Emmanuel Deshayes

Le cancer de l’ovaire est la première cause de décès par cancer gynécologique en France et il présente un fort taux de récidive justifiant la recherche de nouvelles thérapeutiques. Notre projet consiste à développer et à explorer sur des modèles expérimentaux précliniques de carcinose péritonéale de nouveaux agents thérapeutiques radiopharmaceutiques et des voies d’administration innovantes ciblant plus particulièrement la maladie résiduelle micro-métastatique présente après chirurgie de cytoréduction. Nous utilisons des anticorps monoclonaux internalisants spécifiques d’un récepteur membranaire surexprimé dans le cancer de l’ovaire et d’autres cancers gynécologiques, le récepteur de type 2 de l’hormone anti-müllerienne (AMHR2). Ces anticorps sont couplés à des radionucléides aux propriétés thérapeutiques : le Lutecium-177 (un émetteur de particules beta moins) et le Bismuth-213 (un émetteur de particules alpha) réalisant un traitement de radioimmunothérapie. Ils sont évalués après injection intrapéritonéale mais également en utilisant la technique RadioImmunoThérapie Intrapéritonéale Brève (BIP-RIT) consistant à instiller de fortes activités d’anticorps radiomarqués dans le péritoine avant d’en réaliser un rinçage abondant, à l’image de la chimiothérapie hyperthermique intrapéritonéale (CHIP). Sont étudiés sur différents modèles la biodistribution, la dosimétrie, la toxicité et l’efficacité thérapeutique des différentes combinaisons de radionucléides et de voies d’administration. La BIP-RIT présente un profil de biodistribution et de dosimétrie toujours favorable, quel que soit le radionucléide utilisé même si l’utilisation du Bismuth-213 apparait plus particulièrement adaptée à cette technique (bonne efficacité thérapeutique avec absence de toxicité). L’imagerie PET/CT de la biodistribution in-vivo de ces anticorps a été réalisée à l’aide de l’émetteur de positrons Zirconium-89 ouvrant la voie à une approche théragnostique du traitement des cancers gynécologiques AMHR2+ par (radio)immunothérapie. Les mécanismes d’action thérapeutique d’une version humanisée de l’anticorps anti-AMHR2 sont également étudiés. Ce travail ouvre des perspectives cliniques intéressantes dans la prise en charge du cancer de l’ovaire.

18F–FDG PET–CT has emerged as a powerful imaging tool for initial staging and prognosis evaluation of patients with Breast Cancer (BC). However

Background/Objectives: Tumor-associated antigens are not tumor-specific antigens but proteins that are overexpressed by tumor cells and also weakly expressed at the surface of healthy tissues. Therefore, some side effects are observed when targeted by therapeutic antibodies, a phenomenon named “on-target, off-tumor toxicity”. As tumors generate an acidic microenvironment, we investigated whether we could generate pH-dependent antibodies to increase their tumor specificity. For this proof-of-concept study, we selected the tyrosine kinase receptor AXL because we already developed several antibodies against this target. Methods: To generate a pH-dependent anti-AXL antibody, we performed classical panning of a single-chain variable fragment (scFv) library using phage display at an acidic pH throughout the process. Results: After the third round of panning, 9 scFvs, among the 96 picked clones, bound to AXL at acidic pH and showed very low binding at a neutral pH. After reformatting them into IgG, two clones were selected for further study due to their strong pH-sensitive binding. Using molecular docking and alanine scanning, we found that their binding strongly depended on two histidine residues present on AXL at positions 61 and 116. Conclusions: To conclude, we set-up an easy process to generate pH-dependent antibodies that may increase their tumor-binding specificity and potentially decrease toxicity towards healthy tissues.

Background: New therapeutic options are needed for biliary tract cancer (BTC). Regorafenib, a multikinase inhibitor, shows promise in refractory digestive cancers and may be beneficial with conventional chemotherapy for BTC. Patients and Methods: The BREGO study evaluated regorafenib with modified gemcitabine-oxaliplatin (mGEMOX) in advanced or metastatic BTC. Phase I determined the recommended dose (RP2D) of regorafenib (80, 120 or 160 mg, days 1-14) combined with mGEMOX (gemcitabine 900 mg.m−2 IV, 30 min, followed by oxaliplatin 80mg.m−2 IV, 120 min, days 1 and 8). Phase II randomized (1:2) patients to mGEMOX alone (arm A) or mGEMOX + regorafenib (arm B, RP2D, days 1-14), assessing efficacy and safety, with the primary outcome being progression-free survival (PFS). Metabolic tumor features and response were also assessed. Results: In phase Ib, 22 patients were enrolled; in phase II, 66 patients (arm A, n = 24; arm B, n = 42). Four dose-limiting toxicities were observed, but no maximum tolerated dose was reached. The RP2D was 160 mg.d−1. Median PFS (7.2 vs7.8 months; P = .825) and overall survival (15.1 vs 13.5 months; P = .356) were similar between arms. However, posttreatment 18F-FDG tumor uptake (SULpeak) significantly correlated with PFS (P = .001) and OS (P = .016). Baseline plasma stanniocalcin 1 levels < 265 pg.mL−1 were associated with longer PFS (P = .030) and OS (P = .060) in both arms. Conclusions: Combining regorafenib and mGEMOX is feasible as first-line treatment for BTC but did not increase PFS as expected in the phase II cohort. Identifying new biomarkers can help target patients with advanced BTCs who may benefit from regorafenib-associated therapy. Trial registration number: ClinicalTrials.gov, NCT02386397.

Background: Prostate-specific membrane antigen (PSMA) is an ideal target for molecular imaging and targeted radionuclide therapy in prostate cancer. Consequently, various PSMA ligands were developed. Some of these molecules are functionalized with a chelator that can host radiometals, such as ⁶⁸Ga for PET imaging. The ⁶⁸Ga radiolabeling step benefits from process automation, making it more robust and reducing radiation exposure. Objective: To design a single automated radiolabeling protocol for the GMP-compliant preparation of [⁶⁸Ga]Ga-PSMA-11, transposable to the production of [⁶⁸Ga]Ga-PSMA-617 and [⁶⁸Ga]Ga-PSMA-I&T. Methods: A GAIA^® synthesis module and a GALLIAD^® generator were used. Radio-TLC and radio-HPLC methods were validated for radiochemical purity (RCP) determination. Three [⁶⁸Ga]Ga-PSMA-11 validation batches were produced and thoroughly tested for appearance and pH, radionuclide identity and purity, RCP, stability, residual solvent and sterility. Minimal modifications were made to the reagents and disposables for optimal application to other PSMA ligands. Results: [⁶⁸Ga]Ga-PSMA-11 for clinical application was produced in 27 min. The 3 validation batches met the quality criteria expected by the European Pharmacopoeia to allow routine production. For optimal transposition to PSMA-617, the solid phase extraction cartridge was changed to improve purification of the radiolabeled product. For application to PSMA-I&T, the buffer solution initially used was replaced by HEPES 2.7 M to achieve good radiochemical yields. Residual HEPES content was checked in the final product and was below the Ph. Eur. threshold. Conclusion: A single automated radiolabeling method on the GAIA^® module was developed and implemented for ⁶⁸Ga radiolabeling of 3 PSMA ligands, with slight adjustments for each molecule.

[¹⁷⁷Lu]Lu-DOTATATE has been approved for progressive and inoperable gastroenteropancreatic neuroendocrine tumors (GEP-NETs) that overexpress somatostatin receptors. The absorbed doses by limiting organs and tumors can be quantified by serial postinfusion scintigraphy measurements of the γ-emissions from ¹⁷⁷Lu. The objective of this work was to explore how postinfusion [¹⁷⁷Lu]Lu-DOTATATE dosimetry could influence clinical management by predicting treatment efficacy (tumor shrinkage and survival) and toxicity. Methods: Patients with GEP-NETs treated with [¹⁷⁷Lu]Lu-DOTATATE between 2016 and 2022 and who underwent dosimetry were included. Absorbed doses were calculated for healthy organs (liver, kidneys, bone marrow, and spleen) and tumors using PLANET Dose and the local energy deposition method based on serial posttreatment SPECT/CT. Up to 5 lesions per site were selected and measured on images collected at baseline and 3 mo after treatment end (measurement masked to the somatostatin receptor imaging uptake). For toxicity assessment, laboratory parameters were regularly monitored. Clinical data, including time to death or progression, were collected from the patients’ health records. Correlations between absorbed doses by organs and toxicity and between absorbed doses by lesions and tumor volume variation were studied using regression models. Results: In total, 35 dosimetric studies were performed in patients with mostly grade 2 (77%) tumors and metastases in liver (89%), lymph nodes (77%), and bone (34%), and 146 lesions were analyzed: 1–9 lesions per patient, mostly liver metastases (65%) and lymph nodes (25%). The median total absorbed dose by tumors was 94.4 Gy. The absorbed doses by tumors significantly decreased between cycles. The absorbed dose by tumors was significantly associated with tumor volume variation (P < 0.001) 3 mo after treatment end, and it was a significant prognostic factor for survival. Toxicity analysis showed a correlation between the decrease of hematologic parameters such as lymphocytes or platelet concentrations and the absorbed doses by the spleen or bone marrow. The mean absorbed dose by the kidneys was not correlated with nephrotoxicity during the studied period. Conclusion: In patients treated with [¹⁷⁷Lu]Lu-DOTATATE for GEP-NETs, tumor and healthy organ dosimetry can predict survival and toxicities, thus influencing clinical management. Visual Abstract