Commitments and Contingencies	3 Months Ended
Mar. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 13. Commitments and Contingencies Leases The Company currently leases office space for both our U.K. and U.S. headquarters on a short-term basis. The lease for our U.K. headquarters, located in London, expires in July 2025, unless terminated earlier with not less than three months notice. The Company leases its U.S. headquarters virtual office, located in Boston, Massachusetts, on a month-to-month basis. The Company also leases laboratory space, located in San Francisco, California, which expires in September 2025 and is cancellable anytime with 60 days’ notice. The Company is not party to any material lease agreements. For each of the three months ended March 31, 2025 and 2024, the Company incurred lease costs of less than $0.1 million. Employee Benefit Plans The Company adopted an employee benefit plan under Section 401(k) of the Internal Revenue Code for its U.S.-based employees. The plan allows employees to make contributions up to a specified percentage of their compensation. Under the plan, the Company matches 100% of employees’ contributions up to 5% of the annual eligible compensation contributed by each employee, subject to Internal Revenue Code limitations. The Company also adopted a defined contribution pension scheme which allows for U.K. employees to make contributions and provides U.K. employees with a Company contribution of 10% of compensation, subject to U.K. law. During each of the three months ended March 31, 2025 and 2024, the Company charged less than $0.1 million to operating expenses related to the Company's contributions to employee benefit plans. Bayer Acquisition Agreement In November 2024, the Company assumed an assignment, license, development and commercialization agreement dated March 17, 2017 with Bayer (the “Bayer Acquisition Agreement”), to acquire from Bayer all right, title and interest in and to PHP-303, including each and every invention and any priority rights relating to its patents. Under the Bayer Acquisition Agreement, the Company is committed to pay certain development and regulatory milestones up to an aggregate amount of $23,500,000 and high single digit royalties based on the sale of products developed based on the licensed compound. Royalties will be payable on a licensed product-by-licensed product and country-by-country basis until the later of ten years after the first commercial sale of such licensed product in such country and expiration of the last patent covering such licensed product in such country that would be sufficient to prevent generic entry. Either party may terminate the Bayer Acquisition Agreement upon prior written notice for the other party’s material breach that remains uncured for a specified period of time or insolvency. Bayer agreed not to assert any Bayer intellectual property rights that were included in the scope of the Bayer Acquisition Agreement against the Company. The Company incurred zero expenses under this agreement as no milestones have been achieved since inception, and no products were sold from inception through March 31, 2025. Legal Proceedings In December 2024, the Company received demand letters from two individuals formerly serving the Company as consultants outlining claims relating to wrongful termination. The wrongful termination claims included claims for unpaid consulting fees, consulting fees owed due to improper termination notice, unpaid bonuses, severance, and the accelerated vesting of outstanding restricted stock unit awards as of the termination date. On March 3, 2025, the Company signed a Settlement Agreement and Mutual Release with one of its former consultants. The agreement requires the Company to make a payment in the amount of $0.3 million in nine equal monthly installments beginning in March 2025. In addition, the agreement allows for the terms of the restricted stock unit award to continue to govern, including the continued vesting of the restricted stock units through the first anniversary of the grant (May 1, 2025). As of March 31, 2025 and December 31, 2024, the Company recognized $0.5 million in aggregate representing the settlement amount, and an estimate for the second individual's claims, which is presented within “accounts payable” and “accrued expenses” in the Company’s condensed consolidated balance sheets. On November 21, 2024, “Sabby” Volatility Warrant Master Fund Ltd. (“Sabby”) filed a lawsuit against the Company in New York state court for alleged breach of contract. Sabby alleges that it validly exercised a warrant issued to Sabby in September 2022 and alleges that the Company breached the warrant by not honoring Sabby's exercise request. On May 7, 2025, the Company and Sabby entered into a Settlement Agreement pursuant to which the Company will issue ADSs to Sabby at a future date equivalent to the agreed settlement amount, which has been accrued as of March 31, 2025.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2025

Commitments and Contingencies Disclosure [Abstract]

Note 13. Commitments and Contingencies

Leases

The Company currently leases office space for both our U.K. and U.S. headquarters on a short-term basis. The lease for our U.K. headquarters, located in London, expires in July 2025, unless terminated earlier with not less than three months notice. The Company leases its U.S. headquarters virtual office, located in Boston, Massachusetts, on a month-to-month basis. The Company also leases laboratory space, located in San Francisco, California, which expires in September 2025 and is cancellable anytime with 60 days’ notice. The Company is not party to any material lease agreements.

For each of the three months ended March 31, 2025 and 2024, the Company incurred lease costs of less than $0.1 million.

Employee Benefit Plans

The Company adopted an employee benefit plan under Section 401(k) of the Internal Revenue Code for its U.S.-based employees. The plan allows employees to make contributions up to a specified percentage of their compensation. Under the plan, the Company matches 100% of employees’ contributions up to 5% of the annual eligible compensation contributed by each employee, subject to Internal Revenue Code limitations.

The Company also adopted a defined contribution pension scheme which allows for U.K. employees to make contributions and provides U.K. employees with a Company contribution of 10% of compensation, subject to U.K. law.

During each of the three months ended March 31, 2025 and 2024, the Company charged less than $0.1 million to operating expenses related to the Company's contributions to employee benefit plans.

Bayer Acquisition Agreement

In November 2024, the Company assumed an assignment, license, development and commercialization agreement dated March 17, 2017 with Bayer (the “Bayer Acquisition Agreement”), to acquire from Bayer all right, title and interest in and to PHP-303, including each and every invention and any priority rights relating to its patents.

Under the Bayer Acquisition Agreement, the Company is committed to pay certain development and regulatory milestones up to an aggregate amount of $23,500,000 and high single digit royalties based on the sale of products developed based on the licensed compound. Royalties will be payable on a licensed product-by-licensed product and country-by-country basis until the later of ten years after the first commercial sale of such licensed product in such country and expiration of the last patent covering such licensed product in such country that would be sufficient to prevent generic entry.

Either party may terminate the Bayer Acquisition Agreement upon prior written notice for the other party’s material breach that remains uncured for a specified period of time or insolvency. Bayer agreed not to assert any Bayer intellectual property rights that were included in the scope of the Bayer Acquisition Agreement against the Company.

The Company incurred zero expenses under this agreement as no milestones have been achieved since inception, and no products were sold from inception through March 31, 2025.

Legal Proceedings

In December 2024, the Company received demand letters from two individuals formerly serving the Company as consultants outlining claims relating to wrongful termination. The wrongful termination claims included claims for unpaid consulting fees, consulting fees owed due to improper termination notice, unpaid bonuses, severance, and the accelerated vesting of outstanding restricted stock unit awards as of the termination date. On March 3, 2025, the Company signed a Settlement Agreement and Mutual Release with one of its former consultants. The agreement requires the Company to make a payment in the amount of $0.3 million in nine equal monthly installments beginning in March 2025. In addition, the agreement allows for the terms of the restricted stock unit award to continue to govern, including the continued vesting of the restricted stock units through the first anniversary of the grant (May 1, 2025). As of March 31, 2025 and December 31, 2024, the Company recognized $0.5 million in aggregate representing the settlement amount, and an estimate for the second individual's claims, which is presented within “accounts payable” and “accrued expenses” in the Company’s condensed consolidated balance sheets.

On November 21, 2024, “Sabby” Volatility Warrant Master Fund Ltd. (“Sabby”) filed a lawsuit against the Company in New York state court for alleged breach of contract. Sabby alleges that it validly exercised a warrant issued to Sabby in September 2022 and alleges that the Company breached the warrant by not honoring Sabby's exercise request. On May 7, 2025, the Company and Sabby entered into a Settlement Agreement pursuant to which the Company will issue ADSs to Sabby at a future date equivalent to the agreed settlement amount, which has been accrued as of March 31, 2025.