Abstract
Purpose :
The current agents used for systemic and intra-arterial chemotherapy for retinoblastoma (Rb) treatment are similar to drugs used in other childhood cancers. There is associated systemic and ocular morbidity which limit their effectiveness to preserve both the globe and vision. We have utilized single cell RNA-Seq in primary patient Rb tumours to identify signalling pathways and key regulators that underpin the proliferation of cone precursors (cell of origin in Rb) and their malignant conversion. This enabled us to compile a panel of Rb tumour-specific candidate drugs for testing in a patient organoid model to identify the most effective drugs to treat Rb.
Methods :
We applied cytotoxicity screens in RB1-depleted patient and control organoids to ensure that the observed cytotoxic effects are specific to patient RB1-depleted organoids. The most promising candidate drugs were tested by immunofluorescence for proliferating cone precursor reduction, followed by cell cycle progression, apoptosis (7AAD+Annexin V+), and proliferation (Ki67+) analyses. Shortlisted agents with the highest potency and lowest toxicity for healthy tissue will undergo further ocular pharmacokinetic assessment to investigate drug adsorption, distribution, metabolism, and clearance, which will determine the most appropriate mode of administration.
Results :
Preliminary screening identified nine out of forty agents with a marked cytotoxicity profile in retinoblastoma organoids after 72-hour exposure at a concentration of 10µM. Secondary drug screening performed on both cancer and healthy organoids narrowed the number down to six candidates showing high potency with minimal toxicity.
Conclusions :
Our preliminary data affirm a 3D in vitro model of Rb as a sturdy tool for drug screening. In combination with testing Rb-cone specific drugs, this can deliver optimal chemotherapeutics with minimal toxicity to the adjacent healthy retina.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.