A cancer drug originally developed in Singapore is showing unexpected promise as a treatment for two leading causes of blindness worldwide. PRL3-zumab, created by the A*Star Institute of Molecular and Cell Biology (IMCB) and its biotech spin-off Intra-ImmuSG, will soon enter human trials as an intravenous treatment for wet age-related macular degeneration (AMD) and diabetic retinopathy.
The drug represents a potential breakthrough for patients who currently endure monthly injections directly into the eye to manage these vision-threatening conditions. Pre-clinical studies published in Nature Communications demonstrated that intravenous delivery of PRL3-zumab led to an 86% greater reduction in abnormal blood vessel leakage compared to traditional eye injections.
Novel Approach to Common Eye Diseases
Wet AMD and diabetic retinopathy currently require periodic injections administered directly into the sclera, the white part of the eye, as often as once a month. These treatments aim to reduce abnormal blood vessel growth and leakage that can lead to vision loss. However, a significant portion of patients do not respond adequately to these injections.
A*Star senior scientist David Ang Koon Hwee was motivated to explore the intravenous application after witnessing his late father struggle for several years with eye injections to treat diabetic complications. "When the blood vessels are broken and start to leak, it is like a water pipe that is leaking... This drug can reduce the leakage," Ang explained, noting that current standard care treatments cannot be given intravenously due to their toxicity.
Strong Safety Profile from Cancer Research
PRL3-zumab has already been tested in 210 advanced cancer patients with a good safety profile. The drug has undergone Phase II trials in Singapore, the United States, China, and most recently Malaysia. Professor Qi Zeng, A*Star IMCB senior principal scientist and founder of Intra-ImmuSG, has evaluated the drug for 20 years, emphasizing that it targets only diseased tissues and not normal, healthy tissues, making it very safe.
Zeng first identified the PRL3 protein, which is found in many cancers, in 1998. The drug was originally developed as a broad-spectrum anti-cancer treatment capable of targeting multiple types of cancer.
Regulatory Approval and Trial Timeline
Singapore's Health Sciences Authority granted approval on June 16 for the human trial to test PRL3-zumab as an alternative intravenous treatment. The safety trial will include 15 patients and is expected to begin by late 2025. Following this initial study, additional human trials will be needed to demonstrate the drug's effectiveness in treating vision loss.
The research findings offer hope for patients whose eye conditions do not respond well to current therapies, potentially providing a less invasive treatment option for two of the most common causes of vision loss globally.
