despite the initial failures of first-generation antibody-drug conjugates (ADCs) to reach the market, newer generations of ADCs have proven more successful due to technological advances in antibody engineering, linker technology, drug potency, and extended modes of action. Today, there are four FDA-approved ADCs with more than 175 investigational ADCs in various phases of clinical trials. This pace will continue to accelerate as new platform technologies emerge for increasing conjugation site selectivity and the number of drug molecules conjugated to each antibody, as well as further advances in linker structure and stability.
An important aspect of this research is the labeling of antibodies with non-cytotoxic payloads such as fluors, enzymes, and radiolabels for pharmacokinetic and pharmacodynamic studies of the antibody candidates themselves. This not only helps determine their specificity and ability to be internalized into the cell, but also allows for high throughput/high content screening to select new antibody clones for clinical development.
Currently, ADCs are typically used in conjunction with more traditional modes of treatment in combination therapy. However, as potency, stability, and specificity of ADCs improve, it will be possible to achieve clinically favorable outcomes using these conjugates as a monotherapy.
Antisense therapy involves single stranded nucleic acids that are usually highly modified. They act by one of three general mechanisms: 1) cleavage of a DNA/RNA hybrid portion by RNase H for gene silencing, 2) steric blocking of translational initiation for gene silencing, or 3) steric blocking of splice site donors or acceptors to mediate splice switching. RNAi relies on small interfering RNAs (siRNAs) that are generally 21-23 nucleotide duplex RNAs with 2 base 3’ overhangs. Upon transfection into cells, the guide strand of the siRNA duplex is incorporated into the RNA induced silencing complex (RISC). RISC then cleaves mRNAs with homology to the guide strand, silencing them.
Aptamers are nucleic acids that form specific structures to bind a desired ligand, with affinities similar to antibody/antigen interactions. They can evolve using a process called Systematic Evolution of Ligands by Exponential enrichment (SELEX), a process also referred to as In Vitro Evolution. SELEX is an iterative selection process used to generate high affinity aptamers, and to partition members of a library of sequences based on binding or catalytic activity.
The first step in SELEX is to synthesize a DNA library with 20-60 randomized nucleotides, flanked by constant regions that allow polymerase chain reaction (PCR) amplification. These libraries typically contain >1025 possible sequences.
At each round of DNA SELEX, a single stranded library is produced by strand separation of the double stranded PCR product.
In RNA SELEX, one of the constant regions contains a T7 RNA polymerase promoter, which allows for in vitro transcription of the library. For RNA SELEX, 2’-fluoro NTPs are used to impart nuclease stability.
Libraries of DNA or RNA molecules are partitioned to obtain members with appropriate properties. These are then re-amplified, and the process is repeated until the aptamers with the desired properties are produced. Finally, the aptamers are cloned, and individual sequences are built by chemical synthesis.
These nucleic acids are challenging to manufacture due to their highly structured nature. That is why the expertise and specialized nature at TriLink makes us your best source for this type of chemical synthesis. We can support you with next-level aptamer expertise from research to the clinic.
Personalized Cancer Vaccines
TriLink manufactures messenger RNA (mRNA) based personalized cancer vaccines, as well as the plasmids used to produce them. These are one-of-a-kind medicines designed to specifically target neoantigens present in an individual patient's unique tumors. In some cases, self-replicating mRNAs based on viruses, such as alphaviruses, are used as vectors for expressing neoantigens.
CAR T-cells
TriLink manufactures Cas9, zinc-finger nuclease, and Transcription activator-like effector nuclease (TALEN) mRNAs, which are used to produce Chimeric Antigen T-cell therapies. These nucleases cause a double stranded break at a specific genomic location. A donor template encoding the chimeric antigen receptor is then inserted at the cut site by homologous recombination.
The terms "personalized medicine" and "precision medicine" have often been used interchangeably, but scientists are now leaning towards adopting precision medicine as the overarching term for this up-and-coming medical model. This is in light of concerns that the word "personalized" could be misleading, implying that treatments can be developed uniquely for each individual, while this is not the case. Personalized or precision medicine refers to studying, evaluating, and treating conditions based on the biomarkers they display, and environmental factors relevant to the patient. Often, the same condition will display different biomarkers in different patients. Therefore, a precision medicine approach would entail treating patients with tumors that share the same genetic biomarkers with a drug that targets those specific biomarkers, regardless of what type of tumor each patient may have.
Precision medicine refers to the process of customized medical treatment, tailored to the individual characteristics of a patient's condition. These characteristics include but are not limited to genes, proteins, and environmental factors specific to a single person's disease, and evaluating them is helpful for prevention, diagnosis, treatment, and monitoring of disease on a case-by-case basis.
In this medical model, molecular and in vitro diagnostics, are just some of the tools used to help select optimal therapies based on a patient's molecular makeup. Medicine is not one size fits all, and precision medicine, in simple terms, is about providing the right drugs and therapies to the right patients. TriLink offers custom and highly modified solutions for your nucleic acid needs, an ideal that is goes hand-in-hand with personalized and precision medicine. This allows your application development to have boundless potential.