Start of Phase I/II Gene Therapy Clinical Trial for Hemophilia B

AMSTERDAM, March 10, 2010 - Amsterdam Molecular Therapeutics (Euronext: AMT), a leader in
the field of human gene therapy, announced today that the first patient has
been dosed in the Phase I/II exploratory clinical trial with a gene therapy
product for hemophilia B, a seriously debilitating and potentially lethal
disease.

The trial is an open label dose-escalation study using a
vector-gene combination developed at the renowned St. Jude Children's
Research Hospital. Dr. Arthur W. Nienhuis of St. Jude is the principal
investigator of the on-going trial. The work was initiated at St. Jude more
than a decade ago by Drs. Andrew Davidoff and Amit Nathwani and the
collaboration has continued following Dr. Nathwani's return to London. The
collaboration involves St. Jude and University College London and other
institutions in the US and Britain. The objective of the trial is to assess
the safety and efficacy of different doses of hemophilia B gene therapy.
Hemophilia B is an inherited condition in which patients may have repeated
and sometimes life threatening bleeds after accidental trauma or medical
interventions, because they do not have sufficient functioning of an
essential blood clotting factor, called Factor IX.

AMT will build on the outcome of this exploratory trial and is
preparing for additional clinical development to establish safety,
tolerability and proof-of-concept with Factor IX gene therapy produced using
AMT's proprietary, clinically validated production system. AMT has the
exclusive commercialization rights to the Factor IX gene used in the St. Jude
trial and has the ability to produce gene therapy product for hemophilia B at
high quality on a commercial scale. Additional developmental work using AMT's
production system is on-going at St. Jude with AMT support.

Jorn Aldag CEO of AMT said: "Dr. Andrew Davidoff and his group
at St. Jude, together with Professor Nathwani in London, have done very
important scientific work on hemophilia B. We are really looking forward to
the results of the trial for continuing our collaboration, aiming for a real
cure for patients with this bleeding disorder. Use of the Factor IX gene fits
perfectly with AMT's proprietary gene therapy platform and our business
strategy of developing cures for seriously debilitating orphan diseases. "

This hemophilia B gene therapy, administered once, will
introduce the functional gene for the Factor IX protein into the patient's
liver cells with the goal to restore blood clotting functionality long-term.
In pre-clinical studies, Factor IX gene therapy resulted in long-term
production of Factor IX protein at a therapeutically significant level after
a single administration. If this approach is successful, the long term
efficacy of one time administered hemophilia B gene therapy is expected to be
perceived as a significant advance over the current regular dosing of
recombinant Factor IX. In addition, the efficacy profile of this gene therapy
is anticipated to exceed that of current therapy, as the gene therapy should
lead to stable Factor IX levels whereas current recombinant protein treatment
causes peaks and troughs. It is hoped that hemophilia B gene therapy,
therefore, can potentially replace all recombinant Factor IX products.

The UK Medicines and Healthcare products Regulatory Agency as
well as the US Food and Drug Administration have approved the current trial.

About the Disease

Hemophilia B is characterized by severe episodes of external
and internal bleeding, resulting in significant morbidity. The episodes cause
long-term damage, for instance to the joints, and may be fatal if they occur
in the brain. The defect in blood clotting in hemophilia B is caused by the
absence of functional clotting Factor IX as a result of mutations in the gene
encoding this protein. The factor IX gene is located on the X chromosome. It
is an X-linked recessive trait, which explains why only males are usually
affected.

Hemophilia B is a rare disease, occurring in 1 in 30,000
people, almost always in males. The total number of patients in Europe and
the USA together is estimated to be between 35,000 and 40,000.

Currently, frequent intravenous administrations of recombinant
Factor IX are required to stop or prevent bleeding. Protein replacement
therapy is costly, cumbersome, and does not completely prevent bleeding.

About Amsterdam Molecular Therapeutics

AMT, founded in 1998 and based in Amsterdam, is a leader in
the development of human gene based therapies. Using AAV as the delivery
vehicle of choice for therapeutic genes, the company has been able to design
and validate what is probably the first stable and scalable AAV production
platform. This safe and efficacious proprietary platform offers a unique
manufacturing capability which can be applied to a large number of rare
(orphan) diseases that are caused by one faulty gene. Currently, AMT has a
product pipeline with several AAV-based gene therapy products in LPLD,
Hemophilia B, DMD, Acute Intermittent Porphyria and Parkinson's Disease at
different stages of research or development.

For information

AMT will be presenting at Bio Europe Spring 2010 Conference at
the Centre Convencions Internacional, Barcelona, at 1200 (CET) on Wednesday
March 10, 2010.

Certain statements in this press release are "forward-looking
statements" including those that refer to management's plans and expectations
for future operations, prospects and financial condition. Words such as
"strategy," "expects," "plans," "anticipates," "believes," "will,"
"continues," "estimates," "intends," "projects," "goals," "targets" and other
words of similar meaning are intended to identify such forward-looking
statements. Such statements are based on the current expectations of the
management of Amsterdam Molecular Therapeutics only. Undue reliance should
not be placed on these statements because, by their nature, they are subject
to known and unknown risks and can be affected by factors that are beyond the
control of AMT. Actual results could differ materially from current
expectations due to a number of factors and uncertainties affecting AMT's
business, including, but not limited to, the timely commencement and success
of AMT's clinical trials and research endeavors, delays in receiving U.S.
Food and Drug Administration or other regulatory approvals (i.e. EMEA, Health
Canada), market acceptance of AMT's products, effectiveness of AMT's
marketing and sales efforts, development of competing therapies and/or
technologies, the terms of any future strategic alliances, the need for
additional capital, the inability to obtain, or meet, conditions imposed for
required governmental and regulatory approvals and consents. AMT expressly
disclaims any intent or obligation to update these forward-looking statements
except as required by law. For a more detailed description of the risk
factors and uncertainties affecting AMT, refer to the prospectus of AMT's
initial public offering on June 20, 2007, and AMT's public announcements made
from time to time.

Jorn Aldag, CEO, Tel +31(0)20-566-7394, Tel +31(0)6-8195-3060, j.aldag at amtbiopharma.com