Syndecan-1 antigen, a promising new target for triple-negative breast cancer immuno-PET and radioimmunotherapy. A preclinical study on MDA-MB-468 xenograft tumors

International audienceBackgroundOverexpression of syndecan-1 (CD138) in breast carcinoma correlates with a poor prognosis and an aggressive phenotype. The objective of this study was to evaluate the potential of targeting CD138 by immuno-PET imaging and radioimmunotherapy (RIT) using the antihuman syndecan-1 B-B4 mAb radiolabeled with either 124I or 131I in nude mice engrafted with the triple-negative MDA-MB-468 breast cancer cell line.MethodThe immunoreactivity of 125I-B-B4 (80%) was determined, and the affinity of 125I-B-B4 and the expression of CD138 on MDA-MB-468 was measured in vitro by Scatchard analysis. CD138 expression on established tumors was confirmed by immunohistochemistry. A biodistribution study was performed in mice with subcutaneous MDA-MB-468 and 125I-B-B4 at 4, 24, 48, 72, and 96 h after injection and compared with an isotype-matched control. Tumor uptake of B-B4 was evaluated in vivo by immuno-PET imaging using the 124I-B-B4 mAb. The maximum tolerated dose (MTD) was determined from mice treated with 131I-B-B4 and the RIT efficacy evaluated.Results 125I-B-B4 affinity was in the nanomolar range (Kd = 4.39 ± 1.10 nM). CD138 expression on MDA-MB-468 cells was quite low (Bmax = 1.19 × 104 ± 9.27 × 102 epitopes/cell) but all expressed CD138 in vivo as determined by immunohistochemistry. The tumor uptake of 125I-B-B4 peaked at 14% injected dose (ID) per gram at 24 h and was higher than that of the isotype-matched control mAb (5% ID per gram at 24 h). Immuno-PET performed with 124I-B-B4 on tumor-bearing mice confirmed the specificity of B-B4 uptake and its retention within the tumor. The MTD was reached at 22.2 MBq. All mice treated with RIT (n = 8) as a single treatment at the MTD experienced a partial (n = 3) or complete (n = 5) response, with three of them remaining tumor-free 95 days after treatment.ConclusionThese results demonstrate that RIT with 131I-B-B4 could be considered for the treatment of metastatic triple-negative breast cancer that cannot benefit from hormone therapy or anti-Her2/neu immunotherapy. Immuno-PET for visualizing CD138-expressing tumors with 124I-B-B4 reinforces the interest of this mAb for diagnosis and quantitative imaging

Caractérisation de la réponse T cytotoxique à l'aide d'anticorps spécifiques de complexes HLA-A2/Mage3 de tumeur et ciblage des cellules cancéreuses en radioimmunothérapie alpha in vitro

Les lymphocytes T de patients atteints de cancers sont capables de reconnaître les cellules tumorales et de les détruire lorsqu'ils sont stimulés de façon appropriée. Une activité importante de recherche vise à établir les conditions optimales de cette activation et à caractériser les complexes CMH/peptides reconnus. Parmi ces complexes, ceux issus de la famille des " cancer testis antigenes " ont une expression strictement restreinte aux cellules tumorales. Nous avons isolé des anticorps monoclonaux de souris dirigés contre le complexe HLA-A2/Mage3. Ces anticorps nous ont permis de mesurer les densités de complexes exprimées à la surface des cellules, permettant de définir le nombre d'antigènes nécessaires à la réponse cytotoxique de lymphocytes T CD8 spécifiques. D'autre part nous avons évalué la possibilité de cibler ces complexes en radioimmunothérapie à l'aide de radio émetteur alpha dont le fort potentiel radiotoxique permet de compenser la faible expression de surface des complexes CMH/peptide.When stimulated appropriately, the T lymphocytes of cancer patients are able to recognise and destroy tumor cells. A major goal of research in this field is to establish optimal conditions for this T cell response and to characterise the MHC/peptide complexes recognised. Among these complexes, those derived from the family of cancer testis antigens have an expression that is restricted to tumoral cells. We have identified murine monoclonal antibodies directed against the HLA-A2/Mage3 complex. Using these antibodies, we have been able to measure the density of complexes expressed at the cell surface, thus enabling definition of the number of antigens necessary to initiate a cytotoxic response by specific CD8 T lymphocytes. We have additionally evaluated the possibility of targeting these complexes by radioimmunotherapy using an alpha radio emitter whose powerful radiotoxic potential compensates the weak surface expression of MHC/peptide complexes.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Ciblage du système Interleukine-2/récepteur (enjeux thérapeutiques et préventifs dans le rejet d'allogreffe et les hémopathies malignes )

Découvert il y a plus de 30 ans, l'IL-2 reste la cytokine la plus étudiée à l'heure actuelle. Il s'agit d'une cytokine majeure du système immunitaire, de part son rôle essentiel dans les réponses immunitaire dépendantes des lymphocytes T. Ses fonctions principales sont d'assurer l'expansion clonale des lymhocytes T régulateurs et cytotoxiques activés par l'antigène. Le rôle central de ces réponses dans les mécanismes de rejet de greffe allogènique à conduit au développement de stratégies de prévention du rejet en ciblant le système IL2 /récepteur à l'IL2 à l'aide d'agents pharmaceutiques interférant avec les signaux transduits par le récepteur ou plus directement en ciblant spécifiquement le récepteur à l'IL2 avec des anticorps monoclonaux ou avec la cytokine modifiée. Cette possibilité de a également permis, en cancérologie, de développer des stratégies de ciblage des leucémies T. Après une partie introductive sur la physiologie des lymphocytes T, la structure et la fonction du sytème IL-2/récepteur, une étude bibliographique présente les développements expérimentaux et thérapeutiques du ciblage du récepteur à l'IL2 dans la prévention du rejet de greffe et dans le traitement des hémopathies malignes (leucémies T ).NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Nanomedicine to overcome radioresistance in glioblastoma stem-like cells and surviving clones

International audienceRadiotherapy is one of the standard treatments for glioblastoma, but its effectiveness often encounters the phenomenon of radioresistance. This resistance was recently attributed to distinct cell contingents known as glioblastoma stem-like cells (GSCs) and dominant clones. It is characterized in particular by the activation of signaling pathways and DNA repair mechanisms. Recent advances in the field of nanomedicine offer new possibilities for radiosensitizing these cell populations. Several strategies have been developed in this direction, the first consisting of encapsulating a contrast agent or synthesizing metal-based nanocarriers to concentrate the dose gradient at the level of the target tissue. In the second strategy the physicochemical properties of the vectors are used to encapsulate a wide range of pharmacological agents which act in synergy with the ionizing radiation to destroy the cancerous cells. This review reports on the various molecular anomalies present in GSCs and the predominant role of nanomedicines in the development of radiosensitization strategies

Efficacy of Astatine-211 radioimmunotherapy of Multiple Myeloma using an anti-mCD138 monoclonal antibody in a syngeneic murine model

Abstracts of Annual Congress of the European Association of Nuclear Medicine October 13 – 17, 2018 Düsseldorf, GermanyInternational audienceAim: Multiple myeloma is a B-cell malignancy of terminally differentiated plasma cells within the bone marrow. In spite of a very active search for new treatments, cure is almost never achieved. Alpha-radioimmunotherapy (RIT) is a new cancer treatment modality with tumour specific antibodies coupled to alpha particle-emitting radionuclides. CD138 (Syndecan-1) is found mainly in epithelial cells, but was shown to be expressed by most myeloma cells, both in human and in the mouse. The aim of the study was to evaluate the biodistribution, toxicity and efficacy of a rat Astatin-211-labelled anti-mouse CD138 antibody (211At-9E7.4) in a syngeneic mouse myeloma model. Materials and methods: C57BL/KaLwRij mice were grafted with 106 5T33 cells (murine myeloma cell line). Biodistribution was studied 15 min, 1h, 4h, 7h, 14h and 21h post-administration of 211At- 9E7.4 mAb. Toxicity (animal weight, blood cell counts and transaminase) and RIT efficacy were studied after a dose escalation using 370, 555, 740 and 1110 kBq of 211At-9E7.4 and two control groups 211At-IgG2a isotype control at 555 kBq or no treatment, 10 days after tumour engraftment. Results: Studies demonstrated a highly statistical survival benefit for the mice treated with 211At-9E7.4 at 555 kBq (p=0,0006) and 740 kBq (p<0,0001). At 555 kBq, the survival median was increase by 34 days and at 740 kBq 65% of the mice survived 160 days after engraftment. For treatments with 370 kBq with 211At-9E7.4 or 211At-isotype control at 555 kBq no significant benefit was observed. The higher activity with 1110 kBq of 211At-9E7.4 was clearly radiotoxic since mice were euthanized after a lost more than 30% of baseline weight 14 days after radiopharmaceutical injection. For the other groups, except transient decreases of leukocytes and red cells, no other toxicity could be demonstrated, especially on liver function, which does not seem to be affected. Concerning red blood cells, the effect is much weaker than that observed with the use of Bismuth-213 at an injected activity of 3.7 MBq. Conclusions: RIT of MM using Astatine-211 coupled to monoclonal antibody directed against murine CD138 is effective. The activity in astate-211 which allows 60% survival corresponds to an activity injected in Bismuth-213 located between 3.7 and 7.4 MBq, which seems to reflect the influence of the half life of the two radionuclides. In addition, the upper half-life of astatine appears to be a benefit, particularly because of the lower toxicity observed in this syngeneic model of MM

Feasibility of the radioastatination of a monoclonal antibody with astatine-211 purified by wet extraction

International audienceAstatine-211, a most promising a-particle emitter for targeted radiotherapy, is generally obtained by high-temperature distillation. However, a liquid-liquid extraction procedure (wet extraction) has also been described. The purpose of this study was to develop and optimize the labelling of the stannylated-activated ester N-hydroxysuccinimidyl-metatrimethylstannylbenzoate ester (MeSTB) with astatine-211 extracted in di-isopropylether (DIPE) in the presence of the oxidant N-chlorosuccinimide (NCS). The effect of final volume, incubation duration and NCS amounts on radiolabelling yield was studied. The best yields (85-90%) of N-hydroxysuccinimidyl-meta-[ 211 At]astatobenzoate ester (SAB) were obtained with 20 nmol of MeSTB, 100 nmol of NCS in 120 mL of DIPE after 15 min. The astatine-211-labelled-activated ester was then used to radiolabel a monoclonal antibody (mAb). The labelling yield was 20-25% and the radiochemical purity was 97-99%. These results show that mAbs may be efficiently labelled with astatine-211 obtained by wet extraction, a fully automatable technique that may prove to be a useful alternative to dry distillation for high activity labelling of radiopharmaceuticals