Company: SHPH
Filing Date: 2025-04-21
Form Type: DEFR14A
Source: 0001641172-25-005474
Chunk: 1

Company: Shuttle Pharmaceuticals Holdings, Inc.
Filing Date: 2025-04-21
Form: DEFR14A
Chunk 1
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 flexibility of the reverse stock split the Company is seeking stockholder approval
on and corrects a scrivener’s error in the description of the Company’s employment agreements under Proposal No. 5. Aside
from the aforementioned, no other items or disclosures have changed from the Proxy Statement originally filed with the SEC and mailed
to stockholders. For the ease of investor voting, the Company is delivering the fully updated proxy statement to investors.

<div align='center'>SHUTTLE PHARMACEUTICALS HOLdIngS, InC.</div>

2025 Annual Meeting of Stockholders

April 21, 2025

Dear Shareholders,

It is with great excitement
that I write to review the key milestones that have been reached over the past year and those that remain in focus to advance Shuttle
Pharma’s mission to improve outcomes for cancer patients receiving radiation therapy (RT).

LEAD PROGRAM LAUNCHED WITH ENROLLMENT MEETING ALL EXPECTATIONS

The biggest milestone achieved this past year was the successful launch of our Phase 2 trial of Ropidoxuridine and RT for treatment
of patients with glioblastoma. We officially reached that milestone in November 2024 when the first patients had been enrolled and treated
at three of the six cancer center affiliates: UVA Cancer Center, Miami Cancer Institute, part of Baptist Health South Florida, and the
John Theurer Cancer Center at Hackensack University Medical Center.

Since the first patients
were dosed, enrollment into the clinical trial has been robust and has met all expectations. As of writing this letter, we have achieved 43% enrollment in the initial randomized
phase of the clinical trial with a total enrollment of 17 of the initial 40 patients. Further, 11 of the 40 patients have completed all
seven cycles. Our objective is to finalize enrollment later this year with follow up and data read out in 2026.

Leading up to trial
commencement, we successfully onboarded all six nationally recognized, East Coast cancer centers. The six centers were chosen for their recognized state-of-the-art
cancer care and the availability of patients presenting with the most aggressive form of brain tumors – IDH wild-type,
methylation negative glioblastoma, the target of the clinical trial.

As a reminder, the Phase
2 clinical trial design initially randomizes 40 patients into two different dose levels of drug, with 20 patients receiving 1,200 mg/day
and 20 patients receiving 960 mg/day