Therapeutic agents that use DNA, RNA, or their analogs to treat or prevent disease by directly modifying or regulating genetic information inside cells. Targets the root cause at the molecular level rather than the downstream protein.

• Chemical — solid-phase synthesis: builds the chain stepwise on a resin. Ammonium hydroxide then cleaves the DNA off the resin and strips the protecting groups from the nucleobases and phosphate backbone.
• Enzymatic — PCR: amplification using polymerase.
• Contrast with L2: you can synthesize DNA/RNA chemically and cheaply, but proteins must be expressed by living cells. That asymmetry is exactly why mRNA drugs are fast and cheap to make.

mRNA delivers the genetic code for a specific protein to the patient's cells. The ribosomes translate it into the target protein, which then performs the therapeutic function in situ — the patient's own body becomes the manufacturing plant.

• Cancer cells display TAAs (tumor-associated antigens) or neoantigens the immune system often overlooks or tolerates.
• Vaccines bypass tumor immune evasion by deliberately boosting the response against those antigens.
• Usually combined with checkpoint inhibitors (PD-1/PD-L1) or chemo/radiation — the vaccine supplies the target, the checkpoint inhibitor removes the brake.

Personalization: sequence the patient's tumor → encode their specific antigens → antigens are presented on the cell surface → immune system destroys the tumor. This is a n=1 drug every time — the commercial model question that follows is a BDC exam favourite.

• Disease: Glycogen Storage Disease Type 1a.
• Target protein: glucose-6-phosphatase (G6Pase), essential for regulating blood sugar.
• Mechanism: mutation → enzyme deficiency. mRNA encoding G6Pase is delivered to liver cells, which then produce functional enzyme → normal glucose metabolism restored.
• Real-world: Moderna's mRNA therapeutic platform targets GSD1a protein replacement.

siRNA drugs degrade the specific mRNA coding for a disease-causing protein, so the protein is never made. Instead of adding a missing function, you remove a harmful one.

• Short single-stranded nucleic acids (DNA or RNA) or peptides that fold into unique 3D structures and bind a target with high specificity and affinity — functionally like antibodies.
• Can be engineered against proteins, peptides, small molecules, or whole cells.

Applications: cancer (bind tumor-cell markers to block pro-growth signalling, or deliver cytotoxic agents; conjugate with chemo, radioisotopes, or nanoparticles) and antiviral (HIV, hepatitis C, influenza — bind viral surface proteins to block attachment/entry).

• mRNA modifies immune cells (e.g. T cells) to encode receptors that recognise and kill disease cells — the CAR-T principle.
• Problem with the standard approach: most CAR-T cells today are engineered with viral vectors (lentivirus, retrovirus) → risk of insertional mutagenesis, potentially causing unintended genetic effects or cancer.
• mRNA alternative: transient receptor expression, no genomic integration — but you trade permanence for safety, so dosing/re-dosing becomes the new problem.
• CAR-T is also one of the most expensive treatments in medicine — a cost-of-goods and reimbursement case study, not just a science story.

Carbohydrates are built from sugar units (monosaccharides) and matter for cell recognition, signalling, and structural support. As biologics they appear either as polysaccharides on their own or conjugated to proteins, peptides, and lipids — that conjugation is glycosylation, and it is the single most underrated variable in biologic quality.

• Erythropoietin (EPO) is a glycoprotein hormone that stimulates bone marrow to produce red blood cells (oxygen transport).
• Clinical use: recombinant EPO treats anemia — particularly anemia of chronic kidney disease, chemotherapy-induced anemia, and anemia in HIV patients.

Use: metastatic colorectal cancer and head and neck cancers. Binds EGFR.

In many cases a biologic cannot be given alone — it must arrive at the right time, right place, right dose. That is a bioavailability and pharmacokinetics problem, and it is often the difference between a validated target and a failed program.

Common targeted-delivery approaches: antibody-conjugates · nanoparticles · aptamer-conjugates · liposomes · peptide-conjugates · red blood cells · biomaterials (hydrogel).

• Act as drug carriers to overcome poor solubility, rapid clearance, and non-specific distribution.
• Large surface area → can attach targeting ligands (antibodies, peptides) to sharpen specificity.
• Fabricated from polymers, lipids, or inorganic compounds — tunable properties.
• Controlled release by passive diffusion or in response to stimuli (pH, temperature).
• Encapsulation protects the drug from premature degradation, reduces systemic toxicity, improves PK profile.

Mesoporous nanoparticles: porous structure with well-defined uniform pores of 2–50 nm. The pores give a very large surface area, highly effective for drug loading; different mechanisms are engineered to trigger release from the pores on a specific stimulus.

• Small extracellular vesicles (30–150 nm) secreted by most cell types.
• Carry proteins, lipids, nucleic acids, and metabolites that reflect the cell of origin — hence their biomarker value.
• Facilitate intercellular communication; implicated in cancer and neurodegenerative disease pathogenesis.
• Therapeutic & diagnostic potential: drug delivery vehicles and biomarkers.

• Leverage the natural properties of erythrocytes — abundant, long-circulating, biocompatible.
• Biocompatibility / non-immunogenicity: naturally present, so they avoid immune detection and cause no allergic reaction.
• Long circulation time: extended lifespan in the bloodstream → sustained delivery.
• Large loading capacity: can carry a significant amount of drug or biologic.

Short peptides, typically 5–30 amino acids, able to traverse cell membranes and carry cargo inside. They transport small molecules, nucleic acids, proteins, and even nanoparticles across membranes that are normally impermeable to large and hydrophilic substances — solving the intracellular-delivery problem that blocks most nucleic acid drugs.

The source opens Lecture 3 with an explicit seven-item content map that the English card absorbs without reproducing. Use it as navigation:

The card paraphrases this but never quotes it; the source defines nucleic-acid biologics as agents that "utilize nucleic acids—such as DNA, RNA, or their analogs—to treat or prevent diseases" and that "work by directly modifying or regulating genetic information within cells, enabling targeted interventions at the molecular level." This is the through-line: nucleic-acid drugs act one step upstream of protein biologics (L2), at the information layer, not the product layer.

The source treats the RNA family as a distinct block listing miRNA, snoRNA, and siRNA (with mRNA handled separately as "mRNA Therapeutic"). The card merges all four into one table — fine, but note the source's precise snoRNA role: "Non-coding RNA molecules involved in the chemical modification and processing of ribosomal RNA (rRNA) within the nucleolus." snoRNA is a housekeeping/processing RNA, not a therapeutic format — a distinction worth keeping when you sort "which RNA does what."

The source states cancer vaccines "are often combined with other treatments, such as immune checkpoint inhibitors (e.g., PD-1/PD-L1 inhibitors) or traditional therapies (chemotherapy, radiation), to enhance the immune response." The card captures the PD-1/PD-L1 point but omits the explicit chemotherapy/radiation co-treatment branch — include it so the "vaccine supplies the target, checkpoint inhibitor removes the brake" framing is complete.

Why the ionizable lipid is the design problem: it must be neutral at blood pH (so the particle is not toxic or rapidly cleared) but positively charged at endosomal pH (so it can drive escape). That pH switch is the entire cleverness of the delivery system.

The one-line contrast that keeps coming up: mRNA acts in the cytoplasm and never enters the nucleus, so it cannot integrate into the genome — unlike a DNA vector or an integrating viral vector. That single fact answers most of the safety questions about the platform.