August 14, 2011 3:50:36 am
Modern biotech medicines are well established in the treatment of many ailments,including some life-threatening ones,with the likelihood of increasing use in future years. Having said that,patients need to discuss access,cost,safety and efficacy of receiving biosimilars as these are now an emerging source of affordable medicines for more patients.
Also known as follow-on biologics,biosimilars are approved new versions of innovator biologic drugs that are developed after the innovators patent expires. Unlike generics,biosimilars are not exact replicas of biologic drugs. For small molecule generics manufacturers,the product is the product,while manufacturers of innovator biologics claim the process is the product. To understand,we need to take a closer look at how chemical molecule drugs and biologics are made. Biosimilars are large molecules produced by living organisms with high molecular complexity and susceptible to the smallest manufacturing process changes,while small molecule generics are produced by chemical synthesis with high levels of stability. So,even a minor change in the process or materials used in manufacture means the biosimilar drug may have serious differences in treatment outcomes and side effects.
Biologic drugs are manufactured by genetically engineered living cells,making them miniature factories that produce the desired molecules (proteins). Even minor changes in their environment can alter the proteins,these cells are engineered to produce. Any biosimilar manufacturer using similar starting materials and processes may still produce a product that differs from the innovative biologic drug. Given the complexities of biologics,it is impossible to determine in a lab whether a biological product will work in the same way as its original innovator. With the original biologic purification process not available to biosimilars makers,they can never be made in the same manner as the original biologic drug. Among various potential risks,differences in immunogenicity is one. While generics lack immunogenicity,biosimilars are immunogenic (they are inclined to activate an immune response in the patients body). This may cause antibodies in the patients body to attack and neutralise the biosimilar and it could have serious consequences. Since the immunogenicity of biologic drugs is unpredictable,even small changes in a molecule could alter the immunogenicity profile.
Therefore,effects of the differences between a biosimilar drug and its innovator product can only be established by putting the biologic product through clinical testing in patients to determine its safety. Considering these constraints,it is virtually difficult to create an identical generic of a branded biologic. Due to this,regulatory authorities in many countries are wary about approvals to biosimilars and recommend extensive clinical trials to be undertaken. Given these variations,the European Medicines Agency (EMEA) guidelines require extensive testing before approval and also treat each approval on a case-by-case basis. Similar concerns about safety have led the US FDA to rule that each biologic is unique and wholly interlinked with the manufacturing process used to make the drug.
Finally,biosimilars are promoted primarily on the basis of cost advantage,being cheaper than innovative biologic drugs. Unlike US,Europe,Canada and Japan,which have specific regulatory approval processes the risks in India are higher,because so far,there are no established regulatory approvals in place and they can be approved with limited clinical trials. This allows manufacturers to adopt abbreviated pathways and avoid stringent norms,thereby compromising patient safety. But lower drugs costs are not worthwhile if it means risking patients lives and their well-being.
The writer is Professor of Molecular Medicine,School of Life Sciences,JNU
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