Adaptimmune Therapeutics plc (ADAP)

Adaptimmune Therapeutics plc was a clinical-stage and later commercial-stage biotechnology company focused on engineered T-cell receptor (TCR) therapies for solid tumors. It was founded in 2008 in the United Kingdom as a spin-out associated with Oxford-area research and was based at Milton Park in Abingdon, Oxfordshire, with a significant operational presence in Philadelphia, Pennsylvania.

The company's approach was to identify T-cell receptors that recognize cancer-associated antigens, engineer a patient's own T cells to express them, and reinfuse the cells to attack tumors. Its pipeline included afamitresgene autoleucel (afami-cel), directed at the MAGE-A4 antigen, as well as lete-cel, directed at NY-ESO-1, and a number of earlier programs. It also had collaborations with large pharmaceutical companies, including GSK, in its early years.

Adaptimmune listed American depositary shares on the Nasdaq Global Select Market under the symbol ADAP following its initial public offering in 2015. Each ADS represented a number of ordinary shares of the UK parent. In 2024 the U.S. Food and Drug Administration granted accelerated approval to afami-cel, marketed as Tecelra, for certain adults with unresectable or metastatic synovial sarcoma, making it the first engineered TCR cell therapy approved for a solid tumor in the United States.

Despite the approval, the company faced financing constraints typical of cell therapy developers, including the high cost of manufacturing and commercial launch. In 2025 it undertook cost-reduction measures and explored strategic alternatives. In July 2025 it agreed to sell Tecelra, lete-cel and its uza-cel program, along with related assets, to US WorldMeds, a privately held U.S. pharmaceutical company.

After the asset sale, Adaptimmune's remaining operations were limited, and the board concluded that continued listing no longer served the company's circumstances. In October 2025 the company announced its intention to delist its ADSs from Nasdaq, and a Form 25 was filed with the SEC on October 28, 2025 in connection with the removal of the ADSs from listing and registration.

The delisting was therefore voluntary and followed a sale of the business's principal assets rather than a merger or takeover of the company itself. Holders of ADSs were not offered a per-share purchase price as part of the delisting, and the company announced further changes to its board and executive leadership team in November 2025 as it moved to wind down its remaining affairs.