United states securities and exchange commission

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Multiple Sclerosis (MS)
TECFIDERA
For 2017 compared to 2016, the increase in 
U.S. TECFIDERA revenues was primarily due to price 
increases, partially offset by higher discounts and 
allowances and a decrease in unit sales volume of 
3%. 
For 2016 compared to 2015, the increase in 
U.S. TECFIDERA revenues was primarily due to price 
increases, partially offset by higher discounts and 
allowances and a decrease in unit sales volume of 
1%.
For 2017 compared to 2016, the increase in rest 
of world TECFIDERA revenues was primarily due to 
increases in unit sales volume of 19% primarily in the 
E.U., partially offset by pricing reductions in certain 
European countries.
For 2016 compared to 2015, the increase in rest 
of world TECFIDERA revenues was primarily due to 
increases in unit sales volume of 32% in existing 
markets and new markets where we continue to 
launch the product and expand our presence around 
the world. These increases were partially offset by 
pricing reductions in certain European countries. Rest 
of world TECFIDERA revenues for 2016, compared to 
2015, were also negatively impacted by a $50.2 
million decrease in hedge gains recognized under our 
foreign currency hedging program in the comparative 
period. 
We anticipate a modest increase in TECFIDERA 
demand on a global basis in 2018, compared to 
2017, with expected volume growth in our 
international markets partially offset by declines in 
the U.S., due to increased competition from additional 
treatments for MS, including OCREVUS.
Interferon
AVONEX and PLEGRIDY
For 2017 compared to 2016, the decrease in 
U.S. Interferon revenues was primarily due to an 
overall decrease in Interferon unit sales volumes of 
12%, which was primarily attributable to patients 
transitioning to other MS therapies, partially offset by 
price increases.  
For 2016 compared to 2015, the decrease in 
U.S. Interferon revenues was primarily due to an 
overall decrease in Interferon unit sales volume of 
10%, which was attributable to a decrease in AVONEX 
unit sales volume primarily due to patients 
transitioning to other oral MS therapies, as well as 
higher discounts and allowances. These decreases 
were partially offset by price increases.
For 2017 compared to 2016, the decrease in 
rest of world Interferon revenues was primarily due to 
an overall decrease in AVONEX unit sales volume of 
14% primarily due to patients transitioning to other 
MS therapies in the E.U. 
For 2016 compared to 2015, the decrease in 
rest of world Interferon revenues was primarily due to 
pricing reductions in certain European countries and 
an overall decrease in AVONEX unit sales volume of 
10% due primarily to patients transitioning to other 
oral MS therapies, including TECFIDERA. Rest of world 
Interferon revenues for 2016, compared to 2015, 
were also negatively impacted by a $66.1 million 
decrease in hedge gains recognized under our 
hedging program in the comparative period. 

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We expect that overall Interferon revenues will 
continue to decline compared to prior year periods as 
a result of increasing competition from our other 
products as well as other treatments for MS, including 
biosimilars.
AVONEX
For 2017, 2016 and 2015, U.S. AVONEX 
revenues totaled $1,593.6 million, $1,675.3 million 
and $1,790.2 million, respectively.
For 2017, 2016 and 2015 rest of world AVONEX 
revenues totaled $557.9 million, $638.2 million and 
$840.0 million, respectively.
PLEGRIDY
For 2017, 2016 and 2015, U.S. PLEGRIDY 
revenues totaled $295.5 million, $305.0 million and 
$227.1 million, respectively.
For 2017, 2016 and 2015, rest of world 
PLEGRIDY revenues totaled $198.8 million, $176.7 
million and $111.4 million, respectively.
TYSABRI
For 2017 compared to 2016, the decrease in 
U.S. TYSABRI revenues was primarily due to higher 
discounts and allowances and a decrease in unit 
sales volume of 4%, partially offset by price 
increases. 
For 2016 compared to 2015, the increase in 
U.S. TYSABRI revenues was primarily due to an 
increase in unit sales volume of 4% and increases in 
price, partially offset by higher discounts and 
allowances.
For 2017 compared to 2016, the increase in 
rest of world TYSABRI revenues was primarily due to 
the recognition of approximately $45.0 million of 
previously deferred revenue in Italy relating to the 
pricing agreement with AIFA and a 12% increase in 
unit sales volume primarily in our international partner 
markets, partially offset by a prior year favorable 
adjustment of approximately $20.0 million to previous 
reserves estimates related to a government price 
reimbursement program included in our discounts and 
allowances. For information on our agreement with 
AIFA relating to sales of TYSABRI in Italy, please read 
Note 18, Other Consolidated Financial Statement 
Detail, to our consolidated financial statements 
included in this report.
For 2016 compared to 2015, the decrease in 
rest of world TYSABRI revenues was primarily due to 
the impact of a $46.1 million decrease in hedge gains 
recognized under our hedging program in the 
comparative period. This decrease was partially offset 
by an increase in unit sales volume of 8%, primarily in 
Europe.
We anticipate a decline in TYSABRI demand on a 
global basis in 2018, compared to 2017, with 
expected volume declines in the U.S., due to 
increased competition from additional treatments for 
MS, including OCREVUS, offsetting volume growth in 
our international markets.
ZINBRYTA
Under our collaboration agreement with AbbVie, 
we began to recognize revenues on sales of ZINBRYTA 
to third parties in the E.U. in the third quarter of 
2016.
For 2017 compared to 2016, the increase in 
ZINBRYTA revenues was primarily due to an increase 
in unit sales volume.

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