INDEBTEDNESS
Entry into BlackRock Loan Facility
On January 29, 2024, or the Closing Date, the Company entered into the Agreement for the Provision of a Loan Facility, or the BlackRock Credit Agreement, with Kreos Capital VII (UK) Limited, or Kreos, which are funds and accounts managed by BlackRock Inc., collectively, BlackRock, and provides for a senior secured term loan facility in the aggregate principal amount of up to $55.0 million, or the Term Loan Facility. The Term Loan Facility was available in three tranches: (i) Tranche A — $37.0 million was funded on the Closing Date and used to repay the Pharmakon Term Loans (as defined below); (ii) Tranche B — $8.0 million was funded on April 19, 2024, or the Tranche B Closing Date; and (iii) Tranche C — $10.0 million was funded on February 3, 2025, or the Tranche C Closing Date, collectively the Term Loans.
On February 3, 2025, the Company and Kreos entered into a Second Amendment to the BlackRock Credit Agreement, or the Second Amendment, which, among other things, extended the expiry date of Tranche C from December 31, 2024 to the Tranche C Closing Date, or the Extended Tranche C. Tranche C was available subject to receipt of a certain amount of cumulative gross cash proceeds after the Closing Date in the form of equity or equity linked securities in one or more series of transactions. The terms of the Extended Tranche C are substantially similar to the terms of the original Tranche C, however, interest accrued on the Extended Tranche C as if it was advanced on December 31, 2024.
On the Closing Date, the Company received $34.5 million on Tranche A, after deducting debt issuance costs, fees and expenses. On the Tranche B Closing Date, the Company received $7.5 million, after deducting debt issuance costs, fees and expenses. On the Tranche C Closing Date, the Company received $9.3 million, after deducting debt issuance costs, interest, fees and expenses.
The BlackRock Term Loan Facility had an initial maturity date of March 31, 2025, which was automatically extended to January 29, 2028, after the Company received FDA approval for Vafseo, or the BlackRock Maturity Date. The Company is required to make interest-only payments until December 31, 2026, or the BlackRock Interest Only Period, after which the Company will begin paying equal monthly principal on the first calendar day of each month. In the event of certain prespecified events, the repayment schedule will be accelerated.
The Term Loan Facility will accrue interest at a floating annual rate equal to the sum of (i) the term Secured Overnight Financing Rate, or SOFR, for a tenor of one month (subject to a floor of 4.25% per annum) plus (ii) a margin of 6.75% per annum (subject to an overall cap of 15.00% per annum on the all-in interest rate). As of December 31, 2025, the Company's interest rate was 11.00%. During the years ended December 31, 2025 and 2024, the Company recognized interest expense of $8.4 million and $7.1 million, respectively.
During the continuance of any payment event of default under the BlackRock Credit Agreement, the interest rate on such overdue sum will automatically increase by an additional 3.0% per annum, and may be subject to an additional late fee of
2.0% of such overdue sum. The Term Loan Facility also includes transaction fees ranging from 1.00% to 1.25% of the draw down amount as well as exit fees of 0.75% of the amount funded to the relevant tranche.
If the Company prepays the outstanding loan prior to maturity, it will be required to pay a prepayment fee ranging from 1.0% to 4.0% of the amount prepaid.
As of December 31, 2025, future principal payments under the BlackRock Credit Agreement are as follows (in thousands):
Years ended December 31,
Amounts
2026— 
202750,558 
20281,881 
Total before unamortized discount and issuance costs52,439 
Less: unamortized discount and issuance costs(4,189)
Total term loans$48,250 
The BlackRock Term Loan Facility is secured by substantially all of the existing and after-acquired assets of the Company, including intellectual property. The BlackRock Credit Agreement requires the Company to (i) maintain a minimum aggregate cash balance of $15.0 million in one or more controlled accounts or (ii) trailing twelve-month revenue of $150.0 million, both of which are measured monthly. The BlackRock Credit Agreement contains certain representations and warranties, affirmative and negative covenants that limit the Company's ability to engage in specified types of transactions and other provisions typical within a credit agreement. If an event of default occurs and is continuing under the BlackRock Credit Agreement, BlackRock is entitled to take enforcement action, including acceleration of amounts due and it could limit the Company's ability to make certain payments under the Vifor Termination Agreement (as defined below).
On July 10, 2024, in connection with the Termination and Settlement Agreement entered into between the Company and CSL Vifor (as defined below), or the Vifor Termination Agreement, the Company and Kreos entered into a First Amendment to the BlackRock Credit Agreement, which amended certain provisions of the BlackRock Credit Agreement. See Note 8, Liability Related to Settlement Royalties, Working Capital Fund Liability and Liability Related to Sale of Future Royalties, for further information on the Vifor Termination Agreement.
Warrant
On the Closing Date, Kreos Capital VII Aggregator SCSp, an affiliate of Kreos, or the Warrant Holder, received a warrant to purchase 3,076,923 shares of the Company’s common stock, at an exercise price per share of $1.30, or the Initial Warrant. On the Tranche C Closing Date, the Company issued the Warrant Holder an additional warrant to purchase 1,153,846 shares of the Company’s common stock at an exercise price per share of $1.30, or the Tranche C Warrant. Each warrant is exercisable for eight years from the date of issuance.
On July 21, 2025, the Warrant Holder exercised its option to purchase 2,115,384 shares of the Company's common stock under the Initial Warrant on a cashless basis at an exercise price per share of $1.30. A cashless exercise allows the Warrant Holder to convert the warrants into shares of the Company's common stock without the need for a cash payment. Instead of paying cash upon exercise, the Warrant Holder received a reduced number of shares based on a predetermined formula. On July 23, 2025, as a result of the cashless exercise, the Company issued 1,408,588 shares of common stock to the Warrant Holder under the Initial Warrant.
The Initial Warrant and the Tranche C Warrant are liabilities classified under ASC 815, Derivatives and Hedging, as they could potentially require net cash settlement outside of the Company’s control. The Initial Warrant and the Tranche C Warrant are measured at fair value each reporting period and when a warrant is exercised, with the changes in fair value presented within the consolidated statements of operations and comprehensive loss. The fair value of the warrant liability was $3.0 million and $5.2 million as of December 31, 2025 and 2024, respectively. See Note 3, Fair Value of Financial Instruments, for information on the fair value determination.
Other Agreements Accounted for as Debt
The Company has a liability related to settlement royalties and a Working Capital Fund liability with Vifor (International) Ltd. (now a part of CSL Limited), or CSL Vifor, and a liability related to the sale of future royalties, which are accounted for as debt arrangements. See Note 8, Liability Related to Settlement Royalties, Working Capital Fund Liability and Liability Related to Sale of Future Royalties, for further information.
Pharmakon Term Loan (Extinguished January 29, 2024)
On November 11, 2019, the Company, with Keryx as guarantor, entered into a loan agreement, or Pharmakon Loan Agreement, which consisted of a secured term loan facility in an aggregate amount of up to $100.0 million, or Pharmakon Term Loans.
On the Closing Date, using the proceeds from the BlackRock Credit Agreement, the Company paid the then outstanding principal balance on the Pharmakon Term Loans of $35.0 million, plus the outstanding interest and a prepayment fee of $0.2 million. During the year ended December 31, 2024, the Company recorded a debt extinguishment loss of $0.5 million.
The Company recognized immaterial interest expense and $6.0 million of interest expense related to the Pharmakon Loan Agreement during the years ended December 31, 2024 and 2023, respectively.

Historical Timeline

Fiscal YearFiled
2025Feb 26, 2026Showing above
2024Mar 13, 2025
2023Mar 14, 2024
2022Mar 10, 2023
2021Mar 1, 2022
2020Feb 25, 2021
2019Mar 12, 2020
2018Mar 26, 2019

About Debt Disclosures

Debt disclosures detail a company's borrowing structure — the types of instruments, interest rates, maturity schedule, and covenant restrictions that define its financial obligations and flexibility. This section is essential for assessing refinancing risk, interest rate exposure, and the margin of safety against financial distress.

Key signals: the maturity schedule reveals concentration risk — large maturities within 1-2 years during tight credit markets can force dilutive refinancing or asset sales. Compare the fair value of debt against carrying amount to gauge whether the market views the company's credit risk differently than the balance sheet suggests. Watch covenant compliance disclosures for tightening cushions, especially leverage and interest coverage ratios. Variable-rate debt exposure quantifies sensitivity to interest rate changes. Secured versus unsecured mix affects recovery rates and future borrowing capacity. Compare net debt-to-EBITDA against industry peers and covenant limits to assess financial health.