Shuttle Pharmaceuticals pays Alto $75,000 to waive rights to $10 million of notes

Shuttle Pharmaceuticals Holdings, Inc. signed an amendment agreement with Alto Opportunity Master Fund, SPC - Segregated Master Portfolio B on February 26, 2025. Under the amendment, Shuttle paid Alto $75,000. In return, Alto agreed to permanently waive its right to buy up to $10 million of additional notes and additional warrants. Alto also gave a one-time waiver of its right to take part in Shuttle's contemplated registered offering. The company reported the amendment in a Form 8-K signed February 27, 2025 by Chief Executive Officer Anatoly Dritschilo.

What Alto holds

Alto is the registered holder of a warrant to purchase 1,018,079 shares of common stock, which is 127,260 shares after a reverse split. The 8-K says Alto formerly held a $4.3 million convertible note issued by Shuttle, with its wholly owned subsidiary Shuttle Pharmaceuticals, Inc. as guarantor. The amendment changes a securities purchase agreement originally dated January 11, 2023 and amended on May 10, 2023, June 5, 2023 and August 6, 2024. The additional notes and warrants that Alto waived are defined in Section 5 of the May 10, 2023 amendment.

The 8-K does not say why Shuttle agreed to pay for the waiver.

The registered offering

The waiver refers to Shuttle's registration statement on Form S-1, SEC File No. 333-284889, filed with the SEC on February 13, 2025. The 8-K does not name the underwriters, a placement agent or any financial advisor for that offering. It also does not state the size or price of the offering. The amendment itself is attached as Exhibit 10.1, and the 8-K's description of its terms is qualified by that full text.

The company and its lead drug

Shuttle's annual report, filed February 26, 2025, describes a clinical-stage pharmaceutical company developing therapies that it says are designed to cure cancers by extending radiation therapy. Its lead product candidate is Ropidoxuridine, which the report calls a Phase II clinical-stage radiation sensitizer.

The company received a Safe to Proceed letter from the U.S. Food and Drug Administration in January 2024 for an investigational new drug application covering a Phase II study of Ropidoxuridine as a radiation sensitizer during radiotherapy. The study is for patients with newly diagnosed IDH-wildtype glioblastoma with an unmethylated MGMT promoter. The FDA also granted orphan designation for Ropidoxuridine for brain cancer. The annual report says the FDA recommended adding a randomized dose optimization step to the trial, and that Shuttle agreed. It also says the study has commenced.

The report describes the Phase I trial as establishing drug bioavailability and a maximum tolerated dose. It does not report efficacy results for Ropidoxuridine.

Manufacturing and other programs

The annual report names TCG GreenChem, Inc. as the manufacturer of the active pharmaceutical ingredient, and the University of Iowa Pharmaceuticals as the formulator of the capsule drug product. The capsules were shipped to Theradex Oncology, a contract research organization. The company's other candidates include HDAC inhibitors SP-1-161, SP-2-225 and SP-1-303. SP-2-225 is described as an HDAC6 inhibitor in preclinical development.

Shuttle also lists two preclinical prostate cancer diagnostics. The PC-RAD Test is a blood test meant to predict clinical response to radiation therapy, and the PSMA-B ligand is described as a possible theranostic agent.

What the filing leaves open

The 8-K does not give a cash balance or describe how Shuttle will use the registered offering proceeds. The permanent waiver covers up to $10 million of additional notes and warrants, in exchange for the $75,000 payment.

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