A proprietary GMP human platelet lysate for the expansion of dermal fibroblasts for clinical applications.

Recent years have witnessed the introduction of ex vivo expanded dermal fibroblasts for several cell therapy and tissue-engineering applications, including the treatment of facial scars and burns, representing a promising cell type for regenerative medicine. We tested different in-house produced human platelet lysate (HPL) solutions against fetal bovine serum as supplements for in vitro fibroblast expansion by comparing cell yield, molecular marker expression, extracellular matrix (ECM) generation, genomic stability and global gene expression. Our in-house produced HPL supported fibroblast growth at levels similar to those for FBS and commercial HPL products and was superior to AB human serum. Cells grown in HPL maintained a fibroblast phenotype (VIM+, CD44+, CD13+, CD90+), ECM generation capacity (FN+, COL1+) and a normal karyotype, although gene expression profiling revealed changes related to cell metabolism, adhesion and cellular senescence. The HPL manufacturing process was validated within a GMP compliant system and the solution was stable at -80ºC and -20ºC for 2 years. Dermal fibroblasts expanded in vitro with HPL maintain a normal karyotype and expression of fibroblast markers, with only minor changes in their global gene expression profile. Our in-house produced GMP-HPL is an efficient, safe and economical cell culture supplement that can help increase the healthcare activity of blood transfusion centers through the re-use of transfusional plasma and platelets approaching their expiration date. Currently, our HPL solution is approved by the Spanish Agency of Medicines and Medical Devices and is being used in the manufacture of cell therapy products.Abbreviations: AB plasma: plasma group AB; ABHS: AB Human Serum; ABHS+GF: AB Human Serum supplemented with growth factors; ANOVA: Analysis of variance; ATMPs: Advanced Therapies for Medicinal Products; CPE: cytopathic effect; DEGs: Differentially expressed genes; DMEM: Dulbecco's modified Eagle's Medium; ECM: Extracellular matrix; ELISA: enzyme-linked immunosorbent assay; FBS: Fetal bovine serum; FDR: False discovery rate; FGF: Fibroblast growth factor; GMP: Good manufacturing practice; HPL: Human platelet lysate; HPL-CM: commercial human platelet lysate; MSCs: mesenchymal stem cells; NEAA: non-essential amino acids; P/S: penicillin/streptomycin; PBS: phosphate buffered saline; PC: leukodepleted platelet concentrate; PCR: polymerase chain reaction; PDGF: Platelet-derived growth factor; PDGFRA: Platelet-derived growth factor receptor alpha; qPCR: quantitative polymerase chain reaction; RNA: Ribonucleic acid; RT: Room temperature; TAC: Transcriptome analysis console; TGF-ß: Transforming growth factor beta.

Next-generation BCMA-targeted chimeric antigen receptor CARTemis-1: the impact of manufacturing procedure on CAR T-cell features.

PURPOSE: CAR therapy targeting BCMA is under investigation as treatment for multiple myeloma. However, given the lack of plateau in most studies, pursuing more effective alternatives is imperative. We present the preclinical and clinical validation of a new optimized anti-BCMA CAR (CARTemis-1). In addition, we explored how the manufacturing process could impact CAR-T cell product quality and fitness. METHODS: CARTemis-1 optimizations were evaluated at the preclinical level both, in vitro and in vivo. CARTemis-1 generation was validated under GMP conditions, studying the dynamics of the immunophenotype from leukapheresis to final product. Here, we studied the impact of the manufacturing process on CAR-T cells to define optimal cell culture protocol and expansion time to increase product fitness. RESULTS: Two different versions of CARTemis-1 with different spacers were compared. The longer version showed increased cytotoxicity. The incorporation of the safety-gene EGFRt into the CARTemis-1 structure can be used as a monitoring marker. CARTemis-1 showed no inhibition by soluble BCMA and presents potent antitumor effects both in vitro and in vivo. Expansion with IL-2 or IL-7/IL-15 was compared, revealing greater proliferation, less differentiation, and less exhaustion with IL-7/IL-15. Three consecutive batches of CARTemis-1 were produced under GMP guidelines meeting all the required specifications. CARTemis-1 cells manufactured under GMP conditions showed increased memory subpopulations, reduced exhaustion markers and selective antitumor efficacy against MM cell lines and primary myeloma cells. The optimal release time points for obtaining the best fit product were > 6 and < 10 days (days 8-10). CONCLUSIONS: CARTemis-1 has been rationally designed to increase antitumor efficacy, overcome sBCMA inhibition, and incorporate the expression of a safety-gene. The generation of CARTemis-1 was successfully validated under GMP standards. A phase I/II clinical trial for patients with multiple myeloma will be conducted (EuCT number 2022-503063-15-00).