Outcomes from a mechanistic biomarker multi-arm and randomised study of liposomal MTP-PE (Mifamurtide) in metastatic and/or recurrent osteosarcoma (EuroSarc-Memos trial).

The phase III clinical study of adjuvant liposomal muramyl tripeptide (MTP-PE) in resected high-grade osteosarcoma (OS) documented positive results that have been translated into regulatory approval, supporting initial promise for innate immune therapies in OS. There remains, however, no new approved treatment such as MTP-PE for either metastatic or recurrent OS. Whilst the addition of different agents, including liposomal MTP-PE, to surgery for metastatic or recurrent high-grade osteosarcoma has tried to improve response rates, a mechanistic hiatus exists in terms of a detailed understanding the therapeutic strategies required in advanced disease. Here we report a Bayesian designed multi-arm, multi-centre, open-label phase II study with randomisation in patients with metastatic and/or recurrent OS, designed to investigate how patients with OS might respond to liposomal MTP-PE, either given alone or in combination with ifosfamide. Despite the trial closing because of poor recruitment within the allocated funding period, with no objective responses in eight patients, we report the design and feasibility outcomes for patients registered into the trial. We demonstrate the feasibility of the Bayesian design, European collaboration, tissue collection with genomic analysis and serum cytokine characterisation. Further mechanistic investigation of liposomal MTP-PE alone and in combination with other agents remains warranted in metastatic OS.

Functional evolution of IGF2:IGF2R domain 11 binding generates novel structural interactions and a specific IGF2 antagonist.

Among the 15 extracellular domains of the mannose 6-phosphate/insulin-like growth factor-2 receptor (M6P/IGF2R), domain 11 has evolved a binding site for IGF2 to negatively regulate ligand bioavailability and mammalian growth. Despite the highly evolved structural loops of the IGF2:domain 11 binding site, affinity-enhancing AB loop mutations suggest that binding is modifiable. Here we examine the extent to which IGF2:domain 11 affinity, and its specificity over IGF1, can be enhanced, and we examine the structural basis of the mechanistic and functional consequences. Domain 11 binding loop mutants were selected by yeast surface display combined with high-resolution structure-based predictions, and validated by surface plasmon resonance. We discovered previously unidentified mutations in the ligand-interacting surface binding loops (AB, CD, FG, and HI). Five combined mutations increased rigidity of the AB loop, as confirmed by NMR. When added to three independently identified CD and FG loop mutations that reduced the koff value by twofold, these mutations resulted in an overall selective 100-fold improvement in affinity. The structural basis of the evolved affinity was improved shape complementarity established by interloop (AB-CD) and intraloop (FG-FG) side chain interactions. The high affinity of the combinatorial domain 11 Fc fusion proteins functioned as ligand-soluble antagonists or traps that depleted pathological IGF2 isoforms from serum and abrogated IGF2-dependent signaling in vivo. An evolved and reengineered high-specificity M6P/IGF2R domain 11 binding site for IGF2 may improve therapeutic targeting of the frequent IGF2 gain of function observed in human cancer.

Sclerostin expression in bone tumours and tumour-like lesions.

AIMS: To assess the immunophenotypic and mRNA expression of sclerostin in human skeletal tissues and in a wide range of benign and malignant bone tumours and tumour-like lesions. METHODS AND RESULTS: Sclerostin expression was evaluated by immunohistochemistry and quantitative polymerase chain reaction (PCR). In lamellar and woven bone, there was strong sclerostin expression by osteocytes. Osteoblasts and other cell types in bone were negative. Hypertrophic chondrocytes in the growth plate and mineralized cartilage cells in zone 4 of hyaline articular cartilage strongly expressed sclerostin, but most chondrocytes in hyaline cartilage were negative. In primary bone-forming tumours, including osteosarcomas, there was patchy expression of sclerostin in mineralized osteoid and bone. Sclerostin staining was seen in woven bone in fibrous dysplasia, in osteofibrous dysplasia, and in reactive bone formed in fracture callus, in myositis ossificans, and in the wall of solitary bone cysts and aneurysmal bone cysts. Sclerostin was expressed by hypertrophic chondrocytes in osteochondroma and chondroblasts in chondroblastoma, but not by tumour cells in other bone tumours, including myeloma and metastatic carcinoma. mRNA expression of sclerostin was identified by quantitative PCR in osteosarcoma specimens and cell lines. CONCLUSIONS: Sclerostin is an osteocyte marker that is strongly expressed in human woven and lamellar bone and mineralizing chondrocytes. This makes it a useful marker with which to identify benign and malignant osteogenic tumours and mineralizing cartilage tumours, such as chondroblastomas and other lesions in which there is bone formation.

Challenges and solutions to system-wide use of precision oncology as the standard of care paradigm.

The personalised oncology paradigm remains challenging to deliver despite technological advances in genomics-based identification of actionable variants combined with the increasing focus of drug development on these specific targets. To ensure we continue to build concerted momentum to improve outcomes across all cancer types, financial, technological and operational barriers need to be addressed. For example, complete integration and certification of the 'molecular tumour board' into 'standard of care' ensures a unified clinical decision pathway that both counteracts fragmentation and is the cornerstone of evidence-based delivery inside and outside of a research setting. Generally, integrated delivery has been restricted to specific (common) cancer types either within major cancer centres or small regional networks. Here, we focus on solutions in real-world integration of genomics, pathology, surgery, oncological treatments, data from clinical source systems and analysis of whole-body imaging as digital data that can facilitate cost-effectiveness analysis, clinical trial recruitment, and outcome assessment. This urgent imperative for cancer also extends across the early diagnosis and adjuvant treatment interventions, individualised cancer vaccines, immune cell therapies, personalised synthetic lethal therapeutics and cancer screening and prevention. Oncology care systems worldwide require proactive step-changes in solutions that include inter-operative digital working that can solve patient centred challenges to ensure inclusive, quality, sustainable, fair and cost-effective adoption and efficient delivery. Here we highlight workforce, technical, clinical, regulatory and economic challenges that prevent the implementation of precision oncology at scale, and offer a systematic roadmap of integrated solutions for standard of care based on minimal essential digital tools. These include unified decision support tools, quality control, data flows within an ethical and legal data framework, training and certification, monitoring and feedback. Bridging the technical, operational, regulatory and economic gaps demands the joint actions from public and industry stakeholders across national and global boundaries.

Functional evaluation of novel soluble insulin-like growth factor (IGF)-II-specific ligand traps based on modified domain 11 of the human IGF2 receptor.

Ligands transported by the mannose 6-phosphate/insulin-like growth factor (IGF)-II receptor (IGF2R) include IGF-II- and mannose 6-phosphate-modified proteins. Increased extracellular supply of IGF-II, either secondary to loss of the clearance function of IGF2R, loss of IGF binding protein function, or increased IGF2 gene expression, can lead to embryonic overgrowth and cancer promotion. Reduced supply of IGF-II is detrimental to tumor growth, and this suggests that gain of function of IGF-II is a molecular target for human cancer therapy. Domain 11 of IGF2R binds IGF-II with high specificity and affinity. Mutagenesis studies have shown that substitution of glutamic acid for lysine at residue 1554 results in a 6-fold higher affinity for IGF-II (20.5 nmol/L) than native domain 11 (119 nmol/L). Here, we generate a novel high-affinity IGF-II ligand trap by fusion of mutated human 11(E1554K) to a COOH-terminal human IgG1 Fc domain (11(E1554K)-Fc). The resulting homodimer has a significantly increased affinity for IGF-II (1.79 nmol/L) when measured by surface plasmon resonance. IGF-II signaling via the IGF-I receptor and the proliferative effect of IGF-II were specifically inhibited by 11(E1554K)-Fc in both HaCaT and Igf2(-/-) mouse embryonic fibroblast cells. These data confirm that a novel engineered and soluble IGF2R-11(E1554K)-Fc protein functions as an IGF-II-specific and high-affinity ligand trap in vitro and that this protein has potential application as an IGF-II antagonist for cancer therapy following in vivo experimental evaluation.