On March 15, 2017, PTC Therapeutics, Inc. (the Company) entered
into an Asset Purchase Agreement (the Asset Purchase Agreement)
with Marathon Pharmaceuticals, LLC (Marathon) to which the Company
agreed to acquire all rights to Emflaza (deflazacort) (the
Transaction). Emflaza is the first treatment approved in the

United States for all Duchenne muscular dystrophy patients five
years and older, regardless of their genetic mutation. Under the
terms of the Asset Purchase Agreement, the Company has agreed to
pay Marathon total upfront consideration of $140 million upon the
closing of the Transaction, comprised of approximately $75 million
in cash and approximately $65 million of the Companys common stock.
The number of shares of the Companys common stock issuable at
closing will be based on the volume weighted average price per
share of the Companys common stock on the Nasdaq Stock Market for
the 15 trading day period ending on the third trading day
immediately preceding the closing of the Transaction and will be
subject to reduction such that the number of shares issuable will
not exceed 19.9% of the issued and outstanding shares of the
Companys common stock immediately prior to the closing date, which
is expected to be a maximum of approximately 6.9 million shares,
with any shortfall to be made whole with additional cash
consideration. The Company will also assume certain liabilities
with respect to the assets to be acquired. In addition, Marathon
will be entitled to receive contingent payments from the Company
based on annual net sales of Emflaza beginning in 2018, up to a
specified aggregate maximum amount for such payments, and a single
$50 million sales-based milestone, in each case subject to the
terms and conditions of the Asset Purchase Agreement. The Company
expects that the contingent payments will, on a blended average
basis, range in percentages of net sales between the low to
mid-twenties.

The Asset Purchase Agreement includes customary pre-closing
covenants, including with respect to Marathons conduct of business,
capital expenditures and studies and trials relating to the assets
to be acquired as well as provisions with respect to the parties
rights and responsibilities in the event Marathon elects to
commercialize the assets to be acquired prior to closing of the
Transaction.

Additionally, prior to the closing of the Transaction, Marathon is
prohibited from initiating, soliciting, encouraging or otherwise
facilitating any inquiry, proposal, offer or discussion or engaging
in discussions or negotiating with any party other than the Company
with respect to a sale or similar transaction of the assets to be
acquired, subject to the terms and conditions of the Asset Purchase
Agreement. The Asset Purchase Agreement also prohibits Marathon
from engaging in the business of developing, selling,
manufacturing, distributing or marketing any product that is a
steroid or anti-inflammatory for the treatment of Duchenne Muscular
Dystrophy and from soliciting or hiring specified persons and
employees of the Company, subject to certain exceptions as set
forth in the Asset Purchase Agreement, for a period of five years
following the closing of the Transaction. Under the Asset Purchase
Agreement, Marathon has also agreed to a standstill with respect to
the Companys securities, not to dispose of any Company common stock
and to vote any of its Company common stock in accordance with the
Companys governing body for a period of six months following
closing of the Transaction, subject to certain exceptions as set
forth in the Asset Purchase Agreement.

The Asset Purchase Agreement includes customary closing conditions,
including regulatory approval, and termination provisions as well
as indemnification provisions to which the parties agree to
indemnify each other, subject to certain thresholds and caps on
liability as set forth in the Asset Purchase Agreement. The Asset
Purchase Agreement may be terminated by either party if the
Transaction has not closed by July 15, 2017, subject to the terms
and conditions of the Asset Purchase Agreement.

The Asset Purchase Agreement also contains customary
representations and warranties that the Company and Marathon made
to each other as of specific dates. The assertions embodied in
those representations and warranties were made solely for purposes
of the Asset Purchase Agreement and may be subject to important
qualifications and limitations agreed to by the Company and
Marathon in connection with negotiating its terms. Moreover, the
representations and warranties may be subject to a contractual
standard of materiality that may be different from what may be
viewed as material to stockholders or may have been used for the
purpose of allocating risk between the Company and Marathon rather
than establishing matters as facts. For the foregoing reasons, no
person should rely on such representations and warranties as
statements of factual information at the time they were made or
otherwise.

The above description of the Asset Purchase Agreement is a summary
only and is qualified in its entirety by reference to the terms of
the Asset Purchase Agreement, filed as Exhibit 2.1 hereto and
incorporated herein by reference.

Item 3.02. Unregistered Sales of Equity Securities.

The description of the common stock consideration under the terms
of the Asset Purchase Agreement set forth in Item 1.01 is
incorporated herein by reference. In connection with the closing of
the Transaction, the Company will issue to Marathon the common
stock consideration to an exemption from registration afforded by
Section 4(a)(2) of the Securities Act of 1933, as amended (the
Securities Act), and/or Regulation D promulgated thereunder, based
in part on Marathons representations to the Company that it is an
accredited investor as that term is defined under Rule 501(a) under
the Securities Act.

Item 7.01. Regulation FD Disclosure.

On March 16, 2017, the Company issued a press release in which it
announced that it entered into the Asset Purchase Agreement. A copy
of the press release is attached to this Report as Exhibit 99.1 and
is incorporated by reference into this Item 7.01.

The information set forth in or incorporated by reference into this
Item 7.01, including Exhibit 99.1, shall not be deemed to be filed
for purposes of Section 18 of the Securities Exchange Act of 1934,
as amended (the Exchange Act), or otherwise subject to the
liability of that section, and shall not be incorporated by
reference into any registration statement or other document filed
under the Securities Act or the Exchange Act, except as shall be
expressly set forth by specific reference in such filing.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

See Exhibit Index attached hereto.

Cautionary Statement Concerning Forward Looking Statements

This Report contains forward-looking statements addressing the
Transaction and the other transactions contemplated in the Asset
Purchase Agreement and any other statements about future
expectations, prospects, estimates and other matters that are
dependent upon future events or developments. All statements, other
than those of historical fact, contained in this Report are
forward-looking statements, including statements related to the
Companys expectations with respect to the closing of the
Transaction; the potential financial impact and benefits to the
Company of the Transaction, including with respect to a potential
launch of Emflaza and the Companys expectations with respect to
contingent payments to Marathon based on annual net sales; the
potential advantages of Emflaza; the future expectations, plans and
prospects for the Company; the Company’s strategy, future
operations, future financial position, future revenues or projected
costs; and the objectives of management. Other forward-looking
statements may be identified by the words “look forward”,
“plan,” “anticipate,” “believe,” “estimate,” “expect,”
“intend,” “may,” “target,” “potential,” “will,”
“would,” “could,” “should,” “continue,” and similar
expressions. The Company’s actual results, performance or
achievements could differ materially from those expressed or
implied by forward-looking statements it makes as a result of a
variety of risks and uncertainties, including those related to:
satisfaction of the conditions to closing the Transaction
(including the failure to obtain necessary regulatory approvals) in
the anticipated timeframe or at all; the Companys ability to
realize the anticipated benefits of the Transaction, including the
possibility that the expected benefits from the Transaction will
not be realized or will not be realized within the expected time
period; negative effects of the announcement of the Asset Purchase
Agreement on the market price of the Companys common stock;
significant transaction costs; unknown liabilities; the risk of
litigation and/or regulatory actions related to the Transaction;
other business effects, including the effects of industry, market,
economic, political or regulatory conditions; changes in tax and
other laws, regulations, rates and policies; the eligible patient
base and commercial potential of TranslarnaTM (ataluren) and
Emflaza; the sufficiency of the

Company’s cash resources and its ability to obtain adequate
financing in the future for its foreseeable and unforeseeable
operating expenses and capital expenditures; and the factors
discussed in the “Risk Factors” section of the Company’s most
recent Quarterly Report on Form 10-Q or Annual Report on Form 10-K
as well as any updates to these risk factors filed from time to
time in the Company’s other filings with the SEC. As with any
pharmaceutical under development, there are significant risks in
the development, regulatory approval and commercialization of new
products. There are no guarantees that any product will receive or
maintain regulatory approval in any territory, or prove to be
commercially successful, including Translarna or Emflaza. The
forward-looking statements contained herein represent the
Company’s views only as of the date of this Report and the Company
does not undertake or plan to update or revise any such
forward-looking statements to reflect actual results or changes in
plans, prospects, assumptions, estimates or projections, or other
circumstances occurring after the date of this Report except as
required by law.

to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf
by the undersigned hereunto duly authorized.

EXHIBIT INDEX

Exhibit No. Description

Marathon Pharmaceuticals, LLC

99.1 Press Release, dated March 16, 2017, issued by PTC
Therapeutics, Inc.

* Confidential treatment has been requested for certain portions
that are omitted from this exhibit. The omitted information has
been filed separately with the U.S. Securities and Exchange
Commission (the SEC) to the registrants application for
confidential treatment. In addition, schedules have been omitted
from this exhibit