Amsterdam Molecular Therapeutics Reports Promising Data From Cholesterol Lowering Gene Therapy Study

Gene Therapy Vector Successfully Delivers shRNA Into Liver Cells

AMSTERDAM, May 20, 2010 - Amsterdam Molecular Therapeutics (Euronext: AMT) a world
leader in gene therapy, today reported positive preclinical data from a study
using an AAV gene therapy product to lower cholesterol. The data show that a
single dose of the gene therapy carrying a short hairpin RNA to silence
Apolipoprotein B100 (ApoB100), resulted in a reduction of serum cholesterol
of approximately 80%, without any signs of toxicity. These data validate
AMT's technology platform as a powerful tool for successful gene silencing
within target cells. The data were presented by Annemart Koorneef, scientist
at AMT, yesterday during the 13th Annual American Society of Gene and Cell
Therapy (ASGCT) Meeting in Washington, DC.

"With just a single dose of our cholesterol targeting gene
therapy, a long-lasting, significant reduction of serum cholesterol is
achieved. This preliminary study suggest that AMT's technology may have
overcome one of the major problems of shRNA therapies, namely efficient and
non-toxic intracellular delivery," noted Jorn Aldag, CEO of Amserdam
Molecular Therapeutics.

In the study, AMT used its proprietary AAV-based platform to
efficiently deliver a shRNA that silences both human and mouse Apolipoprotein
B100 (ApoB100). A single intravenous administration caused prolonged ApoB100
gene silencing that was sequence-specific and not associated with liver
toxicity, oversaturation of the cellular miRNA machinery or induction of
immune responses. In addition, it was shown that the shRNA constructs against
ApoB100 specifically and efficiently silence human ApoB100 ex vivo.

ApoB100 is the structural protein of Low Density Lipoprotein (LDL)
particles that carry cholesterol. Silencing of ApoB100 with shRNAs results in
a reduction of LDL-cholesterol and has the potential to be used to treat
hypercholesterolaemia and cardiovascular disease.

About Amsterdam Molecular Therapeutics

AMT, founded in 1998 and based in Amsterdam, is a leader in
the development of human gene based therapies. Using adeno-associated viral
(AAV) vectors 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 LPL Deficiency, Hemophilia B, Duchenne Muscular
Dystrophy, Acute Intermittent Porphyria and Parkinson's Disease at different
stages of research or development.

AMT's lead product, Glybera, for the treatment of lipoprotein
lipase deficiency has been filed for market authorization with the EMA. The
current technology enables AMT to further expand its strategy to develop
long-lasting therapies for severe metabolic diseases.

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.

For further information, Jorn Aldag, Chief Executive Officer, Tel +31(0)20-566-7394, j.aldag at amtbiopharma.com