Subsequent events	6 Months Ended
Jun. 30, 2015
Subsequent events	15. Subsequent events Issuance of new 5.75% Convertible Senior Subordinated Exchange Notes due 2018 in exchange for 2015 notes On July 28, 2015, the Company entered into privately-negotiated exchange agreements (the “Note Exchange Agreements”) with select holders of 2015 notes, pursuant to which the Company agreed to issue $27.7 million aggregate principal amount of new 5.75% Convertible Senior Subordinated Exchange Notes due 2018 (the “2018 notes”) to such holders in exchange for the delivery to the Company of the same principal amount of 2015 notes. The 2018 notes were issued at the closing of the exchange on August 10, 2015. The 2018 notes will be the Company’s general, unsecured, senior obligations, except that the 2018 notes will be subordinated in right of payment to the outstanding notes issued pursuant to the Facility Agreement and the Company’s borrowings under its secured loan facility with an affiliate of Sanofi-Aventis U.S. LLC. The 2018 notes will rank equally in right of payment with the Company’s other unsecured senior debt, including any 2015 notes that remain outstanding after the completion of the exchange transactions. The 2018 notes will bear interest at the rate of 5.75% per year on the principal amount, payable semiannually in arrears in cash on February 15 and August 15 of each year, beginning February 15, 2016, with interest accruing from August 15, 2015. The 2018 notes will mature on August 15, 2018. The 2018 notes will be convertible, at the option of the holder, at any time on or prior to the close of business on the business day immediately preceding the stated maturity date, into shares of the Company’s common stock at a conversion rate of 147.0859 shares per $1,000 principal amount of 2018 notes, which is equal to a conversion price of approximately $6.80 per share, the same conversion price as that of the 2015 notes. The conversion rate is subject to adjustment under certain circumstances described in an indenture governing the 2018 notes dated August 10, 2015 with Wells Fargo, National Association (the “2018 Note Indenture”), including in connection with a make-whole fundamental change. If certain fundamental changes occur, the Company will be obligated to pay a fundamental change make-whole premium on any 2018 notes converted in connection with such fundamental change by increasing the conversion rate on such 2018 notes. In such instances, the amount of the fundamental change make-whole premium will be based on the Company’s common stock price and the effective date of the applicable fundamental change. If the Company undergoes certain fundamental changes, except in certain circumstances, each holder of 2018 notes will have the option to require the Company to repurchase all or any portion of that holder’s 2018 notes. The fundamental change repurchase price will be 100% of the principal amount of the 2018 notes to be repurchased plus accrued and unpaid interest, if any. On or after the date that is one year following the original issue date of the 2018 notes, the Company will have the right to redeem for cash all or part of the 2018 notes if the last reported sale price of its common stock exceeds 130% of the conversion price then in effect for 20 or more trading days during the 30 consecutive trading day period ending on the trading day immediately prior to the date of the redemption notice. The redemption price will equal the sum of 100% of the principal amount of the 2018 notes to be redeemed, plus accrued and unpaid interest. $27.7 million principal amount of 2018 notes were issued in exchange for the cancellation of the same principal amount of 2015 notes after June 30, 2015 but prior to the issuance of our quarterly report on Form 10-Q. As a result, in accordance with ASC 470 we reclassified $27.7 million principal amount of our 2015 notes that were outstanding as of June 30, 2015 from current liabilities to non-current liabilities. Issuance of common stock in exchange for 2015 notes On July 28, 2015 and August 3, 2015, the Company entered into separate, privately-negotiated exchange agreements (the “Stock-for-Note Exchange Agreements”) with other select holders of the 2015 notes pursuant to which the Company agreed to issue shares of its common stock to such holders in exchange for the delivery to the Company of up to $61.8 million aggregate principal amount of 2015 notes. Pursuant to the Stock-for-Note Exchange Agreements, the parties agreed to price the exchange transactions over a 10 trading day period spanning from July 29, 2015 to and including August 11, 2015 (each, an “Exchange Date”). Between July 28, 2015 and August 10, 2015, the Company issued an aggregate of 1.9 million shares of common stock to such holders in exchange for such holders’ delivery to the Company of $8.0 million aggregate principal amount of 2015 notes, resulting in a weighted-average exchange price of $4.40 per share. As of August 10, 2015, $64.3 million aggregate principal amount of 2015 notes remained outstanding. As a result in accordance with ASC 470, we reclassified $8.0 million of our 2015 notes that were outstanding as of the balance sheet date from current liabilities to non-current liabilities. The Company offered and issued the foregoing shares of common stock and the 2018 notes in reliance on the exemption from registration provided by Section 4(a)(2) of the Securities Act of 1933, as amended. Borrowings under Sanofi Loan Facility On July 28, 2015, we borrowed $12.8 million under the Sanofi Loan Facility to finance the portion of our losses for the three months ended June 30, 2015 (see Note 7 — Collaboration arrangement).

15. Subsequent events

Issuance of new 5.75% Convertible Senior Subordinated Exchange Notes due 2018 in exchange for 2015 notes

On July 28, 2015, the Company entered into privately-negotiated exchange agreements (the “Note Exchange Agreements”) with select holders of 2015 notes, pursuant to which the Company agreed to issue $27.7 million aggregate principal amount of new 5.75% Convertible Senior Subordinated Exchange Notes due 2018 (the “2018 notes”) to such holders in exchange for the delivery to the Company of the same principal amount of 2015 notes. The 2018 notes were issued at the closing of the exchange on August 10, 2015.

The 2018 notes will be the Company’s general, unsecured, senior obligations, except that the 2018 notes will be subordinated in right of payment to the outstanding notes issued pursuant to the Facility Agreement and the Company’s borrowings under its secured loan facility with an affiliate of Sanofi-Aventis U.S. LLC. The 2018 notes will rank equally in right of payment with the Company’s other unsecured senior debt, including any 2015 notes that remain outstanding after the completion of the exchange transactions. The 2018 notes will bear interest at the rate of 5.75% per year on the principal amount, payable semiannually in arrears in cash on February 15 and August 15 of each year, beginning February 15, 2016, with interest accruing from August 15, 2015. The 2018 notes will mature on August 15, 2018.

The 2018 notes will be convertible, at the option of the holder, at any time on or prior to the close of business on the business day immediately preceding the stated maturity date, into shares of the Company’s common stock at a conversion rate of 147.0859 shares per $1,000 principal amount of 2018 notes, which is equal to a conversion price of approximately $6.80 per share, the same conversion price as that of the 2015 notes. The conversion rate is subject to adjustment under certain circumstances described in an indenture governing the 2018 notes dated August 10, 2015 with Wells Fargo, National Association (the “2018 Note Indenture”), including in connection with a make-whole fundamental change.

If certain fundamental changes occur, the Company will be obligated to pay a fundamental change make-whole premium on any 2018 notes converted in connection with such fundamental change by increasing the conversion rate on such 2018 notes. In such instances, the amount of the fundamental change make-whole premium will be based on the Company’s common stock price and the effective date of the applicable fundamental change.

If the Company undergoes certain fundamental changes, except in certain circumstances, each holder of 2018 notes will have the option to require the Company to repurchase all or any portion of that holder’s 2018 notes. The fundamental change repurchase price will be 100% of the principal amount of the 2018 notes to be repurchased plus accrued and unpaid interest, if any.

On or after the date that is one year following the original issue date of the 2018 notes, the Company will have the right to redeem for cash all or part of the 2018 notes if the last reported sale price of its common stock exceeds 130% of the conversion price then in effect for 20 or more trading days during the 30 consecutive trading day period ending on the trading day immediately prior to the date of the redemption notice. The redemption price will equal the sum of 100% of the principal amount of the 2018 notes to be redeemed, plus accrued and unpaid interest.

$27.7 million principal amount of 2018 notes were issued in exchange for the cancellation of the same principal amount of 2015 notes after June 30, 2015 but prior to the issuance of our quarterly report on Form 10-Q. As a result, in accordance with ASC 470 we reclassified $27.7 million principal amount of our 2015 notes that were outstanding as of June 30, 2015 from current liabilities to non-current liabilities.

Issuance of common stock in exchange for 2015 notes

On July 28, 2015 and August 3, 2015, the Company entered into separate, privately-negotiated exchange agreements (the “Stock-for-Note Exchange Agreements”) with other select holders of the 2015 notes pursuant to which the Company agreed to issue shares of its common stock to such holders in exchange for the delivery to the Company of up to $61.8 million aggregate principal amount of 2015 notes.

Pursuant to the Stock-for-Note Exchange Agreements, the parties agreed to price the exchange transactions over a 10 trading day period spanning from July 29, 2015 to and including August 11, 2015 (each, an “Exchange Date”). Between July 28, 2015 and August 10, 2015, the Company issued an aggregate of 1.9 million shares of common stock to such holders in exchange for such holders’ delivery to the Company of $8.0 million aggregate principal amount of 2015 notes, resulting in a weighted-average exchange price of $4.40 per share. As of August 10, 2015, $64.3 million aggregate principal amount of 2015 notes remained outstanding.

As a result in accordance with ASC 470, we reclassified $8.0 million of our 2015 notes that were outstanding as of the balance sheet date from current liabilities to non-current liabilities.

The Company offered and issued the foregoing shares of common stock and the 2018 notes in reliance on the exemption from registration provided by Section 4(a)(2) of the Securities Act of 1933, as amended.

Borrowings under Sanofi Loan Facility

On July 28, 2015, we borrowed $12.8 million under the Sanofi Loan Facility to finance the portion of our losses for the three months ended June 30, 2015 (see Note 7 — Collaboration arrangement).