Stem Cell Therapy Shows Potential for Challenging Refractory Angina Patients

May 5, 2016—The Society for Cardiovascular Angiography and Interventions (SCAI) announced that results from the RENEW study of stem cell therapy to treat patients with challenging refractory angina (RA) demonstrated promising results, including improved exercise time, reduced angina, and reduced mortality. The RENEW results were presented as a late-breaking clinical trial at the SCAI 2016 scientific sessions in Orlando, Florida. The study was accepted for publication in JACC: Cardiovascular Interventions. 

According to SCAI, RENEW was designed to determine the effectiveness of granulocyte-colony stimulating factor (G-CSF) mobilized CD34+ stem cells to treat RA patients. G-CSF triggers the bone marrow to produce white blood cells and stem cells and release them into the bloodstream. In preclinical models, CD34+ stem cells have been shown to increase blood flow.

RENEW Coprincipal Investigator Timothy D. Henry, MD, commented in the SCAI announcement, “Clinicians are seeing more RA patients because people are living longer. Unfortunately, despite better medical care, these people are still confronting ongoing symptoms that affect their daily lives.” Dr. Henry is Director, Division of Cardiology at the Cedars-Sinai Heart Institute in Los Angeles, California. 

As summarized by SCAI, the patients had class 3 or 4 angina on maximally tolerated medical management, had at least seven episodes of chest pain per week, were not candidates for revascularization, and had treadmill exercise times of 3 to 10 minutes. 

Patients were randomized into three groups: 28 to open-label standard of care (SOC), 27 to blinded placebo injections (PL), and 57 to treatment with CD34+ cells. The investigators assessed treadmill exercise time and angina frequency at 3, 6, and 12 months and major adverse cardiac events (MACE) for up to 2 years.

The investigators found that exercise time for cell-treated patients increased by more than 2 minutes at 3 months (122 seconds), 6 months (142 seconds), and 12 months (124 seconds). This group also experienced a 40% decrease (relative risk, 0.57) of angina at 6 months when compared to the PL group.

At 2 years, the CD34+ cell group demonstrated lower rates of mortality (3.7%) when compared with PL (10%) and SOC (7.1%). The study also reported higher rates of MACE after 2 years for SOC patients (68%) versus CD34+ cell (46%) and PL (43%) patients.

Dr. Henry concluded, “Cell therapy appears to be a promising approach for these patients who have few options. Our results were consistent with phase 2 results from the ACT34 trial.”

The investigators aim was to include 444 RA patients; however, final results are based on 112 patients. The sponsor prematurely terminated the trial because of financial considerations, noted SCAI.

RENEW Coprincipal Investigator Tom Povsic, MD, stated in the SCAI announcement, “It is unfortunate the early termination of this study precludes a full evaluation of the efficacy of this therapy for these patients with very few options. Studies like RENEW are critical to developing reliable and effective cellular therapies for heart patients, and continued funding is essential to advancing the work that this study began. We need to find a way to bring these therapies to patients as quickly and safely as possible.” Dr. Povsic is Associate Professor at the Duke Clinical Research Institute and an interventional cardiologist at Duke University School of Medicine in Durham, North Carolina.