Commitments and Contingencies	6 Months Ended
Jun. 30, 2025
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies medac Matter In April 2021, the Company’s wholly owned subsidiary, Delcath Systems Ltd, issued to medac GmbH, a privately held, multi-national pharmaceutical company based in Germany (“medac”), an invoice for a €1 million milestone payment under a License, Supply and Marketing Agreement dated December 10, 2018 (the “medac Agreement”) between medac and the Company. The medac Agreement provided to medac the exclusive right to market and sell CHEMOSAT in certain designated countries for which the Company was entitled to a combination of upfront and success-based milestone payments as well as a fixed transfer price per unit of CHEMOSAT and specified royalties. In response to medac’s subsequent dispute and non-payment of the invoice, on October 12, 2021, the Company notified medac in writing that it was terminating the medac Agreement due to medac’s nonpayment of the €1 million milestone payment, with the effective date of termination of the medac Agreement being April 12, 2022. On December 16, 2021, the Company initiated an arbitration proceeding pursuant to the dispute resolution procedures of the medac Agreement for the non-payment of the invoice. On December 30, 2022, the parties reached a final settlement of the matter and the Company agreed to pay medac either (a) a royalty on sales of CHEMOSAT units over a defined minimum for a period of five years or until a maximum payment has been reached, or (b) a minimum annual payment of $0.2 million in the event the annual royalty payment does not reach the agreed minimum payment amount. The Company has estimated the remaining fair value of the settlement to be $0.8 million as of June 30, 2025 and recorded $0.6 million as other liabilities, non-current and $0.2 million as accrued expenses on the Company’s condensed consolidated balance sheet as of June 30, 2025. Manufacturing and Supply Agreements The Company has a License, Supply and Contract Manufacturing Agreement (as amended, the “Supply Agreement”) with Synerx Pharma, LLC and Mylan Teoranta for the supply of melphalan provided in the HEPZATO KIT. An amendment to the Supply Agreement was entered into on April 22, 2024, and effective as of May 1, 2024, which extends the term of the agreement through December 31, 2028, with an option to renew for successive five-year periods upon the mutual written consent of both parties. Although the Supply Agreement does not contain an annual minimum purchase quantity, the Agreement requires Delcath to order full lots of labeled melphalan vials. The Company received $2.1 million of melphalan under this Supply Agreement in 2025 which is recorded under accounts payable as of June 30, 2025. Agreements Relating to Clinical Trial Support The Company has engaged Precision for Medicine LLC (“PfM”) a Clinical Research Organization (“CRO”) to support the Company's Phase 2 clinical trials evaluating HEPZATO in combination with standard of care in patients with liver dominant mCRC and HER2-negative mBC. In addition to the CRO engagement, the Company has also contracted with other vendors, including those relating to data management as well as clinical trial sites as the studies progress. Deposits totaling $2.3 million have been made by the Company in connection with these engagements that are to be applied to future payments due under the service agreements

In April 2021, the Company’s wholly owned subsidiary, Delcath Systems Ltd, issued to medac GmbH, a privately held, multi-national pharmaceutical company based in Germany (“medac”), an invoice for a €1 million milestone payment under a License, Supply and Marketing Agreement dated December 10, 2018 (the “medac Agreement”) between medac and the Company. The medac Agreement provided to medac the exclusive right to market and sell CHEMOSAT in certain designated countries for which the Company was entitled to a combination of upfront and success-based milestone payments as well as a fixed transfer price per unit of CHEMOSAT and specified royalties.

In response to medac’s subsequent dispute and non-payment of the invoice, on October 12, 2021, the Company notified medac in writing that it was terminating the medac Agreement due to medac’s nonpayment of the €1 million milestone payment, with the effective date of termination of the medac Agreement being April 12, 2022. On December 16, 2021, the Company initiated an arbitration proceeding pursuant to the dispute resolution procedures of the medac Agreement for the non-payment of the invoice.

On December 30, 2022, the parties reached a final settlement of the matter and the Company agreed to pay medac either (a) a royalty on sales of CHEMOSAT units over a defined minimum for a period of five years or until a maximum payment has been reached, or (b) a minimum annual payment of $0.2 million in the event the annual royalty payment does not reach the agreed minimum payment amount. The Company has estimated the remaining fair value of the settlement to be $0.8 million as of June 30, 2025 and recorded $0.6 million as other liabilities, non-current and $0.2 million as accrued expenses on the Company’s condensed consolidated balance sheet as of June 30, 2025.

The Company has a License, Supply and Contract Manufacturing Agreement (as amended, the “Supply Agreement”) with Synerx Pharma, LLC and Mylan Teoranta for the supply of melphalan provided in the HEPZATO KIT. An amendment to the Supply Agreement was entered into on April 22, 2024, and effective as of May 1, 2024, which extends the term of the agreement through December 31, 2028, with an option to renew for successive five-year periods upon the mutual written consent of both parties. Although the Supply Agreement does not contain an annual minimum purchase quantity, the Agreement requires Delcath to order full lots of labeled melphalan vials. The Company received $2.1 million of melphalan under this Supply Agreement in 2025 which is recorded under accounts payable as of June 30, 2025.