Methionine tumor starvation by erythrocyte‐encapsulated methionine gamma‐lyase activity controlled with per os vitamin B6

Abstract

Erymet is a new therapy resulting from the encapsulation of a methionine gamma‐lyase (MGL; EC number 4.4.1.11) in red blood cells (RBC). The aim of this study was to evaluate erymet potential efficacy in methionine (Met)‐dependent cancers. We produced a highly purified MGL using a cGMP process, determined the pharmacokinetics/pharmacodynamics (PK/PD) properties of erymet in mice, and assessed its efficacy on tumor growth prevention. Cytotoxicity of purified MGL was tested in six cancer cell lines. CD1 mice were injected with single erymet product supplemented or not with vitamin B6 vitamer pyridoxine (PN; a precursor of PLP cofactor). NMRI nude mice were xenografted in the flank with U‐87 MG‐luc2 glioblastoma cells for tumor growth study following five intravenous (IV) injections of erymet with daily PN oral administration. Endpoints included efficacy and event‐free survival (EFS). Finally, a repeated dose toxicity study of erymet combined with PN cofactor was conducted in CD1 mice. Recombinant MGL was cytotoxic on 4/6 cell lines tested. MGL half‐life was increased from <24 h to 9–12 days when encapsulated in RBC. Conversion of PN into PLP by RBC was demonstrated. Combined erymet + PN treatment led to a sustained Met depletion in plasma for several days with a 85% reduction of tumor volume after 45 days following cells implantation, and a significant EFS prolongation for treated mice. Repeated injections in mice exhibited a very good tolerability with only minor impact on clinical state (piloerection, lean aspect) and a slight decrease in hemoglobin and triglyceride concentrations. This study demonstrated that encapsulation of methioninase inside erythrocyte greatly enhanced pharmacokinetics properties of the enzyme and is efficacy against tumor growth. The perspective on these results is the clinical evaluation of the erymet product in patients with Met starvation‐sensitive tumors.

A Translational In Vivo and In Vitro Metabolomic Study Reveals Altered Metabolic Pathways in Red Blood Cells of Type 2 Diabetes

“…This heme glycosylation tends to shift the oxygen dissociation curve to left, leading to an increase in haemoglobin–oxygen affinity and reduced oxygen delivery to tissues [ 26 , 27 , 28 ]. Furthermore, metabolite transport and basal metabolism of RBCs can be compromised in T2D, thus impairing the delivery of certain compounds to several tissues [ 29 , 30 , 31 ].…”

Enzyme-mediated depletion of serum l -Met abrogates prostate cancer growth via multiple mechanisms without evidence of systemic toxicity

“…Unfortunately, neither humans nor other mammals encode L-Met-degrading enzymes. Red blood cell encapsulation of pMGL is being evaluated as a means of preventing immune recognition of the enzyme; however, this approach does not overcome the rapid deactivation of pMGL, which occurs due to loss of its cofactor, pyridoxal phosphate (PLP, or vitamin B 6 ) (41). The closest human homolog to pMGL (61% amino acid identity) is cystathionine-γ-lyase (hCGL), the last enzyme of the mammalian transsulfuration pathway that catalyzes the α,γ-elimination of L-cystathionine to L-Cys, α-ketobutyrate, and NH 3 .…”

Effects in Cancer Cells of the Recombinant l-Methionine Gamma-Lyase fromBrevibacterium aurantiacum.Encapsulation in Human Erythrocytes for Sustained l-Methionine Elimination

“…Furthermore, in this configuration, absence of a,b-elimination of L-cysteine with the MGL-BL929 should have limited or no impact on glutathione synthesis, whose deficiency would shorten enzyme-loaded erythrocyte lifespan (Meister and Anderson, 1983). As reported with the MGL from P. putida (Gay et al, 2017), we successfully built a bioreactor with durable catalytic MGL function by encapsulation of the MGL-BL929 into human erythrocytes. Under present experimental conditions, the intracellular erythrocyte environment durably preserves MGL activity.…”