Platelet proteo-transcriptomic profiling validates mediators of thrombosis and proteostasis in patients with myeloproliferative neoplasms.

Patients with chronic Myeloproliferative Neoplasms (MPN) including polycythemia vera (PV) and essential thrombocythemia (ET) exhibit unique clinical features, such as a tendency toward thrombosis and hemorrhage, and risk of disease progression to secondary bone marrow fibrosis and/or acute leukemia. Although an increase in blood cell lineage counts (quantitative features) contribute to these morbid sequelae, the significant qualitative abnormalities of myeloid cells that contribute to vascular risk are not well understood. Here, we address this critical knowledge gap via a comprehensive and untargeted profiling of the platelet proteome in a large (n= 140) cohort of patients (from two independent sites) with an established diagnosis of PV and ET (and complement prior work on the MPN platelet transcriptome from a third site). We discover distinct MPN platelet protein expression and confirm key molecular impairments associated with proteostasis and thrombosis mechanisms of potential relevance to MPN pathology. Specifically, we validate expression of high-priority candidate markers from the platelet transcriptome at the platelet proteome (e.g., calreticulin (CALR), Fc gamma receptor (FcγRIIA) and galectin-1 (LGALS1) pointing to their likely significance in the proinflammatory, prothrombotic and profibrotic phenotypes in patients with MPN. Together, our proteo-transcriptomic study identifies the peripherally-derived platelet molecular profile as a potential window into MPN pathophysiology and demonstrates the value of integrative multi-omic approaches in gaining a better understanding of the complex molecular dynamics of disease.

A New Risk Prediction Model for Venous Thromboembolism and Death in Ambulatory Lung Cancer Patients.

(1) Background: Venous thromboembolism (VTE) is a frequent complication in ambulatory lung cancer patients during chemotherapy and is associated with increased mortality. (2) Methods: We analyzed 568 newly diagnosed metastatic lung cancer patients prospectively enrolled in the HYPERCAN study. Blood samples collected before chemotherapy were tested for thrombin generation (TG) and a panel of hemostatic biomarkers. The Khorana risk score (KRS), new-Vienna CATS, PROTECHT, and CONKO risk assessment models (RAMs) were applied. (3) Results: Within 6 months, the cumulative incidences of VTE and mortality were 12% and 29%, respectively. Patients with VTE showed significantly increased levels of D-dimer, FVIII, prothrombin fragment 1 + 2, and TG. D-dimer and ECOG performance status were identified as independent risk factors for VTE and mortality by multivariable analysis and utilized to generate a risk score that provided a cumulative incidence of VTE of 6% vs. 25%, death of 19% vs. 55%, and in the low- vs. high-risk group, respectively (p < 0.001). While all published RAMs significantly stratified patients for risk of death, only the CATS and CONKO were able to stratify patients for VTE. (4) Conclusions: A new prediction model was generated to stratify lung cancer patients for VTE and mortality risk, where other published RAMs failed.

The unfolded protein response links ER stress to cancer-associated thrombosis.

Thrombosis is a common complication of advanced cancer, yet the cellular mechanisms linking malignancy to thrombosis are poorly understood. The unfolded protein response (UPR) is an ER stress response associated with advanced cancers. A proteomic evaluation of plasma from patients with gastric and non-small cell lung cancer who were monitored prospectively for venous thromboembolism demonstrated increased levels of UPR-related markers in plasma of patients who developed clots compared with those who did not. Release of procoagulant activity into supernatants of gastric, lung, and pancreatic cancer cells was enhanced by UPR induction and blocked by antagonists of the UPR receptors inositol-requiring enzyme 1α (IRE1α) and protein kinase RNA-like endoplasmic reticulum kinase (PERK). Release of extracellular vesicles bearing tissue factor (EVTFs) from pancreatic cancer cells was inhibited by siRNA-mediated knockdown of IRE1α/XBP1 or PERK pathways. Induction of UPR did not increase tissue factor (TF) synthesis, but rather stimulated localization of TF to the cell surface. UPR-induced TF delivery to EVTFs was inhibited by ADP-ribosylation factor 1 knockdown or GBF1 antagonism, verifying the role of vesicular trafficking. Our findings show that UPR activation resulted in increased vesicular trafficking leading to release of prothrombotic EVTFs, thus providing a mechanistic link between ER stress and cancer-associated thrombosis.

Utility of the Khorana and the new-Vienna CATS prediction scores in cancer patients of the HYPERCAN cohort.

BACKGROUND: Risk assessment models (RAMs) are relevant approaches to identify cancer outpatients at high risk of venous thromboembolism (VTE). Among the proposed RAMs, the Khorana (KRS) and the new-Vienna CATS risk scores have been externally validated in ambulatory patients with cancer. OBJECTIVES: To test KRS and new-Vienna CATS scores in 6-month VTE prediction and mortality in a large prospective cohort of metastatic cancer outpatients during chemotherapy. PATIENTS/METHODS: Newly diagnosed patients with metastatic non-small cell lung, colorectal, gastric, or breast cancers were analyzed (n = 1286). The cumulative incidence of objectively confirmed VTE was estimated with death as a competing risk and multivariate Fine and Gray regression. RESULTS: Within 6 months, 120 VTE events (9.7%) occurred. The KRS and the new-Vienna CATS scores showed comparable c-stat. Stratification by KRS provided VTE cumulative incidences of 6.2%, 11.4%, and 11.5% in the low-, intermediate-, and high-risk categories, respectively (p = ns), and of 8.5% vs. 11.8% (p = ns) in the low- vs. high-risk group by the single 2-point cut-off value stratification. Using a pre-defined 60-point cut-off by the new-Vienna CATS score, 6.6% and 12.2% cumulative incidences were obtained in the low- and high-risk groups, respectively (p < 0.001). Furthermore, having a KRS ≥2 = or a new-Vienna CATS score >60 points was also an independent risk factor for mortality. CONCLUSION: In our cohort, the 2 RAMs showed a comparable discriminating potential; however, after the application of cut-off values, the new-Vienna CATS score provided statistically significant stratification for VTE. Both RAMs proved to be effective in identifying patients at increased risk of mortality.

Cancer-associated thrombosis: enhanced awareness and pathophysiologic complexity.

Thrombosis, both venous and arterial, is a leading cause of morbidity and mortality in patients with cancer. Studies on the molecular basis of cancer-associated thrombophilia have a long story starting from the first observation of the presence of tumor cells in circulating microthrombi 2 centuries ago. The profound link between pathways of blood coagulation and tumor biology has been more and more unraveled, and new actors in this complex interaction have been identified. The unfavorable impact of thrombosis in a patient with cancer, on which also hangs a high bleeding risk as compared to the noncancer population, has led during years to the production of large clinical studies to adopt the best prophylaxis and treatment strategies of venous thromboembolism in different medical and surgical settings, now incorporated in dedicated international guidelines. This field, however, still represents an open challenge due to the intrinsic variability of the patient with cancer with his/her personal medical history and cardiovascular risk factors, as well as the type, site and stage of the tumor, and the use of a wide array of new sophisticated anticancer drugs. This review aims to highlight some of the many key observations in the field of cancer and thrombosis, spanning the scope from fundamental tumor biology to advanced clinical trials of new anticoagulants. We hope that some of the examples we have included will inspire readers to explore and discuss these topics, thereby increasing awareness of cancer-related thrombosis in both physicians and patients.

Hemostatic system activation in breast cancer: Searching for new biomarkers for cancer risk prediction and outcomes.

In malignant diseases, the development of a systemic hypercoagulable state is the consequence of the procoagulant activity of cancer cells on the hemostatic system and based on this close relationship, alterations in the levels of hemostatic biomarkers and/or biomarkers of blood clotting activation are under investigation as a potential tool in predicting for different cancer outcomes. Today, breast cancer remains the most common tumor and the second cause of mortality for cancer in women. There is still a need for novel biomarkers for making a diagnosis at a very early stage of disease and for the classification of individuals at different risks of disease recurrence or progression. In this review, we will discuss the pathogenesis of the thrombophilic state in breast cancer patients and its interconnection with the mechanisms of malignant progression, and report on the latest results from the HYPERCAN study in the context of hemostatic biomarker development in the breast cancer setting.

Fibrinogen levels in relation to colorectal cancer onset: A nested case-cohort study from the Moli-sani cohort.

Background: Patients with cancer are commonly characterized by abnormalities in laboratory coagulation tests, underlying a subclinical hypercoagulable condition. Due to the involvement of the hemostatic system in cancer patients, some of its biomarkers, such as fibrinogen, could be a useful tool in predicting cancer risk. We performed a case-cohort study to evaluate the relationship among fibrinogen levels and colorectal cancer (CRC). Methods: In the framework of Moli-sani Study (N = 24,325, enrolled 2005-2010) a subcohort of 1,290 individuals (55.0% women; mean age 55.0 ± 12.0 years) was selected and compared with 126 CRC cases identified during a follow-up of 4.3 years. Incident cases of colorectal cancer were ascertained by direct linkage with hospital discharge forms according to the International Classification of Disease (ICD-9-CM) codes: 153-154. Events were validated through medical records and confirmed by histological reports. Fibrinogen levels were measured in frozen citrated plasma samples. Hazard Ratio (HR) and 95% confidence interval (CI), adjusted by relevant covariates were estimated by a Cox regression model using Prentice method. Results: Individuals with levels of fibrinogen ≥400 mg/dL had a higher hazard to develop colorectal cancer when compared to those with lower levels after adjustment for sex and age (HR: 1.81; 95% CI 1.12-2.92). Additional adjustment for CRC family history, income, physical activity, diabetes medication and hypercholesterolemia did not modify the result (HR: 1.91; 95% CI 1.15-3.17). Analyses stratified by age and sex showed a most evident association in elderly (HR: 2.30; 95% CI: 1.10-4.81) and in women (HR: 2.28; 95% CI: 1.08-4.81). Sensitivity analyses confirmed the main findings, showing independence from a potential role of confounding by a large panel of biomarkers, including inflammation and hemostasis factors. Conclusion: Our results, based on a case-cohort study from a general adult population apparently free from any cancer during the recruitment, showed that fibrinogen levels ≥400 mg/dL were positively and independently associated with CRC, suggesting that this glycoprotein could be a potential biomarker for this type of cancer and supporting the "common soil hypothesis" in the pathophysiology of cardiovascular disease and tumors.

Thrombin Generation and D-Dimer for Prediction of Disease Progression and Mortality in Patients with Metastatic Gastrointestinal Cancer.

Background: the tight and reciprocal interaction between cancer and hemostasis has stimulated investigations on the possible role of hemostatic biomarkers in predicting specific cancer outcomes, such as disease progression (DP) and overall survival (OS). In a prospective cohort of newly diagnosed metastatic gastrointestinal (GI) cancer patients from the HYPERCAN study, we aimed to assess whether the hemostatic biomarker levels measured before starting any anticancer therapy may specifically predict for 6-months DP (6m-DP) and for 1-year OS (1y OS). Methods: plasma samples were collected and tested for thrombin generation (TG) as global hemostatic assay, and for D-dimer, fibrinogen, and prothrombin fragment 1 + 2 as hypercoagulation biomarkers. DP and mortality were monitored during follow-up. Results: A prospective cohort of 462 colorectal and 164 gastric cancer patients was available for analysis. After 6 months, DP occurred in 148 patients, providing a cumulative incidence of 24.8% (21.4−28.4). D-dimer and TG endogenous thrombin potential (ETP) were identified as independent risk factors for 6m-DP by multivariate Fine−Gray proportional hazard regression model corrected for age, cancer site, and >1 metastatic site. After 1 year, we observed an OS of 75.7% (71.9−79.0). Multivariate Cox regression analysis corrected for age, site of cancer, and performance status identified D-dimer and ETP as independent risk factors for 1y OS. Patients with one or both hemostatic parameters above the dichotomizing threshold were at higher risk for both 6m-DP and 1-year mortality. Conclusion.: in newly diagnosed metastatic GI cancer patients, pretreatment ETP and D-dimer appear promising candidate biomarkers for predicting 6m-DP and 1y OS. In this setting, for the first time, the role of TG as a prognostic biomarker emerges in a large prospective cohort.

Increased platelet thrombus formation under flow conditions in whole blood from polycythaemia vera patients.

BACKGROUND: Polycythaemia vera is a myeloproliferative neoplasm characterised by a high incidence of thrombosis. The contribution of platelets, key players in haemostasis, in this setting is still unclear. So far, the majority of studies have been focussed on specific platelet abnormalities but not on their actual capacity to form thrombi. The aim of this study was to characterise, ex vivo under flow conditions, the capacity of platelets from patients with polycythaemia vera to adhere to collagen and induce thrombus formation. MATERIALS AND METHODS: Thirty-nine patients and 30 healthy controls were studied. Thrombus formation was induced by perfusing whole blood over a collagen-coated surface, in a parallel-plate flow chamber coupled to a fluorescent microscope. This dynamic system enables platelet adhesion and thrombus formation to be followed in real time and also allows measurements of the extent of the thrombus and platelet surface antigen expression. Laboratory data were analysed in the light of the patients' main haematological parameters and therapies. RESULTS: Platelet adhesion was significantly greater in patients than in control subjects. Patient thrombi were usually larger and more complex than those formed by control platelets. A significant positive correlation was found between platelet adhesion and both the haematocrit and red blood cell count. These parameters remained significantly correlated with platelet adhesion also after multivariable analysis adjusted for gender, age, therapy and JAK2V617F allele burden. Furthermore, subjects with a haematocrit >45% had significantly greater platelet adhesion than subjects with a haematocrit <45%. DISCUSSION: Our data indicate that increased platelet adhesion participates in the thrombotic diathesis of patients with polycythaemia vera, and that the haematocrit level can affect the adhesive and thrombus forming capacities of platelets.

Autoimmune disorders of platelet function: systematic review of cases of acquired Glanzmann thrombasthenia and acquired delta storage pool disease.

Acquired platelet function disorders (PFD) are rare bleeding diseases that should be suspected in all patients with unexplained mucocutaneous bleedings of recent onset, with no previous history of haemorrhages, and with normal coagulation test and platelet count. Drug-induced platelet function bleeding disorders are the most frequent PFDs and can easily be identified on the basis of recent administration of platelet-inhibiting drugs. Apart from these, the most challenging acquired PFDs are those caused by autoimmune mechanisms. In fact, demonstration of autoantibodies inhibiting platelet function may be difficult in most non-specialised centres. Among autoimmune PFDs (aPFDs), acquired Glanzmann thrombasthenia (aGT), which is caused by autoantibodies that bind to platelet αIIbß3 integrin, inhibiting its function, is the most frequent. aGT can be associated with underlying haematological malignancies or autoimmune diseases but can also be idiopathic. More rarely, other immune-mediated PFDs can occur, such as acquired delta storage pool disease (aδSPD). Treatment of aPFDs must rely on the control of acute and chronic bleedings, treatment of the underlying disease in secondary forms, and immunosuppressive treatment for autoantibody reduction or eradication. aPFDs may completely resolve upon treatment of any underlying disease that may be present. In primary aPFDs, and in the majority of secondary forms, treatment relies on immunosuppressive therapies.Here we present a systematic review of previously described immune-mediated aGT and aδSPD cases. Clinical and laboratory characteristics, treatments for the control of bleedings and for the eradication of autoantibodies, and responses to treatments are also discussed. Although no guidelines are available for the management of these very rare conditions, presentation of all cases reported so far can help clinicians in the diagnosis and treatment of these life-threatening diseases.

Hemostatic Biomarkers and Cancer Prognosis: Where Do We Stand?

Cancer patients are characterized by hypercoagulable state and an increased rate of thrombotic events, the most common being venous thromboembolism. Several hemostatic pathways that are significantly implicated in mechanisms of thromboembolic disease are also involved in growth, invasion, and metastatic spread of malignant cells as well in tumor-induced neo-angiogenesis. This close connection between cancer and the hemostatic system has prompted numerous studies on the role of alterations in the level plasma biomarkers of the different compartments of hemostasis in predicting cancer prognosis. In this review, we collect the results of several exemplificative studies that have evaluated clotting activation biomarkers in relation to different cancer outcomes with a final emphasis on current research and forthcoming directions in this field.

Case Report: Effects of Anti-SARS-CoV-2 Convalescent Antibodies Obtained With Double Filtration Plasmapheresis.

Passive antibody therapy has been used to treat outbreaks of viral disease, including the ongoing pandemic of severe respiratory acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) or COVID-19. However, the real benefits of the procedure are unclear. We infused a concentrated solution of neutralizing anti-SARS-CoV-2 antibodies obtained from a convalescent donor with a single session of double filtration plasmapheresis (DFPP) into a 56-year-old woman with long history of unremitting, severe COVID-19. She was unable to establish an adequate antiviral immune response because of previous chemotherapy, including the infusion of the anti-CD20 monoclonal antibody rituximab, administered to treat a diffuse large B-cell lymphoma. The disease promptly recovered despite evidence of no endogenous anti-SARS-CoV-2 antibody production. The observation that passive antibody therapy might prove particularly effective in immunodepressed COVID-19 patients requires evaluation in prospective randomized controlled trial.

Validation of the Role of Thrombin Generation Potential by a Fully Automated System in the Identification of Breast Cancer Patients at High Risk of Disease Recurrence.

Background The measurement of thrombin generation (TG) potential by the calibrated automated thrombogram (CAT) assay provides a strong contribution in identifying patients at high risk of early disease recurrence (E-DR). However, CAT assay still needs standardization and clinical validation. Objective In this study, we aimed to validate the role of TG for E-DR prediction by means of the fully automated ST Genesia system. Methods A prospective cohort of 522 patients from the HYPERCAN study with newly diagnosed resected high-risk breast cancer was included. Fifty-two healthy women acted as controls. Plasma samples were tested for protein C, free-protein S, and TG by ST Genesia by using the STG-ThromboScreen reagent with and without thrombomodulin (TM). Results In the absence of TM, patients showed significantly higher peak and ETP compared with controls. In the presence of TM, significantly lower inhibition of ETP and Peak were observed in patients compared with controls. E-DR occurred in 28 patients; these patients had significantly higher peak and endogenous thrombin potential (ETP) in the absence of TM compared with disease-free patients. Multivariable analysis identified mastectomy, luminal B HER2-neg, triple negative subtypes, and ETP as independent risk factors for E-DR. These variables were combined to generate a risk assessment score, able to stratify patients in three-risk categories. The E-DR rates were 0, 4.7, and 13.5% in the low-, intermediate-, and high-risk categories (hazard ratio = 8.7; p < 0.05, low vs. high risk). Conclusion Our data validate the ETP parameter with a fully automated standardized system and confirm its significant contribution in identifying high-risk early breast cancer at risk for E-DR during chemotherapy.

Prevention and Management of Thrombosis in BCR/ABL-Negative Myeloproliferative Neoplasms.

Myeloproliferative neoplasms (MPNs) are clonal disorders of the hematopoietic stem cell. Classical BCR/ABL-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Thrombotic events are a major cause of morbidity and mortality in these patients. Pathogenesis of blood clotting activation involves various abnormalities of platelets, erythrocytes, and leukocytes, as well as dysfunctions of endothelial cells. Patients with MPN can be stratified in "high risk" or "low risk" of thrombosis according to established risk factors. ET and PV clinical management is highly dependent on the patient's thrombotic risk, and a risk-oriented management strategy to treat these diseases is strongly recommended. In this review, we give an overview of risk factors, pathogenesis, and thrombosis prevention and treatment in MPN.

Tissue Plasminogen Activator Levels and Risk of Breast Cancer in a Case-Cohort Study on Italian Women: Results from the Moli-sani Study.

BACKGROUND: Elevated levels of key enzymes of the fibrinolytic system, such as tissue plasminogen activator (tPA), are reported as predictors of poor outcome in cancer patients. Limited information is available about their potential predictive value for breast cancer (BC) risk in the general population. AIM: We examined the association of tPA levels with BC risk in a case-cohort study including women from the prospective Moli-sani cohort. METHODS: A sample of 710 women (mean age: 54.6 ± 12.1 years) was selected as a subcohort and compared with 84 BC cases, in a median follow-up of 4.2 years. Incident cases of BC were validated through medical records. tPA plasma levels were measured using an enzyme-linked immunosorbent assay kit. Hazard ratio (HR) and 95% confidence interval (CI), adjusted for relevant covariates, were estimated by a Cox regression model using the Prentice method. RESULTS: Compared with the lowest quartile (<4.9 ng/mL), women in the highest quartile of tPA (>11.2 ng/mL) had increased risk of BC (HRIVvsI: 2.20, 95% CI: 1.13-4.28) after adjusted for age, smoking, education, menopause, and residence. Further adjustment for biochemical markers did not modify this association. The risk of BC increased by 34% for each increase in 1 standard deviation of log-transformed tPA levels (p = 0.046). Elevated levels of tPA were associated mainly with estrogen-receptor-positive BC (2.08, 95% CI: 1.18-3.66). CONCLUSION: Higher levels of tPA, reported to predict cardiovascular risk, are a potential biomarker for BC risk, supporting the hypothesis of a "common soil" linking the pathogenic mechanisms of hormone-dependent tumors and cardiovascular disease.

Hemostatic biomarkers in occult cancer and cancer risk prediction.

Cancer patients present with abnormalities of coagulation tests, reflecting a hypercoagulable state, often asso- ciated with a high incidence of thrombotic complications and poor disease prognosis. Different degrees of blood clotting abnormalities are described in diverse cancers, depending on tumor types and stage. The mechanisms of hemostasis that are critically involved in thrombosis are also implicated in tumor progression, angiogenesis, and metastatic spread. In this review, we summarize the results of published studies and focus on ongoing research and future directions of clotting factors and clotting activation bioproducts as biomarkers for cancer disease diagnosis and in cancer risk prediction.

Thrombin generation predicts early recurrence in breast cancer patients.

BACKGROUND: Cancer patients present with a hypercoagulable state often associated with poor disease prognosis. OBJECTIVES: This study aims to evaluate whether thrombin generation (TG), a global coagulation test, may be a useful tool to improve the identification of patients at high risk of early disease recurrence (ie, E-DR within 2 years) after breast cancer surgery. PATIENTS/METHODS: A cohort of 522 newly diagnosed patients with surgically resected high-risk breast cancer were enrolled in the ongoing prospective HYPERCAN study. TG potential was measured in plasma samples collected before starting systemic chemotherapy. Significant predictive hemostatic and clinic-pathological parameters were identified in the derivation cohort by Cox regression analysis. A risk prognostic score for E-DR was generated in the derivation and tested in the validation cohort. RESULTS: After a median observation period of 3.4 years, DR occurred in 51 patients, 28 of whom were E-DR. E-DR subjects presented with the highest TG values as compared to both late-DR (from 2 to 5 years) and no relapse subjects (P < .01). Multivariate analysis in the derivation cohort identified TG, mastectomy, triple negative and Luminal B HER2-neg molecular subtypes as significant independent predictors for E-DR, which were utilized to generate a risk assessment score. In the derivation and validation cohorts, E-DR rates were 2.3% and 0% in the low-risk, 10.1% and 6.3% in the intermediate-risk, and 18.2% and 16.7%, in the high-risk categories, respectively. CONCLUSIONS: Inclusion of TG in a risk-assessment model for E-DR significantly helps the identification of operated breast cancer patients at high risk of very early relapse.

Thrombotic biomarkers for risk prediction of malignant disease recurrence in patients with early stage breast cancer.

In cancer patients, hypercoagulability is a common finding. It has been associated with an increased risk of venous thromboembolism, but also to tumor proliferation and progression. In this prospective study of a large cohort of breast cancer patients, we aimed to evaluate whether pre-chemotherapy abnormalities in hemostatic biomarkers levels: (i) are associated with breast cancer-specific clinico-pathological features; and (ii) can predict for disease recurrence. D-dimer, fibrinogen, prothrombin fragment 1+2, and FVIIa/antithrombin levels were measured in 701 early-stage resected breast cancer patients candidate to adjuvant chemotherapy and prospectively enrolled in the HYPERCAN study. Significant prognostic parameters for disease recurrence were identified by Cox regression multivariate analysis and used for generating a risk assessment model. Pre-chemotherapy D-dimer, fibrinogen, and pro-thrombin fragment 1+2 levels were significantly associated with tumor size and lymph node metastasis. After 3.4 years of follow up, 71 patients experienced a recurrence. Cox multivariate analysis identified prothrombin fragment 1+2, tumor size, and Luminal B HER2-negative or triple negative molecular subtypes as independent risk factors for disease recurrence. Based on these variables, we generated a risk assessment model that significantly differentiated patients at low- and high-risk of recurrence (cumulative incidence: 6.2 vs 20.7%; Hazard Ratio=3.5; P<0.001). Our prospective clinical and laboratory data from the HYPERCAN study were crucial for generating a scoring model for assessing risk of disease recurrence in resected breast cancer patients, candidate to systemic chemotherapy. This finding stimulates future investigations addressing the role of plasma prothrombin fragment 1+2 in the management of breast cancer patients to provide the rationale for new therapeutic strategies. (The HYPERCAN study is registered at clinicaltrials.gov identifier 02622815).

Two Missense Variants Detected in Breast Cancer Probands Preventing BRCA2-PALB2 Protein Interaction.

PALB2 (partner and localizer of BRCA2) was initially identified as a binding partner of BRCA2. It interacts also with BRCA1 forming a complex promoting DNA repair by homologous recombination. Germline pathogenic variants in BRCA1, BRCA2 and PALB2 DNA repair genes are associated with high risk of developing breast cancer. Mutation screening in these breast cancer predisposition genes is routinely performed and allows the identification of individuals who carry pathogenic variants and are at risk of developing the disease. However, variants of uncertain significance (VUSs) are often detected and establishing their pathogenicity and clinical relevance remains a central challenge for the risk assessment of the carriers and the clinical decision-making process. Many of these VUSs are missense variants leading to single amino acid substitutions, whose impact on protein function is uncertain. Typically, VUSs are rare and due to the limited genetic, clinical, and pathological data the multifactorial approaches used for classification cannot be applied. Thus, these variants can only be characterized through functional analyses comparing their effect with that of normal and mutant gene products used as positive and negative controls. The two missense variants BRCA2:c.91T >G (p.Trp31Gly) and PALB2:c.3262C >T (p.Pro1088Ser) were detected in two breast cancer probands originally ascertained at Breast Cancer Units of Institutes located in Milan and Bergamo (Northern Italy), respectively. These variants were located in the BRCA2-PALB2 interacting domains, were predicted to be deleterious by in silico analyses, and were very rare and clinically not classified. Therefore, we initiate to study their functional effect by exploiting a green fluorescent protein (GFP)-reassembly in vitro assay specifically designed to test the BRCA2-PALB2 interaction. This functional assay proved to be easy to develop, robust and reliable. It also allows testing variants located in different genes. Results from these functional analyses showed that the BRCA2:p.Trp31Gly and the PALB2:p.Pro1088Ser prevented the BRCA2-PALB2 binding. While caution is warranted when the interpretation of the clinical significance of rare VUSs is based on functional studies only, our data provide initial evidences in favor of the possibility that these variants are pathogenic.