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EURopean Endeavour for Chimeric Antigen Receptor Therapies

Periodic Reporting for period 3 - EURE-CART (EURopean Endeavour for Chimeric Antigen Receptor Therapies)

Reporting period: 2020-01-01 to 2021-06-30

The EURE-CART project aims to study adoptive immunotherapy with autologous T cells genetically modified with a tumor-reactive chimeric antigen receptor (CAR). CART cells specific for CD19 and BCMA, have received a conditional marketing authorization in EU and US, for the treatment of some haematological tumors. On this ground, EURE-CART is dealing with a new CAR directed against CD44v6, which is expressed in acute myeloid leukemias (AML) and multiple myelomas (MM), as well as in the majority of carcinomas. Main objective of EURE-CART is to conduct a multicentre, first-in-man Phase I/IIa clinical trial in different EU member countries, to demonstrate safety and efficacy of CD44v6 CART cells in AML and MM. Moreover, a key objective of EURE-CART is to obtain regulatory approval for a single, harmonised CART cell product in 4 EU member countries. In addition, EURE-CART has designed a preclinical program aimed at identifying and validating new target antigens and receptors, to improve CART cell therapy.
First step of the EURE-CART project was the preparation of the Clinical Trial Application (CTA) required for activation of the clinical study. To this aim: i) efficacy and safety studies of lymphocytes expressing the CD44v6.CAR and the HSV-TK suicide gene (EURE-CART cells) were successfully performed in AML and MM tumor models (WP1); ii) a reproducible method to measure CD44v6 expression was developed and validated on tumor samples from AML and MM patients, to screen enrolled patients (WP1); iii) manufacturing process and analytical methods to produce clinical-grade EURE-CART cells, were developed (WP2); iv) Cytokine analysis, FACS and qPCR assays for patient’s follow-up were set up and validated to harmonize the procedures between local and central laboratories (WP5); v) Top-level experts were appointed as members of the Regulatory Advisory Committee to give inputs on the strategy for approaching regulatory issues of EURE-CART (WP3).
Submission of the Investigational Medicinal Product Dossier and the Clinical Protocol, through the Voluntary Harmonized Procedure (VHP) was denied. Therefore, the EURE-CART-1 study was submitted to the single National Competent Authorities (NCA) of Italy, Czech Republic, Germany and Spain.
During CTA assessment different /inconsistent concerns were raised leading to the approval only in Italy and Czech Republic (WP2 WP3 WP4). To address the concerns raised by the Spanish NCA, a second CTA submission was made, but the outcome was negative. Since the activities required to address the raised concerns were not compatible with the timelines and budget of the EURE-CART grant, only the Italian and Czech clinical centres were activated to recruit patients in the EURE-CART-1 study.
Until the early termination of the study, 8 MM patients were recruited. Six were excluded from the study due to disease progression, infection or lack of CD44v6 expression by their tumor cells. Two patients underwent treatment with the lowest dose level of EURE-CART cells, produced by MLM (WP2). The infusion was safe and well tolerated. No signs of activity were observed and patients underwent disease progression about 1 month post infusion. The faint and transient amount of CART cells detected in the circulation of 1 of the 2 treated patients, from day 7 to day 14 post-infusion, suggested that the absence of CART cells engraftment, is probably related to the low number of cells infused (WP5).
In parallel with the clinical activities, the studies aimed at the validation of the next-generation EURE-CART cells have obtained the following results (WP06). i) SLAMF7 and Siglec-6 were identified as novel candidate antigens for CART cell therapy of MM and AML, respectively. Their expression is absent or low on healthy tissues, with the exception of B cells and some T cell subpopulation for SLAMF7, and memory B cells and basophils for Siglec-6, thus suggesting the potential for limited on-target/off-tumor reactivity in patients; ii) the validation of a critical improvement in CART cell manufacturing, which through prevention of fratricide by CRISPR/Cas9 gene editing, increases the scalability and industrial applicability of CART cell products; iii) a successful approach for the early identification of suitable CART target antigens, based on the combined use of gene profiling, qPCR, western blotting and super-resolution microscopy; iv) the setting of pre-clinical in vivo models to support translational development, based on the use of primary AML and autologous patient-derived CART cells; v) the development of strategies to prevent antigen escape and tumor relapse by targeting multiple antigens with bi-specific CART cells or by sensitizing tumors to CART cell attack with deglycosilating agents that decrease CART cell activation threshold and exhaustion.
Concerning the overall management of the EURE-CART project (WP7) and the dissemination and exploitation of EURE-CART results (WP8): i) All the required relevant authorisations for the Project activities were submitted as deliverables to the EU Commission (WP9); ii) Procedures, management methods and tools, to facilitate the fulfilment of contractual duties were set up; iii) Online submission of deliverables was carried out and rules for decision-making processes were made fully operational; iv) A regular update of the WPs activities was ensured by teleconference, and face to face meeting. A total of 6 General Assembly meetings (2 remotely) and 9 Steering Committee meetings were organised; v) Amendments were submitted for a no-cost extension of the project due to COVID emergency and for adjustments of the DoA; vi) A detailed plan of the dissemination and communication was implemented. The public website was set up providing all relevant information about the project. Twitter and Linkedin accounts have been set up and used. Workshops were organised and press releases were published by several partners.
Overall, the preliminary safety indications obtained will allow future clinical studies to start treatments from a high dose level. This, along with the ability of CD44v6.CART cells to control the growth of carcinomas, most of which are known to express the CD44v6 antigen, makes the CD44v6.CART cell product developed by EURE-CART an attractive product for academic and industrial investors in gene therapy. Moreover, additional CAR targets (i.e. SLAMF7) and new agents for combinatorial strategies were identified. Thus, in the long run, the outcome of the EURE-CART project should benefit the EU population by improving its health and increasing at the same time the competitiveness of the EU biomedical and pharmaceutical industry through the generation of new scientific knowledge. In addition, the negative experience of the EURE-CART Consortium in the assessment and approval of a multicentre clinical study of gene therapy has been described in a White Paper, which has been disseminated to the EU commission, academic and regulatory bodies for the benefit of upcoming clinical trials with CAR-T cell medicinal products.