RNF43 mutations predict response to anti-BRAF/EGFR combinatory therapies in BRAFV600E metastatic colorectal cancer

Anti-BRAF/EGFR therapy was recently approved for the treatment of metastatic BRAF^V600E colorectal cancer (mCRC^BRAF-V600E). However, a large fraction of patients do not respond, underscoring the need to identify molecular determinants of treatment response. Using whole-exome sequencing in a discovery cohort of patients with mCRC^BRAF-V600E treated with anti-BRAF/EGFR therapy, we found that inactivating mutations in RNF43, a negative regulator of WNT, predict improved response rates and survival outcomes in patients with microsatellite-stable (MSS) tumors. Analysis of an independent validation cohort confirmed the relevance of RNF43 mutations to predicting clinical benefit (72.7% versus 30.8%; P = 0.03), as well as longer progression-free survival (hazard ratio (HR), 0.30; 95% confidence interval (CI), 0.12–0.75; P = 0.01) and overall survival (HR, 0.26; 95% CI, 0.10–0.71; P = 0.008), in patients with MSS-RNF43^mutated versus MSS-RNF43^wild-type tumors. Microsatellite-instable tumors invariably carried a wild-type-like RNF43 genotype encoding p.G659fs and presented an intermediate response profile. We found no association of RNF43 mutations with patient outcomes in a control cohort of patients with MSS-mCRC^BRAF-V600E tumors not exposed to anti-BRAF targeted therapies. Overall, our findings suggest a cross-talk between the MAPK and WNT pathways that may modulate the antitumor activity of anti-BRAF/EGFR therapy and uncover predictive biomarkers to optimize the clinical management of these patients.

The presence of inactivating mutations in RNF43, a negative regulator of WNT, in tumor cells predicts improved response rates and survival outcomes in patients with metastatic BRAF^V600E colorectal cancer treated with anti-BRAF/EGFR therapy.

ERANET JTC 2011: Submission and Activation of an International Academic Translational Project in Advanced Breast Cancer. Experience From the ET-FES Study

Background: Academic research is important to face unmet medical needs. The Oncological community encounters many hurdles in setting up multicenter investigator-driven trials mainly due to administrative complexity. The purpose of a network organization at a multinational level is to facilitate clinical trials through standardization, coordination, and education for drug development and regulatory approval.

Methods: The application of an European grant foresees the creation of a consortium which aims at facilitating multi-center academic clinical trials.

Results: The ERA-NET TRANSCAN Call 2011 on “Validation of biomarkers for personalized cancer medicine” was released on December 2011. This project included Italian, Spanish, French and German centers. The approval process included Consortium constitution, project submission, Clinical Trial Submission, and activation on a national level. The different timescales for submitting study documents in each Country and the misalignment of objections by each Competent Authority CA, generated several requests for changes to the study documents which meant amendments had to be made; as requested by the 2001/20/EC Directive, the alignment of core documents is mandatory. This procedure impacted significantly on study activation timelines. Time to first patient in was 14, 10, 28, and 31 months from the date of submission in Italy, France, Spain, and Germany, respectively. Accrual was stopped on 22nd January 2021 due to an 18F FES shortage as the primary reason but also for having exceeded the project deadlines with consequent exhaustion of the funds allocated for the project.

Conclusions: Pharmaceutical companies might be reluctant to fund research projects aimed at treatment individualization if the approval for a wider indication has already been achieved. Academic trials therefore become fundamental for promoting trials which are not attractive to big pharma. It was very difficult and time consuming to activate an academic clinical trial, for this reason, a study may become “old” as new drugs entered into the market. National institutions should promote the development of clinical research infrastructures and network with competence in regulatory, ethical, and legal skills to speed up academic research.

Abstract 985: The EurOPDX EDIReX project: Towards a European research infrastructure on patient-derived cancer models

Counteracting high attrition rates in anticancer drug development and providing optimal therapeutic management of cancer patients require preclinical models that properly recapitulate the complexity and diversity of human tumours. Patient-derived cancer xenografts (PDXs), developed by transplanting human tumor fragments into immunodeficient mice, retain the idiosyncratic characteristics of different tumors from different patients. The possibility of population-scale correlations between therapeutic response in PDXs and extensive, multidimensional molecular annotation has enabled the identification of several sensitivity and resistance biomarkers in a number of different tumor types, with immediate clinical relevance. To effectively recapitulate and therapeutically interrogate through patient-derived models the heterogeneity that typifies human cancer, 13 European cancer centres and university hospitals joined forces in 2013 to start EurOPDX, an academic research consortium that now gathers 19 institutions throughout Europe and in the US. EurOPDX includes world-renowned experts at the forefront of research in basic, preclinical, translational and clinical oncology across multiple pathologies, and displays a wide range of expertise in technological platforms. The primary goal of the Consortium is to maximize exploitation of PDXs and other patient-derived cancer models for cancer research by: (i) integrating institutional collections into an organic, multicentre collection of patient-derived models, now reaching 2,000 subcutaneous and orthotopic models for 30+ different pathologies (www.europdx.eu); (ii) defining common operating procedures to improve and standardize molecular and pharmacologic characterization of the models; (iii) sharing models within and outside the consortium to perform collaborative precision oncology “xenopatient” trials, to discover predictive biomarkers, new targets, and new strategies to overcome drug resistance. Towards these objectives, the EC granted 5 million euros under the H2020 programme for a “EurOPDX Distributed Infrastructure for Research on patient-derived Xenografts" - EDIReX EU project n. 731105, starting on February 2018. By teaming up with other key academic, technological and SME partners, our goal with EDIReX is to establish a cutting-edge European infrastructure offering transnational access to PDX resources to academic and industrial cancer researchers, including the distribution of cryopreserved samples to third parties, the structured biobanking of user-developed models, and the performance of drug efficacy studies. We will provide an overview of the current achievements of the Consortium and the objectives of the EDIReX project.

Citation Format: Enzo Medico, Mohamed Bentires-Alj, Andrew V. Biankin, Alejandra Bruna, Annette T. Byrne, Carlos Caldas, Robert B. Clarke, Georges Coukos, Olivier Elemento, Manuel Hidalgo, Giorgio Inghirami, Steven de Jong, Jos Jonkers, Ales Krenek, Eleonora Leucci, Gunhild Mari Maelandsmo, Michaela Th. Mayrhofer, Terrence F. Meehan, Simone P. Niclou, Pier Giuseppe Pelicci, Alejandro Piris-Gimenez, Leo Price, Sergio Roman-Roman, Livio Trusolino, Luca Vezzadini, Alberto Villanueva, Emilie Vinolo, on behalf of the EurOPDX Consortium. The EurOPDX EDIReX project: Towards a European research infrastructure on patient-derived cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 985.

Interrogating open issues in cancer medicine with patient-derived xenografts

This corrects the article DOI: 10.1038/nrc.2016.140.

Interrogating open issues in cancer precision medicine with patient-derived xenografts

Patient-derived xenografts (PDXs) have emerged as an important platform to elucidate new treatments and biomarkers in oncology. PDX models are used to address clinically relevant questions, including the contribution of tumour heterogeneity to therapeutic responsiveness, the patterns of cancer evolutionary dynamics during tumour progression and under drug pressure, and the mechanisms of resistance to treatment. The ability of PDX models to predict clinical outcomes is being improved through mouse humanization strategies and the implementation of co-clinical trials, within which patients and PDXs reciprocally inform therapeutic decisions. This Opinion article discusses aspects of PDX modelling that are relevant to these questions and highlights the merits of shared PDX resources to advance cancer medicine from the perspective of EurOPDX, an international initiative devoted to PDX-based research.

In vivo germination of Bacillus anthracis spores during murine cutaneous infection

BACKGROUND

Germination is a key step for successful Bacillus anthracis colonization and systemic dissemination. Few data are available on spore germination in vivo, and the necessity of spore and host cell interactions to initiate germination is unclear.

METHODS

To investigate the early interactions between B. anthracis spores and cutaneous tissue, spores were inoculated in an intraperitoneal cell-free device in guinea pigs or into the pinna of mice. Germination and bacterial growth were analyzed through colony-forming unit enumeration and electron microscopy.

RESULTS

In the guinea pig model, germination occurred in vivo in the absence of cell contact. Similarly, in the mouse ear, germination started within 15 minutes after inoculation, and germinating spores were found in the absence of surrounding cells. Germination was not observed in macrophage-rich draining lymph nodes, liver, and spleen. Edema and lethal toxin production were not required for germination, as a toxin-deficient strain was as effective as a Sterne-like strain. B. anthracis growth was locally controlled for 6 hours.

CONCLUSIONS

Spore germination involving no cell interactions can occur in vivo, suggesting that diffusible germinants or other signals appear sufficient. Different host tissues display drastic differences in germination-triggering capacity. Initial control of bacterial growth suggests a therapeutic means to exploit host innate defenses to hinder B. anthracis colonization.

Encapsulated Bacillus anthracis interacts closely with liver endothelium

BACKGROUND

The Bacillus anthracis poly-gamma-D-glutamate capsule is essential for virulence. It impedes phagocytosis and protects bacilli from the immune system, thus promoting systemic dissemination.

METHODS

To further define the virulence mechanisms brought into play by the capsule, we characterized the interactions between encapsulated nontoxinogenic B. anthracis and its host in vivo through histological analysis, perfusion, and competition experiments with purified capsule.

RESULTS

Clearance of encapsulated bacilli from the blood was rapid (>90% clearance within 5 min), with 75% of the bacteria being trapped in the liver. Competition experiments with purified capsule polyglutamate inhibited this interaction. At the septicemic phase of cutaneous infection with spores, the encapsulated bacilli were trapped in the vascular spaces of the liver and interacted closely with the liver endothelium in the sinusoids and terminal and portal veins. They often grow as microcolonies containing capsular material shed by the bacteria.

CONCLUSION

We show that, in addition to its inhibitory effect on the interaction with the immune system, the capsule surrounding B. anthracis plays an active role in mediating the trapping of the bacteria within the liver and may thus contribute to anthrax pathogenesis. Because other microorganisms produce polyglutamate, it may also represent a general mechanism of virulence or in vivo survival.

Primary involvement of pharynx and peyer's patch in inhalational and intestinal anthrax

Bacillus anthracis causes three forms of anthrax: inhalational, gastrointestinal, and cutaneous. Anthrax is characterized by both toxemia, which is caused by secretion of immunomodulating toxins (lethal toxin and edema toxin), and septicemia, which is associated with bacterial encapsulation. Here we report that, contrary to the current view of B. anthracis pathogenesis, B. anthracis spores germinate and establish infections at the initial site of inoculation in both inhalational and cutaneous infections without needing to be transported to draining lymph nodes, and that inhaled spores establish initial infection in nasal-associated lymphoid tissues. Furthermore, we found that Peyer's patches in the mouse intestine are the primary site of bacterial growth after intragastric inoculation, thus establishing an animal model of gastrointestinal anthrax. All routes of infection progressed to the draining lymph nodes, spleen, lungs, and ultimately the blood. These discoveries were made possible through the development of a novel dynamic mouse model of B. anthracis infection using bioluminescent non-toxinogenic capsulated bacteria that can be visualized within the mouse in real-time, and demonstrate the value of in vivo imaging in the analysis of B. anthracis infection. Our data imply that previously unrecognized portals of bacterial entry demand more intensive investigation, and will significantly transform the current perception of inhalational, gastrointestinal, and cutaneous B. anthracis pathogenesis.

Anthrax is caused by Bacillus anthracis, a bacterial pathogen that forms spores, dormant bacteria that are highly resistant to destruction. Infections initiate from the introduction of spores into airways or damaged skin, or from the consumption of contaminated food. Within the host, spores germinate, then bacteria secrete toxins that cripple the immune response and sheath themselves in a capsule that prevents them from being phagocytosed. We strove to determine in real space and time where and when spores introduced by these three routes of infection germinate and how bacteria subsequently disseminate in a mouse model. This was achieved through the development of light-emitting B. anthracis that could be tracked inside a living mouse. Contrary to current models, our studies indicated that spores germinated in situ in the skin, the intestines, and the nasal passages without needing to be transported to lymph nodes. Furthermore, bacteria disseminate from initial sites of infection in a similar fashion, first to the draining lymph nodes, then the spleen, and finally the lungs and blood. These findings imply that spore interactions with local sites of entry are critical in the development of systemic disease and that disruption of these interactions may offer new methods of anthrax prevention.

In Vivo Protective Role of Human Group IIA Phospholipase A2against Experimental Anthrax

Anthrax is an acute disease caused by Bacillus anthracis. Some animal species are relatively resistant to anthrax infection. This trait has been correlated to the extent of the local inflammatory reaction, suggesting innate immunity to be the first line of defense against B. anthracis infection in nonimmunized hosts. Group IIA secreted phospholipase A2 (sPLA2-IIA) is produced in particular by macrophages and possesses potent antibacterial activity especially against Gram-positive bacteria. We have previously shown in vitro that sPLA2-IIA kills both germinated B. anthracis spores and encapsulated bacilli. Here we show that sPLA2-IIA plays in vivo a protective role against experimental anthrax. Transgenic mice expressing human sPLA2-IIA are resistant to B. anthracis infection. In addition, in vivo administration of recombinant human sPLA2-IIA protects mice against B. anthracis infection. The protective effect was observed both with a highly virulent encapsulated nontoxinogenic strain and a wild-type encapsulated toxinogenic strain, showing that toxemia did not hinder the sPLA2-IIA-afforded protection. sPLA2-IIA, a natural component of the immune system, may thus be considered a novel therapeutic agent to be used in adjunct with current therapy for treating anthrax. Its anthracidal activity would be effective even against strains resistant to multiple antibiotics.