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Biosimilars
are biological products that are ‘highly similar’ to an approved biological
product with expired patent protection.
A number of other terms that are more widely accepted descriptors of
biosimilars, including: follow on biologic (FOB), follow-on protein (FOP), and
subsequent entry biologic (SEB).
Protective patents on new biological therapies are near expiration, and
it is estimated that in the next five years, patent expiries in the biologics
market will make room for approximately $65 billion worth of biosimilar products.
According to Datamonitor
analysis, the global biologics market reached $116 billion in 2010 with a lion share
by monoclonal antibodies (mAbs) and is predicted to grow to $145 billion by end
of 2016.
FDA approved two biosimilars recently Zarxio® (filgrastim-sndz;Sandoz/Novartis) in March 2015 and Inflectra™ (infliximab-dyyb;Janssen Biotech) in April 2016.
Biosimilars are already making their presence felt globally with the current
approval of 19 such products and 400 million patient days of experience.
Biosimilars are large complex molecules that are assumed to be similar
to the reference product in terms of purity, safety and potency, allowing some
minor differences in clinically inactive compounds. But, these properties make
them immunogenic and the composition might drift from the reference compound
over time.
Biosimilars are different than generic drugs as generics are chemically
identical to brand name and show similar efficacy, safety, dosage, route of
administration and performance while biosimilars are biological molecule
produced in a living system which may be a plant or animal cell or
microorganism. So, the way they are synthesized pose unique challenges unlike
generic drugs and results in ‘batch to batch’ variability.
In fact, when approving a biosimilar product FDA adopts the totality of
evidence approach. Assessing the immune response is a major deciding factor in
clearing a biosimilar application. Immune response affects the
pharmacokinetics, producing antibodies or anaphylaxis that neutralizes the
compound and produce no clinical efficacy.
A biosimilar is usually approved for all conditions for which the
reference product is approved. But the use of the reference drug may be patent
protected for a particular indication averting the approval of biosimilar for
that particular condition.
Over the last 2 decades the healthcare costs in US have catapulted
sky-high, with the cost of cancer care topping the list of health care
expenditure. In fact, 8 out of top 10 most expensive drugs are cancer care
biologics that were developed because of recent research and understanding of
the molecular basis of malignancy.
Biosimilars are 20-30% cheaper than the reference products and rigorously
met the safety standards by FDA. These products are approved for all the clinical
indication as the reference biologic or may be approved for part of the indications.
But, they can never be approved or indicated for use in a disease the parent
drug was not approved for.
After a biosimilar product hits the market, robust post marketing
safety monitoring and vigilance is required to ensure that the efficacy is
maintained.
Controversies about naming of the biosimilars is still ongoing and FDA
is currently considering nonproprietary names, (e.g., filgrastim) to reduce the
confusion regarding the therapeutic class the drug belongs. FDA has issued a
draft guidance in 2015 “Nonproprietary Naming of Biological Products: Guidance for Industry.” This is yet to be finalized as FDA is reviewing comments received
on that matter. The issue will be resolved in the near future as more and more manufactures
enter the markets.
FDA recently released a continuing education course, FDA Overview of Biosimilar Products,that shares important information about biosimilar and interchangeable products
to help healthcare professionals make informed decisions when considering,
prescribing, or dispensing biosimilar products.
Recent approval of the biosimilars is a milestone in pharmaceutical development.
Oncology treatment armamentarium will be enriched by the introduction of more
biosimilars in future beneficiating patients and physicians. However, lots of hurdles have to be crossed
before the full potential of these drugs is realized.
Careful review of the immunogenicity potential with safety and efficacy required during the approval process along with rigorous post marketing monitoring for
any adverse effect will help build physician and patient confidence for their
use instead of the reference product.
References:
http://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/HowDrugsareDevelopedandApproved/ApprovalApplications/TherapeuticBiologicApplications/Biosimilars/UCM428732.pdf
http://www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation/guidances/ucm459987.pdf
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