STL Therapy V3.1: Absolute Eradication Strain

STL Therapy V3.1: Absolute Eradication Strain
I: The Chassis – Engineered Circular RNA (e-circRNA)
Self-Circularization: Using Permuted Intron-Exon (PIE) sequences, the RNA autocatalytically splices its 5’ and 3’ ends post-transcription.
Exonuclease Resistance: Lacking free ends, the e-circRNA evades RNase R degradation, extending half-life from hours to >120 hours in the cytosol.
Rolling Circle Translation (RCT): This is our amplification engine. Because the RNA is infinite (circular), the ribosome does not disengage. It continues to translate, producing a concatemeric "super-protein" that is subsequently cleaved into active units by P2A self-cleaving peptides.
Efficiency: 1 RNA molecule $\rightarrow$ 1,000+ payload proteins.
II: The CPU – Biological Boolean Logic
Riboregulators to create a physical AND Gate:
$$\text{Activation} = (\text{Input A} \cap \text{Input B}) + \text{Hypoxia}$$
The Lock (Toehold Switch): The Ribosome Binding Site (RBS) and Start Codon (AUG) are sequestered within a tight hairpin structure.
The Key (OncomiR inputs):
Input A: miR-21 (High expression in tumors).
Input B: miR-145/155 (Secondary confirmation).
The Trigger: Only when both miRNAs bind to the switch does the hairpin unfold, exposing the RBS for translation. This ensures zero leakage in healthy tissue.
III: The Payload – The "Triad of Destruction"
Once activated, the Rolling Circle Translation churns out a multi-modal arsenal designed to overcome tumor heterogeneity:
CRISPR-Cas13b (The RNA Shredder):
Unlike Cas9 (which risks permanent DNA damage), Cas13b targets RNA only.
It is programmed with gRNAs targeting survival genes (e.g., KRAS-G12C, BCL-2).
Collateral Effect: Upon target recognition, Cas13b enters a "frenzy mode," degrading non-target cellular RNA, inducing rapid apoptosis specifically within the cancer cell.
Secretable BiTEs (Bi-specific T-cell Engagers):
The cancer cell is forced to secrete antibodies that bind CD3 (on T-cells) and EGFR/EpCAM (on neighboring tumor cells).
Result: This creates an artificial immune synapse, dragging T-killers into the "cold" tumor microenvironment.
shRNA Anti-PD-L1:
Silences the immune-checkpoint signal, stripping the tumor of its "don't eat me" mask.
IV: Delivery & The "Fail-Safe"
How do we deliver this without triggering a cytokine storm?
Hybrid Exosome-LNPs (HEL): We cloak synthetic LNPs in mesenchymal stem cell (MSC) exosome membranes.
CD47 Enrichment: The surface is engineered with CD47, signaling phagocytes to "stand down," drastically increasing circulation time.
iRGD Peptide: Facilitates CendR pathway activation, allowing the nanoparticle to penetrate deep into the dense tumor stroma.
The Ultimate Safety Net: The Degron Switch
Mechanism: If an adverse event occurs, the patient is administered a standard antibiotic (e.g., Trimethoprim).
Action: The drug binds to the Degron tag, inducing immediate ubiquitination and proteasomal degradation of the therapeutic proteins.