Blinded Cell Therapy Trial Reveals Significant Treatment Effect in Study Arms

An interim analysis of results from a phase 2 clinical trial evaluating an allogeneic bone marrow-derived mesenchymal stem cell (MSC) therapy for the treatment of Parkinson disease (PD) showed a significant difference in treatment effect between its 3 arms; although, the results are blinded, and it is unclear whether the patients in the arm with the highest treatment effect received treatment with the MSC therapy or a placebo alone. The results were presented in a poster at the 2023 International Congress of Parkinson’s Disease and Movement Disorders (MDS), held August 27-31, in Copenhagen, Denmark.

Participants in the study were divided into treatment arms referred to as Arm 0 (n = 14), Arm 1 (n = 15), and Arm 2 (n = 16). One of these arms received treatment with 2 infusions of 1x10⁶ MSC/kg and 1 infusion of a placebo; another of these arms received treatment with 3 infusions of 1x10⁶ MSC/kg; and another arm received treatment with 3 infusions of placebo alone. Because of the blinding, it is not known at this time which of these treatment courses was given to Arms 0-2.

The interim analysis, which was conducted at 1 month after each patient received their last infusion, used the MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) total score and score for Part III (MDS-UPDRS-III); lower scores on this scale represent less severe symptoms. It was found that patients in Arm 0 experienced an estimated treatment effect on MDS-UPDRS-III of 0.355 (95% CrL 0.141-0.631). For patients in Arm 1 this was 0.946 (95% CrL 0.752-0.998) and for patients in Arm 2 this was >0.99 (95% CrL 0.933->0.99). Furthermore, the probability of a decrease of 5 points or greater in MDS-UPDRS-III score was 36%, 93%, and 100% for Arm 0, Arm 1, and Arm 2 respectively. Patients in Arm 0 showed a mean decrease from baseline in MDS-UPDRS-III score of 5.86 (9.5% decrease), patients in Arm 1 showed a mean decrease of 12.20 (34.6%), and patients in Arm 2 showed a mean decrease of 16.13 (43.4%). With regard to MDS-UPDRS total score, patients in arm 0 showed a mean decrease from baseline of 7.09 (11.3% decrease), patients in arm 1 showed a mean decrease of 18.87 (28.6%), and patients in arm 2 showed a mean decrease of 26.50 (40.1%).

The characteristics of the patients across the 3 arms at baseline were deemed similar to one another with no statistically significant differences recorded. In terms of demographics, Arm 0 included 3 women and 11 men with a median age of 66.9 years and a median disease duration of 4.7 years. This group included 2 patients of hispanic ethnicity and 12 patients of caucasian ethnicity. Arm 1 included 3 women and 12 men with a median age of 68.6 years and a median disease duration of 5.5 years; the group included 2 patients of hispanic ethnicity, 1 patient of Asian ethnicity, and 12 patients of caucasian ethnicity. Arm 2 included 4 women and 12 men; the group’s median age was 64.3 years, and the median disease duration was 5.1 years; 6 patients of hispanic ethnicity and 10 patients of caucasian ethnicity were included.

“This is an interim analysis, and we are still blinded as to which group got placebo and which groups received MSC's,” first author Mya C. Schiess, MD, a professor of neurology and program director of the Movement Disorders Fellowship Training Program at UT Health McGovern Medical School, told CGTLive™. “We do not know which is the placebo group. The analysis was done to make sure no detrimental effects (worsening of scores which would be reflected as an increase in the scores—both motor and total) and to show that there was a difference between groups… Each group does show a decline in scores—certainly some greater than others, and there is reportedly a placebo effect noted in most PD trials.”

Schiess additionally noted to CGTLive that the study was the first FDA-cleared trial in the US for an allogeneic adult bone-marrow-derived MSC therapy aimed at slowing the progression of PD. She also noted that as of September 8, 2023, the trial is completed, having lasted 88 weeks. Patients have now been followed-up for 52 weeks after their last infusions, but data entry and analysis remain ongoing. Schiess stated that the final outcomes of the trial will likely be reported in December 2023.

REFERENCE
Schiess M, Suescun J, Green C, et al. Preliminary Report on the efficacy of Allogeneic Bone marrow-derived Mesenchymal Stem Cells as a disease-modifying therapy for idiopathic Parkinson’s disease: Phase IIa double-blind, randomized controlled trial. Presented at: the 2023 International Congress of Parkinson’s Disease and Movement Disorders (MDS), held August 27-31, in Copenhagen, Denmark. Abstract #117