On July 3, 2018, Spark Therapeutics, Inc. (the “Company”) entered into a credit agreement with Wells Fargo Bank, National Association (“Wells Fargo”) as lender (the “Credit Agreement”), to which Wells Fargo extended a $50.0 million term loan to the Company. The term loan was fully drawn on the date of the Credit Agreement and matures on July 3, 2023 (the “Maturity Date”). During approximately the first year of the term, the term loan will not amortize, and the Company will only be obligated to make monthly interest payments with respect to the term loan. In connection with the Credit Agreement, the Company entered into a cash collateral agreement with Wells Fargo (the “Security Agreement”) on July 3, 2018. The Company also entered into a swap agreement with Wells Fargo (the "Swap Agreement") on July 3, 2018.

Interest Rate. Under the Credit Agreement, the outstanding principal amount of the term loan bears interest at one-month LIBOR, plus 0.65%. Under the Swap Agreement, this floating rate obligation is converted to a fixed rate per annum at 3.463%. Interest is due monthly on the last day of each month, commencing on July 31, 2018.

Repayment. Commencing on June 30, 2019, and on the last day of each calendar quarter thereafter, the Company is obligated to make consecutive quarterly installment payments of principal in the amount of $1.5 million each, with all interest and remaining principal to be paid in full on the Maturity Date.

Prepayments. The Company may voluntarily prepay the loan in whole or in part without premium or penalty under the Credit Agreement, at any time or from time to time upon 3 business days’ prior written notice.

Security. Under the Credit Agreement and the Security Agreement, the Company has provided a first priority, perfected security interest in favor of Wells Fargo in cash, certificates of deposit and/or other approved credit support maintained in one or more blocked, interest bearing collateral accounts at Wells Fargo in an amount equal to the greater of (x) then outstanding principal amount of the term loan plus all other secured obligations and (y) such other amount agreed to by the parties.

Representations and Warranties and Certain Covenants. The Credit Agreement contains certain customary representations and warranties, affirmative covenants and conditions. The Credit Agreement also contains a number of negative covenants that, among other things and subject to certain exceptions, restrict the ability of the Company and its subsidiaries to:

Events of Default. The Credit Agreement contains customary events of default (subject to grace periods as appropriate), including nonpayment of principal or interest; noncompliance with covenants; noncompliance with collateral obligations; failure to make payment on any other outstanding debt in excess of $5.0 million; judgments or orders for the payment of money not covered by insurance in excess of $5.0 million or that could reasonably be expected to have a material adverse effect; bankruptcy, liquidation, reorganization or other relief; an ERISA Event in excess of $5.0 million; or a change of control of the Company.

Customary Fees. Additionally, in connection with the Credit Agreement, the Company agreed to pay Wells Fargo’s customary fees, including a closing fee.

The foregoing summary of the Credit Agreement and the Security Agreement is not complete and is qualified in its entirety by reference to the Credit Agreement and the Security Agreement, copies of which will be filed as exhibits to the Company’s Quarterly Report on Form 10-Q for the quarter ending September 30, 2018.

The information set forth in Item 1.01 of this Current Report on Form 8-K is incorporated herein by reference in this Item 1.01.

About Spark Therapeutics, Inc. (NASDAQ:ONCE)

Spark Therapeutics, Inc. (Spark) is engaged in developing products in the field of gene therapy. The Company focuses on treating orphan diseases. It has a pipeline of product candidates targeting multiple rare blinding conditions, hematologic disorders and neurodegenerative diseases. Its SPK-RPE65 (voretigene neparvovec) targets genetic blinding conditions known as inherited retinal dystrophies (IRDs). Its product candidates include SPK-CHM and SPK-FIX. Its product development portfolio includes product candidates targeting expression of genes in the liver, with an initial focus on hematologic disorders. It is engaged in the development and commercialization of SPK-FIX product candidates for the treatment of hemophilia B. The Company is developing a lead product candidate for the treatment of a form of Batten disease in SPK-TPP1 program. The Company is also conducting preclinical studies on a product candidate for the treatment of Huntington’s disease, a hereditary genetic disorder.