Contrived Materials and a Data Set for the Evaluation of Liquid Biopsy Tests: A Blood Profiling Atlas in Cancer (BLOODPAC) Community Study

The Blood Profiling Atlas in Cancer (BLOODPAC) Consortium is a collaborative effort involving stakeholders from the public, industry, academia, and regulatory agencies focused on developing shared best practices on liquid biopsy. This report describes the results from the JFDI (Just Freaking Do It) study, a BLOODPAC initiative to develop standards on the use of contrived materials mimicking cell-free circulating tumor DNA, to comparatively evaluate clinical laboratory testing procedures. Nine independent laboratories tested the concordance, sensitivity, and specificity of commercially available contrived materials with known variant-allele frequencies (VAFs) ranging from 0.1% to 5.0%. Each participating laboratory utilized its own proprietary evaluation procedures. The results demonstrated high levels of concordance and sensitivity at VAFs of >0.1%, but reduced concordance and sensitivity at a VAF of 0.1%; these findings were similar to those from previous studies, suggesting that commercially available contrived materials can support the evaluation of testing procedures across multiple technologies. Such materials may enable more objective comparisons of results on materials formulated in-house at each center in multicenter trials. A unique goal of the collaborative effort was to develop a data resource, the BLOODPAC Data Commons, now available to the liquid-biopsy community for further study. This resource can be used to support independent evaluations of results, data extension through data integration and new studies, and retrospective evaluation of data collection.

A Preclinical and Phase 1b Study of Palbociclib Plus Nab-Paclitaxel in Patients With Metastatic Adenocarcinoma of the Pancreas

Purpose: To assess the preclinical efficacy, clinical safety and efficacy, and maximum tolerated dose (MTD) of palbociclib plus nab-paclitaxel in patients with advanced pancreatic ductal adenocarcinoma (PDAC). Experimental Design: Preclinical activity was tested in patient-derived xenograft (PDX) models of PDAC. In the open-label, phase 1 clinical study, the dose-escalation cohort received oral palbociclib initially at 75 mg/day (range 50‒125mg/day; modified 3+3 design; 3/1 schedule); intravenous nab-paclitaxel was administered weekly for 3 weeks/28 day cycle at 100‒125mg/m2. The modified dose–regimen cohorts received palbociclib 75mg/day (3/1 schedule or continuously) plus nab-paclitaxel (biweekly 125 or 100mg/m2, respectively). The prespecified efficacy threshold was 12-month survival probability of ≥65% at the MTD. Results: Palbociclib plus nab-paclitaxel was more effective than gemcitabine plus nab-paclitaxel in 3 of 4 PDX models tested; the combination was not inferior to paclitaxel plus gemcitabine. In the clinical trial, 76 patients (80% received prior treatment for advanced disease) were enrolled. Four dose-limiting toxicities were observed (mucositis [n=1], neutropenia [n=2], febrile neutropenia [n=1]). The MTD was palbociclib 100mg for 21 of every 28 days and nab-paclitaxel 125mg/m2 weekly for 3 weeks in a 28-day cycle. Among all patients, the most common all-causality any-grade adverse events were neutropenia (76.3%), asthenia/fatigue (52.6%), nausea (42.1%), and anemia (40.8%). At the MTD (n=27), the 12-month survival probability was 50% (95% CI, 29.9%–67.2%). Conclusions: This study showed the tolerability and antitumor activity of palbociclib plus nab-paclitaxel treatment in patients with PDAC; however, the prespecified efficacy threshold was not met.

Phase 3 trial of lorlatinib in treatment-naive patients (Pts) with ALK-positive advanced non–small cell lung cancer (NSCLC): Comprehensive plasma and tumor genomic analyses

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Background: Lorlatinib, a third-generation ALK tyrosine kinase inhibitor, has shown overall and intracranial activity in ALK+ advanced NSCLC. In the randomized, multicenter, phase 3 study in pts with previously untreated ALK+ advanced NSCLC (CROWN; NCT03052608), lorlatinib showed a statistically significant and clinically meaningful improvement in progression-free survival (PFS) vs crizotinib (Shaw AT, et al. N Engl J Med. 2020;383:2018-2029). Comprehensive molecular profiling of circulating tumor DNA (ctDNA) and tumor tissue was performed to identify molecular correlates of response. Methods: At baseline (BL), plasma samples were available from 134 and 129 pts in the lorlatinib and crizotinib arms, respectively. Analyses returned results for tumor tissue (archived or new biopsy) from 147 pts across both arms. Plasma and tumor DNA were analyzed by next-generation sequencing (NGS; Guardant360 and TissueNext, respectively, Guardant Health, Inc.). Objective response rate (ORR), duration of response, and PFS based on the September 20, 2021, cutoff, all assessed by blinded independent central review, were summarized according to mutation and tumor mutation burden (TMB) status. Results: At BL, 22% of pts had no detectable ctDNA. ALK missense mutations (n=19) or deletion (n=1) were detected in plasma of 12 pts (n=5 and 7 in the lorlatinib and crizotinib arms, respectively). Most pts harbored 1 mutation, but 3 pts harbored ≥3 mutations. In tumor samples, no somatic ALK mutation was detected. ALK fusions were detected in plasma of 48% of pts and in tumor of 80%. EML4-ALK variant (v) subtypes were highly concordant between ctDNA and tumor tissue. Based on ctDNA, ORRs were generally higher in the lorlatinib vs crizotinib arm, reaching 80% and 72% for EML4-ALK v1 and v3, respectively, in the lorlatinib arm, and 50% and 74% in the crizotinib arm. Median PFS was not reached for v1 in the lorlatinib arm and was 7.4 mo in the crizotinib arm; for v3, mPFS was 33.3 and 5.5 mo, respectively. TP53 mutations were found in 42% of pts with detectable ctDNA, and their presence did not seem to influence lorlatinib activity. In the crizotinib arm, absence of TP53 mutations led to longer PFS. These findings are being verified in tumor tissue. A pt treated with lorlatinib with an ongoing partial response in tumor lesions at the data cutoff date was found to have a KRAS G12V mutation and the presence of ALK fusion in tumor tissue but had no ctDNA detected at BL. Conclusions: Pts with untreated ALK+ advanced NSCLC had higher ORRs and potentially longer PFS across predefined biomarker subgroups when treated with lorlatinib compared with crizotinib in the phase 3 CROWN study. Based on pretreatment ctDNA and tumor tissue analyses, lorlatinib led to strong clinical benefit regardless of the type of ALK rearrangement or presence of potential driver co-mutation. Clinical trial information: NCT03052608.

Early circulating tumor (ct) DNA dynamics and efficacy of lorlatinib: Analysis from the CROWN study

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Background: Lorlatinib, a third-generation ALK tyrosine kinase inhibitor, significantly improved progression-free survival (PFS) and overall/intracranial responses vs crizotinib in patients (pts) with previously untreated ALK-positive advanced non-small cell lung cancer (NSCLC) in the ongoing randomized Phase 3 CROWN study (NCT03052608). To identify whether additional molecular biomarker analysis correlated with efficacy, we evaluated early ctDNA dynamics compared with clinical outcomes. Methods: Plasma samples were prospectively collected at screening (SC), week 4 (cycle 2, day 1 [C2D1]), week 24 (C7D1), and end of treatment for ctDNA analysis. ctDNA was analyzed using Guardant360CDx (Guardant Health, Inc., Redwood City, CA, USA). Mean variant allele fraction (VAF) of ALK alterations (fusions and/or mutations) and overall detected alterations at each time point and longitudinal mean change (dVAF) as (VAFC2D1) – (VAFSC) were calculated; dVAF <0 indicated decreased ctDNA at week 4. Objective tumor response and PFS were evaluated according to dVAF. These analyses were repeated vs ctDNA results at week 24. Additional correlation analyses between depth of molecular response and/or ctDNA clearance and clinical outcomes are ongoing. Results: Paired samples were available at SC and week 4 from 232 of 255 pts included in the ctDNA analysis: 118/130 (90.8%) in the lorlatinib arm and 114/125 (91.2%) in the crizotinib arm. ALK alterations were detected in 122/232 (52.6%) pts at SC (62/118 [52.5%] from the lorlatinib arm) but only 19/232 (8.2%) at week 4 (8/118 [6.8%] from the lorlatinib arm). Mean VAF of ALK alterations at week 4 was significantly decreased compared with SC in both treatment arms (lorlatinib -1.54, crizotinib -1.25; both P<0.0001; P=0.4239 between arms). In the lorlatinib arm, mean VAF at week 4 was significantly decreased compared with SC in pts with a complete or partial response (dVAF -1.53; n=47; P<0.0001), or stable disease (dVAF -1.37; n=12; P=0.0304). Similar results were observed in the crizotinib arm. In pts with dVAF <0 for ALK alterations, mean percent change from screening in tumor size was -40.8% with lorlatinib (n=59) and -38.7% with crizotinib (n=58). Only 2 pts had dVAF ≥0, both from the crizotinib arm. Median PFS for pts with dVAF <0 for ALK alterations was not reached in the lorlatinib arm (n=62), and was 7.4 months (95% CI, 7.2–9.3) in the crizotinib arm (n=58). Similar response and PFS data were observed in the analysis of dVAF for ALK alterations at week 24. Conclusions: Early ctDNA dynamics may predict lorlatinib efficacy in pts with previously untreated ALK-positive NSCLC. The magnitude of reduction in ctDNA at 4 weeks may be associated with better responses and potentially longer PFS. These findings further support the utility of dynamic ctDNA monitoring in ALK-positive NSCLC. Reference: Shaw AT, et al. N Engl J Med. 2020;383:2018-2029. Clinical trial information: NCT03052608.

Angiogenic and immunomodulatory biomarkers in axitinib-treated patients with advanced renal cell carcinoma

Aim:

Immunomodulatory mechanisms contributing to angiogenic inhibition in renal tumors are not well characterized. We report associations between efficacy and tumor-associated immune cells and mRNA/miRNA expression in patients from AXIS.

Materials & methods:

Immunohistochemistry (n = 52) and mRNA/miRNA expression analyses (n = 72) were performed on tumor samples.

Results:

In axitinib-treated patients, higher CXCR4 and TLR3 expression, respectively, was associated with longer progression-free survival (hazard ratio; 95% CI: 0.3; 0.1–0.8 and 0.4; 0.2–0.9) and showed interaction with treatment (p = 0.029 and p < 0.001); lower CCR7 expression was associated with objective response (odds ratio: 0.1; 95% CI: 0.01–1.0) and longer overall survival (hazard ratio: 3.9; 95% CI: 1.4–10.3).

Conclusion:

CCR7, CXCR4 and TLR3 expression levels may be prognostic/predictive of clinical benefit with axitinib.

Clinical trial identifier:ClinicalTrials.gov NCT00678392.

Lorlatinib in advanced ROS1-positive non-small-cell lung cancer: a multicentre, open-label, single-arm, phase 1-2 trial

BACKGROUND

Lorlatinib is a potent, brain-penetrant, third-generation tyrosine kinase inhibitor (TKI) that targets ALK and ROS1 with preclinical activity against most known resistance mutations in ALK and ROS1. We investigated the antitumour activity and safety of lorlatinib in advanced, ROS1-positive non-small-cell lung cancer (NSCLC).

METHODS

In this open-label, single-arm, phase 1-2 trial, we enrolled patients (aged ≥18 years) with histologically or cytologically confirmed advanced ROS1-positive NSCLC, with or without CNS metastases, with an Eastern Cooperative Oncology Group performance status of 2 or less (≤1 for phase 1 only) from 28 hospitals in 12 countries worldwide. Lorlatinib 100 mg once daily (escalating doses of 10 mg once daily to 100 mg twice daily in phase 1 only) was given orally in continuous 21-day cycles until investigator-determined disease progression, unacceptable toxicity, withdrawal of consent, or death. The primary endpoint was overall and intracranial tumour response, assessed by independent central review. Activity endpoints were assessed in patients who received at least one dose of lorlatinib. This study is ongoing and is registered with ClinicalTrials.gov, NCT01970865.

FINDINGS

Between Jan 22, 2014, and Oct 2, 2016, we assessed 364 patients, of whom 69 with ROS1-positive NSCLC were enrolled. 21 (30%) of 69 patients were TKI-naive, 40 (58%) had previously received crizotinib as their only TKI, and eight (12%) had previously received one non-crizotinib ROS1 TKI or two or more ROS1 TKIs. The estimated median duration of follow-up for response was 21·1 months (IQR 15·2-30·3). 13 (62%; 95% CI 38-82) of 21 TKI-naive patients and 14 (35%; 21-52) of 40 patients previously treated with crizotinib as their only TKI had an objective response. Intracranial responses were achieved in seven (64%; 95% CI 31-89) of 11 TKI-naive patients and 12 (50%; 29-71) of 24 previous crizotinib-only patients. The most common grade 3-4 treatment-related adverse events were hypertriglyceridaemia (13 [19%] of 69 patients) and hypercholesterolaemia (ten [14%]). Serious treatment-related adverse events occurred in five (7%) of 69 patients. No treatment-related deaths were reported.

INTERPRETATION

Lorlatinib showed clinical activity in patients with advanced ROS1-positive NSCLC, including those with CNS metastases and those previously treated with crizotinib. Because crizotinib-refractory patients have few treatment options, lorlatinib could represent an important next-line targeted agent.

FUNDING

Pfizer.

Abstract CT093: Axitinib in combination with pembrolizumab (AXI+PEMBRO) in patients (pts) with advanced renal cell carcinoma (aRCC): Analysis of immune-related biomarkers

Background: In an open-label, phase Ib dose-finding and dose-expansion study in pts with aRCC, AXI+PEMBRO was tolerable; objective response rate (ORR) was 73.1%, and median progression free survival (mPFS) was 20.9 months (Lancet Oncol. 2018;19:405-15). These planned exploratory analyses evaluated candidate biomarkers that may confer sensitivity/resistance to AXI+PEMBRO.

Materials & Methods: Tumor tissue (de novo biopsy or archival), serum and whole blood samples were collected at baseline (BL). Biomarkers were chosen based on known angiogenesis/immunomodulation roles. Clinical outcomes included ORR and PFS. Comparisons for responders vs non-responders were made using Wilcoxon rank sum test. Comparisons of PFS for &lt;median vs ≥median analyte values were made using Kaplan-Meier analysis. All statistical analyses were univariate. For T-cell receptor (TCR) repertoire sequencing analysis, richness, a measure of the number of different species in a repertoire, was assessed using the Daley-Smith estimate (Nat Methods. 2013;10:325-7). Dose-finding and dose-expansion cohorts were analysed together.

Results: 52 pts were treated. Tumor tissue, serum and whole blood samples were analyzed from 39 (75.0%), 51 (98.1%) and 52 (100%) pts, respectively. Immunohistochemical analysis of tumor tissue biomarkers revealed no significant associations between CD68, CD8 or PD-L1 levels at BL and ORR or PFS. However, pts whose tumor CD8 % positive cells was ≥median had a numerically longer PFS than pts whose CD8 % positive cells was &lt;median (median PFS 26.2 vs 15.4 months, respectively; hazard ratio (HR): 0.4; 95% CI: 0.2, 1.2; unadjusted 2-sided p=0.091). For serum biomarkers, higher CXCL10 levels at BL were associated with better ORR (2-sided p=0.0197; false discovery rate-adjusted p=0.2235). In addition, pts with BL CEACAM1 levels ≥median (26.0ng/mL) had a numerically longer PFS (HR: 0.5; 95% CI: 0.2, 1.1; unadjusted 2-sided p=0.085). There was no association between BL levels of other serum biomarkers and ORR or PFS. Whole blood sample assessment of TCR repertoire dynamics showed no association with clinical outcomes. While the Daley-Smith richness estimate at BL was not associated with ORR, the Daley-Smith estimates at cycle 2, day 1 and end of treatment showed a trend toward greater richness estimate being associated with better response (unadjusted p-values = 0.0866 and 0.0324, respectively).

Conclusions: In pts with aRCC, higher tumor levels of CD8 and serum levels of CXCL10 and CEACAM1 at BL may indicate potential sensitivity to AXI+PEMBRO treatment. Further validation of the value of these biomarkers in an independent cohort with a large sample size is warranted.

Citation Format: Michael Atkins, Jean-Francois Martini, Elizabeth Plimack, David McDermott, Igor Puzanov, Mayer Fishman, Daniel Cho, Ulka Vaishampayan, Brad Rosbrook, Kathrine Fernandez, Jamal Tarazi, Saby George, Toni Choueiri. Axitinib in combination with pembrolizumab (AXI+PEMBRO) in patients (pts) with advanced renal cell carcinoma (aRCC): Analysis of immune-related biomarkers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT093.

Pharmacogenomic analyses of sunitinib in patients with pancreatic neuroendocrine tumors

Aim: Evaluate associations between clinical outcomes and SNPs in patients with well-differentiated pancreatic neuroendocrine tumors receiving sunitinib. Patients & methods: Kaplan–Meier and Cox proportional hazards models were used to analyze the association between SNPs and survival outcomes using data from a sunitinib Phase IV (genotyped, n = 56) study. Fisher’s exact test was used to analyze objective response rate and genotype associations. Results: After multiplicity adjustment, progression-free and overall survivals were not significantly correlated with SNPs; however, a higher objective response rate was significantly associated with IL1B rs16944 G/A versus G/G (46.4 vs 4.5%; p = 0.001). Conclusion: IL1B SNPs may predict treatment response in patients with pancreatic neuroendocrine tumors. VEGF pathway SNPs are potentially associated with survival outcomes.

Palbociclib plus cetuximab versus placebo plus cetuximab in platinum-resistant, cetuximab-naive, HPV-unrelated head and neck cancer: A double-blind randomized phase II trial (PALATINUS)

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Background: Cetuximab monotherapy results in a median overall survival (OS) of approximately 6 months (mo) in platinum-resistant recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). HNSCC unrelated to human papillomavirus (HPV) is driven by hyperactivation of the CDK4/6 and cyclin D1 (CD1) regulatory complex, resulting in cell cycle progression and tumor growth, suggesting that CDK4/6 inhibition can be a rational therapeutic strategy in this setting. Palbociclib (PAL) is a selective CDK4/6 inhibitor that may reverse cetuximab resistance by countering the actions of deregulated CD1. PAL plus an epidermal growth factor receptor inhibitor synergistically reduced cell viability of HPV-unrelated HNSCC cell lines. In a single-arm, multicenter trial of platinum-resistant, cetuximab-naive, HPV-unrelated HNSCC, PAL in combination with cetuximab resulted in a median OS of 9.5 mo. Methods: In a double-blind randomized phase II trial, patients (pts) with platinum-resistant, cetuximab-naïve, HPV-unrelated HNSCC were treated with cetuximab plus either PAL (arm A) or placebo (arm B). Pts were stratified by performance status (PS) and prior immunotherapy (IT). 120 pts were required for 1:1 randomization to have ≥ 80% power to detect a hazard ratio (HR) of 0.6 (corresponding to a median OS of 10 mo in arm A and 6 mo in arm B) using a 1-sided log-rank test P=0.10). Key secondary endpoints included progression-free survival (PFS), adverse events (AEs), and p16 status. Results: Pts (n=125) were randomized (arm A, 65; arm B, 60). PS and prior IT were balanced between the arms. Median (95% CI) follow-up for OS was 15.9 (15.0–19.4) mo. Median OS was 9.7 (7.3–13.9) mo in arm A and 7.8 (6.7–10.6) mo in Arm B (stratified by PS: HR=0.82 [95% CI, 0.54–1.25], P=0.18). Median PFS was 3.9 mo in arm A and 4.6 mo in arm B (stratified by PS: HR=1.00 [0.7–1.5], P=0.5). Hematologic AEs were more common in arm A. Only 11 pts (9%) received IT after being treated on the trial. Conclusions: Among pts with platinum-resistant, HPV-unrelated HNSCC, PAL plus cetuximab resulted in a trend of prolongation of median OS compared with cetuximab. Clinical trial information: NCT02499120.

Early circulating tumor (ct)DNA dynamics and efficacy of lorlatinib in patients (pts) with advanced ALK-positive non-small cell lung cancer (NSCLC)

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Background: Lorlatinib is a selective, potent, brain-penetrant, 3rd generation (gen) ALK/ROS1 TKI approved for pts with advanced ALK+ NSCLC previously treated with a 2nd gen ALK TKI. We recently showed that ALK mutation tumor genotyping after failure of a 2nd gen ALK TKI may identify pts more likely to respond to lorlatinib.1 To identify other molecular response correlates, we evaluated if early ctDNA dynamics predict clinical outcome on lorlatinib. Methods: In pts enrolled on the ongoing ph 2 study (NCT01970865), plasma samples were prospectively collected for ctDNA analysis at baseline (BL), cycle 3 day 1 (C3D1, or 6 weeks) and end of treatment. Plasma DNA was analyzed using Guardant360. Change in variant allele fraction (dVAF)2 of ALK alterations (fusions and/or mutations) was calculated as (mean VAFC3D1) – (mean VAFBL); dVAF < 0 indicated decreased ctDNA at C3D1. BOR, PFS and OS were evaluated according to dVAF. Results: Of 121 paired BL/C3D1 samples collected from 158 ALK+ pts previously treated with one or more 2nd gen ALK TKIs, 57 (47%) harbored a detectable ALK alteration at BL. At C3D1, mean VAF of ALK fusions and/or mutations was significantly decreased compared to BL (-1.07, p = 0.0014). Mean tumor volume was reduced by 26% in pts with dVAF < 0 (n = 40), but only by 12% in pts with dVAF ≥0 (n = 13) (p = 0.049). Mean dVAF at C3D1 was significantly decreased compared to BL for pts with CR/PR, while there was no significant difference with SD or PD/IND; mean dVAF -1.84, -0.74, and +0.35 in pts with CR/PR, SD, or PD/IND, respectively (p = 0.0011, 0.1444 and 0.3383). Median PFS was 6.6 months (mo) in pts with dVAF < 0 (n = 44) and 2.6 mo in pts with dVAF ≥0 (n = 13) (HR = 2.6, 95% CI: 1.2, 5.8). Median OS was 18.0 mo in pts with dVAF < 0 (n = 34) and 8.6 mo in pts with dVAF ≥0 (n = 13) (HR 2.0, 95% CI, HR 0.9–4.6). Conclusions: Early ctDNA dynamics may predict lorlatinib efficacy in ALK+ NSCLC, with decreased ctDNA at 6 wks associated with better response and longer PFS. Further studies are needed to validate these findings and to determine whether early intervention based on dynamic ctDNA monitoring may improve outcome. References: 1. Shaw, et al. J Clin Oncol. 2019. 2. Raja, et al. Clin Cancer Res. 2018. Clinical trial information: NCT01970865.

Real-world treatment patterns and outcomes of patients with stage IV squamous cell carcinoma of the head and neck

Aim: To understand the treatment patterns and outcomes for stage IV squamous cell carcinoma of the head and neck, patients receiving second-line or later drug therapy. Materials & methods: Real-world data were collected from 1152 patients in the USA, France, Germany and the UK through a retrospective chart analysis and patient-reported outcomes were collected using validated questionnaires in a subgroup of patients. Results: Forty-four percent of patients had stage IVA/B disease. A total of 77, 19 and 3% of patients had received two, three and four plus lines of active drug treatment. Platinum- and cetuximab-based regimens were common at early treatment lines. Time to progression was short (5.2 months post first line), survival rates low and patient-reported health status poor. Conclusion: Novel therapies that could improve clinical and patient-reported outcomes would address a significant unmet need.

Sunitinib in patients with pancreatic neuroendocrine tumors (panNETs): Exploratory pharmacogenomic analyses

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Background: In a phase IV trial (NCT01525550), median progression-free survival (PFS) was 13.2 mo in sunitinib-treated patients (pts) with well-differentiated panNETs. Objective response rate (ORR) was 24.5% and median overall survival (OS) was 37.8 mo. Exploratory analyses evaluated potential associations between single nucleotide polymorphisms (SNP) in genes involved in angiogenesis, protein transport or inflammatory response and clinical outcomes. Methods: Blood samples were genotyped using TaqMan assays for 12 SNPs previously associated with panNET risk, prognosis or drug effect. Associations between SNP and PFS or OS were assessed by comparing genotypes within treatment-naïve (TN), previously treated (PT) and combined groups, and within a genotype between treatment groups, using Kaplan-Meier analysis and Cox proportional hazards models. Fisher’s exact test was used for association between ORR and genotype. PFS and ORR were investigator-assessed. P values displayed are unadjusted and Bonferroni method was used for multiplicity adjustment. Results: 56 pts were genotyped: 25 TN and 31 PT. There were no significant associations between genotype and PFS or OS but there was a trend toward shorter PFS in pts with VEGFR1 rs9554320 C/A versus C/C (hazard ratio [HR] 1.78; 95% confidence interval [CI] 0.83–3.82; p = 0.117) and VEGFR1 rs9582036 A/C versus A/A (HR 1.88; 95% CI 0.9–3.93; p = 0.102). The genotypes G/G of VEGFA rs2010963 (p = 0.041) , G/G of VEGFA rs833068 (p = 0.041) and A/C of VEGFR1 rs9582036 (p = 0.046) showed a trend toward a higher ORR in the PT versus TN group. Genotype T/T of VEGFR2 rs7692791 (p = 0.103) showed a trend toward to a lower ORR in the TN versus PT group. Higher ORR was associated with IL1B rs16944 G/A versus G/G (46.4% vs 4.5%; p = 0.001) in the combined group. Conclusions: Potential associations between ORR and VEGFA rs2010963 and rs833068, VEGFR1 rs9582036 and VEGFR2 rs7692791 were observed. IL1B rs16944 was significantly associated with ORR, consistent with the role of IL1B in panNET etiology and development. Most correlations were not significant after adjustment for multiplicity. Clinical trial information: NCT01525550.

Phase III Trial of Adjuvant Sunitinib in Patients with High-Risk Renal Cell Carcinoma: Exploratory Pharmacogenomic Analysis

PURPOSE

In the S-TRAC trial, adjuvant sunitinib prolonged disease-free survival (DFS) versus placebo in patients with loco-regional renal cell carcinoma at high risk of recurrence after nephrectomy. An exploratory analysis evaluated associations between SNPs in several angiogenesis- or hypoxia-related genes and clinical outcomes in S-TRAC.

PATIENTS AND METHODS

Blood samples were genotyped for 10 SNPs and one insertion/deletion mutation using TaqMan assays. DFS was compared using log-rank tests for each genotype in sunitinib versus placebo groups and between genotypes within each of three (sunitinib, placebo, and combined sunitinib plus placebo) treatment groups. P values were unadjusted.

RESULTS

In all, 286 patients (sunitinib, n = 142; placebo, n = 144) were genotyped. Longer DFS [HR; 95% confidence interval (CI)] was observed with sunitinib versus placebo for VEGFR1 rs9554320 C/C (HR 0.44; 95% CI, 0.21-0.91; P = 0.023), VEGFR2 rs2071559 T/T (HR 0.46; 95% CI, 0.23-0.90; P = 0.020), and eNOS rs2070744 T/T (HR 0.53; 95% CI, 0.30-0.94; P = 0.028). Shorter DFS was observed for VEGFR1 rs9582036 C/A versus C/C with sunitinib, placebo, and combined therapies (P ≤ 0.05), and A/A versus C/C with sunitinib (P = 0.022). VEGFR1 rs9554320 A/C versus A/A was associated with shorter DFS in the placebo (P = 0.038) and combined (P = 0.006) groups.

CONCLUSIONS

Correlations between VEGFR1 and VEGFR2 SNPs and longer DFS with sunitinib suggest germline SNPs are predictive of improved outcomes with adjuvant sunitinib in patients with renal cell carcinoma. Independent validation studies are needed to confirm these findings.

Validation of the 16-Gene Recurrence Score in Patients with Locoregional, High-Risk Renal Cell Carcinoma from a Phase III Trial of Adjuvant Sunitinib

Purpose: Adjuvant sunitinib prolonged disease-free survival (DFS; HR, 0.76) in patients with locoregional high-risk renal cell carcinoma (RCC) in the S-TRAC trial (ClinicalTrials.gov NCT00375674). The 16-gene Recurrence Score (RS) assay was previously developed and validated to estimate risk for disease recurrence in patients with RCC after nephrectomy. This analysis further validated the prognostic value of RS assay in patients from S-TRAC and explored the association of RS results with prediction of sunitinib benefit.Patients and Methods: The analysis was prospectively designed with prespecified genes, algorithm, endpoints, and analytical methods. Primary RCC was available from 212 patients with informed consent; primary analysis focused on patients with T3 RCC. Gene expression was quantitated by RT-PCR. Time to recurrence (TTR), DFS, and renal cancer-specific survival (RCSS) were analyzed using Cox proportional hazards regression.Results: Baseline characteristics were similar between patients with and those without RS results, and between the sunitinib and placebo arms among patients with RS results. RS results predicted TTR, DFS, and RCSS in both arms, with the strongest results observed in the placebo arm. When high versus low RS groups were compared, HR for recurrence was 9.18 [95% confidence interval (CI), 2.15-39.24; P < 0.001) in the placebo arm; interaction of RS results with treatment was not significant.Conclusions: The strong prognostic performance of the 16-gene RS assay was confirmed in S-TRAC, and the RS assay is now supported by level IB evidence. RS results may help identify patients at high risk for recurrence who may derive higher absolute benefit from adjuvant therapy. Clin Cancer Res; 24(18); 4407-15. ©2018 AACR.

Regional Differences in Efficacy, Safety, and Biomarkers for Second-Line Axitinib in Patients with Advanced Hepatocellular Carcinoma: From a Randomized Phase II Study

BACKGROUND

An unmet need exists for treatment of patients with advanced hepatocellular carcinoma (HCC) who progress on or are intolerant to sorafenib. A global randomized phase II trial (ClinicalTrial.gov No. NCT01210495) of axitinib, a vascular endothelial growth factor receptor 1-3 inhibitor, in combination with best supportive care (BSC) did not prolong overall survival (OS) over placebo/BSC, but showed improved progression-free survival in some patients. Subgroup analyses were conducted to identify potential predictive/prognostic factors.

METHODS

The data from this phase II study were analyzed for the efficacy and safety of axitinib/BSC in patients from Asia versus non-Asia versus Asian subgroups (Japan, Korea, or mainland China/Hong Kong/Taiwan) and predictive/prognostic values of baseline microRNAs and serum soluble proteins, using the Cox proportional hazards model.

RESULTS

Of 202 patients, 78 were from non-Asia and 124 from Asia (37 Japanese, 36 Korean, and 51 Chinese). No significant differences in OS were found between axitinib/BSC and placebo/BSC in non-Asians, Asians, or Asian subgroups. However, in an exploratory analysis, axitinib/BSC showed favorable OS in Asians, especially Japanese, when patients intolerant to prior antiangiogenic therapy were excluded from the data set. Axitinib/BSC was well tolerated by non-Asians and Asians alike. The presence of 4 circulating microRNAs, including miR-5684 and miR-1224-5p, or a level lower than or equal to the median protein level of stromal cell-derived factor 1 at baseline was significantly associated with longer OS in axitinib/BSC-treated Asians or non-Asians.

CONCLUSIONS

Axitinib/BSC did not prolong survival over placebo/BSC in non-Asians, Asians, or Asian subgroups, but favorable OS with axitinib/BSC was observed in a subset of Japanese patients. A patient population that excludes sorafenib-intolerant patients might potentially be more suitable for clinical trials of new agents in advanced HCC. Since these results are very preliminary, further investigation is warranted. The potential predictive/prognostic value of several baseline microRNAs and soluble proteins identified in this study would require validation in prospective studies on a large cohort of patients.

Phase III trial of adjuvant sunitinib in patients with high-risk renal cell carcinoma: Exploratory pharmacogenomic analysis

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Background: In the phase III S-TRAC trial, adjuvant sunitinib (SU) prolonged disease-free survival (DFS) vs placebo (PBO) in patients with locoregional renal cell carcinoma at high risk of recurrence after nephrectomy (median 6.8 vs 5.6 y; hazard ratio [HR] 0.76, 95% confidence interval [CI] 0.59–0.98; P= 0.03). An exploratory analysis evaluated associations between single nucleotide polymorphisms (SNPs) in angiogenesis-related genes and clinical outcomes in S-TRAC. Methods: Prospectively collected blood samples were genotyped for 10 SNPs and 1 insertion/deletion mutation with TaqMan assays. DFS was compared with a log-rank test for each SNP genotype in SU vs PBO arms and between SNP genotypes within each arm. P-values are unadjusted for multiplicity comparison. Results: Of 615 patients, 286 (142 SU; 144 PBO) were analyzed. There were generally no genotype frequency deviations from the Hardy-Weinberg equilibrium, but linkage disequilibrium was seen between VEGFA rs699947 and rs833061 on chromosome 6 (D′ = 1.000, r2 = 0.979). Longer DFS was observed with SU vs PBO for VEGFR1 rs9554320 C/C (median: not reached [NR] vs 5.56 y; HR 0.44, 95% CI 0.21–0.91; P= 0.023), VEGFR2 rs2071559 T/T (median: NR vs 4.47 y; HR 0.46, 95% CI 0.23–0.90; P= 0.020), and eNOS rs2070744 T/T (median: 7.07 vs 3.44 y; HR 0.53, 95% CI 0.30–0.94; P= 0.028), with a trend for VEGFR1 rs9582036 A/A (median: NR in both arms; P= 0.054) and SH3GL2 rs10963287 C/T (median: NR vs 5.35 y; P= 0.088). Shorter DFS was observed for VEGFR1 rs9582036 C/A vs C/C in the SU, PBO, and combined arms ( P< 0.05); for A/A vs common, the association was only seen in the SU arm ( P= 0.022). VEGFR1 rs9554320 A/C was associated with shorter DFS vs A/A in the PBO ( P= 0.038) and combined arm ( P= 0.006), with a trend in the SU arm ( P= 0.051). VEGFR2 rs1870377 T/T was associated with longer DFS vs A/A in the combined arms, but not in the PBO arm (n = 7 with A/A genotype in the SU arm precluded statistical tests). Conclusions: Correlations between common VEGFR1 and VEGFR2 SNPs and longer DFS with SU suggest germline SNPs are predictive of improved outcomes with adjuvant SU. Due to the exploratory nature of this analysis, prospective validation studies are needed to confirm these findings. Clinical trial information: NCT00375674.

Abstract 1771: Phase 3 trial of adjuvant sunitinib in patients with high-risk renal cell carcinoma: exploratory molecular analysis of tumor biomarkers

Background: Adjuvant therapy with sunitinib (SU) compared with placebo (PBO) prolonged disease-free survival (DFS) in patients (pts) with loco-regional high-risk renal cell carcinoma (HR=0.76, 95% CI: 0.59-0.98; P=0.03; median[m] DFS, 6.8 vs 5.6 years). Here, we report the results of a retrospective exploratory molecular biomarker analysis using nephrectomy biospecimens from the S-TRAC trial.

Materials and Methods: Formalin-fixed paraffin-embedded tumor tissue blocks from patients who provided informed consent were used for immunohistochemistry (IHC) staining of PD-L1, CD4, CD8, and CD68. Biomarker quantification was done by automated image analysis of the regions of interest (ROI). The analysis algorithm utilized an immunoscore approach applied to ROI, reflecting assessment of both the center and invasive margin of tumors (for PD-L1 and CD8 staining). DFS was compared between biomarker stratum by &lt; median vs ≥ median values of a particular IHC parameter using Kaplan-Meier (K-M) analysis. Receiver Operating Characteristics (ROC) curves were generated to further assess the potential clinical utility of biomarkers for which significant (P &lt; 0.05) results were obtained in K-M analysis.

Results: In total, 191/615 (101, SU and 90, PBO) pts in the intent-to-treat population were included for IHC analysis. Baseline characteristics were similar in the subpopulations with and without IHC data. Shorter DFS was observed in the PBO group for pts with PD-L1+ vs PD-L1- tumors, although not statistically significant (HR=1.75; 95% CI: 0.89-3.46; P=0.103). In pts with PD-L1+ tumors, DFS was numerically longer for SU vs PBO (mDFS=6.17 vs 2.67 years) (HR=0.58; 95% CI: 0.26-1.29; P=0.175). In the SU group, pts with CD8+ T-cell density ≥ median (cutoff=269.5 CD8+ cells/mm2) had longer DFS (mDFS=not reached [NR]; 95% CI: 6.83-NR) than pts with CD8+ T-cell density &lt; median (mDFS=3.47 years; 95% CI: 1.73-NR), and the difference was statistically significant (HR=0.40, 95% CI: 0.20-0.81; P=0.009), while CD8+ T-cell density showed no significant difference in DFS for PBO pts (HR=0.80, 95% CI: 0.42-1.50; P=0.484). The sensitivity and specificity for CD8+ T-cell density in predicting DFS were 0.604 and 0.658, respectively, and the optimal cutoff was 222.22 cells/mm2 with an area under ROC curve of 0.622.

Conclusions: Increased density of CD8+ T-cells in tumor tissue was associated with longer DFS in SU-randomized pts but not PBO, suggesting this may be predictive of treatment effect. Further validation in an independent cohort is warranted. The prognostic value of PD-L1 expression in primary tumors from patients with high-risk non-metastatic RCC should be further explored.

Citation Format: Daniel J. George, Jean-Francois Martini, Yen-Hwa Chang, Michael Staehler, Jan Breza, Jean-Jacques Patard, Robert J. Motzer, Ahmed Magheli, Bernard Escudier, Giacomo Carteni, Paola Gerletti, Sherry Li, Michelle Casey, Brigitte Laguerre, Hardev S. Pandha, Allan J. Pantuck, Anup Patel, Maria Lechuga, Alain Ravaud. Phase 3 trial of adjuvant sunitinib in patients with high-risk renal cell carcinoma: exploratory molecular analysis of tumor biomarkers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1771. doi:10.1158/1538-7445.AM2017-1771

Efficacy and safety of lorlatinib in patients (pts) with ALK+ non-small cell lung cancer (NSCLC) with one or more prior ALK tyrosine kinase inhibitor (TKI): A phase I/II study

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Background: Lorlatinib is a selective, potent, brain-penetrant, next generation ALK/ROS1 TKI active against most known resistance mutations. In Ph I of this Ph I/II study, lorlatinib showed robust clinical activity in ALK+ or ROS1+ advanced NSCLC pts, most of whom had CNS metastases (mets) and were heavily pre-treated. In Ph II of this study, efficacy was explored based on prior ALK TKI tx as well as safety across all patients treated at the recommended Ph II dose. Methods: In this ongoing Ph II study (NCT01970865), pts with ALK+ or ROS1+ NSCLC, ± asymptomatic untreated or treated CNS mets, were enrolled into 6 expansion cohorts (EXP) based on prior tx (EXP 1-5, ALK+) and rearrangement status (EXP 6, ROS1+). Pts received lorlatinib 100mg QD. Primary objective was ORR and intracranial ORR (IC-ORR) by independent central review (ICR). Results: Efficacy (ALK+ pts with prior tx): At data cut-off (15 Aug 2016), 82 ALK+ pts were enrolled in cohorts EXP 2-5, received C1 no later than 31 Mar 2016 and were evaluated for ORR (ITT population); 52 were evaluated for IC-ORR and 35 were evaluated for IC-ORR response based on target lesions only (≥5mm; no prior radiotherapy or progression post prior radiotherapy). Confirmed response rates by ICR are reported in the table below. Safety (all pts): 116 ALK/ROS1+ pts were evaluated for safety at data cut-off. Most common tx-related AEs (TRAEs) and grade 3/4 TRAEs were hypercholesterolemia (90%, 17%) and hypertriglyceridemia (72%, 17%). Dose interruptions and reductions due to TRAEs were reported in 29% and 20% of pts, respectively. 14% of pts had tx-related SAEs. 5 pts (4%) discontinued tx due to TRAEs and there were no tx-related deaths. 74/116 pts (64%) remain on tx. Conclusions: Lorlatinib showed compelling clinical activity, with substantial IC activity, in ALK+ pts who received ≥1 prior ALK TKI, many of whom were heavily pre-treated. Clinical trial information: NCT01970865. [Table: see text]

Phase III trial of adjuvant sunitinib in patients with high-risk renal cell carcinoma (RCC): Validation of the 16-gene Recurrence Score in stage III patients

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Background: Adjuvant therapy with sunitinib (SU) compared with placebo (PBO) prolonged disease-free survival (DFS) in 615 patients (pts) with high-risk RCC (hazard ratio [HR] 0.76; P= 0.03) in the S-TRAC trial. The 16-gene Recurrence Score (RS) was developed and validated to predict risk of recurrence of RCC after nephrectomy in 2 cohorts of stage I–III pts (Rini et al., Lancet Oncol 2015;16:676-85). We present further validation of RS results in high-risk stage III pts from S-TRAC. Methods: The study was prospectively designed with prespecified genes, algorithm, endpoints, analytical methods, and analysis plan using primary RCC tissues from 212 evaluable pts with informed consent. Gene expression was quantitated by RT-PCR; primary analysis focused on stage III (n = 193 pts). Time to recurrence (TTR) and DFS were analyzed using Cox proportional hazard regression. Results: Baseline characteristics were similar in SU and PBO arms and in pts with and without gene expression data; effect of SU was numerically similar to that in the entire trial (DFS HR 0.78, 95% CI 0.48–1.24; P= 0.29). RS predicted TTR and DFS in both treatment arms with the strongest results observed in PBO arm where high RS group had significantly higher risk (Table). Interaction of RS with treatment was not significant (TTR P= 0.192; DFS P= 0.219); however, the number of events was relatively low. Conclusions: The prognostic value of the 16-gene assay was confirmed in S-TRAC. RS is now validated with consistent results in 2 separate studies (level IB evidence). RS results may help identify patients at high risk who could derive higher absolute benefit from adjuvant treatment. The predictive value of RS to select patients for adjuvant SU requires further investigation in independent adjuvant trials. [Table: see text]

Patterns of HPV testing and treatment decision in patients with SCCHN

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Background: Human papillomavirus (HPV) is one of the main risk factors associated with squamous cell carcinoma of the head and neck (SCCHN). Although it is a prognostic factor, SCCHN patients are not routinely tested for HPV status because it may not be informative for therapy initiation. The objective of this study was to understand the real world testing patterns, and treatment decision of SCCHN patients. Methods: Real world data was gathered using Adelphi’s Disease-Specific Programme (DSP) - a real world, cross-sectional survey conducted in the USA, France, Germany and the UK (April - September 2016). The DSP incorporated 182 physician interviews (54 US, 128 EU) covering all stages of SCCHN caseloads and treatment patterns. Physicians also provided data for 8 consecutive consulting SCCHN patients regarding treatment patterns, progression, and symptoms. Results: A total of 2193 SCCHN patient cases were captured. HPV testing was carried out in 42% of patients within the DSP data set with no particular difference across the 4 countries. Of those tested, 35% of patients were HPV positive. Testing was mainly performed at the local level (51%, onsite or local hospital) apart from Germany where central testing was higher (73%). In over half of patients cases (54%) , physicians are unaware of the type of test performed for the HPV status determination; in fact, up to 10 different types of tests were used to determine the HPV status in this real world experience. Platinum based cetuximab and fluorouracil was used in 30% of the HPV positive patients while 20% received platinum monotherapy. In 2nd line, docetaxel/paclitaxel monotherapy was used in 22% of the patients. HPV negative patients also mainly received platinum based cetuximab and fluorouracil (27%) in 1st line, while in 2ndline, docetaxel/paclitaxel monotherapy was used in 20% of the patients. Conclusions: This analysis of real world treatment patterns and outcomes among SCCHN patients shows that HPV testing is not widely carried out for either patient characterization or to guide treatment decisions within this disease. Therapy choices were generally consistent standard clinical guidelines.

Adjuvant Sunitinib in High-Risk Renal-Cell Carcinoma after Nephrectomy

BACKGROUND

Sunitinib, a vascular endothelial growth factor pathway inhibitor, is an effective treatment for metastatic renal-cell carcinoma. We sought to determine the efficacy and safety of sunitinib in patients with locoregional renal-cell carcinoma at high risk for tumor recurrence after nephrectomy.

METHODS

In this randomized, double-blind, phase 3 trial, we assigned 615 patients with locoregional, high-risk clear-cell renal-cell carcinoma to receive either sunitinib (50 mg per day) or placebo on a 4-weeks-on, 2-weeks-off schedule for 1 year or until disease recurrence, unacceptable toxicity, or consent withdrawal. The primary end point was disease-free survival, according to blinded independent central review. Secondary end points included investigator-assessed disease-free survival, overall survival, and safety.

RESULTS

The median duration of disease-free survival was 6.8 years (95% confidence interval [CI], 5.8 to not reached) in the sunitinib group and 5.6 years (95% CI, 3.8 to 6.6) in the placebo group (hazard ratio, 0.76; 95% CI, 0.59 to 0.98; P=0.03). Overall survival data were not mature at the time of data cutoff. Dose reductions because of adverse events were more frequent in the sunitinib group than in the placebo group (34.3% vs. 2%), as were dose interruptions (46.4% vs. 13.2%) and discontinuations (28.1% vs. 5.6%). Grade 3 or 4 adverse events were more frequent in the sunitinib group (48.4% for grade 3 events and 12.1% for grade 4 events) than in the placebo group (15.8% and 3.6%, respectively). There was a similar incidence of serious adverse events in the two groups (21.9% for sunitinib vs. 17.1% for placebo); no deaths were attributed to toxic effects.

CONCLUSIONS

Among patients with locoregional clear-cell renal-cell carcinoma at high risk for tumor recurrence after nephrectomy, the median duration of disease-free survival was significantly longer in the sunitinib group than in the placebo group, at a cost of a higher rate of toxic events. (Funded by Pfizer; S-TRAC ClinicalTrials.gov number, NCT00375674 .).

Regional differences in efficacy/safety/biomarkers in a randomised study of axitinib in 2nd line patients (pts) with advanced hepatocellular carcinoma (HCC)

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Background: A randomised, double-blind phase II study of axitinib plus BSC [AXI] vs placebo plus BSC [PBO] was conducted in HCC pts after failure of one antiangiogenic therapy. Primary outcome was presented at ESMO 2014. No significant differences in overall survival (OS) between two arms were noted overall and in pre-specified subgroup analysis (non-Asian [nA] and Asian [A]). Interestingly, improvements favouring AXI (P < 0.01) were observed in secondary efficacy endpoints and retained among A. Methods: Exploratory efficacy/safety/biomarker analyses were performed by geographic region (nA; A; A subgroups: Japan/Korea [JK] and China/Hong Kong/Taiwan [CHT]) including: OS excluding pts intolerant to prior therapy; relationship between a subset of 26 baseline micro RNAs (miR) and AXI effect. Results: 78 nA pts (76% male, 60% with vascular invasion/extrahepatic spread) and 124 A pts (73JK/51CHT) (86% [84% JK, 90% CHT] male; 86% [82% JK, 92% CHT] with vascular invasion/extrahepatic spread) were randomized. In regional subgroups, OS HR excluding pts intolerant to prior therapy was: nA HR = 0.700 (95% CI 0.373–1.316; p = 0.1318) for AXI (45) vs PBO (16); A HR = 0.653 (95% CI 0.415–1.027; p = 0.0312) for AXI (76) vs PBO (35); JK HR = 0.479 (95% CI 0.250–0.918; p = 0.0118) for AXI (46) vs PBO (17); CHT HR = 0.918 (95% CI 0.480–1.756; p = 0.3954) for AXI (30) vs PBO (18). AXI safety profile was generally similar in regional subgroups. Differences were seen in dose modification pattern: dose reduction or discontinuation due to adverse events in 24% nA / 41% A / 51% JK / 26% CHT or in 39% nA / 22% A / 16% JK / 32% CHT, respectively. miR analysis for OS showed a trend of predictive and/or prognostic effect in overall population (e.g., let-7e-5p); a strong predictive effect of multiple miR (e.g., miR-3648) was seen in A but not in nA. Conclusions: AXI showed favorable OS vs PBO in nA and A, particularly in JK, when pts intolerant to prior therapy were excluded, suggesting that pts who progress on prior therapy are more suitable population for new agent studies in HCC. Appropriate dose modifications may also play a role in treatment duration. Baseline miR signature may have predictive value for AXI OS in A. Clinical trial information: NCT01210495.

Correlation of KIT and PDGFRA mutational status with clinical benefit in patients with gastrointestinal stromal tumor treated with sunitinib in a worldwide treatment-use trial

Background

Several small studies indicated that the genotype of KIT or platelet-derived growth factor receptor-α (PDGFRA) contributes in part to the level of clinical effectiveness of sunitinib in gastrointestinal stromal tumor (GIST) patients. This study aimed to correlate KIT and PDGFRA mutational status with clinical outcome metrics (progression-free survival [PFS], overall survival [OS], objective response rate [ORR]) in a larger international patient population.

Methods

This is a non-interventional, retrospective analysis in patients with imatinib-resistant or intolerant GIST who were treated in a worldwide, open-label treatment-use study (Study 1036; NCT00094029) in which sunitinib was administered at a starting dose of 50 mg/day on a 4-week-on, 2-week-off schedule. Molecular status was obtained in local laboratories with tumor samples obtained either pre-imatinib, post-imatinib/pre-sunitinib, or post-sunitinib treatment, and all available data were used in the analyses regardless of collection time. The primary analysis compared PFS in patients with primary KIT exon 11 versus exon 9 mutations (using a 2-sided log-rank test) and secondary analyses compared OS (using the same test) and ORR (using a 2-sided Pearson χ² test) in the same molecular subgroups.

Results

Of the 1124 sunitinib-treated patients in the treatment-use study, 230 (20 %) were included in this analysis, and baseline characteristics were similar between the two study populations. Median PFS was 7.1 months. A significantly better PFS was observed in patients with a primary mutation in KIT exon 9 (n = 42) compared to those with a primary mutation in exon 11 (n = 143; hazard ratio = 0.59; 95 % confidence interval, 0.39–0.89; P = 0.011), with median PFS times of 12.3 and 7.0 months, respectively. Similarly, longer OS and higher ORR were observed in patients with a primary KIT mutation in exon 9 versus exon 11. The data available were limited to investigate the effects of additional KIT or PDGFRA mutations on the efficacy of sunitinib treatment.

Conclusions

This large retrospective analysis confirms the prognostic significance of KIT mutation status in patients with GIST. This analysis also confirms the effectiveness of sunitinib as a post-imatinib therapy, regardless of mutational status.

Trial registration

NCT01459757.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2051-5) contains supplementary material, which is available to authorized users.

A 16-gene assay to predict recurrence after surgery in localised renal cell carcinoma: development and validation studies

BACKGROUND

The likelihood of tumour recurrence after nephrectomy in localised clear cell renal cell carcinoma is well characterised by clinical and pathological parameters. However, these assessments can be improved and personalised by the addition of molecular characteristics of each patient's tumour. We aimed to develop and validate a prognostic multigene signature to improve prediction of recurrence risk in clear cell renal cell carcinoma.

METHODS

In the development stage, we investigated the association between expression of 732 genes, measured by reverse-transcription PCR, and clinical outcome in 942 patients with stage I-III clear cell renal cell carcinoma who had undergone a nephrectomy at the Cleveland Clinic (OH, USA). 516 genes were associated with recurrence-free interval. 11 of these genes were selected by further statistical analyses, and were combined with five reference genes (ie, 16 genes in total), from which a recurrence score algorithm was developed. The recurrence score was then validated in an independent cohort of 626 patients from France with stage I-III clear cell renal cell carcinoma who had also undergone nephrectomy. The association between the recurrence score and the risk of recurrence and cancer-specific survival in the first 5 years after surgery was assessed using Cox proportional hazard regression, stratified by tumour stage (stage I vs stage II vs III).

FINDINGS

In our primary univariate analysis, the continuous recurrence score (median 37, IQR 31-45) was significantly associated with recurrence-free interval (hazard ratio 3·91 [95% CI 2·63-5·79] for a 25-unit increase in score, p<0·0001). In multivariable analyses, the recurrence score was significantly associated with the risk of tumour recurrence (hazard ratio per 25-unit increase in the score 3·37 [95% CI 2·23-5·08], p<0·0001) after stratification by stage and adjustment for tumour size, grade, or Leibovich score. The recurrence score was able to identify a clinically significant number of both high-risk stage I and low-risk stage II-III patients. A heterogeneity study on separate samples showed little to no intratumoural variability among the 16 genes.

INTERPRETATION

Our findings validate the recurrence score as a predictor of clinical outcome in patients with stage I-III clear cell renal cell carcinoma, providing a more accurate and individualised risk assessment beyond existing clinical and pathological parameters.

FUNDING

Genomic Health Inc and Pfizer Inc.

Identification of tumor biomarkers for sunitinib in advanced renal cell carcinoma (RCC)

470

Background: Sunitinib is a standard of care for advanced RCC. Despite efforts to identify predictive molecular markers for patient selection, none are available, likely due to multiple resistance mechanisms. Using the Total Cancer Care (TCC) database, which integrates patient clinical, molecular, and biospecimen data, we devised a tumor genomics and transcriptomics experiment to identify differences between RCC patients who derive prolonged clinical benefit from sunitinib versus those who are resistant. Methods: A discovery set of 34 RCC patients treated with sunitinib at the approved regimen were identified in the TCC database (n=16 treated for ≤6 months, having primarily discontinued for reasons other than tolerability; n=18 treated for ≥18 months). Tumor samples were analyzed by whole exome sequencing (WES) and by parallel 400-gene expression profiling. Following gene mutation identification and supervised gene expression analysis, molecular differences between the two groups were identified and tested for potential association with treatment duration. Results: Of the 34 cases identified, 24 remained for analysis following sample QC failure and clinical review (n=10 and 14 treated for ≤6 and ≥18 months, respectively). Gene expression analysis revealed a 37-gene signature associated with treatment duration: MAPK8 (JNK1) was a leading candidate biomarker (Pearson correlation with log [treatment duration]=–0.70; p=0.06 after Bonferroni multiplicity correction). Pathway-based WES analyses identified 25 potential variants of interest, none remaining statistically significant after correction. However, following genome-wide analysis, a single variant in an intronic region of ING3 was statistically associated with treatment duration (p=0.02). Conclusions: Activation of the PI3K/AKT pathway was a marker of resistance to sunitinib. In contrast, activation of the angiogenic, NOTCH, or JAK-STAT pathways was, to some degree, associated with sensitivity to therapy. However, neither VHL alteration nor lack of expression, nor alteration in chromatin-rearrangement genes, was associated with sunitinib treatment duration. These findings require further validation in a larger and independent cohort.

Robustness of the 16-gene signature for prediction of recurrence-free interval in localized clear cell renal cell carcinoma

455

Background: The Renal Cancer assay is a clinically validated RT-PCR assay developed to estimate the risk of recurrence in stage I-III clear cell renal cell carcinoma (ccRCC) patients (pts) treated with nephrectomy. The assay measures expression of 16 genes that are combined to calculate the Recurrence Score result (RS). The RS is associated with recurrence, renal cancer-specific survival and overall survival (all p<0.001) (Escudier, ASCO 2014). The performance of the RS in clinically relevant subgroups, compared to the Leibovich score, and its within-patient variability was examined. Methods: The algorithm, endpoints, methods, and analysis plan were pre-specified prior to merging clinical and molecular data. RT-PCR of RNA from fixed paraffin-embedded ccRCC tissue was performed without knowledge of clinical data. Recurrence-free internval (RFI) was analyzed using Cox regression stratified by stage with data censored at 5 years, and Kaplan-Meier methods. Multivariable models incorporating the Leibovich score were used to assess the additional contribution of the RS to prediction of recurrence. Within- and between-tumor block reproducibility was assessed in an independent study using two separate tumor blocks from 8 pts, where each block was analyzed at 3 depths. Results: RS was generated in 626/645 pts (97%): 398 stage I, 54 stage II, 174 stage III. Median follow up was 5.5 yrs. The RS was significantly associated with risk of recurrence after adjustment for the Leibovich score (HR=4.20, p<0.001). Additionally, the performance of RS was similar across age groups (<60, 60-70 or ≥70), gender, nephrectomy type, tumor size (≤4, 4-7 or >7cm), grade, and presence/absence of invasion (all interaction p>0.29). Within-patient variability in the score (std. dev. of 1.73 and 4.74 RS units for within- and between-tumor block, respectively) was lower than patient-to-patient variability (std. dev. of 15.6 in validation study). Conclusions: The 16-gene signature remains strongly associated with risk of recurrence after adjustment for the Leibovich score and performs consistently across clinically relevant subgroups. Examination of within-patient and between-patient variability indicates that the score is robust to tumor heterogeneity.

Cell Index Database (CELLX): a web tool for cancer precision medicine

The Cell Index Database, (CELLX) (http://cellx.sourceforge.net) provides a computational framework for integrating expression, copy number variation, mutation, compound activity, and meta data from cancer cells. CELLX provides the computational biologist a quick way to perform routine analyses as well as the means to rapidly integrate data for offline analysis. Data is accessible through a web interface which utilizes R to generate plots and perform clustering, correlations, and statistical tests for associations within and between data types for ~20,000 samples from TCGA, CCLE, Sanger, GSK, GEO, GTEx, and other public sources. We show how CELLX supports precision oncology through indications discovery, biomarker evaluation, and cell line screening analysis.

Novel Carboxamide-Based Allosteric MEK Inhibitors: Discovery and Optimization Efforts toward XL518 (GDC-0973)

The ERK/MAP kinase cascade is a key mechanism subject to dysregulation in cancer and is constitutively activated or highly upregulated in many tumor types. Mutations associated with upstream pathway components RAS and Raf occur frequently and contribute to the oncogenic phenotype through activation of MEK and then ERK. Inhibitors of MEK have been shown to effectively block upregulated ERK/MAPK signaling in a range of cancer cell lines and have further demonstrated early evidence of efficacy in the clinic for the treatment of cancer. Guided by structural insight, a strategy aimed at the identification of an optimal diphenylamine-based MEK inhibitor with an improved metabolism and safety profile versus PD-0325901 led to the discovery of development candidate 1-({3,4-difluoro-2-[(2-fluoro-4-iodophenyl)amino]phenyl}carbonyl)-3-[(2S)-piperidin-2-yl]azetidin-3-ol (XL518, GDC-0973) (1). XL518 exhibits robust in vitro and in vivo potency and efficacy in preclinical models with sustained duration of action and is currently in early stage clinical trials.

Bridging the gap between preclinical and clinical studies using pharmacokinetic-pharmacodynamic modeling: an analysis of GDC-0973, a MEK inhibitor

PURPOSE

GDC-0973 is a potent and selective mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor. Pharmacokinetic-pharmacodynamic (PK-PD) modeling was used to relate GDC-0973 plasma and tumor concentrations, tumor pharmacodynamics and antitumor efficacy to establish pharmacokinetic endpoints and predict active doses in the clinic.

EXPERIMENTAL DESIGN

A PK-PD model was used to characterize GDC-0973 tumor disposition and in vivo potency in WM-266-4 xenograft mice. Simulations were conducted using the PK-PD model along with human pharmacokinetics to identify a target plasma concentration and predict active doses. In vivo potency and antitumor efficacy were characterized in A375 melanoma xenograft mice, and a population-based integrated PK-PD-efficacy model was used to relate tumor pharmacodynamics (%pERK decrease) to antitumor activity.

RESULTS

GDC-0973 showed a sustained tumor pharmacodynamic response due to longer residence in tumor than in plasma. Following single doses of GDC-0973, estimated in vivo IC(50) values of %pERK decrease based on tumor concentrations in xenograft mice were 0.78 (WM-266-4) and 0.52 μmol/L (A375). Following multiple doses of GDC-0973, the estimated in vivo IC(50) value in WM-266-4 increased (3.89 μmol/L). Human simulations predicted a minimum target plasma concentration of 83 nmol/L and an active dose range of 28 to 112 mg. The steep relationship between tumor pharmacodynamics (%pERK decrease) and antitumor efficacy suggests a pathway modulation threshold beyond which antitumor efficacy switches on.

CONCLUSIONS

Clinical observations of %pERK decrease and antitumor activity were consistent with model predictions. This article illustrates how PK-PD modeling can improve the translation of preclinical data to humans by providing a means to integrate preclinical and early clinical data.

Inhibition of the T790M gatekeeper mutant of the epidermal growth factor receptor by EXEL-7647

PURPOSE

Agents inhibiting the epidermal growth factor receptor (EGFR) have shown clinical benefit in a subset of non-small cell lung cancer patients expressing amplified or mutationally activated EGFR. However, responsive patients can relapse as a result of selection for EGFR gene mutations that confer resistance to ATP competitive EGFR inhibitors, such as erlotinib and gefitinib. We describe here the activity of EXEL-7647 (XL647), a novel spectrum-selective kinase inhibitor with potent activity against the EGF and vascular endothelial growth factor receptor tyrosine kinase families, against both wild-type (WT) and mutant EGFR in vitro and in vivo.

EXPERIMENTAL DESIGN

The activity of EGFR inhibitors against WT and mutant EGFRs and their effect on downstream signal transduction was examined in cellular assays and in vivo using A431 and MDA-MB-231 (WT EGFR) and H1975 (L858R and T790M mutant EGFR) xenograft tumors.

RESULTS

EXEL-7647 shows potent and long-lived inhibition of the WT EGFR in vivo. In addition, EXEL-7647 inhibits cellular proliferation and EGFR pathway activation in the erlotinib-resistant H1975 cell line that harbors a double mutation (L858R and T790M) in the EGFR gene. In vivo efficacy studies show that EXEL-7647 substantially inhibited the growth of H1975 xenograft tumors and reduced both tumor EGFR signaling and tumor vessel density. Additionally, EXEL-7647, in contrast to erlotinib, substantially inhibited the growth and vascularization of MDA-MB-231 xenografts, a model which is more reliant on signaling through vascular endothelial growth factor receptors.

CONCLUSIONS

These studies provide a preclinical basis for clinical trials of XL647 in solid tumors and in patients bearing tumors that are resistant to existing EGFR-targeted therapies.

IL-1beta induction of RANTES (regulated upon activation, normal T cell expressed and secreted) chemokine gene expression in endometriotic stromal cells depends on a nuclear factor-kappaB site in the proximal promoter

A complex network of cytokines mediates immunoregulatory responses in the pathogenesis of endometriosis. RANTES (regulated upon activation, normal T cell expressed and secreted) is a chemoattractant for monocytes and T cells. Endometriotic lesions express RANTES, and its concentration in peritoneal fluid correlates with the severity of endometriosis. We investigated the influence of IL-1beta, a potent macrophage cytokine, on RANTES production in endometriotic stromal cells and determined the region of the RANTES promoter responsible for IL-1beta action. RANTES mRNA was induced 5-fold in endometriotic stromal cells, and the conditioned medium RANTES protein concentrations were 12-fold higher in IL-1beta-treated endometriotic stromal cells vs. untreated controls (P < 0.05). IL-1beta activated the full-length (-940 bp) RANTES promoter as well as a truncated 456-bp 5'-flanking construct by 2-fold. Mutagenesis of a nuclear factor-kappaB response element at -30 bp abolished the IL-1beta effect, whereas mutation of a nearby TNF response element did not affect the IL-1beta induction. An IL-1beta time-course Western assay revealed a rapid diminution of IkappaB (endogenous inhibitor of nuclear factor-kappaB) in endometriotic stromal cells. Overexpression of IkappaB in endometriotic stromal cells inhibited the IL-1beta response of the RANTES gene promoter. Transcription of RANTES mRNA is up-regulated by IL-1beta via a nuclear factor-kappaB response element in the proximal RANTES gene promoter. These results demonstrate a feed-forward regulatory loop in the pathogenesis of endometriosis by which IL-1beta produced from activated macrophages can lead to further macrophage recruitment via RANTES production in endometriotic stromal cells.

Expression of the antiangiogenic factor 16K hPRL in human HCT116 colon cancer cells inhibits tumor growth in Rag1(-/-) mice

The M(r) 16,000 NH(2)-terminal fragment of human prolactin (16K hPRL) is a potent antiangiogenic factor inhibiting endothelial cell function in vitro and neovascularization in vivo. The present study was undertaken to test the ability of 16K hPRL to inhibit the growth of human HCT116 colon cancer cells transplanted s.c. into Rag1(-/-) mice. For this purpose, HCT116 cells were stably transfected with an expression vector encoding a peptide that included the signal peptide and first 139 amino acid residues of human prolactin (HCT116(16K)). Stable clones of HCT116(16K) cells secreted large amounts of biologically active 16K hPRL into the culture medium. Growth of HCT116(16K) cells in vitro was not different from wild-type HCT116 (HCT116(wt)) or vector-transfected HCT116 (HCT116(vector)) cells. Addition of recombinant 16K hPRL had no effect on the proliferation of HCT116(wt) cells in vitro. Tumor growth of HCT116(16K) cells implanted into Rag1(-/-) mice was inhibited 63% in four separate experiments compared with tumors formed from HCT116(wt) or HCT116(vector) cells. Inhibition of tumor growth of HCT116(16K) cells was correlated with a decrease in microvascular density by 44%. These data demonstrate that biologically active 16K hPRL can be expressed and secreted from human colon cancer cells using a gene transfer approach and that production of 16K hPRL by these cells was capable of inhibiting tumor growth and neovascularization. These findings support the potential of 16K hPRL as a therapeutic agent for the treatment of colorectal cancer.

The antiangiogenic factor 16K PRL induces programmed cell death in endothelial cells by caspase activation

We asked whether the antiangiogenic action of 16K human PRL (hPRL), in addition to blocking mitogen-induced vascular endothelial cell proliferation, involved activation of programmed cell death. Treatment with recombinant 16K hPRL increased DNA fragmentation in cultured bovine brain capillary endothelial (BBE) and human umbilical vein endothelial (HUVE) cells in a time- and dose-dependent fashion, independent of the serum concentration. The activation of apoptosis by 16K hPRL was specific for endothelial cells, and the activity of the peptide could be inhibited by heat denaturation, trypsin digestion, and immunoneutralization, but not by treatment with the endotoxin blocker, polymyxin-B. 16K hPRL-induced apoptosis was correlated with the rapid activation of caspases 1 and 3 and was blocked by pharmacological inhibition of caspase activity. Caspase activation was followed by inactivation of two caspase substrates, poly(ADP-ribose) polymerase (PARP) and the inhibitor of caspase-activated deoxyribonuclease (DNase) (ICAD). Furthermore, 16K hPRL increased the conversion of Bcl-X to its proapoptotic form, suggesting that the Bcl-2 protein family may also be involved in 16K hPRL-induced apoptosis. These findings support the hypothesis that the antiangiogenic action of 16K hPRL includes the activation of programmed cell death of vascular endothelial cells.

Role of the cAMP signaling pathway in the regulation of gonadotropin-releasing hormone secretion in GT1 cells

We studied the signaling pathways coupling gonadotropin-releasing hormone (GnRH) secretion to elevations in cAMP levels in the GT1 GnRH-secreting neuronal cell line. We hypothesized that increased cAMP could be acting directly by means of cyclic nucleotide-gated (CNG) cation channels or indirectly by means of activation of cAMP-dependent protein kinase (PKA). We showed that GT1 cells express the three CNG subunits present in olfactory neurons (CNG2, -4.3, and -5) and exhibit functional cAMP-gated cation channels. Activation of PKA does not appear to be necessary for the stimulation of GnRH release by increased levels of cAMP. In fact, pharmacological inhibition of PKA activity caused an increase in the basal secretion of GnRH. Consistent with this observation activation PKA inhibited adenylyl cyclase activity, presumably by inhibiting adenylyl cyclase V expressed in the cells. Therefore, the stimulation of GnRH release by elevations in cAMP appears to be the result of depolarization of the neurons initiated by increased cation conductance by cAMP-gated cation channels. Activation of PKA may constitute a negative-feedback mechanisms for lowering cAMP levels. We hypothesize that these mechanisms could result in oscillations in cAMP levels, providing a biochemical basis for timing the pulsatile release of GnRH.

Ischemic preconditioning attenuates ischemia/reperfusion-induced activation of caspases and subsequent cleavage of poly(ADP-ribose) polymerase in rat hearts in vivo

Recently, we have demonstrated that ischemic preconditioning (IP) both limits infarct size and decreases internucleosomal DNA fragmentation in rat hearts in vivo, and that there was a direct correlation between myocardial infarct size and DNA fragmentation even after IP. In this study, we examined the ability of IP to attenuate processing and activation of caspase-1 and caspase-3, and cleavage of poly(ADP-ribose) polymerase (PARP), after prolonged ischemia and reperfusion using the same in vivo animal model. Rats that underwent IP and controls (Ctrl) were subjected to 30 min of left coronary artery occlusion followed by 180 min of reperfusion. IP was accomplished by five 5-min cycles of ischemia, each followed by 5 min of reperfusion. The amount of soluble nucleosomes was measured by enzyme-linked immunosorbent assay. Cleavage of caspases-1 and -3, and of one of their substrates PARP, was analyzed by Western blotting. Nucleosomal DNA fragmentation was significantly reduced in ischemic left ventricular (LV) tissue obtained from IP compared with Ctrl animals. The proforms of caspases-1 and -3, and the active form of PARP were not cleaved in the nonischemic LV region of both IP and Ctrl hearts. In contrast, the proform of caspase-3 and the active form of PARP were cleaved in the ischemic LV region of Ctrl hearts, while processing of caspase-1 was increased. Cleavages of caspases-1 and -3, and inactivation of PARP were prevented by IP. The results of this study indicate that IP attenuates both internucleosomal DNA fragmentation and caspases processing, and suggest that the prevention of caspases activation by IP may be important steps in protecting the heart against ischemia/reperfusion injury in vivo.

16K human prolactin inhibits vascular endothelial growth factor-induced activation of Ras in capillary endothelial cells

Signaling pathways mediating the antiangiogenic action of 16K human (h)PRL include inhibition of vascular endothelial growth factor (VEGF)-induced activation of the mitogen-activated protein kinases (MAPK). To determine at which step 16K hPRL acts to inhibit VEGF-induced MAPK activation, we assessed more proximal events in the signaling cascade. 16K hPRL treatment blocked VEGF-induced Raf-1 activation as well as its translocation to the plasma membrane. 16K hPRL indirectly increased cAMP levels; however, the blockade of Raf-1 activation was not dependent on the stimulation of cAMP-dependent protein kinase (PKA), but rather on the inhibition of the GTP-bound Ras. The VEGF-induced tyrosine phosphorylation of the VEGF receptor, Flk-1, and its association with the Shc/Grb2/Ras-GAP (guanosine triphosphatase-activating protein) complex were unaffected by 16K hPRL treatment. In contrast, 16K hPRL prevented the VEGF-induced phosphorylation and dissociation of Sos from Grb2 at 5 min, consistent with inhibition by 16K hPRL of the MEK/MAPK feedback on Sos. The inhibition of Ras activation was paralleled by the increased phosphorylation of 120 kDa proteins comigrating with Ras-GAP. Taken together, these findings show that 16K hPRL inhibits the VEGF-induced Ras activation; this antagonism represents a novel and potentially important mechanism for the control of angiogenesis.

The D152H mutation found in growth hormone insensitivity syndrome impairs expression and function of human growth hormone receptor but is silent in rat receptor

In two patients with growth hormone (GH) insensitivity syndrome (Laron syndrome), in whom the GH receptor is able to bind the hormone, the D152H mutation was identified, and lack of dimerization was proposed to explain GH resistance in these patients. To examine further the consequences of the substitution of conserved aspartate 152 on the function of the GH receptor (GHR), we reproduced the mutation in vitro on the full length GH receptor cDNA from man and rat. Effects of the mutation on expression and activity of the GHR were analyzed in 293 cells transfected with wild-type and mutant GHR cDNAs. Mutant human receptor protein was expressed at a lower level than wild-type receptor and its activity was reduced: GH-dependent signal transducer and activator of transcription 5 (Stat5)-mediated transactivation of a reporter gene was lower in 293 cells transfected with mutant GHR cDNA than in transfected cells expressing a comparable level of wild-type GHR. The membrane-bound form of the mutant and of the wild-type human GHR were able to homodimerize, as suggested by the size of the complexes detected in cross-linking experiments with 125I-human (h) GH, and also by the activity in the functional test. With the soluble GHR resulting from proteolysis of the wild-type membrane form, no dimeric complexes could be detected. However, when a soluble receptor lacking the transmembrane and cytoplasmic domains of the receptor was expressed, wild-type and not mutant GH binding protein (GHBP) was able to form dimers in the presence of hGH. The amino acid substitution has no effect on either expression or function of the rat receptor. Structural modeling of D152H soluble human and rat GHR (GHBP) supports the species-specific functional consequences of the mutation. Evaluation of the functional importance of the mutation strongly suggests that impairment in expression and activity of the mutant receptor, rather than complete lack of dimerization, explains the GH resistance of the patients.

Increased expression of prolactin receptor gene assessed by quantitative polymerase chain reaction in human breast tumors versus normal breast tissues

The role of PRL in human breast tumorigenesis is not well understood. One of the limitations is the difficulty of accurately measuring PRL receptors (PRLR) in human tissues. We established a quantitative PCR method (Q-PCR) in T-47D human breast cancer cells and applied it to 29 patients, 25 of whom presented with either cancer or fibroadenoma. Four patients underwent a mammoplasty, and normal epithelial cells were cultured before Q-PCR. In T-47D cells, 31 x 10(6) messenger RNA molecules were detected per microgram of total RNA. In all patients, expression of the PRLR gene was detected, varying from 1500 to 1 x 10(6) molecules/microgram of RNA in normal tissues and from 4500 to 34.7 x 10(6) molecules/microgram of RNA in tumors. PRLR expression was always greater in tumor than in normal contiguous tissue and similar in cultured mammary epithelial cells and normal breast tissues. Estradiol and progesterone receptor-negative tumors expressed low levels of PRLR transcripts, similar to normal breast tissue from menopausal women. Immunocytochemical analysis of PRLR confirmed stronger staining in almost all tumor samples compared with normal tissues. A messenger RNA encoding locally produced human PRL was also identified by RT-PCR in every sample tested. Our results confirm PRLR gene expression in all tissues studied, and moreover, indicate that this expression is increased in human breast tumors vs. normal contiguous tissues.

Monkey growth hormone (GH) receptor gene expression. Evidence for two mechanisms for the generation of the GH binding protein

The growth hormone receptor (GHR) cDNA was cloned from the liver of Rhesus macaque using polymerase chain reaction. As deduced from the nucleotide sequence, the mature GHR is a protein of 620 amino acids which presents 94.1% identity with the human receptor. The monkey GHR (mkGHR) expressed in 293 cells presented the expected specificity for a primate GHR and was able to transduce a transcriptional effect of GH. Human GH was able to activate tyrosine phosphorylation of both the tyrosine kinase JAK2 and the receptor in 293 cells co-transfected with mkGHR and JAK2 cDNAs. The GH binding protein (GHBP), the soluble short form of the GHR, was also present in monkey serum. Expression of the GHR cDNA in eucaryotic cells indicated that the GHBP can be produced by proteolytic cleavage of the membrane receptor. Northern blot analysis of GHR gene expression in different tissues allowed us to identify three different transcripts of 5.0 and 2.8 kilobase pairs and a smaller one of 1.7 kilobase pairs which could encode a GHBP. Rapid amplification of cDNA extremities (3'-RACE-polymerase chain reaction) was used to identify a cDNA encoding a protein in which the transmembrane and cytoplasmic domains of the receptor are substituted by a short sequence of 9 amino acids. This transcript was present in various tissues and could encode a GHBP as well, suggesting for the first time that two different mechanisms can coexist for the generation of the GHBP: proteolytic cleavage of the membrane receptor and a specific mRNA produced by alternative splicing.