Locally developed cancer drug shows promise as treatment for blindness; trial to start soon

Straits Times

4 days ago

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Professor Qi Zeng (seated) and her team of scientists, including Dr David Ang (standing behind her), have evaluated the drug known as PRL3-zumab for 20 years.
SINGAPORE – A locally developed drug for cancer treatment will be used in a trial in Singapore on patients to prevent vision loss.
It will be administered intravenously to patients with wet age-related macular degeneration (AMD) or diabetic retinopathy, both currently treated with a shot of medicine injected into the eye. The two conditions are among the most common causes of vision loss globally.
In pre-clinical studies published in Nature Communications, the drug known as PRL3-zumab effectively reduced leakage from damaged blood vessels – a major cause of vision loss. This pointed to a possible new treatment option for patients whose eye conditions do not respond well to current therapies.
The findings for the drug came from the A*Star Institute of Molecular and Cell Biology (IMCB), which had originally developed it, and its biotech spin-off Intra-ImmuSG.
Wet AMD and diabetic retinopathy share a common treatment approach: periodic injections administered directly into the white part of the eye, or sclera, as often as once a month. This is done to reduce abnormal blood vessel growth and leakage.
A*Star senior scientist David Ang Koon Hwee said he was driven to explore the intravenous application of PRL3-zumab for the two eye conditions after witnessing his late father struggle for several years with the injections to treat his diabetic eye complication.
Moreover, a significant portion of the patients who need these injections do not respond adequately to them.
The pre-clinical studies showed that the intravenous delivery of PRL3-zumab led to an 86 per cent greater reduction in abnormal blood vessel leakage, compared with injections into the eye.
'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,' said Dr Ang, who added that the current standard care treatments cannot be given intravenously because of their toxicity.
PRL3-zumab has been tested in 210 advanced cancer patients so far, with a good safety profile, he said. Phase II trials for the drug were conducted in Singapore, the United States, China and, most recently, Malaysia.
Professor Qi Zeng, A*Star IMCB senior principal scientist and founder of Intra-ImmuSG, said she and a team of researchers have evaluated the drug for 20 years now – it targets only diseased tissues and not normal, healthy tissues, rendering it very safe.
She first identified the PRL3 protein, which is found in many cancers, in 1998.
Singapore's Health Sciences Authority granted approval on June 16 for the human trial to test PRL3-zumab as an alternative intravenous treatment to eye injections in treating wet AMD and diabetic retinopathy.
The safety trial, which will have 15 patients, is expected to begin by late 2025, following which more human trials will be needed to show that it is effective.