NOTCH1 PEST domain variants are responsive to standard of care treatments despite distinct transformative properties in a breast cancer model.

Activating variants in the PEST region of NOTCH1 have been associated with aggressive phenotypes in human cancers, including triple-negative breast cancer (TNBC). Previous studies suggested that PEST domain variants in TNBC patients resulted in increased cell proliferation, invasiveness, and decreased overall survival. In this study, we assess the phenotypic transformation of activating NOTCH1 variants and their response to standard of care therapies. AAV-mediated gene targeting was used to isogenically incorporate 3 NOTCH1 variants, including a novel TNBC frameshift variant, in two non-tumorigenic breast epithelial cell lines, MCF10A and hTERT-IMEC. Two different variants at the NOTCH1 A2241 site (A2441fs and A2441T) both demonstrated increased transformative properties when compared to a non-transformative PEST domain variant (S2523L). These phenotypic changes include proliferation, migration, anchorage-independent growth, and MAPK pathway activation. In contrast to previous studies, activating NOTCH1 variants did not display sensitivity to a gamma secretase inhibitor (GSI) or resistance to chemotherapies. This study demonstrates distinct transformative phenotypes are specific to a given variant within NOTCH1 and these phenotypes do not correlate with sensitivities or resistance to chemotherapies or GSIs. Although previous studies have suggested NOTCH1 variants may be prognostic for TNBC, our study does not demonstrate prognostic ability of these variants and suggests further characterization would be required for clinical applications.

The Long and Winding Road for Breast Cancer Biomarkers to Reach Clinical Utility.

Tumor data from the ABCSG 5 trial of chemotherapy versus endocrine therapy for premenopausal ER+ breast cancer supports molecular subtyping by Ki-67 IHC as a prognostic marker. But while this tissue was handled uniformly, Ki-67 testing overall is unstandardized, complicating clinical utility. Increasing potential biomarkers herald more challenges in biomarker validation.See related article by Bago-Horvath et al., p. 5682.

Resource-Stratified Guideline-Based Cancer Care Should Be a Priority: Historical Context and Examples of Success.

Low- and middle-income countries (LMICs) are shouldering most of the burden of the rapidly increasing cancer incidence and mortality worldwide, and this situation is projected to worsen in coming decades. Studies estimate that more than one million deaths could be prevented annually if all patients received high-quality care, but most LMICs lack the resources and infrastructure to adopt U.S. or European clinical oncology practice guidelines. Several organizations have developed resource-stratified guidelines (RSGs) to provide graduated and/or region-specific strategies for cancer diagnosis and treatment. The birth of these efforts traces to 2002, when the World Health Organization (WHO) called for tailoring cancer treatments to the level of available resources by country; the Breast Health Global Initiative (BHGI) formalized the first stratified guidelines for breast cancer shortly thereafter. Since then, multiple organizations including ASCO and the National Comprehensive Cancer Network (NCCN) have created guidelines customized for various cancer subtypes and regions. These RSGs offer roadmaps for policy makers, clinicians, and health care administrators in LMICs to design projects in implementation science that can gradually and strategically raise the quality of cancer care in their nation or region. Although the same resource limitations that complicate cancer care in these areas also pose barriers to data gathering and research, some countries have met the challenge and are improving cancer care using RSGs as a metric for success.

Undetectable Tumor Cell-Free DNA in a Patient With Metastatic Breast Cancer With Complete Response and Long-Term Remission.

The ability to serially monitor tumor-derived cell-free DNA (cfDNA) brings with it the potential to measure response to anticancer therapies and detect minimal residual disease (MRD). This report describes a patient with HER2-positive metastatic breast cancer with an exceptional response to trastuzumab and nab-paclitaxel who remains in complete remission several years after cessation of therapy. Next-generation sequencing of the patient's primary tumor tissue showed several mutations, including an oncogenic hotspot PIK3CA mutation. A sample of cfDNA was collected 6 years after her last therapy and then analyzed for mutant PIK3CA using digital PCR. No detectable mutations associated with the primary tumor were found despite assaying >10,000 genome equivalents, suggesting that the patient had achieved a molecular remission. Results of this case study suggest that serial monitoring of MRD using liquid biopsies could provide a useful method for individualizing treatment plans for patients with metastatic disease with extreme responses to therapy. However, large-scale clinical studies are needed to validate and implement these techniques for patient care.

TrkA overexpression in non-tumorigenic human breast cell lines confers oncogenic and metastatic properties.

BACKGROUND/PURPOSE: TrkA overexpression occurs in over 20% of breast cancers, including triple-negative breast cancers (TNBC), and has recently been recognized as a potential driver of carcinogenesis. Recent clinical trials of pan-Trk inhibitors have demonstrated targeted activity against tumors harboring NTRK fusions, a relatively rare alteration across human cancers. Despite this success, current clinical trials have not investigated TrkA overexpression as an additional therapeutic target for pan-Trk inhibitors. Here, we evaluate the cancerous phenotypes of TrkA overexpression relative to NTRK1 fusions in human cells and assess response to pharmacologic Trk inhibition. EXPERIMENTAL DESIGN/METHODS: To evaluate the clinical utility of TrkA overexpression, a panel of TrkA overexpressing cells were developed via stable transfection of an NTRK1 vector into the non-tumorigenic breast cell lines, MCF10A and hTERT-IMEC. A panel of positive controls was generated via stable transfection with a CD74-NTRK1 fusion vector into MCF10A cells. Cells were assessed via various in vitro and in vivo analyses to determine the transformative potential and targetability of TrkA overexpression. RESULTS: TrkA overexpressing cells demonstrated transformative phenotypes similar to Trk fusions, indicating increased oncogenic potential. TrkA overexpressing cells demonstrated growth factor-independent proliferation, increased PI3Kinase and MAPKinase pathway activation, anchorage-independent growth, and increased migratory capacity. These phenotypes were abrogated by the addition of the pan-Trk inhibitor, larotrectinib. In vivo analysis demonstrated increased tumorgenicity and metastatic potential of TrkA overexpressing breast cancer cells. CONCLUSIONS: Herein, we demonstrate TrkA overexpressing cells show increased tumorgenicity and are sensitive to pan-Trk inhibitors. These data suggest that TrkA overexpression may be an additional target for pan-Trk inhibitors and provide a targeted therapy for breast cancer patients.

Biotinylated amplicon sequencing: A method for preserving DNA samples of limited quantity.

BACKGROUND: Genomic testing is often limited by the exhaustible nature of human tissue and blood samples. Here we describe biotinylated amplicon sequencing (BAmSeq), a method that allows for the creation of PCR amplicon based next-generation sequencing (NGS) libraries while retaining the original source DNA. DESIGN AND METHODS: Biotinylated primers for different loci were designed to create NGS libraries using human genomic DNA from cell lines, plasma, and formalin-fixed paraffin embedded (FFPE) tissues using the BAmSeq protocol. DNA from the original template used for each BAmSeq library was recovered after separation with streptavidin magnetic beads. The recovered DNA was then used for end-point, quantitative and droplet digital PCR (ddPCR) as well as NGS using a cancer gene panel. RESULTS: Recovered DNA was analyzed and compared to the original DNA after one or two rounds of BAmSeq. Recovered DNA revealed comparable genomic distributions and mutational allelic frequencies when compared to original source DNA. Sufficient quantities of recovered DNA after BAmSeq were obtained, allowing for additional downstream applications. CONCLUSIONS: We demonstrate that BAmSeq allows original DNA template to be recovered with comparable quality and quantity to the source DNA. This recovered DNA is suitable for many downstream applications and may prevent sample exhaustion, especially when DNA quantity or source material is limiting.

Treatment of HIV-Associated Lymphomas: The Latest Approaches for Optimizing Outcomes.

Treatment outcomes for patients with HIV-related lymphoma have improved since the advent of combination antiretroviral therapy. Standard regimens, including intensive regimens, are being used with encouraging results in patients with diffuse large B-cell lymphoma, Burkitt lymphoma, Hodgkin lymphoma, and primary central nervous system lymphoma. Approaches to salvage therapy also parallel those used in patients without HIV infection, including autologous and allogeneic hematopoietic stem cell transplant. Drug interactions with particular antiretrovirals warrant close attention. At a population level, outcomes in patients with HIV infection and lymphoma remain inferior to outcomes achieved in the general population-but a great deal of progress has been made.

Developing a national collaborative of medical educators who lead clinical skills courses.

BACKGROUND: The majority of US medical schools now have pre-clerkship clinical skills (PCCS) courses. Course directors for these often logistically complicated courses may be in different medical specialties and, historically, have had few formal opportunities for communication and collaboration with their counterparts at other institutions. As such, we hypothesized that leaders of PCCS courses would benefit from a national network. SUMMARY: In this paper, we outline the methodology used to form a national collaborative from grass roots interest. Over three years, a self-identified eleven-person task force with national representation has created an organization for PCCS course directors from US medical schools called Directors Of Clinical Skills courses (DOCS) that meets annually. CONCLUSIONS: Through iterative presentations at regional and national medical education meetings, we have produced an inventory of educational issues for those developing, administering, and evaluating PCCS courses. Further development of this nascent organization is ongoing. Our process is generalizable.