Pathologist-trained machine learning classifiers developed to quantitate celiac disease features differentiate endoscopic biopsies according to modified marsh score and dietary intervention response.

BACKGROUND: Histologic evaluation of the mucosal changes associated with celiac disease is important for establishing an accurate diagnosis and monitoring the impact of investigational therapies. While the Marsh-Oberhuber classification has been used to categorize the histologic findings into discrete stages (i.e., Type 0-3c), significant variability has been documented between observers using this ordinal scoring system. Therefore, we evaluated whether pathologist-trained machine learning classifiers can be developed to objectively quantitate the pathological changes of villus blunting, intraepithelial lymphocytosis, and crypt hyperplasia in small intestine endoscopic biopsies. METHODS: A convolutional neural network (CNN) was trained and combined with a secondary algorithm to quantitate intraepithelial lymphocytes (IEL) with 5 classes on CD3 immunohistochemistry whole slide images (WSI) and used to correlate feature outputs with ground truth modified Marsh scores in a total of 116 small intestine biopsies. RESULTS: Across all samples, median %CD3 counts (positive cells/enterocytes) from villous epithelium (VE) increased with higher Marsh scores (Type 0%CD3 VE = 13.4; Type 1-3%CD3 VE = 41.9, p < 0.0001). Indicators of villus blunting and crypt hyperplasia were also observed (Type 0-2 villous epithelium/lamina propria area ratio = 0.81; Type 3a-3c villous epithelium/lamina propria area ratio = 0.29, p < 0.0001), and Type 0-1 crypt/villous epithelial area ratio = 0.59; Type 2-3 crypt/villous epithelial area ratio = 1.64, p < 0.0001). Using these individual features, a combined feature machine learning score (MLS) was created to evaluate a set of 28 matched pre- and post-intervention biopsies captured before and after dietary gluten restriction. The disposition of the continuous MLS paired biopsy result aligned with the Marsh score in 96.4% (27/28) of the cohort. CONCLUSIONS: Machine learning classifiers can be developed to objectively quantify histologic features and capture additional data not achievable with manual scoring. Such approaches should be further investigated to improve biopsy evaluation, especially for clinical trials.

Targeted Quantitative Mass Spectrometry Analysis of Protein Biomarkers From Previously Stained Single Formalin-Fixed Paraffin-Embedded Tissue Sections.

Formalin-fixed, paraffin-embedded tissues represent a majority of all biopsy specimens commonly analyzed by histologic or immunohistochemical staining with adhesive coverslips attached. Mass spectrometry (MS) has recently been used to precisely quantify proteins in samples consisting of multiple unstained formalin-fixed, paraffin-embedded sections. Here, we report an MS method to analyze proteins from a single coverslipped 4-µm section previously stained with hematoxylin and eosin, Masson trichrome, or 3,3'-diaminobenzidine-based immunohistochemical staining. We analyzed serial unstained and stained sections from non-small cell lung cancer specimens for proteins of varying abundance (PD-L1, RB1, CD73, and HLA-DRA). Coverslips were removed by soaking in xylene, and after tryptic digestion, peptides were analyzed by targeted high-resolution liquid chromatography with tandem MS with stable isotope-labeled peptide standards. The low-abundance proteins RB1 and PD-L1 were quantified in 31 and 35 of 50 total sections analyzed, respectively, whereas higher abundance CD73 and HLA-DRA were quantified in 49 and 50 sections, respectively. The inclusion of targeted ß-actin measurement enabled normalization in samples where residual stain interfered with bulk protein quantitation by colorimetric assay. Measurement coefficient of variations for 5 replicate slides (hematoxylin and eosin stained vs unstained) from each block ranged from 3% to 18% for PD-L1, from 1% to 36% for RB1, 3% to 21% for CD73, and 4% to 29% for HLA-DRA. Collectively, these results demonstrate that targeted MS protein quantification can add a valuable data layer to clinical tissue specimens after assessment for standard pathology end points.

Association of Donanemab Treatment With Exploratory Plasma Biomarkers in Early Symptomatic Alzheimer Disease: A Secondary Analysis of the TRAILBLAZER-ALZ Randomized Clinical Trial.

Importance: Plasma biomarkers of Alzheimer disease may be useful as minimally invasive pharmacodynamic measures of treatment outcomes. Objective: To analyze the association of donanemab treatment with plasma biomarkers associated with Alzheimer disease. Design, Setting, and Participants: TRAILBLAZER-ALZ was a randomized, double-blind, placebo-controlled clinical trial conducted from December 18, 2017, to December 4, 2020, across 56 sites in the US and Canada. Exploratory biomarkers were prespecified with the post hoc addition of plasma glial fibrillary acidic protein and amyloid-ß. Men and women aged 60 to 85 years with gradual and progressive change in memory function for at least 6 months were included. A total of 1955 participants were assessed for eligibility. Key eligibility criteria include Mini-Mental State Examination scores of 20 to 28 and elevated amyloid and intermediate tau levels. Interventions: Randomized participants received donanemab or placebo every 4 weeks for up to 72 weeks. The first 3 doses of donanemab were given at 700 mg and then increased to 1400 mg with blinded dose reductions as specified based on amyloid reduction. Main Outcomes and Measures: Change in plasma biomarker levels after donanemab treatment. Results: In TRAILBLAZER-ALZ, 272 participants (mean [SD] age, 75.2 [5.5] years; 145 [53.3%] female) were randomized. Plasma levels of phosphorylated tau217 (pTau217) and glial fibrillary acidic protein were significantly lower with donanemab treatment compared with placebo as early as 12 weeks after the start of treatment (least square mean change difference vs placebo, -0.04 [95% CI, -0.07 to -0.02]; P = .002 and -0.04 [95% CI, -0.07 to -0.01]; P = .01, respectively). No significant differences in plasma levels of amyloid-ß 42/40 and neurofilament light chain were observed between treatment arms at the end of treatment. Changes in plasma pTau217 and glial fibrillary acidic protein were significantly correlated with the Centiloid percent change in amyloid (Spearman rank correlation coefficient [R] = 0.484 [95% CI, 0.359-0.592]; P < .001 and R = 0.453 [95% CI, 0.306-0.579]; P < .001, respectively) following treatment. Additionally, plasma levels of pTau217 and glial fibrillary acidic protein were significantly correlated at baseline and following treatment (R = 0.399 [95% CI, 0.278-0.508], P < .001 and R = 0.393 [95% CI, 0.254-0.517]; P < .001, respectively). Conclusions and Relevance: Significant reductions in plasma biomarkers pTau217 and glial fibrillary acidic protein compared with placebo were observed following donanemab treatment in patients with early symptomatic Alzheimer disease. These easily accessible plasma biomarkers might provide additional evidence of Alzheimer disease pathology change through anti-amyloid therapy. Usefulness in assessing treatment response will require further evaluation. Trial Registration: ClinicalTrials.gov Identifier: NCT03367403.

Analytical Accuracy of RET Fusion Detection by Break-Apart Fluorescence In Situ Hybridization.

CONTEXT.­: RET gene fusions are oncogenic drivers in nonsmall cell lung cancer and nonmedullary thyroid cancer. Selpercatinib (RETEVMO), a targeted inhibitor of RET, was approved by the US Food and Drug Administration for the treatment of RET fusion-positive nonsmall cell lung cancer and nonmedullary thyroid cancer emphasizing the need for rapid and accurate diagnosis of RET fusions. Fluorescence in situ hybridization (FISH) has been used to detect gene rearrangements, but its performance detecting RET rearrangements is understudied. OBJECTIVE.­: To validate and describe the performance of Abbott Molecular RET break-apart FISH probes for detecting RET rearrangements. DESIGN.­: A training set with RET fusion-positive (13) and RET fusion-negative nonsmall cell lung cancer and nonmedullary thyroid cancer samples (12) was used to establish criteria for FISH scoring. The scoring criteria was then applied to a larger validation set of samples (96). RESULTS.­: A cutoff of 19% or more positive nuclei by FISH was established in the training set and determined by the mean ±3 SD. The validation set was tested using Abbott Molecular RET break-apart FISH compared with sequencing. With this cutoff, a sensitivity of 86% (12 of 14) and specificity of 99% (81 of 82) was achieved. Bootstrapping showed sensitivity could be optimized by using a greater than 13% cutoff with indeterminate samples of 13% to 18% abnormal nuclei requiring confirmation by an orthogonal method. Using this 3-tier scoring system sensitivity increased to 100% (14 of 14) and specificity was 96% (79 of 82). CONCLUSIONS.­: Abbott Molecular break-apart FISH probes can be used to detect RET fusions. Laboratories can optimize cutoffs and/or testing algorithms to maximize sensitivity and specificity to ensure appropriate patients receive effective, timely therapy.

A Randomized, Placebo-Controlled Clinical Trial of Bamlanivimab and Etesevimab Together in High-Risk Ambulatory Patients With COVID-19 and Validation of the Prognostic Value of Persistently High Viral Load.

BACKGROUND: Based on interim analyses and modeling data, lower doses of bamlanivimab and etesevimab together (700/1400 mg) were investigated to determine optimal dose and expand availability of treatment. METHODS: This Phase 3 portion of the BLAZE-1 trial characterized the effect of bamlanivimab with etesevimab on overall patient clinical status and virologic outcomes in ambulatory patients ≥12 years old, with mild-to-moderate coronavirus disease 2019 (COVID-19), and ≥1 risk factor for progressing to severe COVID-19 and/or hospitalization. Bamlanivimab and etesevimab together (700/1400 mg) or placebo were infused intravenously within 3 days of patients' first positive COVID-19 test. RESULTS: In total, 769 patients were infused (median age [range]; 56.0 years [12, 93], 30.3% of patients ≥65 years of age and median duration of symptoms; 4 days). By day 29, 4/511 patients (0.8%) in the antibody treatment group had a COVID-19-related hospitalization or any-cause death, as compared with 15/258 patients (5.8%) in the placebo group (Δ[95% confidence interval {CI}] = -5.0 [-8.0, -2.1], P < .001). No deaths occurred in the bamlanivimab and etesevimab group compared with 4 deaths (all COVID-19-related) in the placebo group. Patients receiving antibody treatment had a greater mean reduction in viral load from baseline to Day 7 (Δ[95% CI] = -0.99 [-1.33, -.66], P < .0001) compared with those receiving placebo. Persistently high viral load at Day 7 correlated with COVID-19-related hospitalization or any-cause death by Day 29 in all BLAZE-1 cohorts investigated. CONCLUSIONS: These data support the use of bamlanivimab and etesevimab (700/1400 mg) for ambulatory patients at high risk for severe COVID-19. Evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants will require continued monitoring to determine the applicability of this treatment. CLINICAL TRIALS REGISTRATION: NCT04427501.

Bamlanivimab plus Etesevimab in Mild or Moderate Covid-19.

BACKGROUND: Patients with underlying medical conditions are at increased risk for severe coronavirus disease 2019 (Covid-19). Whereas vaccine-derived immunity develops over time, neutralizing monoclonal-antibody treatment provides immediate, passive immunity and may limit disease progression and complications. METHODS: In this phase 3 trial, we randomly assigned, in a 1:1 ratio, a cohort of ambulatory patients with mild or moderate Covid-19 who were at high risk for progression to severe disease to receive a single intravenous infusion of either a neutralizing monoclonal-antibody combination agent (2800 mg of bamlanivimab and 2800 mg of etesevimab, administered together) or placebo within 3 days after a laboratory diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The primary outcome was the overall clinical status of the patients, defined as Covid-19-related hospitalization or death from any cause by day 29. RESULTS: A total of 1035 patients underwent randomization and received an infusion of bamlanivimab-etesevimab or placebo. The mean (±SD) age of the patients was 53.8±16.8 years, and 52.0% were adolescent girls or women. By day 29, a total of 11 of 518 patients (2.1%) in the bamlanivimab-etesevimab group had a Covid-19-related hospitalization or death from any cause, as compared with 36 of 517 patients (7.0%) in the placebo group (absolute risk difference, -4.8 percentage points; 95% confidence interval [CI], -7.4 to -2.3; relative risk difference, 70%; P<0.001). No deaths occurred in the bamlanivimab-etesevimab group; in the placebo group, 10 deaths occurred, 9 of which were designated by the trial investigators as Covid-19-related. At day 7, a greater reduction from baseline in the log viral load was observed among patients who received bamlanivimab plus etesevimab than among those who received placebo (difference from placebo in the change from baseline, -1.20; 95% CI, -1.46 to -0.94; P<0.001). CONCLUSIONS: Among high-risk ambulatory patients, bamlanivimab plus etesevimab led to a lower incidence of Covid-19-related hospitalization and death than did placebo and accelerated the decline in the SARS-CoV-2 viral load. (Funded by Eli Lilly; BLAZE-1 ClinicalTrials.gov number, NCT04427501.).

Effect of Bamlanivimab vs Placebo on Incidence of COVID-19 Among Residents and Staff of Skilled Nursing and Assisted Living Facilities: A Randomized Clinical Trial.

Importance: Preventive interventions are needed to protect residents and staff of skilled nursing and assisted living facilities from COVID-19 during outbreaks in their facilities. Bamlanivimab, a neutralizing monoclonal antibody against SARS-CoV-2, may confer rapid protection from SARS-CoV-2 infection and COVID-19. Objective: To determine the effect of bamlanivimab on the incidence of COVID-19 among residents and staff of skilled nursing and assisted living facilities. Design, Setting, and Participants: Randomized, double-blind, single-dose, phase 3 trial that enrolled residents and staff of 74 skilled nursing and assisted living facilities in the United States with at least 1 confirmed SARS-CoV-2 index case. A total of 1175 participants enrolled in the study from August 2 to November 20, 2020. Database lock was triggered on January 13, 2021, when all participants reached study day 57. Interventions: Participants were randomized to receive a single intravenous infusion of bamlanivimab, 4200 mg (n = 588), or placebo (n = 587). Main Outcomes and Measures: The primary outcome was incidence of COVID-19, defined as the detection of SARS-CoV-2 by reverse transcriptase-polymerase chain reaction and mild or worse disease severity within 21 days of detection, within 8 weeks of randomization. Key secondary outcomes included incidence of moderate or worse COVID-19 severity and incidence of SARS-CoV-2 infection. Results: The prevention population comprised a total of 966 participants (666 staff and 300 residents) who were negative at baseline for SARS-CoV-2 infection and serology (mean age, 53.0 [range, 18-104] years; 722 [74.7%] women). Bamlanivimab significantly reduced the incidence of COVID-19 in the prevention population compared with placebo (8.5% vs 15.2%; odds ratio, 0.43 [95% CI, 0.28-0.68]; P < .001; absolute risk difference, -6.6 [95% CI, -10.7 to -2.6] percentage points). Five deaths attributed to COVID-19 were reported by day 57; all occurred in the placebo group. Among 1175 participants who received study product (safety population), the rate of participants with adverse events was 20.1% in the bamlanivimab group and 18.9% in the placebo group. The most common adverse events were urinary tract infection (reported by 12 participants [2%] who received bamlanivimab and 14 [2.4%] who received placebo) and hypertension (reported by 7 participants [1.2%] who received bamlanivimab and 10 [1.7%] who received placebo). Conclusions and Relevance: Among residents and staff in skilled nursing and assisted living facilities, treatment during August-November 2020 with bamlanivimab monotherapy reduced the incidence of COVID-19 infection. Further research is needed to assess preventive efficacy with current patterns of viral strains with combination monoclonal antibody therapy. Trial Registration: ClinicalTrials.gov Identifier: NCT04497987.

Effect of Bamlanivimab as Monotherapy or in Combination With Etesevimab on Viral Load in Patients With Mild to Moderate COVID-19: A Randomized Clinical Trial.

Importance: Coronavirus disease 2019 (COVID-19) continues to spread rapidly worldwide. Neutralizing antibodies are a potential treatment for COVID-19. Objective: To determine the effect of bamlanivimab monotherapy and combination therapy with bamlanivimab and etesevimab on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load in mild to moderate COVID-19. Design, Setting, and Participants: The BLAZE-1 study is a randomized phase 2/3 trial at 49 US centers including ambulatory patients (N = 613) who tested positive for SARS-CoV-2 infection and had 1 or more mild to moderate symptoms. Patients who received bamlanivimab monotherapy or placebo were enrolled first (June 17-August 21, 2020) followed by patients who received bamlanivimab and etesevimab or placebo (August 22-September 3). These are the final analyses and represent findings through October 6, 2020. Interventions: Patients were randomized to receive a single infusion of bamlanivimab (700 mg [n = 101], 2800 mg [n = 107], or 7000 mg [n = 101]), the combination treatment (2800 mg of bamlanivimab and 2800 mg of etesevimab [n = 112]), or placebo (n = 156). Main Outcomes and Measures: The primary end point was change in SARS-CoV-2 log viral load at day 11 (±4 days). Nine prespecified secondary outcome measures were evaluated with comparisons between each treatment group and placebo, and included 3 other measures of viral load, 5 on symptoms, and 1 measure of clinical outcome (the proportion of patients with a COVID-19-related hospitalization, an emergency department [ED] visit, or death at day 29). Results: Among the 577 patients who were randomized and received an infusion (mean age, 44.7 [SD, 15.7] years; 315 [54.6%] women), 533 (92.4%) completed the efficacy evaluation period (day 29). The change in log viral load from baseline at day 11 was -3.72 for 700 mg, -4.08 for 2800 mg, -3.49 for 7000 mg, -4.37 for combination treatment, and -3.80 for placebo. Compared with placebo, the differences in the change in log viral load at day 11 were 0.09 (95% CI, -0.35 to 0.52; P = .69) for 700 mg, -0.27 (95% CI, -0.71 to 0.16; P = .21) for 2800 mg, 0.31 (95% CI, -0.13 to 0.76; P = .16) for 7000 mg, and -0.57 (95% CI, -1.00 to -0.14; P = .01) for combination treatment. Among the secondary outcome measures, differences between each treatment group vs the placebo group were statistically significant for 10 of 84 end points. The proportion of patients with COVID-19-related hospitalizations or ED visits was 5.8% (9 events) for placebo, 1.0% (1 event) for 700 mg, 1.9% (2 events) for 2800 mg, 2.0% (2 events) for 7000 mg, and 0.9% (1 event) for combination treatment. Immediate hypersensitivity reactions were reported in 9 patients (6 bamlanivimab, 2 combination treatment, and 1 placebo). No deaths occurred during the study treatment. Conclusions and Relevance: Among nonhospitalized patients with mild to moderate COVID-19 illness, treatment with bamlanivimab and etesevimab, compared with placebo, was associated with a statistically significant reduction in SARS-CoV-2 viral load at day 11; no significant difference in viral load reduction was observed for bamlanivimab monotherapy. Further ongoing clinical trials will focus on assessing the clinical benefit of antispike neutralizing antibodies in patients with COVID-19 as a primary end point. Trial Registration: ClinicalTrials.gov Identifier: NCT04427501.

SARS-CoV-2 Neutralizing Antibody LY-CoV555 in Outpatients with Covid-19.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (Covid-19), which is most frequently mild yet can be severe and life-threatening. Virus-neutralizing monoclonal antibodies are predicted to reduce viral load, ameliorate symptoms, and prevent hospitalization. METHODS: In this ongoing phase 2 trial involving outpatients with recently diagnosed mild or moderate Covid-19, we randomly assigned 452 patients to receive a single intravenous infusion of neutralizing antibody LY-CoV555 in one of three doses (700 mg, 2800 mg, or 7000 mg) or placebo and evaluated the quantitative virologic end points and clinical outcomes. The primary outcome was the change from baseline in the viral load at day 11. The results of a preplanned interim analysis as of September 5, 2020, are reported here. RESULTS: At the time of the interim analysis, the observed mean decrease from baseline in the log viral load for the entire population was -3.81, for an elimination of more than 99.97% of viral RNA. For patients who received the 2800-mg dose of LY-CoV555, the difference from placebo in the decrease from baseline was -0.53 (95% confidence interval [CI], -0.98 to -0.08; P = 0.02), for a viral load that was lower by a factor of 3.4. Smaller differences from placebo in the change from baseline were observed among the patients who received the 700-mg dose (-0.20; 95% CI, -0.66 to 0.25; P = 0.38) or the 7000-mg dose (0.09; 95% CI, -0.37 to 0.55; P = 0.70). On days 2 to 6, the patients who received LY-CoV555 had a slightly lower severity of symptoms than those who received placebo. The percentage of patients who had a Covid-19-related hospitalization or visit to an emergency department was 1.6% in the LY-CoV555 group and 6.3% in the placebo group. CONCLUSIONS: In this interim analysis of a phase 2 trial, one of three doses of neutralizing antibody LY-CoV555 appeared to accelerate the natural decline in viral load over time, whereas the other doses had not by day 11. (Funded by Eli Lilly; BLAZE-1 ClinicalTrials.gov number, NCT04427501.).

Analysis of Immune Checkpoint Drug Targets and Tumor Proteotypes in Non-Small Cell Lung Cancer.

New therapeutics targeting immune checkpoint proteins have significantly advanced treatment of non-small cell lung cancer (NSCLC), but protein level quantitation of drug targets presents a critical problem. We used multiplexed, targeted mass spectrometry (MS) to quantify immunotherapy target proteins PD-1, PD-L1, PD-L2, IDO1, LAG3, TIM3, ICOSLG, VISTA, GITR, and CD40 in formalin-fixed, paraffin-embedded (FFPE) NSCLC specimens. Immunohistochemistry (IHC) and MS measurements for PD-L1 were weakly correlated, but IHC did not distinguish protein abundance differences detected by MS. PD-L2 abundance exceeded PD-L1 in over half the specimens and the drug target proteins all displayed different abundance patterns. mRNA correlated with protein abundance only for PD-1, PD-L1, and IDO1 and tumor mutation burden did not predict abundance of any protein targets. Global proteome analyses identified distinct proteotypes associated with high PD-L1-expressing and high IDO1-expressing NSCLC. MS quantification of multiple drug targets and tissue proteotypes can improve clinical evaluation of immunotherapies for NSCLC.

Accelerated instability testing reveals quantitative mass spectrometry overcomes specimen storage limitations associated with PD-L1 immunohistochemistry.

Immunohistochemistry (IHC) using formalin-fixed, paraffin embedded (FFPE) tissue is limited by epitope masking, posttranslational modification and immunoreactivity loss that occurs in stored tissue by poorly characterized mechanisms. Conformational epitopes recognized by many programmed-death-ligand-1 (PD-L1) IHC assays are particularly susceptible to degradation and provide an ideal model for understanding signal loss in stored FFPE tissue. Here we assessed 1206 tissue sections to evaluate environmental factors impacting immunoreactivity loss. PD-L1 IHC using four antibodies (22C3, 28-8, E1L3N, and SP142), raised against intracellular and extracellular epitopes, was assessed in stored FFPE tissue alongside quantitative mass spectrometry (MS). Global proteome analyses were used to assess proteome-wide oxidation across an inventory of 3041 protein groups (24,737 distinct peptides). PD-L1 quantitation correlated well with IHC expression on unaged sections (R2 = 0.744; P < 0.001), with MS demonstrating no loss of PD-L1 protein, even in sections with significant signal loss by IHC impacting diagnostic category. Clones 22C3 and 28-8 were most susceptible to signal loss, with E1L3N demonstrating the most robust signal (56%, 58%, and 33% reduction respectively; p < 0.05). Increased humidity and temperature resulted in significant acceleration of immunoreactivity loss, which was mitigated by storage with desiccant. MS demonstrated only modest oxidation of 274 methionine-containing peptides and aligned with IHC results suggesting peptide oxidation is not a major factor. These data imply immunoreactivity loss driven by humidity and temperature results in structural distortion of epitopes rendering them unsuitable for antibody binding following epitope retrieval. Limitations of IHC biomarker analysis from stored tissue sections may be mitigated by cost-effective use of desiccant when appropriate. In some scenarios, complementary MS is a preferred approach for retrospective analyses of archival FFPE tissue collections.

A Phase I Study of LY3009120, a Pan-RAF Inhibitor, in Patients with Advanced or Metastatic Cancer.

Mutations in ERK signaling drive a significant percentage of malignancies. LY3009120, a pan-RAF and dimer inhibitor, has preclinical activity in RAS- and BRAF-mutated cell lines including BRAF-mutant melanoma resistant to BRAF inhibitors. This multicenter, open-label, phase I clinical trial (NCT02014116) consisted of part A (dose escalation) and part B (dose confirmation) in patients with advanced/metastatic cancer. In part A, oral LY3009120 was dose escalated from 50 to 700 mg twice a day on a 28-day cycle. In part B, 300 mg LY3009120 was given twice a day. The primary objective was to identify a recommended phase II dose (RP2D). Secondary objectives were to evaluate safety, pharmacokinetics, and preliminary efficacy. Identification of pharmacodynamic biomarkers was exploratory. In parts A and B, 35 and 16 patients were treated, respectively (N = 51). In part A, 6 patients experienced eight dose-limiting toxicities. The RP2D was 300 mg twice a day. Common (>10%) any-grade drug-related treatment-emergent adverse events were fatigue (n = 15), nausea (n = 12), dermatitis acneiform (n = 10), decreased appetite (n = 7), and maculopapular rash (n = 7). The median duration of treatment was 4 weeks; 84% of patients completed one or two cycles of treatment. Exposures observed at 300 mg twice a day were above the preclinical concentration associated with tumor regression. Eight patients had a best overall response of stable disease; there were no complete or partial clinical responses. Despite adequate plasma exposure levels, predicted pharmacodynamic effects were not observed.

Differential expression of VEGFR2 protein in HER2 positive primary human breast cancer: potential relevance to anti-angiogenic therapies.

BACKGROUND: Clinically relevant predictive biomarkers to tailor anti-angiogenic therapies to breast cancer (BRC) patient subpopulations are an unmet need. METHODS: We analyzed tumor vascular density and VEGFR2 protein expression in various subsets of primary human BRCs (186 females; Mean age: 59 years; range 33-88 years), using a tissue microarray. Discrete VEGFR2+ and CD34+ tumor vessels were manually scored in invasive ductal, lobular, mixed ductal-lobular and colloid (N = 139, 22, 18, 7) BRC cores. RESULTS: The observed CD34+ and VEGFR2+ tumor vascular counts in individual cases were heterogeneous. Mean CD34+ and VEGFR2+ tumor vessel counts were 11 and 3.4 per tumor TMA core respectively. Eighty-nine of 186 (48%) cases had >10 CD34+ tumor vessels, while 97/186 (52%) had fewer CD34+ vessels in each TMA core. Of 169 analyzable cores in the VEGFR2 stained TMA, 90 (53%) showed 1-5 VEGFR2+ tumor vessels/TMA core, while 42/169 (25%) cores had no detectable VEGFR2+ tumor vessels. Thirteen of 169 (8%) cases also showed tumor cell (cytoplasmic/membrane) expression of VEGFR2. Triple-negative breast cancers (TNBCs) appeared to be less vascular (Mean VD = 9.8, range 0-34) than other breast cancer subtypes. Overall, VEGFR2+ tumor vessel counts were significantly higher in HER2+ as compared to HR+ (p = 0.04) and TNBC (p = 0.02) tissues. Compared to HER2- cases, HER2+ breast cancers had higher VEGFR2+ tumor vessel counts (p = 0.007). CONCLUSION: Characterization of pathologic angiogenesis in HER2+ breast cancer provides scientific rationale for future investigation of clinical activity of agents targeting the VEGF/VEGFR2 axis in this clinically aggressive breast cancer subtype.

Variability in Platelet-Derived Growth Factor Receptor Alpha Antibody Specificity May Impact Clinical Utility of Immunohistochemistry Assays.

Aberrant regulation of the receptor tyrosine kinase platelet-derived growth factor alpha (PDGFRα) is implicated in several types of cancer. Inhibition of the PDGFRα pathway may be a beneficial therapy, and detection of PDGFRα in tumor biopsies may lead to insights about which patients respond to therapy. Exploratory or clinical biomarker use of PDGFRα IHC has been frequently reported, often with polyclonal antibody sc-338. An sc-338-based assay was systematically compared with anti-PDGFRα rabbit monoclonal antibody D13C6 using immunoblot profiling and IHC in formalin-fixed and paraffin-embedded human tumor cell lines. Application of sc-338 to blots of whole cell lysates showed multiple bands including some of unknown origin, whereas application of D13C6 resulted in a prominent band at the expected molecular mass of PDGFRα. The IHC assay using D13C6 showed appropriate staining in cell lines, whereas the assay using sc-338 suggested nonspecific detection of proteins. An optimized IHC assay using D13C6 showed a range of staining in the tumor stromal compartment in lung and ovarian carcinomas. These observations suggest that use of clone sc-338 produced unreliable results and should not be used for an IHC research grade assay. In addition, this precludes its use as a potential antibody for a clinical diagnostic tool.

Profiling of Vascular Endothelial Growth Factor Receptor Heterogeneity Identifies Protein Expression-defined Subclasses of Human Non-small Cell Lung Carcinoma.

BACKGROUND: the vascular endothelial growth factor (VEGF) pathway plays a prominent role in the growth and progression of human cancer, including non-small cell lung carcinoma (NSCLC). The key mediators of VEGF signaling are a family of related receptor tyrosine kinases that include VEGFR1, VEGFR2, and VEGFR3. The relative expression levels, activity, and cross-talk among these receptors may contribute to response of NSCLC to anti-angiogenic therapies, and a better systematic, translatable approach to categorizing tumors is needed. MATERIALS AND METHODS: We comparatively evaluated immunohistochemical expression of the three VEGFRs in archival primary NSCLC tissues (n=96). RESULTS: VEGFR1 and VEGFR2 were localized both in vessels and tumor cells, while VEGFR3 was only localized in tumor vessels. A set of eight VEGFR staining subclasses were identified: Triple VEGFR positive (n=11, 11.5%), VEGFR1 predominant (n=22, 22.9%), VEGFR2 predominant (n=9, 9.4%), VEGFR3 predominant (n=3, 3.1%), VEGFR1/2 predominant (13, 13.5%), VEGFR1/3 predominant (2, 2.1%), VEGFR2/3 predominant (n=8, 8.3%), and triple VEGFR negative (n=28, 29.2%). An objective categorization based on K-means clustering revealed four clusters, three of which showed high VEGFR2 compared to VEGFR3 (30.7% of cases), cases high in both VEGFR2 and VEGFR3 (18.2%), and cases that were negative/low for both VEGFR2 and VEGFR3 (45.4%). A positive association between VEGFR2 and VEGFR3 was found, however no associations were observed between VEGFR1 and VEGFR2, nor VEGFR1 and VEGFR3. CONCLUSION: The proposed subclasses of NSCLC are an approach for complementing lines of investigation of anti-angiogenic therapies beginning with systematic characterization of the disease.

Heterogeneity of Vascular Endothelial Growth Factor Receptors 1, 2, 3 in Primary Human Colorectal Carcinoma.

BACKGROUND: The vascular endothelial growth factor (VEGF) pathway plays an important role in growth and progression of human cancer, including colorectal carcinomas (CRC). The key mediators of VEGF signaling are VEGFR1, VEGFR2, and VEGFR3, part of a family of related receptor tyrosine kinases. The relative expression, activity, or interplay among these receptors may determine the response of CRC patients to anti-angiogenic therapies. MATERIALS AND METHODS: We developed technically sound immunohistochemical (IHC) assays to quantify VEGFR1, 2 and 3, and using a well-annotated CRC tissue microarray (TMA), we carried out comprehensive comparative evaluation of the three VEGFRs in archival primary CRC tissues (n=84). For each TMA core, tumor cell VEGFR1 expression was reported as H-score (range=0-300); vascular VEGFR2/VEGFR3 expression was manually scored as the number of receptor-positive tumor stromal vessels. Each case was defined as VEGFR1/ VEGFR2/VEGFR3-negative, low, medium or high. RESULTS: Based on the differential expression of the three VEGFRs, eight VEGFR staining profiles were observed: Triple VEGFR positive (n=12, 14%), VEGFR1 predominant (n=17, 20%), VEGFR2 predominant (n=7, 8%), VEGFR3 predominant (n=1, 1%), VEGFR1/2 predominant (n=39, 46%), VEGFR1/3 predominant (n=2, 2%), VEGFR2/3 predominant (n=3, 4%), and triple-VEGFR-negative (n=3, 4%). CONCLUSION: Herein we demonstrated heterogeneity of expression of VEGFRs in human CRC stromal vessels and tumor cells. The observed VEGFR expression-based subsets of human CRCs may reflect differences in biology of pathologic angiogenesis in primary CRC tissues. Furthermore, the heterogeneity of expression of VEGFRs unraveled in this analysis merits independent validation in larger cohorts of primary and metastatic human CRC tissues and in pertinent experimental models treated with various anti-angiogenic therapies.

Efficacy and Safety of Abemaciclib, an Inhibitor of CDK4 and CDK6, for Patients with Breast Cancer, Non-Small Cell Lung Cancer, and Other Solid Tumors.

UNLABELLED: We evaluated the safety, pharmacokinetic profile, pharmacodynamic effects, and antitumor activity of abemaciclib, an orally bioavailable inhibitor of cyclin-dependent kinases (CDK) 4 and 6, in a multicenter study including phase I dose escalation followed by tumor-specific cohorts for breast cancer, non-small cell lung cancer (NSCLC), glioblastoma, melanoma, and colorectal cancer. A total of 225 patients were enrolled: 33 in dose escalation and 192 in tumor-specific cohorts. Dose-limiting toxicity was grade 3 fatigue. The maximum tolerated dose was 200 mg every 12 hours. The most common possibly related treatment-emergent adverse events involved fatigue and the gastrointestinal, renal, or hematopoietic systems. Plasma concentrations increased with dose, and pharmacodynamic effects were observed in proliferating keratinocytes and tumors. Radiographic responses were achieved in previously treated patients with breast cancer, NSCLC, and melanoma. For hormone receptor-positive breast cancer, the overall response rate was 31%; moreover, 61% of patients achieved either response or stable disease lasting ≥6 months. SIGNIFICANCE: Abemaciclib represents the first selective inhibitor of CDK4 and CDK6 with a safety profile allowing continuous dosing to achieve sustained target inhibition. This first-in-human experience demonstrates single-agent activity for patients with advanced breast cancer, NSCLC, and other solid tumors. Cancer Discov; 6(7); 740-53. ©2016 AACR.See related commentary by Lim et al., p. 697This article is highlighted in the In This Issue feature, p. 681.

Immunohistochemical application of a highly sensitive and specific murine monoclonal antibody recognising the extracellular domain of the human hepatocyte growth factor receptor (MET).

AIMS: Development of novel targeted therapies directed against hepatocyte growth factor (HGF) or its receptor (MET) necessitates the availability of quality diagnostics to facilitate their safe and effective use. Limitations of some commercially available anti-MET antibodies have prompted development of the highly sensitive and specific clone A2H2-3. Here we report its analytical properties when applied by an automated immunohistochemistry method. METHODS AND RESULTS: Excellent antibody specificity was demonstrated by immunoblot, ELISA, and IHC evaluation of characterised cell lines including NIH3T3 overexpressing the related kinase MST1R (RON). Sensitivity was confirmed by measurements of MET in cell lines or characterised tissues. IHC correlated well with FISH and quantitative RT-PCR assessments of MET (P < 0.001). Good total agreement (89%) was observed with the anti-MET antibody clone SP44 using whole-tissue sections, but poor positive agreement (21-47%) was seen in tissue microarray cores. Multiple lots displayed appropriate reproducibility (R(2)  > 0.9). Prevalence of MET positivity by IHC was higher in non-squamous cell NSCLC, MET or EGFR amplified cases, and in tumours harbouring abnormalities in EGFR exon 19 or 21. CONCLUSIONS: The anti-MET antibody clone A2H2-3 displays excellent specificity and sensitivity. These properties make it suitable for clinical trial investigations and development as a potential companion diagnostic.

Tumor cell expression of vascular endothelial growth factor receptor 2 is an adverse prognostic factor in patients with squamous cell carcinoma of the lung.

A robust immunohistochemical (IHC) assay for VEGFR2 was developed to investigate its utility for patient tailoring in clinical trials. The sensitivity, specificity, and selectivity of the IHC assay were established by siRNA knockdown, immunoblotting, mass spectrometry, and pre-absorption experiments. Characterization of the assay included screening a panel of multiple human cancer tissues and an independent cohort of non-small cell lung carcinoma (NSCLC, n = 118) characterized by TTF-1, p63, CK5/6, and CK7 IHC. VEGFR2 immunoreactivity was interpreted qualitatively (VEGFR2 positive/negative) in blood vessels and by semi-quantitative evaluation using H-scores in tumor cells (0-300). Associations were determined among combinations of VEGFR2 expression in blood vessels and tumor cells, and clinico-pathologic characteristics (age, sex, race, histologic subtype, disease stage) and overall survival using Kaplan-Meier analyses and appropriate statistical models. VEGFR2 expression both in blood vessels and in tumor cells in carcinomas of the lung, cervix, larynx, breast, and others was demonstrated. In the validation cohort, 99/118 (83.9%) NSCLC tissues expressed VEGFR2 in the blood vessels and 46/118 (39.0%) showed high tumor cell positivity (H-score ≥10). Vascular and tumor cell expression were inversely correlated (p = 0.0175). High tumor cell expression of VEGFR2 was associated with a 3.7-fold reduction in median overall survival in lung squamous-cell carcinoma (SCC, n = 25, p = 0.0134). The inverse correlation between vascular and tumor cell expression of VEGFR2 and the adverse prognosis associated with high VEGFR2 expression in immunohistochemically characterized pulmonary SCC are new findings with potential therapeutic implications. The robustness of this novel IHC assay will support further evaluation of its utility for patient tailoring in clinical trials of antiangiogenic agents.