11. Notes payable

Loan agreement

On April 14, 2014, the Company executed a Loan Agreement with a lender, as subsequently amended multiple times, most recently in April 2019. As of September 30, 2019, there were no additional amounts available to borrow under the debt facility. The interest rate on this term loan is variable based on a calculation of the prime rate less 5.25% with a minimum interest rate of 8.25%. Interest is paid monthly beginning the month following the borrowing date. At loan inception and in connection with the amendments, the Company issued the lender warrants to purchase shares of stock. The Loan Agreement also contains prepayment penalties and an end of term charge. Fees incurred upon execution of the agreements, and the fair value of warrants on the date of grant were accounted for as a reduction in the book value of debt and accreted through interest expense, using the effective interest rate method, over the term of the debt.

No end of term charges or principal payments were paid during the nine months ended September 30, 2019. On April 15, 2019, the Company signed Amendment 7 to the Loan Agreement, which extends the interest only payment period through July 1, 2021 and also extends the maturity date until October 1, 2021. As part of this Amendment 7, a “2019 End of Term Fee” for $50,000 was added to the Loan Agreement due on the earliest to occur of (i) the Term Loan Maturity Date, (ii) the date that the Company prepays the outstanding Secured Obligations and (iii) the date that the Secured Obligations become due and payable. In addition, the Company is required to pay the loan principal in five equal installments starting July 1, 2021 with the final principal payment to be made on October 1, 2021. As of September 30, 2019, the remaining loan balance is classified as a long term liability since all principal payments are due greater than twelve months after the balance sheet date.

As of September 30, 2019, debt payment obligations due based on principal payments are as follows (in thousands):


2019	$	—
2020		—
2021		7,688
	$	7,688

Non‑cash interest expense related to debt discount amortization and accretion of end of term fees was $0.1 million or less for each of the three months ended September 30, 2019 and 2018, and nine months ended September 30, 2019 and 2018.