Report on computational assessment of Tumor Infiltrating Lymphocytes from the International Immuno-Oncology Biomarker Working Group

Funder: U.S. Department of Health & Human Services | NIH | National Cancer Institute (NCI)Funder: National Center for Research Resources under award number 1 C06 RR12463-01, VA Merit Review Award IBX004121A from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service, the DOD Prostate Cancer Idea Development Award (W81XWH-15-1-0558), the DOD Lung Cancer Investigator-Initiated Translational Research Award (W81XWH-18-1-0440), the DOD Peer Reviewed Cancer Research Program (W81XWH-16-1-0329), the Ohio Third Frontier Technology Validation Fund, the Wallace H. Coulter Foundation Program in the Department of Biomedical Engineering and the Clinical and Translational Science Award Program (CTSA) at Case Western Reserve University.Funder: Susan G Komen Foundation (CCR CCR18547966) and a Young Investigator Grant from the Breast Cancer Alliance.Funder: The Canadian Cancer SocietyFunder: Breast Cancer Research Foundation (BCRF), Grant No. 17-194Abstract: Assessment of tumor-infiltrating lymphocytes (TILs) is increasingly recognized as an integral part of the prognostic workflow in triple-negative (TNBC) and HER2-positive breast cancer, as well as many other solid tumors. This recognition has come about thanks to standardized visual reporting guidelines, which helped to reduce inter-reader variability. Now, there are ripe opportunities to employ computational methods that extract spatio-morphologic predictive features, enabling computer-aided diagnostics. We detail the benefits of computational TILs assessment, the readiness of TILs scoring for computational assessment, and outline considerations for overcoming key barriers to clinical translation in this arena. Specifically, we discuss: 1. ensuring computational workflows closely capture visual guidelines and standards; 2. challenges and thoughts standards for assessment of algorithms including training, preanalytical, analytical, and clinical validation; 3. perspectives on how to realize the potential of machine learning models and to overcome the perceptual and practical limits of visual scoring

Pitfalls in assessing stromal tumor infiltrating lymphocytes (sTILs) in breast cancer

Abstract: Stromal tumor-infiltrating lymphocytes (sTILs) are important prognostic and predictive biomarkers in triple-negative (TNBC) and HER2-positive breast cancer. Incorporating sTILs into clinical practice necessitates reproducible assessment. Previously developed standardized scoring guidelines have been widely embraced by the clinical and research communities. We evaluated sources of variability in sTIL assessment by pathologists in three previous sTIL ring studies. We identify common challenges and evaluate impact of discrepancies on outcome estimates in early TNBC using a newly-developed prognostic tool. Discordant sTIL assessment is driven by heterogeneity in lymphocyte distribution. Additional factors include: technical slide-related issues; scoring outside the tumor boundary; tumors with minimal assessable stroma; including lymphocytes associated with other structures; and including other inflammatory cells. Small variations in sTIL assessment modestly alter risk estimation in early TNBC but have the potential to affect treatment selection if cutpoints are employed. Scoring and averaging multiple areas, as well as use of reference images, improve consistency of sTIL evaluation. Moreover, to assist in avoiding the pitfalls identified in this analysis, we developed an educational resource available at www.tilsinbreastcancer.org/pitfalls

Application of a risk-management framework for integration of stromal tumor-infiltrating lymphocytes in clinical trials

Funder: Breast Cancer Research Foundation (BCRF); doi: https://doi.org/10.13039/100001006Abstract: Stromal tumor-infiltrating lymphocytes (sTILs) are a potential predictive biomarker for immunotherapy response in metastatic triple-negative breast cancer (TNBC). To incorporate sTILs into clinical trials and diagnostics, reliable assessment is essential. In this review, we propose a new concept, namely the implementation of a risk-management framework that enables the use of sTILs as a stratification factor in clinical trials. We present the design of a biomarker risk-mitigation workflow that can be applied to any biomarker incorporation in clinical trials. We demonstrate the implementation of this concept using sTILs as an integral biomarker in a single-center phase II immunotherapy trial for metastatic TNBC (TONIC trial, NCT02499367), using this workflow to mitigate risks of suboptimal inclusion of sTILs in this specific trial. In this review, we demonstrate that a web-based scoring platform can mitigate potential risk factors when including sTILs in clinical trials, and we argue that this framework can be applied for any future biomarker-driven clinical trial setting

Study on the anisotropy and heterogeneity of microstructure and mechanical properties in additive manufactured Ti-6Al-4V parts by selective electron beam melting

Selective electron beam melting (SEBM) is a metal additive manufacturing (AM) technique that can produce high-quality metal parts with high strength and ductility. Due to the layer-by-layer approach and selective melting of the powder bed during the AM process, anisotropy and heterogeneity in the as-fabricated microstructure are challenges in the production of metal AM parts. An understanding of the formation mechanism that results in such microstructures in SEBM built Ti-6Al-4V is not yet fully understood. This study thus aims to further the understanding of the anisotropy and heterogeneity within the as-fabricated microstructure of Ti-6Al-4V alloy for microstructural control and the development of new materials. The control of the microstructure and the development of new materials are important to enable more applications for SEBM-built parts. Firstly, the phases within the as-built SEBM Ti-6Al-4V were studied and identified via phase characterisation techniques (e.g. TEM EDX, XRD and APT). Secondly, the influence of build geometry (e.g. thickness, height, and shape) on the microstructure and the mechanical properties were studied quantitatively via microstructural characterisation techniques (e.g. OM, SEM and TEM) and mechanical testing (e.g. Tensile test and Vickers microhardness). Lastly, the columnar grains within the as-built SEBM Ti-6Al-4V were studied as well. Numerical simulations to support the experimental observations and findings were also done via collaborations with other researchers. The results showed that anisotropy and heterogeneity in the microstructure and mechanical properties indeed existed within the SEBM Ti-6Al-4V part. The phase transformation process that occurs during the fabrication process of SEBM-built Ti-6Al-4V was also shown. Differences in the build geometry thus terminated the phase transformation process at various stages led to heterogeneity in its final mechanical properties. The columnar grain growth study showed that there existed strong texture intensity in the part with large cross sectional area that suggested competition between the columnar grains. Additionally, phenomenon of sub-columnar grain formation was also observed. The study contributes to the scientific knowledge with regards to the phase and microstructural evolution that happens during the SEBM fabrication process. It can also be a useful reference guide on both microstructural control and development of new materials for SEBM process.Doctor of Philosophy (MAE

Comparison of Two Metallic Additive Manufacturing Technologies: Selective Laser Melting and Electron Beam Melting

This general review paper compares two powder-bed fusion metallic additive manufacturing processes. The method is by reviewing past literature from sources such as scientific databases, journals, conferences and webpages. The scope of this review is on the selective laser melting and electron beam melting additive manufacturing method. The findings have shown large advances in the manufacturing quality of these two methods commercially. This review thus facilitates the choice of using either a laser based or electron based method for a given application.Published versio

Application of Electron Beam Melting (EBM) in Additive Manufacturing of an Impeller

An industrial impeller has been successfully fabricated by using Ti-6Al-4V ELI powder via a newly installed Arcam A2XX electron beam melting (EBM) machine. EBM was found to be preferable to build the circular or complex-shaped parts with thin walls. Several problems that frequently take place during the EBM fabrication are proposed based on the practical experience. It is found that metallization peeling-off, warpage, “swelling” and arc trips are the main reasons resulting in the failures of building jobs. It is suggested to pay close attention to the following aspects: a thorough cleanliness of the entire EBM system before start, a reasonable placement of builds on the start plate, an optimized design on geometries, etc., for a successfully built part.Published versio

Geometrical-based characterisation of complex ti-6al-4v parts fabricated by selective electron beam melting

In an additive manufactured metallic part, distinct and different microstructure and mechanical properties may exist on different areas due to differences in shape and location. Two parts, one with straight-finned structure and one with curvefinned structure, were fabricated by selective electron beam melting method using prealloyed Ti-6Al-4V powder. Microstructural characterization of these two parts that have varying fin thickness and shape were carried out in order to investigate the synthetically influence of build geometry and in-fill hatching strategy on selective electron beam melting. It was found that the β-spacing is larger in the curve-finned structure, leading to a lower micro-hardness as compared to the straight-finned structure. It suggests a slower cooling rate in the curve-finned structure due to the differences in build geometry and infill hatching strategy.Published versio

Revealing competitive columnar grain growth behavior and periodic microstructural banding in additively manufactured Ti-6Al-4 V parts by selective electron beam melting

Powder-bed fusion additive manufacturing of Ti-6Al-4 V has been of tremendous interest in both academia and industry. As the two ubiquitous microstructural features, columnar grain and microstructural banding in selective electron beam melting of Ti-6Al-4 V are systematically studied by experimental and simulation methods. Three basic build geometries (i.e. V-, I- and A-shaped parts) are employed to study the columnar grain growth behavior. We find that columnar prior β-Ti grains grow epitaxially and competitively by following the classic competitive grain growth model in additive manufacturing of Ti-6Al-4 V. It results in increasingly stronger crystallographic texture with the rising build height. We also observe the consistently occurring microstructural banding (∼100 µm in period) normal to build direction due to the overlapped heat affected zones that are formed in the layerwise thermal cyclic process. In addition, a large quantity of sub-columnar grains exist within the microstructure for selective electron beam melted Ti-6Al-4 V. It is demonstrated that the periodic microstructural banding determines the appearance of sub-columnar grains which may affect the competition behavior for the growth of columnar grains.NRF (Natl Research Foundation, S’pore)Accepted versio

Anisotropy and heterogeneity of microstructure and mechanical properties in metal additive manufacturing: A critical review

Metal additive manufacturing (AM) has developed rapidly over the last decade to become a disruptive technology capable of revolutionizing the way that products from various industrial sectors such as biomedical, aerospace, automotive, marine and offshore are designed. Early adopters of the technology like the biomedical and aerospace industries have shown that the better-designed components offer substantial performance improvements over current designs. However, in-depth and comprehensive views on the microstructure and mechanical properties of additively manufactured metals and alloys are less reported. To realize the full design potential that metal AM can offer, especially for load-bearing structural components, it is imperative to provide a thorough understanding on the anisotropic and heterogeneous microstructure and mechanical properties that often occur within metal AM parts. This paper outlines a broad range of metal AM technologies and reviews literatures on the anisotropy and heterogeneity of microstructure and mechanical properties for metal AM parts. It can be highlighted that the contributing factors to the anisotropy and heterogeneity within metal AM parts were either their unique microstructural features or manufacturing deficiencies. Concluding remarks on the state-of-the-art research regarding this topic and the possible solutions to overcome the anisotropy and heterogeneity of metal AM parts are provided.ASTAR (Agency for Sci., Tech. and Research, S’pore)Accepted versio