How off-label cancer medicine preventing vision loss among diabetics?

ISLAMABAD: The ‘off-label’ use of cancer drug Bevacizumab is helping eye specialists in preventing loss among diabetics across the globe including Pakistan for the last 15 years, experts said on Monday.

“Bevacizumab sold under the brand name of Avastin is a Monoclonal Antibody (MAB), a targeted cancer therapy registered for the treatment of colorectal cancer including cervical cancer, colorectal cancer, brain cancer and several others. Alongside it’s ‘off-label’ use is preventing and slowing vision loss among patients living with diabetes.

A very small amount (1.25mg/0.05ml) of this drug is injected in the retina of diabetes patients to slow down vision loss”, Dr Shayan Shadmani, a consultant ophthalmologist (eye specialist) told The News.

A study conducted in 2021 showed that approximately 9.6 million people had diabetic retinopathy, ie 26.43 percent of all diabetic individuals. Of the 9.6 million people with diabetic retinopathy, it is estimated that approximately 5 percent, or 1.84 million people, have vision-threatening forms of diabetic retinopathy.

Dr. Shayan, who is associated with the Prevention of Blindness Trust (POB) hospital in Karachi, said Bevacizumab blocks the growth of abnormal blood vessels in the back of the eye among diabetes patients, adding that it also blocks the leakage of fluid from these blood vessels. “The fluid leakage can affect vision, causing vision loss from wet Age-related Macular Degeneration (AMD) and diabetic eye disease. Studies have proved that Bevacizumab is a safe and effective drug for the treatment of eye disease for the last 15 years”, he added.

He further informed that in addition to wet age-related macular degeneration (AMD), the drug is used for the treatment of swelling of the retina, called macular edema, diabetic retinopathy, retinal vein occlusion and choroidal neovascularization (small abnormal blood vessels that can grow under the retina and lead to vision loss.)

At the moment, some leading healthcare facilities including Aga Khan University Hospital (AKUH), Shaukat Khanum Memorial Hospital, Lahore and Shifa International Hospital in Islamabad have the compounding licenses to prepare small injections of this drug from the bigger vials and provide it to the eye hospitals, eye specialists and even patients for taking it to their consultants for administration.

“Although in the developed world, this injection is administered in OPDs but in Pakistan we recommend that this injection is given to the patient in an operation theatre, in a safe and sterile environment to minimize the chances of any infection”, Dr. Shayan added.

“As a very small amount of this drug is injected in the eye for the treatment of these diseases, the medicine is filled in a small syringe from the large vial and often these syringes are filled in bulk quantity to treat a large number of patients in a given day. Sometimes, during filling of these syringes, the drug gets contaminated and causes infection of the eye, which can result in vision loss if not treated with antibiotics”, he informed. He further informed that in some cases, repackaging or filling small syringes with the drug Bevacizumab in unhygienic conditions has been linked to a condition called endophthalmitis, saying sometimes compounding procedure deficiencies lead to microbial contamination and subsequent endophthalmitis, which is potentially vision loss.

To a query, Dr Shayan said Bevacizumab is a ‘wonder and cost-effective drug’ for diabetes patients in countries like Pakistan where the branded, approved drugs for the treatment of diabetic eye diseases cost between Rs 50,000 to 75,000, which is not affordable for the majority.

Leading epidemiologist Dr Rana Jawad Asghar says endophthalmitis or inflammation of the eye due to infection has been reported worldwide following Bevacizumab use when a tailor-made dose is prepared for the treatment of eye diseases and called for ‘scientific investigation’ into incidents that led to vision loss in several cities of Punjab.

“It is not the first time that people have lost vision following the use of Bevacizumab by eye specialists. There is a need for conducting scientific investigation to see if the drug was contaminated, and if not, what went wrong during the compounding process”, he added.