An optimized single chain TCR scaffold relying on the assembly with the native CD3-complex prevents residual mispairing with endogenous TCRs in human T-cells

In recent years, onco-metabolites like D-2-hydroxyglutarate, which is produced in isocitrate dehydrogenase-mutated tumors, have gained increasing interest. Here, we report a metabolite in human specimens that is closely related to 2-hydroxyglutarate: the intramolecular ester of 2-hydroxyglutarate, 2-hydroxyglutarate-γ-lactone. Using ¹³C₅-L-glutamine tracer analysis, we showed that 2-hydroxyglutarate is the endogenous precursor of 2-hydroxyglutarate-lactone and that there is a high exchange between these two metabolites. Lactone formation does not depend on mutated isocitrate dehydrogenase, but its formation is most probably linked to transport processes across the cell membrane and favored at low environmental pH. Furthermore, human macrophages showed not only striking differences in uptake of 2-hydroxyglutarate and its lactone but also in the enantiospecific hydrolysis of the latter. Consequently, 2-hydroxyglutarate-lactone may play a critical role in the modulation of the tumor microenvironment.

Manufacturing immune effector cells (T or NK cells) with CAR-encoding DNA sequences requires efficient and safe genetic engineering procedures. For this purpose, an appropriate genetic vector is chosen according to numerous factors, including the vector genome packaging capacity, cellular tropism, genomic integration, immune toxicity, and other factors. In clinical trials, genomes integrating viral vectors, in particular vectors based on members of the Retroviridae family, such as retroviruses and lentiviruses, have been successfully used for more than 20 years. These vectors contain an RNA genome that when transcribed into double-stranded DNA by reverse transcriptase integrates into the genome of the transduced cell.

Background/objectives: MDG1011 is a Preferentially Expressed Antigen in Melanoma (PRAME)-specific autologous T cell receptor (TCR) T cell therapy for HLA-A*02:01-positive patients. Data from the first-in-human (FIH) clinical trial, CD-TCR-001, are reported here regarding treatment feasibility, safety, tolerability, and clinical activity of MDG1011 in patients with relapsed/refractory (r/r) acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and multiple myeloma (MM). Methods: Nine of thirteen enrolled patients received MDG1011 at dose levels ranging from 0.1 to 5 × 10⁶ TCR-T cells per kg body weight. In addition to clinical assessments, immune monitoring of cytokines associated with cytokine release syndrome (CRS), presence and persistence of MDG1011, and changes in levels of PRAME mRNA were used to assess safety and potential biological activity at defined time points. Results: The treatment was well tolerated. No dose-limiting toxicities (DLTs) were observed, and the most common serious adverse events were associated with lymphodepleting chemotherapy and/or disease progression. Various parameters, such as measurable clinical responses in two patients, the occurrence of CRS in two additional patients, and reductions in PRAME mRNA levels in bone marrow (BM) or peripheral blood (PB) in seven patients, served as signs of the clinical and biological activity of MDG1011 TCR-T therapy. Conclusions: Patients enrolled in the phase 1 part of CD-TCR-001 displayed signs of potential clinical and biological activity of MDG1011 among the small number of patients studied. Advanced disease stage and rapid progression in the r/r AML patients limited clinical impact. The acceptable safety profile of MDG1011 merits further investigation of this TCR-T therapy, potentially in patients at an earlier stage of their disease and with lower tumor burden.