Leprosy drug to treat cancer? Docs hunt for new uses of old meds

Can a leprosy tablet priced at Rs 2 be the miracle cure to treat blood-cell cancer? Or can expensive injections given to treat osteoporosis in post-menopausal women be replaced with a pill that costs as little as Rs 100 for a month’s supply? These are questions Indian doctors have set out to answer as they look towards repurposing old drugs as affordable treatments for new diseases.
At the Central Drug Research Institute, Lucknow, scientists recently found certain leprosy drugs might help treat myeloma, a type of blood cancer. Sabyasachi Sanyal, a researcher at CDRI, in collaboration with clinical haematology department of King George’s Medical University, Lucknow, screened FDA-approved drugs in chronic myeloid leukemia (CML) cells and found that a leprosy drug — clofazimine, priced at Rs 2 per tablet — was a potent inhibitor of these cells.
Sanyal’s colleague and chief scientist at CDRI Lucknow, Dr Naibedya Chattopadhyay, screened a library of over 1,000 drugs with the aim to discover an oral substitute for teriparatide — an injectable given to women suffering from postmenopausal osteoporosis. “Our pre-clinical studies found that Pentoxifylline, a drug prescribed for treatment of a disease of peripheral artery, when given to osteoporotic female rabbits mimicked effects of teriparatide including restoration of bone mass, strength, micro-structure and quality,” Chattopadhyay told TOI.
The cost of launching a repurposed drug is approximately 85% less than that incurred on launching a new drug, said Chattopadhyay.
Doctors at AIIMS, New Delhi, are conducting clinical trials on repurposed drugs. Dr Kameshwar Prasad, professor of neurology at AIIMS, recently wrote to ICMR to set up a task force to identify and validate low-cost alternatives to expensive drugs. He said doctors were already prescribing cheaper therapies. For instance, a single cycle immune therapy for treatment of Guillain-Barre-Syndrome (GBS), an acute inflammatory disorder of the peripheral nervous system, currently costs between Rs 3 lakh and Rs 8 lakh. To those who can’t afford it, physicians are recommending steroids that cost less than Rs 5,000 and are equally effective.
“One of our residents, Dr Bhavna Kaul, conducted a survey of physicians in India to assess use of cheaper alternatives for GBS. We were surprised to find that most physicians and neurologists were prescribing them since the standard treatment, in this case immunoglobulin, was not affordable. They also claimed that the response of patients was satisfactory,” he added.
The significance of repurposing drugs is considerable. Global spending on medicines is predicted to reach $1.4 trillion in 2020. Drug repositioning can help curb expenditure while safeguarding access to quality healthcare. But roadblocks remain. New indications for a drug need huge investment to move from ‘proof of concept’ to registered therapeutic use. Often, researchers lack funding to undertake clinical trials and pharmaceutical companies can be disinterested in repurposing generic drugs as it would fetch them little financial returns.
Like in Australia, Canada or Europe, India does not offer patent protection for new uses of known drugs. Experts said that companies which hold a current patent for a medicine could invest in the discovery of additional indications.