CD24-targeted fluorescence imaging in patient-derived xenograft models of high-grade serous ovarian carcinoma

Abstract

Background: The survival rate of patients with advanced high-grade serous ovarian carcinoma (HGSOC) remains disappointing. Clinically translatable orthotopic cell line xenograft models and patient-derived xenografts (PDXs) may aid the implementation of more personalised treatment approaches. Although orthotopic PDX reflecting heterogeneous molecular subtypes are considered the most relevant preclinical models, their use in therapeutic development is limited by lack of appropriate imaging modalities. Methods: We developed novel orthotopic xenograft and PDX models for HGSOC, and applied a near-infrared fluorescently labelled monoclonal antibody targeting the cell surface antigen CD24 for non-invasive molecular imaging of epithelial ovarian cancer. CD24-Alexa Fluor 680 fluorescence imaging was compared to bioluminescence imaging in three orthotopic cell line xenograft models of ovarian cancer (OV-90 luc+ , Skov-3 luc+ and Caov-3 luc+ , n = 3 per model). The application of fluorescence imaging to assess treatment efficacy was performed in carboplatin-paclitaxel treated orthotopic OV-90 xenografts (n = 10), before the probe was evaluated to detect disease progression in heterogenous PDX models (n = 7). Findings: Application of the near-infrared probe, CD24-AF680, enabled both spatio-temporal visualisation of tumour development, and longitudinal therapy monitoring of orthotopic xenografts. Notably, CD24-AF680 facilitated imaging of multiple PDX models representing different histological subtypes of the disease. Interpretation: The combined implementation of CD24-AF680 and orthotopic PDX models creates a state-ofthe-art preclinical platform which will impact the identification and validation of new targeted therapies, fluorescence image-guided surgery, and ultimately the outcome for HGSOC patients.

CD24-targeted intraoperative fluorescence image-guided surgery leads to improved cytoreduction of ovarian cancer in a preclinical orthotopic surgical model

“…We have previously developed a surgically relevant orthotopic model of HGSOC [26,40]. In the current study we build upon this by employing OV-90 luc+ and PDX orthotopic xenograft models, where disease dissemination better mimics clinical characteristics of HGSOC [25]. To increase the clinical translatability of our work we introduce a preclinical staging system based on FIGO staging used clinically in EOC patients ( Fig.…”

“…In vitro OV-90 cell proliferation was evaluated in the presence of 10 À10 À 10 À7 M CD24-AF750 to test the safety of the conjugate. A water soluble tetrazolium salts (WST-1) assay (cat # 5015944001, Roche Applied Science, Pensberg, Germany) was used to validate cell proliferation 48 h after the incubation with four different CD24-AF750 concentrations (4 h after WST-1 incubation) and performed according to the manufacturers protocol and as previously described [25]. The spectrophotometrically measured formazan signal concentration of all metabolically active cells of all samples were normalised to 48-h cultures of OV-90 cells without CD24-AF750.…”

“…We have previously demonstrated that CD24 is a suitable target for non-invasive molecular imaging of EOC [25]. To determine the targeting capacity and intraoperative detectability of the CD24-AF750 tracer, we investigated the expression of CD24 in clinically relevant cell lines and patient-derived xenograft tumours.…”

“…In the current study, we evaluate CD24, a small, heavily glycosylated, mucin-like cell surface protein which has been identified as a stem cell marker in ovarian cancer [24], as a target for NIR FIGS in orthotopic xenograft models of metastatic HGSOC. We have previously demonstrated the usefulness of non-invasive fluorescence imaging with CD24 conjugated to Alexa Fluor 680 [25], but due to autofluorescence in the 700 nm wavelength range during abdominal intraoperative imaging, we conjugated the human specific monoclonal antibody targeting CD24 to the longer wavelength NIR fluorophore Alexa Fluor 750 (CD24-AF750) in the current study. In vitro verification of CD24-AF750 targeting and subsequent in vivo pharmacokinetic and pharmacodynamic profiling of CD24-AF750 determined optimal contrast conditions for FIGS.…”

The Emerging Role of CD24 in Cancer Theranostics—A Novel Target for Fluorescence Image-Guided Surgery in Ovarian Cancer and Beyond

“…As a result, CD24 overexpression has been exploited as a diagnostic marker and as a marker for treatment resistance and prognosis, and evaluated for targeted therapy [17,60,61]. In recent years, CD24 has evolved as an encouraging molecular biomarker for EOC [78] in the field of immunotherapy, and as a tumor-specific biomarker for targeted drug delivery and imaging [14,16,19]. CD24 expression in ovarian cancer has been found to correlate with clinicopathological parameters, such as higher tumor grade, higher tumor stage, omental metastasis, relapse, and a more aggressive course of the disease [17,66,79].…”