Periodic Reporting for period 5 - RETHRIM (Restoring tissue regeneration in patients with visceral Graft versus Host Disease.)
Período documentado: 2021-01-01 hasta 2021-12-31
In addition to the clinical trial, quality of life, health technology assessments and ethical studies regarding patient access to care were to be performed. Output from these studies were foreseen to allow the consortium to formulate a set of measures to convince health authorities, regulatory bodies and insurance companies on the usefulness of MSC therapy and provide suggestions and recommendations for changes in clinical practise, legislation and regulation of MSC regenerative therapy.
However, due to insufficient accrual of patients, the trial did not have sufficient power to detect the anticipated difference between the two treatment arms. With 42 patients included, no statistically significant effect of MSC infusions on aGvHD response on day 28, overall survival, or safety could be demonstrated.
For the drug product, a fully harmonized production protocol was introduced and a detailed IMPD provided. All MSC products were generated, for the reduced number of 42 patients, before recruitment was terminated. To evaluate the purity and identity of the drug product, an 8-color flow cytometry panel based on the Euroflow platform was developed. A potency assay was designed. For both assays a patent was submitted which is currently under consideration at EPO.
To study the immune reconstitution profile, a dedicated sampling collection and handling protocol was developed. Screening of whole blood and biopsy samples for immune markers was performed using CyTOF analysis. Two marker panels (T-cell and non T-cell panels), consisting of lineage-specific markers as well as a set of differentiation, activation and homing markers, allowed for the identification of distinct innate and B cell populations as well as effector T cell subsets with tissue destructive potential which remained persistently high in aGvHD patients who failed to respond to MSC therapy. These cells are equipped with receptors for migration towards aGvHD tissues (GI-tract and skin).
RNA sequencing of PBMC obtained at various time intervals after MSC infusion was performed. This resulted in the identification of a robust immunological neutrophil activation signature in poorly-surviving patients, while an eligibility signature associated with outcome, could not be established. Neutrophil enrichment changed from immature to a granule-rich inflammatory phenotype. Patients who ultimately not survived, were defined by strong neutrophil activation at day 7 post treatment, that persisted throughout the duration of the study. Soluble CD163 was found to be elevated in plasma of the deceased patient subgroup, possibly reflecting the uncontrollable inflammatory responses occurring in these patients. This was supported by the increase of other pro-inflammatory biomarkers such as CXCL9, CD40, altogether indicating the severity of tissue inflammation and the degree of innate and adaptive immune cell activation.
The project dedicated considerable attention to ethical analysis of the method adopted in this trial involving placebo-controls. The analysis justified their use in both adult and paediatric populations in the light of existing international ethical guidelines. Besides placebo-control use, other ethical aspects were analysed such as: difficulties involved in obtaining Europe-wide approval for Phase III randomized placebo-controlled trials; hospital exemption; strong and weak sides of academia-initiated trials as compared to industry-initiated trials; influence of internationally emerging “conditional approval” programs; A manuscript was produced addressing these issues, highlighting the need for a debate about the interpretation and application of current ethical guidelines. Recommendations were developed for conducting randomized placebo-controlled trials where the benefit of the potentially successful experimental treatment amounted to potentially life-saving therapy and the efficacy of existing “best proven” therapy was poor. These recommendations were in no way concurring with the existing ethical guidelines and were rather intended as a checklist of specific issues to be considered in these difficult cases and not an imperative list of steps applicable in all situations. Each recommendation was accompanied by a brief explanatory text of the rationale why it was important to be considered.
The RETHRIM consortium initiated the EU-MSC2 meeting series which assembled all consortia working on MSC therapy. The EU-MSC2 meeting were a success, 10 EU consortia working on MSC therapy joined to discuss progress in the field, EU project officers attended the meetings and participation of regulatory bodies, patient representatives and policy makers allowed for lively discussions to further the field.