Background:Oestrogen receptor-negative (ER−) breast cancer is intrinsically sensitive to chemotherapy. However, tumour response is often incomplete, and relapse occurs with high frequency. The aim of this work was to analyse the molecular characteristics of residual tumours and early response to chemotherapy in patient-derived xenografts (PDXs) of breast cancer.Methods:Gene and protein expression profiles were analysed in a panel of ER− breast cancer PDXs before and after chemotherapy treatment. Tumour and stromal interferon-gamma expression was measured in xenografts lysates by human and mouse cytokine arrays, respectively.Results:The analysis of residual tumour cells in chemo-responder PDX revealed a strong overexpression of IFN-inducible genes, induced early after AC treatment and associated with increased STAT1 phosphorylation, DNA-damage and apoptosis. No increase in IFN-inducible gene expression was observed in chemo-resistant PDXs upon chemotherapy. Overexpression of IFN-related genes was associated with human IFN-γ secretion by tumour cells.Conclusions:Treatment-induced activation of the IFN/STAT1 pathway in tumour cells is associated with chemotherapy response in ER− breast cancer. Further validations in prospective clinical trials will aim to evaluate the usefulness of this signature to assist therapeutic strategies in the clinical setting.

Triple negative breast cancer (TNBC) is a tumor subtype characterized by the absence of overexpressed estrogen receptor-alpha (ER), progesterone receptor (PR), and HER2 receptor, encoded by ERBB2, a known proto-oncogene. This type of tumors account for approximately 15–25% of breast cancers at diagnosis, and is one of the most aggressive subtypes, with 77% of patients that live free of disease 5 years post-diagnosis. One of the most reliable predictive markers of patient outcome is the pathological complete response (pCR), which indicates that the surgical specimen removed after neoadjuvant chemotherapy contains no viable tumor cells detectable at histopathological level. For patients with pCR, the probability of surviving the disease is very high, however, pCR is observed only in about 20–30% of TNBC. On the other hand, for patients with no pCR the probablity of developing recurrent disease at 5 years is 50%.\ud \ud As pCR is strongly correlated with treatment efficacy, it is mandatory to develop methods that allow to tell as quick as possible if the treatment chosen for a given patient is efficiently working or if it should be abandoned in favor of an alternative strategy that could prove more efficacious. XenTech collection of breast cancer patient-derived xenografts (PDXs) includes 25 models of TNBC that display heterogeneous response to different chemotherapy agents. We used our models to investigate if transcriptional changes could be detected in PDXs that responded well to genotoxic agents. To do this we analyzed the gene expression profile of laser-microdissected residual tumor nodules interspersed in the murine stroma upon very efficient response to Adriamycin/Cyclophosphamide (AC). When doing so, we identified several genes of the IFN/STAT1 pathway that were over-expressed when compared to untreated tumors. This activation seems to be a transient event, as it was lost in tumors relapsing after the residual tumor nodule stage.\ud \ud The finding that residual cells from tumors strongly responding to AC treatment over-expressed IFN/STAT1 pathway-related genes prompted us to investigate whether this effect could be detected as an early event upon tumor exposure to chemotherapy. All TNBC models tested that were good responders to AC treatment displayed over-expression of IFN/STAT1 pathway-related genes as early as 3 days post-treatment, most of them reaching a plateau of intensity at day 7 post-treatment. By contrast, TNBC insensitive or low responders to AC treatment failed to show over-expression of IFN/STAT1 pathway-related genes.\ud \ud To verify if the selective over-expression of these genes in TNBC models sensitive to AC was independent of the treatment administered, Irinotecan and Capecitabine were used to treat TNBC models with heterogeneous response to these drugs. Again, we found that overexpression of IFN/STAT1 pathway-related genes was specifically identified at early stages only in TNBC models that responded well to these drugs.\ud \ud These results suggest that genes of the IFN/STAT1 pathway ...

As it is often the case with innovative technologies, regulatory agencies are highly demanding in product safety demonstration from those pioneering breakthrough therapy products. Since the first historically approved gene therapy medicinal product (Gencidine in 2003) by the Chinese National Medicinal Products Administration, gene therapy medicinal products have slowly been emerging in other regions, as illustrated by the first European-approved gene therapy medicinal product (Glybera in 2012) and the first US-approved product (Imlygic in 2015). From then, with the rise of new molecular technologies (e.g., non-viral and viral vector systems), an exponential growth of gene therapies development could be gauged with, for example, the approval of more than thirty gene therapies between 2016-2022. Using a method based on Preferred Reporting Items for Systematic reviews and Meta-Analyses principle, throughout different literature databases, this review is restricted to the evaluation of viral vector-based gene therapy medicinal products (VV-GTMPs). It also considered relevant guidelines and public assessment reports issued by the EMA and / or the FDA on the products these agencies approved. Then, a benchmark was performed to help stakeholders to identify regulatory trends and to design appropriate nonclinical programs establishing the benefit / risk ratio for patients to be enrolled in clinical trials. The analysis was focused on the nonclinical activities (pharmacology, biodistribution / persistence / shedding, and toxicology) performed by Applicants / Sponsors. As of 30 March 2023, 18 VV-GTMPs have been authorized by the EMA and 14 by the FDA to treat either orphan diseases or limited number of oncology patients. The majority of these therapies are based on adeno-associated or retroviral viruses (often lentiviruses able to transfect hematopoietic CD34+ cells or T-cells). Based on an analysis of the ongoing clinical trials, there is now a trend for developing gene therapies for larger patient populations. In conclusion, given the VV-GTMPs diversity and targeted indications, a “one-size fits all” nonclinical development plan cannot be considered by default. Instead, individual, risk-based, tailored nonclinical development programs appear more appropriate to assess such products, taking into consideration the lessons learned from the past. In such fast-evolving environment, regulatory agencies need to adapt their evaluation process very rapidly.

Background: The ability of tumor cells to spread and form metastasis is one of the key parameters used to classify tumor aggressiveness. Metastasis detection at diagnosis or during follow-up post-surgery is associated with poor prognosis. The lack of pertinent models to investigate the biology of metastasis renders problematic the set-up of anti-metastasis therapies. We took advantage of our tumorgraft collection to develop models suitable to assess anti-metastatic therapy. Furthermore, to enable measurement of metastasis response to treatment, we labeled tumors with lentivirus-mediated luciferase insertion into tumor cells, allowing the follow up of metastasis formation by non invasive imaging. Methods: In order to obtain a bioluminescent model, upon tumor resection, HBCx-12B tumor cells were dissociated and transduced with a defective lentivirus bearing the firefly luciferase gene. One million cells were injected subcutaneously in different strains of immunocompromised mice (RAG γC−/−; RAG γC−/− FLK; Nude; SCID; NOD SCID), tumor growth and metastasis formation were monitored throughout passages by whole body visualization using the Xenogen IVIS® Lumina. Mice were imaged over 10 to 24 weeks, and in order to prolong the follow-up window for metastasis detection, tumor resection was performed when primary tumor size reached 500 mm3. During this period, bioluminescence was measured every two weeks to assess metastasis appearance and progression. Bio-imaging allowed metastasis detection with a threshold of 100 to 400 cells per metastatic focus. The presence of metastases was confirmed by both histological analysis, and ex vivo organ fluorescence imaging. The pro-drug 5-aminolevulinic acid was injected intravenously, transformed into protoporphyrin IX, a fluorescent compound accumulated into tumor cells. Results: Metastases developped in all tested strains with different efficiency. RAG γC −/− and SCID strains had the highest susceptibility, with fast and high metastasis incidence. RAG γC (9/9), RAG γC−/− FLK (2/2) and SCID (4/5) mice presented lung metastases after an average of 50-day independently of the passage, while metastases developed in 1/7 in nude mice after 90 days. Histological examination confirmed the adenocarcinomatous origin of metastases, extravading into the lung arteriolar vessels. Conclusions and perspectives: Bioluminescent metastasis models could be successfully established by growing luciferase-enginered tumorgrafts into appropriate strains of immunocompromised mice. At present, other bioluminescent models of melanoma, pancreatic, and breast cancer tumorgrafts are being validated as metastatic. The establishment of bioluminescent metastasis models of different types of cancer will provide an useful tool to explore the biology of metastasis development and anti-metastatic therapies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C47.

No abstract