Companion Diagnostics: Lessons Learned and the Path Forward From the Programmed Death Ligand-1 Rollout.

CONTEXT.­: Programmed death ligand-1 (PD-L1) immunohistochemistry companion diagnostic assays play a crucial role as predictive markers in patients being considered for immune checkpoint inhibitor therapy. However, because of a convergence of several factors, including recognition of increased types of cancers susceptible to immunotherapy, increasing numbers of immune checkpoint inhibitors, and release of multiple PD-L1 immunohistochemistry antibodies with differing reporting systems, this complex testing environment has led to significant levels of confusion for pathologists and medical oncologists. OBJECTIVE.­: To identify which processes and procedures have contributed to the current challenges surrounding programmed death receptor-1 (PD-1)/PD-L1 companion diagnostics and to propose potential remedies to this issue. This is based upon input from key industrial stakeholders in conjunction with the College of American Pathologists Personalized Health Care Committee. DESIGN.­: A meeting of representatives of pharmaceutical and in vitro diagnostic companies along with the Personalized Health Care Committee reviewed the process of release of the PD-L1 companion diagnostic assays using a modified root cause analysis format. The modified root cause analysis envisioned an ideal circumstance of development and implementation of a companion diagnostic to identify shortcomings in the rollout of the PD-L1 assay and to suggest actions to improve future companion diagnostic assay releases. RESULTS.­: The group recommended improvements to key principles in companion diagnostics implementation related to multi-stakeholder communication, increased regulatory flexibility to incorporate postapproval medical knowledge, improved cross-disciplinary information exchange between medical oncology and pathology societies, and enhanced postmarket training programs. CONCLUSIONS.­: The rapidly changing nature of and increasing complexity associated with companion diagnostics require a fundamental review of processes related to their design, implementation, and oversight.

Getting Your Laboratory on Track With Neurotrophic Receptor Tyrosine Kinase.

CONTEXT.­: Neurotrophic receptor tyrosine kinase (NTRK) fusion testing has both diagnostic and therapeutic implications for patient care. With 2 tumor-agnostic US Food and Drug Administration-approved tropomyosin receptor kinase (TRK) inhibitors, testing is increasingly used for therapeutic decision making. However, the testing landscape for NTRK fusions is complex, and optimal testing depends on the clinicopathologic scenario. OBJECTIVE.­: To compare different NTRK testing methods to help pathologists understand test features and performance characteristics and make appropriate selections for NTRK fusion detection for their laboratory and individual patient specimens. DATA SOURCES.­: A literature search for NTRK gene fusions and TRK protein was performed, including papers that discussed treatment, testing methodology, and detection or prevalence of fusion-positive cases. CONCLUSIONS.­: As standard of care in some tumor types, next-generation sequencing (NGS) panel testing is a cost effective and reliable way to detect a broad range of NTRK fusions. The design of the panel and use of DNA or RNA will affect performance characteristics. Pan-TRK immunohistochemistry may be used as a rapid, less expensive screen in cases that will not undergo routine NGS testing, or on specimens unsuitable for NGS testing. Fluorescence in situ hybridization may be appropriate for low-tumor-content specimens that are unsuitable for NGS testing. Quantitative reverse transcription polymerase chain reaction is best suited for monitoring low-level disease of a specific, previously identified target. This information should help laboratories develop a laboratory-specific NTRK testing algorithm that best suits their practice setting and patients' needs.

Proceedings From the ASCO/College of American Pathologists Immune Checkpoint Inhibitor Predictive Biomarker Summit.

PURPOSE: Immune checkpoint inhibition (ICI) therapy represents one of the great advances in the field of oncology, highlighted by the Nobel Prize in 2018. Multiple predictive biomarkers for ICI benefit have been proposed. These include assessment of programmed death ligand-1 expression by immunohistochemistry, and determination of mutational genotype (microsatellite instability or mismatch repair deficiency or tumor mutational burden) as a reflection of neoantigen expression. However, deployment of these assays has been challenging for oncologists and pathologists alike. METHODS: To address these issues, ASCO and the College of American Pathologists convened a virtual Predictive Factor Summit from September 14 to 15, 2021. Representatives from the academic community, US Food and Drug Administration, Centers for Medicare and Medicaid Services, National Institutes of Health, health insurance organizations, pharmaceutical companies, in vitro diagnostics manufacturers, and patient advocate organizations presented state-of-the-art predictive factors for ICI, associated problems, and possible solutions. RESULTS: The Summit provided an overview of the challenges and opportunities for improvement in assay execution, interpretation, and clinical applications of programmed death ligand-1, microsatellite instability-high or mismatch repair deficient, and tumor mutational burden-high for ICI therapies, as well as issues related to regulation, reimbursement, and next-generation ICI biomarker development. CONCLUSION: The Summit concluded with a plan to generate a joint ASCO/College of American Pathologists strategy for consideration of future research in each of these areas to improve tumor biomarker tests for ICI therapy.

The Best of Both Worlds: Eliminating Creatine Kinase-Muscle/Brain (CK-MB) Testing in the Emergency Department Leads to Lower Costs Without Missed Clinical Diagnoses.

The 2014 American Heart Association/American College of Cardiology (AHA/ACC) clinical guidelines recommend cardiac troponin as a superior biomarker to creatine kinase (CK) and creatine kinase-muscle/brain (CK-MB) for the detection of acute coronary syndrome (ACS), namely myocardial infarction and unstable angina. In April 2018, our Emergency Department (ED) transitioned from using standard troponin to using high-sensitivity troponin T, and adopted a clinical guideline consistent with the AHA/ACC. The guideline recommended high-sensitivity troponin T without CK/CK-MB testing in the majority of clinical situations, limiting CK/CK-MB testing to two specific clinical cases: 1) estimated glomerular filtration rate (eGFR) value <15 mL/min, or 2) recent acute coronary syndrome (ACS) event. Per our ED's policy, a "negative" troponin T was defined as being below the limit of detection (LOD) (i.e., <6 ng/L); such a value obtained at least 3 hours after symptom onset "ruled out" an ACS event and did not require a repeat troponin. The goal of this retrospective study was to determine whether the guideline limiting CK-MB testing missed clinically-significant cardiac outcomes (ACS or new diagnosis of coronary artery disease [CAD]) or was associated with mortality. Pre-implementation data (July 1, 2017 - December 31, 2017) was compared with post-implementation data (July 1, 2018 - December 31, 2018). After guideline introduction, CK/CK-MB ordering decreased by nearly 90%, while troponin ordering increased by nearly 20%, likely due to the introduction in June 2018 of high-sensitivity troponin T, which yielded numerous intermediate/indeterminate-range results that prompted repeat testing. Fewer than 1.5% of patients with a "negative" troponin (below the LOD) and a "positive" CK-MB (above the upper limit of normal [ULN]) had ACS or new-diagnosis CAD; patients with either diagnosis did not expire during their hospital stay or within 30 days of their index visit. CK-MB Index, which has a higher specificity than CK, only found ACS or new CAD among 0.8% of positive results. Considering both decreased CK/CK-MB and increased troponin ordering, the net annual direct cost savings in cardiac biomarker testing was extrapolated to $12,700. Had our institution not transitioned to higher cost high-sensitivity troponin ($2.054/unit) from standard troponin ($1.65/unit), and had the rate of troponin ordering increased solely proportionate to the rate of ED visit increase (2% year-over-year) rather than increase nearly 20% (likely due to the transition to high-sensitivity troponin), then the total six-month direct costs on troponin testing would have been $14,632 instead of $21,267.12, and annual direct cost savings would have been $18,945.80 instead of $12,700. The new ED clinical guideline did not result in a significant number of missed ACS or new-diagnosis CAD, and was associated with direct cost savings. These savings probably underestimate total savings, as the reduced number of "false-positive" CK-MB results likely prevented additional costs, such as hospitalization, specialty consultation, coronary calcium CT, echocardiogram, cardiac stress test, and coronary artery catheterization.

Improving Turnaround Times through a Process Improvement Initiative Involving Barcoding, Floorplans, Dual Measuring Cells, Chemistry Analyzers, and Staff Shifts.

BACKGROUND: Specimen turnaround time (TAT) is an important metric for laboratory safety and quality. Various methods to improve TAT have seen success using process improvement initiatives. However, there are limited data on barcoding, pneumatic receiving proximity to modular preanalytics, 1 vs 2 measuring cells, and upgrading to Cobas 8000. The example describes the complete execution of a process improvement initiative to improve TAT within these areas over a 20-month period. The study aimed to improve specimen timeliness by decreasing the TAT for preanalytic and analytic specimen processing through a systematic process improvement initiative and to empower staff to "own" their scientific method. METHODS: The primary outcome TAT was reported from a prospective quality initiative beginning January 2017 for 2 analytes: troponin and potassium. TATs for albumins from the complete metabolic panels were added to the study design retrospectively during team rounds. Mean TAT was defined as time from arrival to verified times. Process improvement tools within the study design were borrowed from Lean management. RESULTS: After implementation of the process improvement initiative, the number of steps medical laboratory assistants and technologists performed per specimen decreased from 8 to 5. Mean TATs decreased for all analytes. Preimplementation to postimplementation comparisons from 2017 to 2018 decreased for all 3 analytes and within 2017. The number of troponin specimens verified within 60 min improved from 70% in January 2017 to 95% in August 2018, with an improvement from 64% in January 2017 to 87% in August 2018 during peak hours. CONCLUSIONS: A systematic process improvement initiative whereby employees "own" the scientific process within specimen preanalytic and analytic testing phases can significantly improve metrics for laboratory quality and safety.

Preanalytics and Precision Pathology: Pathology Practices to Ensure Molecular Integrity of Cancer Patient Biospecimens for Precision Medicine.

Biospecimens acquired during routine medical practice are the primary sources of molecular information about patients and their diseases that underlies precision medicine and translational research. In cancer care, molecular analysis of biospecimens is especially common because it often determines treatment choices and may be used to monitor therapy in real time. However, patient specimens are collected, handled, and processed according to routine clinical procedures during which they are subjected to factors that may alter their molecular quality and composition. Such artefactual alteration may skew data from molecular analyses, render analysis data uninterpretable, or even preclude analysis altogether if the integrity of a specimen is severely compromised. As a result, patient care and safety may be affected, and medical research dependent on patient samples may be compromised. Despite these issues, there is currently no requirement to control or record preanalytical variables in clinical practice with the single exception of breast cancer tissue handled according to the guideline jointly developed by the American Society of Clinical Oncology and College of American Pathologists (CAP) and enforced through the CAP Laboratory Accreditation Program. Recognizing the importance of molecular data derived from patient specimens, the CAP Personalized Healthcare Committee established the Preanalytics for Precision Medicine Project Team to develop a basic set of evidence-based recommendations for key preanalytics for tissue and blood specimens. If used for biospecimens from patients, these preanalytical recommendations would ensure the fitness of those specimens for molecular analysis and help to assure the quality and reliability of the analysis data.

Is Low Positive JAK2 V617F Mutation Test Result Clinically Significant?: Multi-Institutional Study.

OBJECTIVES: Acquired somatic mutation Janus kinase 2 (JAK2) V617F is associated with various myeloproliferative neoplasms (MPN). Allele-specific real-time polymerase chain reaction has been widely adopted to detect mutation; however, the utility of low positive results is not well understood. The aim of this study is to investigate the clinical significance of low positivity of JAK2 V617F. MATERIALS AND METHODS: Retrospective analysis was performed for JAK2 V617F mutation tests performed using JAK2 MutaQuant kit (Ipsogen) in molecular laboratories at 2 major academic medical centers between 2010 and 2012. Cases with low positive JAK2 V617F, defined as 0.2% to 5% mutant allele, were documented. Chart review was performed for the clinical correlation. RESULTS: A total of 1697 JAK2 V617F tests was performed. Forty-five cases (2.65%) yielded a low JAK2 V617F positivity (average 1.45%), the majority of which (n=26, 62%) had <1%. Eight cases had a history of MPN. The remaining cases were related to reactive conditions without a clonal disease. Our data indicate that a low positivity of JAK2 V617F can be seen in MPN as well as reactive conditions. CONCLUSIONS: An interpretation of JAK2 V617F status should not be performed simply following some arbitrary cutoff. Any low positivity of JAK2 V617F should be reported and a correlation with clinical information is warranted for proper interpretation.

Primary extranodal marginal zone lymphoma of the endometrium: report of four cases and review of literature.

Primary extranodal marginal zone lymphoma of the endometrium (PEMZL-EM) is exceedingly rare and has not been well characterized. Herein, we study the clinicopathological, cytogenetic and molecular features of four cases, the largest case series reported to date. The median age of the four patients was 59 years. Clinical presentations included abnormal vaginal bleeding (three cases) and incidental finding (one case). There were no constitutional symptoms in any of the cases. None of the patients had evidence of lymphoma in any other anatomic sites including bone marrow. Histologically, the lymphoma was characterized by a nodular proliferation of small lymphocytes admixed with occasional immunoblasts and variable number of plasma cells, which was restricted to the endometrium in most cases. Lymphoepithelial lesions were not identified in any of the cases. All cases displayed the immunophenotype of marginal zone B-cell lymphoma. Cytogenetics and FISH studies revealed absence of characteristic chromosomal translocations. Molecular analysis demonstrated immunoglobulin heavy chain gene rearrangement in all cases, two of which were found to use IgVH3-30 gene by DNA sequencing. Three of the four patients were still alive after a median follow-up of three years. PEMZL-EM predominantly affects postmenopausal women and is characterized by distinct histological patterns, lack of specific genomic alterations, and indolent clinical course.

Reporting incidental findings in genomic scale clinical sequencing--a clinical laboratory perspective: a report of the Association for Molecular Pathology.

Advances in sequencing technologies have facilitated concurrent testing for many disorders, and the results generated may provide information about a patient's health that is unrelated to the clinical indication, commonly referred to as incidental findings. This is a paradigm shift from traditional genetic testing in which testing and reporting are tailored to a patient's specific clinical condition. Clinical laboratories and physicians are wrestling with this increased complexity in genomic testing and reporting of the incidental findings to patients. An enormous amount of discussion has taken place since the release of a set of recommendations from the American College of Medical Genetics and Genomics. This discussion has largely focused on the content of the incidental findings, but the laboratory perspective and patient autonomy have been overlooked. This report by the Association of Molecular Pathology workgroup discusses the pros and cons of next-generation sequencing technology, potential benefits, and harms for reporting of incidental findings, including the effect on both the laboratory and the patient, and compares those with other areas of medicine. The importance of genetic counseling to preserve patient autonomy is also reviewed. The discussion and recommendations presented by the workgroup underline the need for continued research and discussion among all stakeholders to improve our understanding of the effect of different policies on patients, providers, and laboratories.

Localized crystal-storing histiocytosis presenting as a breast nodule: an unusual presentation of a rare entity.

Crystal-storing histiocytosis (CSH) is a rare disorder associated with crystalline immunoglobulin deposition in the cytoplasm of histiocytes and is usually associated with lymphoproliferative or plasma cell disorders (LP-PCD) that express monoclonal immunoglobulin. Localized CSH without underlying LP-PCD are extremely rare. We report a case of localized CSH in breast which was an unexpected difficult diagnosis. The awareness of this entity is of importance to delineate it morphologically from other common differential diagnosis and enable appropriate management. To date, this is the first case of localized CSH reported in breast in a patient with no known history of LP-PCD.

Team-based learning in a pathology residency training program.

OBJECTIVES: Team-based learning (TBL) has been integrated into undergraduate and medical education curricula in many institutions. However, TBL has not been widely introduced into postgraduate medical education. Our study aimed to measure the effect of TBL on promoting learning and teamwork in the setting of pathology residency training. METHODS: Four TBL sessions were held and individual and group readiness assurance tests (IRAT/GRATs) were performed; scores were compared using Wilcoxon matched-pairs signed rank tests. Residents completed 18-item validated team performance surveys measuring the quality of team interactions on a scale of 0 (none of the time) to 6 (all of the time). Mean and standard deviation were calculated for each item. RESULTS: Scores on the IRAT vs GRAT were significantly different (P < .05). The team performance survey received mean scores ranging from 5.3 ± 1.1 to 6.0 ± 0.0. CONCLUSIONS: The use of TBL promotes teamwork and learning in a pathology residency program. Residents scored higher on the readiness assurance tests when working in teams, demonstrating the effectiveness of team learning and achievement. In addition, the Accreditation Council for Graduate Medical Education competencies of professionalism and interpersonal and communication skills were further enhanced by incorporating TBL into pathology residency training.

Mantle cell lymphoma with in situ or mantle zone growth pattern: a study of five cases and review of literature.

We present two rare cases of in situ mantle cell lymphoma ("in situ MCL") and three cases of MCL with mantle zone growth pattern (MCL-MZGP). The patients include four males and one female, with a median age of 66 years (range, 52 to 86 years). Two present with isolated lymphadenopathy and three with multiple lymphadenopathy. At presentation, the complete blood count (CBC) and serum lactate dehydrogenase (LDH) are normal in all cases. Histologic examination reveals an in situ pattern in two cases and a mantle zone growth pattern in three cases. The staging bone marrow biopsies show minimal involvement by lymphoma in one case and no morphologic evidence of lymphoma in four cases. All cases are positive for cyclin D1, including two with typical MCL phenotype and three with CD5-negativity. Four out of five cases express kappa light chain. FISH study for t(11;14) is performed in three cases, of which one is positive and two are inconclusive. For four patients with a median follow-up of 38 months, three are in clinical remission and one has persistent disease. In conclusion, the "in situ MCL" is associated with incidental finding, indolent clinical course and lower tumor burden. The predominant usage of kappa light chain and frequent CD5-negativity observed in our cases are unusual. We review the clinical and laboratory features of "in situ MCL" cases in the literature.

Cellular senescence in usual type uterine leiomyoma.

OBJECTIVE: To evaluate the role of senescence in symptomatic patients with multifibroids. DESIGN: A cohort study. SETTING: University research laboratory. PATIENT(S): Eighty-six fibroids collected from 14 patients who underwent myomectomy or hysterectomy. INTERVENTION(S): Senescence-associated beta-galactosidase (SA-beta-Gal) stain in fresh-frozen tissue; reverse-transcription polymerase chain reaction (RT-PCR); MicroRNA in situ hybridization (MISH); immunohistochemistry in formalin-fixed paraffin-embedded tissue. MAIN OUTCOME MEASURE(S): Senescence measured by percentage of SA-beta-Gal-positive cells; levels of let-7 microRNAs measured by RT-PCR and MISH; expression of p16(INK4a), Ki-67, HMGA1, and HMGA2 scaled by immunoreactivity. RESULT(S): About 58% (48 of 82) of tumors showed significant senescent change (SA-beta-Gal positive) in >10% of the tumor volume. The overall trend was a higher level of senescence in small fibroids and older-aged women. Senescent fibroids were additionally shown to have, high levels of let-7 c, d, and f-2 and a low Ki-67 index. CONCLUSION(S): Senescence is a common cellular change in a large proportion of usual type fibroids. Similarly, senescence may explain the variation in growth rates of these tumors, and may prove to be an important molecular and cellular target in prevention of fibroid growth.

Invasive lobular carcinoma of the breast: role of endothelial lymphatic marker D2-40.

Lymphovascular invasion (LVI) of breast cancer is an independent adverse prognosticator that is associated with increased regional and distant tumor recurrence. LVI is infrequently encountered in invasive lobular carcinoma when compared to invasive ductal carcinoma. We employed D2-40 antibody, a novel marker for lymphatic endothelial cells, in an attempt to enhance the detection of LVI in invasive lobular carcinomas. We identified 78 patients with invasive lobular carcinoma with known axillary status, who were studied between 2003 and 2006. D2-40 antibody was applied to one representative paraffin block from each case and the results were compared to LVI on routine histology. LVI was identified in 12 (15%) and 19 (24%) cases by routine histology and D2-40 antibody, respectively. Eleven of 12 patients (92%) with LVI identified by routine histology had axillary nodal metastasis compared to 14 of 19 patients (74%) with LVI identified by D2-40 antibody. LVI was missed by routine histology in 8 cases (10%). D2-40 antibody enhanced the identification of LVI by 9% in node negative patients. D2-40 antibody increased the identification of LVI by 12% in classic invasive lobular carcinoma. In conclusion, D2-40 antibody staining may be useful as an adjunct in detecting LVI in invasive lobular carcinoma, especially in node-negative patients with the classic variant of invasive lobular carcinoma.

Antiproliferative effects by Let-7 repression of high-mobility group A2 in uterine leiomyoma.

High-mobility group A2 (HMGA2) is commonly overexpressed in large leiomyomas. HMGA2 is an important regulator of cell growth, differentiation, apoptosis, and transformation. As a predicted target of Let-7 microRNAs (Let-7s), HMGA2 can be repressed by Let-7s in vitro. MicroRNA profiling analysis revealed that Let-7s were significantly dysregulated in uterine leiomyomas: high in small leiomyomas and lower in large leiomyomas. To evaluate whether Let-7 repression of HMGA2 plays a major role in leiomyomas, we analyzed the molecular relationship of HMGA2 and Let-7s, both in vitro and in vivo. We first characterized that exogenous Let-7 microRNAs could directly repress the dominant transcript of HMGA2, HMGA2a. This repression was also identified for two cryptic HMGA2 transcripts in primary leiomyoma cultures. Second, we found that the endogenous Let-7s were biologically active and played a major role in the regulation of HMGA2. Then, we illustrated that Let-7 repression of HMGA2 inhibited cellular proliferation. Finally, we examined the expression levels of Let-7c and HMGA2 in a large cohort of leiomyomas (n = 120), and we found high levels of Let-7 and low levels of HMGA2 in small leiomyomas, and low levels of Let-7 and high levels of HMGA2 in large leiomyomas. Our findings suggest that the Let-7-mediated repression of HMGA2 mechanism can be an important molecular event in leiomyoma growth.

Intrahepatic portal cavernoma as an indication for liver transplantation.

Cavernous transformation of the portal vein (portal cavernoma) consists of a periportal or/and intrahepatic venous collateral network, developed as a result of acute or long-standing portal vein thrombosis. Better control of hemorrhagic and thrombotic complications in the patients with portal cavernoma substantially improves their life span and the clinical outcome. However, biliary complications that occur in the late stages of this disease have been recently recognized as challenging management issues because they recur and are difficult to treat. Because of the relatively small number of the patients with cholangiopathy due to portal cavernoma, there is no current standardized treatment approach. We report the case of a predominantly intrahepatic portal cavernoma occurring in a patient with chronic idiopathic portal vein thrombosis, which led to severe cholangiopathy that mimicked primary sclerosing cholangitis and cholangiocarcinoma, was unresponsive to endoscopic stent placement, and finally required liver transplantation.

Immunohistochemical evaluation of necrotic malignant melanomas.

We evaluated 35 cases of malignant melanomas with substantial necrosis immunostained with S-100, HMB-45, Melan-A, tyrosinase, PNL2, and microphthalmia transcription factor (MITF). Staining patterns were evaluated in viable and necrotic areas of the tumors. S-100 was the most sensitive marker (97%) in the viable tumors, but necrotic areas demonstrated nonspecific staining. Viable tumors stained variably for HMB-45 (25 [71%]), Melan-A (28 [80%]), tyrosinase (30 [86%]), and PNL2 (23 [66%]). Necrotic areas focally reacted to the same antibodies. The necrotic areas that retained immunoreactivity for these markers corresponded to areas where the outline of the tumor cells could still be recognized as ghost cells on the H&E-stained section. Areas that showed complete coagulative necrosis were negative for melanoma markers. MITF variably stained in the viable tumors but was completely negative in necrotic areas. Our study demonstrated that a combination of antibodies to HMB-45, tyrosinase, and PNL2 detected melanocytic differentiation in necrotic areas in 80% of cases.

A micro-RNA signature associated with race, tumor size, and target gene activity in human uterine leiomyomas.

Human uterine leiomyomas (ULMs) are the most common neoplasms of women. Many genes are dysregulated in ULMs and some of this dysregulation may be due to abnormal expression of micro-RNAs (miRNAs). In this study, 55 ULMs and matched myometrium were collected from 41 patients for microarray-based global miRNA expression analysis. Of 206 miRNAs examined, 45 miRNAs were significantly up- or down-regulated in ULMs in comparison to the matched myometrium (P < 0.001). The top five dysregulated miRNAs in ULMs are the let-7 family, miR-21, miR-23b, miR-29b, and miR-197. Four polycistronic clusters of miRNAs were either up- or down-regulated, but not in a mixed pattern, indicative of coordinated regulation of these miRNAs. Significance analysis revealed that subsets of miRNAs were strongly associated with tumor sizes and race. By prediction analysis we identified some important tumorigenic genes previously identified in ULMs that may be targeted by the dysregulated miRNAs. HMGA2 was identified as one of target genes of the let-7 family of miRNAs and has been found to be suppressed by let-7 in vitro. This article contains Supplementary material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.