Cardiac Function Improvement and Bone Marrow Response -: Outcome Analysis of the Randomized PERFECT Phase III Clinical Trial of Intramyocardial CD133+ Application After Myocardial Infarction

Abstract

Objective: The phase III clinical trial PERFECT was designed to assess clinical safety and efficacy of intramyocardial CD133⁺ bone marrow stem cell treatment combined with CABG for induction of cardiac repair.

Design: Multicentre, double-blinded, randomised placebo controlled trial.

Setting: The study was conducted across six centres in Germany October 2009 through March 2016 and stopped due slow recruitment after positive interim analysis in March 2015.

Participants: Post-infarction patients with chronic ischemia and reduced LVEF (25-50%).

Interventions: Eighty-two patients were randomised to two groups receiving intramyocardial application of 5ml placebo or a suspension of 0.5-5×10⁶ CD133⁺.

Outcome: Primary endpoint was delta (∆) LVEF at 180days (d) compared to baseline measured in MRI.

Findings (prespecified): Safety (n=77): 180d survival was 100%, MACE n=2, SAE n=49, without difference between placebo and CD133⁺. Efficacy (n=58): The LVEF improved from baseline LVEF 33.5% by +9.6% at 180d, p=0.001 (n=58). Treatment groups were not different in ∆LVEF (ANCOVA: Placebo +8.8% vs. CD133⁺ +10.4%, ∆CD133⁺vs placebo +2.6%, p=0.4).

Findings (post hoc): Responders (R) classified by ∆LVEF≥5% after 180d were 60% of the patients (35/58) in both treatment groups. ∆LVEF in ANCOVA was +17.1% in (R) vs. non-responders (NR) (∆LVEF 0%, n=23). NR were characterized by a preoperative response signature in peripheral blood with reduced CD133⁺ EPC (RvsNR: p=0.005) and thrombocytes (p=0.004) in contrast to increased Erythropoeitin (p=0.02), and SH2B3 mRNA expression (p=0.073). Actuarial computed mean survival time was 76.9±3.32months (R) vs. +72.3±5.0months (NR), HR 0.3 [Cl 0.07-1.2]; p=0.067.Using a machine learning 20 biomarker response parameters were identified allowing preoperative discrimination with an accuracy of 80% (R) and 84% (NR) after 10-fold cross-validation.

Interpretation: The PERFECT trial analysis demonstrates that the regulation of induced cardiac repair is linked to the circulating pool of CD133+ EPC and thrombocytes, associated with SH2B3 gene expression. Based on these findings, responders to cardiac functional improvement may be identified by a peripheral blood biomarker signature.

Trial registration: ClinicalTrials.govNCT00950274.

Keywords: Angiogenesis; CD133(+); CD34(+); Cardiac repair; Cardiac stem cell therapy; Endothelial progenitor cell (EPC); Lnk adaptor; Randomised double-blinded phase III multicentre trial; SH2B3.

Graphical abstract

Fig. 1

PERFECT Trial flowchart and prespecified or post hoc analysis sets. The randomised multicentre trial was performed double-blinded placebo controlled through six heart centres in Germany according to ICH-GCP and is depicted according to CONSORT and STARD guidelines:1 A total of 119 patients were screened in 6 centres in Germany from Sept. 2009 through June 2015. All patients signed the informed consent form and were included in the study. Thirty-seven participants were excluded before randomisation due to newly identified exclusion criteria such as severe arrhythmia. 2 Eighty-two (82) patients were randomised to active treatment or placebo. Two (Stamm et al., 2003) patients were randomised but not treated because the CD 133 + preparation did not comply with the release criteria for GMP. 3 Forty (48.8%) patients received an injection of CD133 + cells and 40 (48 ⋅ 8%) received an injection of placebo. 4 Three patients were excluded because of insufficient CD133 + cell count below minimum dosis resulting in the safety-analysis-population (n = 77). 5 After a careful review of the blinded data in a blind data review meeting conducted on the 20 May 2016 a total of 19 patients were excluded from the full analysis population due to protocol violations with incomplete MRI follow-up data leading to the Per Protocol Set (PPS) efficacy-analysis-population (n = 58). Patient distribution for PPS efficacy population by study centres: German Heart Center Berlin 8%, Medical School Hannover 28%, University Medicine Rostock 38%, Heart and Diabetes Center Bad Oeynhausen 5%, Heart Center Leipzig 13%, University Medicine Hamburg 10%. 6 Additional MRI at day 10 postoperative for subanalysis of early and late postoperative changes for subgroup analysis early and late postoperative changes. 7 Post hoc analysis for actuarial survival was performed in registry analysis 7 years after FPI on Nov. 1, 2016. 8 Post hoc analysis was additionally performed in the efficacy group (n = 58) to unravel contributing non CD133⁺ injection related factors of late improvement. Patients were grouped in the efficacy analysis set according to effective response in primary endpoint as responder or non-responder (Δ LVEF 180 d vs.0 responder ≥ 5% vs. non-responder < 5%). According to this post hoc analysis 35 patients from 58 (60.3%) were responders to treatment. This Responder/non-responder (R/NR) ratio was similar respectively in the placebo group 56 ⋅ 5% (R/NR 17/30 pt.) and in the CD133 + group 64% (R/NR 18/28 pt.) (Placebo vs. CD133 +; p = 0 ⋅ 373). Responder (35/58) and non-responder (23/58) analysis was performed in efficacy group (n = 58). 9 Biomarkers were studied in 39 patients of the efficacy group (n = 58) independent on placebo/CD133 + or responder/non-responder group. All laboratory tests were realized in patients located in the Rostock centre (n = 31), where immediate laboratory analysis of FACS and CFU was guaranteed. Additional patients from other centres (8/58) were evaluated also in the Biomarker cohort according to realized parameters. Biobank at time point (pre- and postoperative day) − 2, − 1, + 1, + 3, + 10, + 180: Peripheral blood MNC/FACS (CD 133, 34, 117, 184, 309, 45, 31, 14), CFU-Hill, serum analysis angiogenesis factors and cytokines; Bone-marrow MNC, Isolated CD133 + FACS (CD133, 34, 117, 184, 309, 45, 31, 14), CFU-EC, RNA-seq.

Fig. 2

Early and late recovery of LVEF in Placebo and CD133⁺ groups. MRI analysis of LVEF (%) is depicted in 29 patients with intermediate MRI at day 10 postoperatively and at 180 days. *p value for delta LVEF at 10 days versus 0. #p value for delta LVEF at 6 months versus 10 days.

Fig. 3

a: Kaplan-Meier survival analysis in longterm follow-up: Placebo vs. CD133⁺. b: Kaplan-Meier survival analysis in longterm follow-up: Responder vs. Non-responder

Fig. 4

SH2B3 expression analysis in peripheral blood of responder and non-responder. Whole blood samples were obtained from 21 patients before coronary artery bypass graft (CABG) revascularization. Relative expression of SH2B3 (a) and corresponding ΔCT values (b) were calculated using the 2^− ΔΔCT method. All values are presented as mean ± SEM and normalized to GAPDH and POLR2A. n = 13 (responder); n = 8 (non-responder). ΔCT values: p = 0.073.

Fig. 5

a Three-dimensional t-SNE calculation of the Rostock subgroup. The variables x and y refer to the newly calculated features that are used to classify the patients into distinct groups. The model was subsequently fitted by a polynomial (n³) equation to visualize the z-axis as a geographic profile. The respective colors for the responder (red dot) and non-responder (grey dot) patients have been added afterwards. The classified groups have been roughly summarized by a red and grey dashed line. Results are obtained after 3000 iterations. The calculation of the ratio between responder and non-responder is indicated for each circle. It is more likely for the non-responder group to be located at smaller z-values (z < 20, ratio < 42%). The responders tend to be enriched within the light blue areas (z > 20) including a ration > 69%. b Obtained supervised ML prediction results for pre- and postoperative time points (0 days to 180 days) of the clinical and clinical & laboratory dataset to distinguish between responder and non-responder. The graph shows the true positive prediction results of five independent feature selected ML models (AdaBoost for feature selection and RF for final prediction).The error bars indicate the respective accuracy standard deviation for the constructed models that have been obtained after 100 iterations. The 100 model iterations are significant different according to one-way ANOVA (p < 0.001).

Fig. 6

Outcome results of the PERFECT trial.