Fruquintinib versus placebo in patients with refractory metastatic colorectal cancer (FRESCO-2): an international, multicentre, randomised, double-blind, phase 3 study

BACKGROUND

There is a paucity of effective systemic therapy options for patients with advanced, chemotherapy-refractory colorectal cancer. We aimed to evaluate the efficacy and safety of fruquintinib, a highly selective and potent oral inhibitor of vascular endothelial growth factor receptors (VEGFRs) 1, 2, and 3, in patients with heavily pretreated metastatic colorectal cancer.

METHODS

We conducted an international, randomised, double-blind, placebo-controlled, phase 3 study (FRESCO-2) at 124 hospitals and cancer centres across 14 countries. We included patients aged 18 years or older (≥20 years in Japan) with histologically or cytologically documented metastatic colorectal adenocarcinoma who had received all current standard approved cytotoxic and targeted therapies and progressed on or were intolerant to trifluridine-tipiracil or regorafenib, or both. Eligible patients were randomly assigned (2:1) to receive fruquintinib (5 mg capsule) or matched placebo orally once daily on days 1-21 in 28-day cycles, plus best supportive care. Stratification factors were previous trifluridine-tipiracil or regorafenib, or both, RAS mutation status, and duration of metastatic disease. Patients, investigators, study site personnel, and sponsors, except for selected sponsor pharmacovigilance personnel, were masked to study group assignments. The primary endpoint was overall survival, defined as the time from randomisation to death from any cause. A non-binding futility analysis was done when approximately one-third of the expected overall survival events had occurred. Final analysis occurred after 480 overall survival events. This study is registered with ClinicalTrials.gov, NCT04322539, and EudraCT, 2020-000158-88, and is ongoing but not recruiting.

FINDINGS

Between Aug 12, 2020, and Dec 2, 2021, 934 patients were assessed for eligibility and 691 were enrolled and randomly assigned to receive fruquintinib (n=461) or placebo (n=230). Patients had received a median of 4 lines (IQR 3-6) of previous systemic therapy for metastatic disease, and 502 (73%) of 691 patients had received more than 3 lines. Median overall survival was 7·4 months (95% CI 6·7-8·2) in the fruquintinib group versus 4·8 months (4·0-5·8) in the placebo group (hazard ratio 0·66, 95% CI 0·55-0·80; p<0·0001). Grade 3 or worse adverse events occurred in 286 (63%) of 456 patients who received fruquintinib and 116 (50%) of 230 who received placebo; the most common grade 3 or worse adverse events in the fruquintinib group included hypertension (n=62 [14%]), asthenia (n=35 [8%]), and hand-foot syndrome (n=29 [6%]). There was one treatment-related death in each group (intestinal perforation in the fruquintinib group and cardiac arrest in the placebo group).

INTERPRETATION

Fruquintinib treatment resulted in a significant and clinically meaningful benefit in overall survival compared with placebo in patients with refractory metastatic colorectal cancer. These data support the use of fruquintinib as a global treatment option for patients with refractory metastatic colorectal cancer. Ongoing analysis of the quality of life data will further establish the clinical benefit of fruquintinib in this patient population.

FUNDING

HUTCHMED.

Health-related quality of life (HRQoL) associated with fruquintinib in the global phase 3, placebo-controlled, double-blind FRESCO-2 study

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Background: The global phase 3 FRESCO-2 study, (NCT04322539) demonstrated that fruquintinib (F) vs placebo (P) significantly improved OS (HR=0.66 [95% CI: 0.55-0.80]; p<0.001) and PFS (HR=0.32 [95% CI: 0.27-0.39]; p<0.001) in heavily pre-treated patients (pts) with refractory metastatic colorectal cancer (mCRC). F safety profile was consistent with the established monotherapy profile. Here we report the HRQoL and tolerability results. Methods: Pts were randomized 2:1 to F + BSC or P + BSC. EORTC QLQ-C30 and EQ-5D-5L were assessed at baseline and on Day (D) 1 of each Cycle (C) until treatment discontinuation, and ECOG PS was assessed at baseline, D1 of each C, and D21 of C1 to C3. Least-squares mean (LSM) change from baseline to post-baseline visits and the difference between F and P in QLQ-C30 scale scores (e.g. global health status [GHS]/QoL) and EQ-5D-5L scale scores (e.g. visual analog scale [VAS]) were calculated using mixed model repeated measures approach. For each scale, the appropriate minimally important difference (MID) thresholds were determined to evaluate the improvement or deterioration. Time to deterioration (TTD), defined as worsening from baseline in scale-specific MID or death, was analyzed using Kaplan-Meier method, adjusted log-rank test, and stratified Cox PH model. QLQ-C30 and EQ-5D-5L analyses were conducted on the ITT population, and ECOG PS was on the safety population. Results: 691 pts were randomized (F: 461 vs P: 230) and 686 pts received study drug (F: 456 vs P: 230). Median treatment Cycles received (range) were 3 (1, 20) for F vs 2 (1, 13) for P. More than 79% of pts on both arms had a baseline and ≥1 post-baseline assessment for QLQ-C30, EQ-5D-5L, and ECOG PS. GHS/QoL was similar between F and P at baseline; the LSM differences between F and P were 1.7 (95% CI: -1.7, 5.0) for C2 and 1.6 (95% CI: -3.2, 6.4) for C3. At C4, <30 P patients were available. The % of patients who remained stable (MID -6.38 to <8.43) or improved (≥8.43) was numerically higher for F vs P (C2: 61.5% vs 57.1%; C3: 56.4% vs 50.9%). Median TTD was 2.1 months in F and 1.8 months in P (HR=0.9; 95% CI: 0.7-1.0; P=0.098). EQ-5D VAS was similar between F and P at baseline; the LSM differences between F and P were 0.6 (95% CI: -2.3, 3.5) for C2 and 1.4 (95% CI: -2.8, 5.6) for C3. The % of patients who remained stable (MID -7 to <7) or improved (≥7) was similar for F and P (C2: 64.6% vs 58.3%; C3: 64.2% vs 64.8%). Median TTD was 2.6 months in F and 1.9 months in P (HR=0.8; 95% CI: 0.6-0.9; P=0.001). The % of patients with ≥1-point increase from baseline in ECOG PS was 52.1% in F vs 54.0% in P. Conclusions: HRQoL is not negatively impacted by treatment with F. TTD in health utility instrument EQ-5D is improved for patients receiving F. These results, along with improved OS and PFS and favorable toxicity profile, further support F as a potential new treatment option for patients with refractory mCRC. Clinical trial information: NCT04322539 .

Phase 1/1b trial of fruquintinib in patients with advanced solid tumors: Preliminary results of the dose expansion cohorts in refractory metastatic colorectal cancer

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Background: Fruquintinib (F) is a highly selective, novel, oral tyrosine kinase inhibitor (TKI) of vascular endothelial growth factor receptors (VEGFR) -1, -2, and -3. The phase (Ph) 3 FRESCO study (NCT02314819) that investigated F (5mg daily, 3 weeks (wks) on 1 wk off) showed improved median overall survival in patients (pts) with metastatic colorectal cancer (mCRC) in third line and beyond when compared to placebo (9.3 vs. 6.6 months); hazard ratio 0.65 (P < 0.001) and led to its approval in China. Methods: This is an ongoing Ph 1/1b open-label, dose escalation/expansion study conducted in the US. Here we present the preliminary safety and antitumor efficacy data from pts with refractory mCRC in Cohort (Coh) B (progressed on all standard therapies including TAS-102 [TAS] and/or regorafenib [R]) and in Coh C (did not receive TAS or R). Results: As of data cutoff on 27 July 2021, 81 mCRC pts had been treated (41 in Coh B and 40 in Coh C); median age of 57 years (range: 34─77), Caucasian (81.5%), female (44.4%), and ECOG PS 1 (59.3%). In Coh B, the median number of prior therapies was 5 (range: 3-9), 8 pts (19.5%) received R, 19 (46.3%) received TAS and 14 (34.1%) received both R and TAS. In Coh C, the median number of prior therapies was 4 (range: 1-10). Five pts remain on treatment; reasons for treatment discontinuation included: 56 pts (69.1%) due to progressive disease or death, 8 pts (9.9%) due to adverse events (AE), and 12 pts (14.8%) due to withdrawal of consent or physician decision. The median duration of F treatment was 4.4 months (range: 0.7– 20.0) in Coh B and 3.7 months (range: 0.02-14.3) in Coh C. The most frequently reported AEs of any grade in Coh B were fatigue (53.7%), proteinuria (51.2%), and hypertension (HTN; 48.8%). In Coh C the most frequently reported AEs of any grade were HTN (75.0%), proteinuria (40.0%), and myalgia (32.5%). Hand-foot syndrome (HFS) was reported in 29.3% of Coh B pts and 22.5% of Coh C pts. The disease control rate [DCR] was 68.3% in Coh B (1 partial response [PR] and 27 stable disease [SD]) and 59.5% for the 37 patients with at least one post-baseline tumor assessment in Coh C (2 PRs and 20 SDs). Conclusions: F is generally well-tolerated in heavily-pretreated pts with refractory mCRC. Evidence of antitumor activity was observed in cohorts B and C. The multi-cohort dose expansion is ongoing. F is being further investigated in refractory mCRC in a global Ph 3 study (NCT04322539). Clinical trial information: NCT03251378.

Pattern of progression in advanced hepatocellular carcinoma treated with ramucirumab

BACKGROUND & AIMS

Radiological progression patterns to first-line sorafenib have been associated with post-progression and overall survival in advanced hepatocellular carcinoma, but these associations remain unknown for therapies in second- and later-line settings. This post hoc analysis of REACH and REACH-2 examined outcomes by radiological progression patterns in the second-line setting of patients with advanced hepatocellular carcinoma treated with ramucirumab or placebo.

METHODS

Patients with advanced hepatocellular carcinoma, Child-Pugh A and Eastern Cooperative Oncology Group Performance Status 0 or 1 with prior sorafenib were randomized to receive ramucirumab 8mg/kg or placebo every 2 weeks. Among 625 patients with ≥1 progression pattern (new extrahepatic lesion [including new macrovascular invasion], new intrahepatic lesion, extrahepatic growth or intrahepatic growth), data were analysed by trial and for pooled individual patient data for REACH-2 and REACH (alpha-fetoprotein ≥400 ng/mL). Cox models evaluated prognostic implications of progression patterns on overall and post-progression survival.

RESULTS

Post-progression survival was worse among those with new extrahepatic lesions in REACH (HR 2.33, 95% CI 1.51-3.60), REACH-2 (HR 1.49, 95% CI 0.72-3.08) and the pooled population (HR 1.75, 95% CI 1.12-2.74) compared to other progression patterns. Overall survival was also significantly reduced in those with new extrahepatic lesions across studies. Ramucirumab provided an overall survival benefit across progression patterns, including patients with new extrahepatic lesions (HR 0.56, 95% CI 0.39-0.80) in the pooled population.

CONCLUSIONS

The emergence of new extrahepatic lesions in the second-line setting is a poor prognostic factor for post-progression survival. The benefit of ramucirumab for overall survival was consistent across progression patterns.

FRESCO-2: A global phase III study of the efficacy and safety of fruquintinib in patients (pts) with metastatic colorectal cancer (mCRC)

TPS154

Background: Pts with mCRC have limited treatment options following progression on standard therapies. Current standard of care (SOC) after pts progress on trifluridine/tipiracil (TAS-102) or regorafenib is re-challenge with previous systemic treatments, enrollment in a clinical trial, or best supportive care (BSC). Fruquintinib (Elunate) is a novel, highly selective, vascular endothelial growth factor (VEGF) receptor (VEGFR)-1, -2, and -3 tyrosine kinase inhibitor (TKI) ( Cancer Biol Ther 2014;15:1635-1645). Fruquintinib is approved in China to treat pts with mCRC who received or are intolerant to fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy, anti-VEGF therapy, and, if RAS wild type, anti-epidermal growth factor receptor (EGFR) therapy. Approval was based on results of the phase 3 FRESCO study (2013-013-00CH1; NCT02314819; JAMA 2018;319:2486-2496), in which fruquintinib 5 mg daily (QD), 3 weeks on, 1 week off (3 on/1 off), significantly improved overall survival (OS) in pts with mCRC in the 3rd-line+ setting when compared to placebo (median OS 9.3 months [mo] versus 6.6 mo; hazard ratio [HR] 0.65; p < .001). Progression-free survival (PFS) was also superior (median PFS 3.7 mo versus 1.8 mo; HR 0.26; p < .001). The toxicities of fruquintinib were consistent with those of other VEGF TKIs and were manageable. At the time FRESCO was conducted in China, SOC for pts with mCRC differed from that in the US, EU, and Japan. We describe here a global phase 3 study (FRESCO-2; 2019-013-GLOB1; NCT04322539) being conducted to investigate fruquintinib’s efficacy and safety in pts with refractory mCRC and a treatment profile representative of the global SOC. Methods: FRESCO-2 is a randomized, double-blind, placebo-controlled study to compare fruquintinib + BSC to placebo + BSC. Key inclusion criteria are progression on or intolerance to treatment with TAS-102 and/or regorafenib; previous treatment with standard approved therapies including chemotherapy, anti-VEGF therapy, and, if RAS wild type, anti-EGFR therapy. Prior therapy with immune checkpoint or BRAF inhibitors is required for pts with corresponding tumor alterations. Pts (~522) will be randomized 2:1 to receive either fruquintinib 5 mg orally (PO) QD + BSC or placebo 5 mg PO QD + BSC, with a 3 on/1 off schedule. Randomization will be stratified by prior therapy, RAS status, and duration of metastatic disease. The primary endpoint is OS; secondary endpoints include PFS, disease control rate, objective response rate, duration of response, and safety. Final OS analyses will be performed when 364 OS events are observed; futility analysis will be conducted with 1/3 (121) OS events. If enrichment of post-regorafenib pts occurs, enrollment to that strata will be capped at approximately 262. FRESCO-2 will be activated in the US, EU, and Japan; global enrollment is anticipated over 13 mo. Clinical trial information: NCT04322539.

Reliability of Conclusions from Early Analyses of Real-World Data for Newly Approved Drugs in Advanced Gastric Cancer in the United States

Background

As real-world data resources expand and improve, there will increasingly be opportunities to study the effectiveness of interventions. There is a need to ensure that study designs explore potential sources of bias and either acknowledge or mitigate them, in order to improve the accuracy of findings. The objective of this study was to understand newly approved drug utilization patterns in real-world clinical settings over time.

Methods

This retrospective study included three sources of real-world data (claims, electronic health records, and recoded data from a quality care program) collected from patients diagnosed with gastric cancer who initiated therapy with either trastuzumab or ramucirumab. Linear regression was used to investigate trends in the use of these drugs for the care of patients with gastric cancer over time from Food and Drug Administration (FDA) approval.

Results

Eligible patients (n=1700) had consistent demographic and clinical characteristics over time. After regulatory approval, trastuzumab was used in later lines of therapy and then shifted to earlier lines (p=0.002), while ramucirumab utilization remained consistent over time after FDA approval (p=0.49). Ramucirumab augmentation, defined as the addition of the drug after initiation of a line of therapy, decreased over time (p=0.03), and trastuzumab augmentation remained consistent over time (p=0.58).

Conclusion

Since treatment effectiveness may change across lines of treatment, bias may arise if there are changes in the use of the drug (such as line migration) during the time period of analysis using real-world data.

Pattern of progression in advanced HCC treated with ramucirumab/placebo: Results from two randomized phase III trials (REACH/REACH-2)

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Background: REACH (NCT01140347) and REACH-2 (NCT02435433) studied ramucirumab (RAM) in pts with advanced hepatocellular carcinoma (HCC) following sorafenib; REACH-2 enrolled pts with baseline alpha-fetoprotein (AFP) ≥400 ng/mL, and met its primary endpoint of overall survival (OS) for RAM vs placebo. This post-hoc analysis examined radiological progression patterns (RPP) incidence every 6 weeks per RECIST v1.1, and if RPP were related to OS and post-progression survival (PPS). Methods: Pts with advanced HCC, Child-Pugh A, and ECOG PS 0-1 with prior sorafenib were randomized (REACH 1:1; REACH-2 2:1) to receive RAM 8 mg/kg or placebo Q2W. Among pts with ≥1 RPP (new extrahepatic lesion [NEH], new intrahepatic lesion [NIH], extrahepatic growth [EHG], or intrahepatic growth [IHG]), results were analyzed by trial and for pooled individual patient data of REACH-2 and REACH (AFP ≥400 ng/mL). Cox models evaluated treatment effect of RPP on OS, and prognostic implications of RPP on OS (adjusting baseline ECOG PS, AFP, macrovascular invasion, arm) and on PPS (adjusting ECOG PS, AFP at progression). Results: RPP incidence in the pooled population was: NEH 39%; NIH 24%; EHG 39%; IHG 37%. When examining NEH vs other RPP, PPS was worse among those with NEH in REACH (HR 2.33, 95% CI 1.51, 3.60), REACH-2 (HR 1.49, 95% CI 0.72, 3.08), and the pooled data (HR 1.75, 95% CI 1.12, 2.74). Use of post-discontinuation therapy may have influenced results. OS was also significantly reduced in those with NEH across studies (Table). RAM provided OS benefit in the pooled population, including pts with NEH (HR 0.56, 95% CI 0.39, 0.80). Conclusions: Acknowledging limitations of post-randomization RPP analysis, the emergence of NEH on RAM or placebo may be an independent poor prognostic factor for PPS. The impact of RAM on OS was consistent across all RPP subgroups. Clinical trial information: NCT01140347 and NCT02435433.

[Table: see text]

Biology and significance of alpha-fetoprotein in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related deaths globally due, in part, to the majority of patients being diagnosed with intermediate or advanced stage disease. Our increased understanding of the heterogeneous molecular pathogenesis of HCC has led to significant developments in novel targeted therapies. Despite these advances, there remains a high unmet need for new treatment options. HCC is a complex disease with multiple pathogenic mechanisms caused by a variety of risk factors, making it difficult to characterize with a single biomarker. In fact, numerous biomarkers have been studied in HCC, but alpha-fetoprotein (AFP) remains the most widely used and accepted serum marker since its discovery over 60 years ago. This review summarizes the most relevant studies associated with the regulation of AFP at the gene and protein levels; the pathophysiology of AFP as a pro-proliferative protein; and the correlation of AFP with molecular HCC subclasses, the vascular endothelial growth factor pathway and angiogenesis. Also described are the historical and current uses of AFP for screening and surveillance, diagnosis, its utility as a prognostic and predictive biomarker and its role as a tumour antigen in HCC. Taken together, these data demonstrate the relevance of AFP for patients with HCC and identify several remaining questions that will benefit from future research.

Ramucirumab (RAM) for sorafenib intolerant patients with hepatocellular carcinoma (HCC) and elevated baseline alpha fetoprotein (AFP): Outcomes from two randomized phase 3 studies (REACH, REACH2)

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Background: Oral multikinase inhibitors that have shown improvements in overall survival (OS) in HCC are associated with clinically important toxicities that commonly require dose adjustment or discontinuation (D/C) due to intolerance. REACH and REACH-2 studied RAM in patients (pts) with HCC who progressed on or were intolerant to sorafenib (SOR), and REACH-2 only enrolled pts with baseline AFP ≥400 ng/mL. In REACH-2 RAM treatment (trt) improved OS compared to placebo (P), supporting findings in REACH pts with baseline AFP ≥400 ng/mL. An exploratory analysis of outcomes by reason for D/C of SOR was performed. Methods: Pts had advanced HCC, Child-Pugh A, ECOG PS 0-1, and prior SOR. Pts were randomized to RAM 8 mg/kg or P Q2W. A pooled independent pt data analysis (stratified by study) of REACH-2 and REACH pts (AFP ≥400 mg/mL) was performed. Results are reported by reason for SOR D/C (intolerance or disease progression). OS and PFS were evaluated using Kaplan-Meier method and Cox proportional hazard model. Objective response rate (ORR), disease control rate (DCR) and safety are reported. Results: Baseline characteristics in the pooled population were generally balanced between trt arms in each subgroup. Median durations of prior SOR were 2.5 mo for SOR intolerant (n = 70) and 4.0 mo for SOR progressors (n = 472). Median OS (RAM v P) was 10.2 v 6.7 mo for SOR intolerant and 8.0 v 4.7 mo for SOR progressors (Table). Rates of D/C due to trt-related adverse events (AEs) (Table) (7% in each subgroup), and Grade ≥3 AEs (most frequently hypertension) were consistent with those observed in each study. Conclusions: Acknowledging limitations of sample size, the RAM trt benefit in SOR intolerant pts was consistent with that in the ITT population. RAM was well tolerated in SOR intolerant pts with low rates of D/C due to related-AEs. Clinical trial information: NCT01140347, NCT02435433. [Table: see text]

Geographic and site variability in the treatment of patients with metastatic gastric cancer

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Background: Previous work has demonstrated substantial heterogeneity in the treatment of metastatic gastric cancer (mGC) in the U.S. across all lines of therapy. However, the distribution of variability by region and clinical practice site is not well understood. Methods: De-identified patient-level electronic medical record (EMR) and claims data from IMS Oncology EMR and from Truven Marketscan, respectively, were used for this study. Eligible patients were age ≥ 18 years with newly diagnosed GC between 2007 and 2014. Metastases were identified by ICD-9 codes in the EMR and claims data or with evidence of stage IV or M1 disease in EMR. Patients classified with locally advanced/advanced disease were those who received chemotherapy without surgical intervention following diagnosis, regardless of absence or presence of metastases. Variability of treatment by line of therapy was measured by the Herfindahl-Herschman Index (HHI), a commonly used measure of market concentration in the business sector. The HHI was reported overall, by geographic region and practice site over time. Results: Overall, 2,368 IMS and 6,444 Truven patients treated for GC were identified; of these, 728 and 2,457 patients were classified with mGC in the IMS and Truven cohorts, respectively; 5,044 were diagnosed with advanced disease in Truven. Geographically (HHI regional scores ranged from 7-17), by line of therapy (7-17 in first line; 4-15 in second line), and over time, treatment variability was high. Practices treating a high volume of patients did not demonstrate lower variability than sites treating few patients with mGC. In the first-line setting, 83 of 87 and 223 of 228 regimens were used less than 5% of the time in patients with mGC in the IMS and Truven cohorts, respectively. Conclusions: Treatment variability was consistently high for all practice sites, geographic regions and year of diagnosis; in the business world a HHI score > 2000 is reflective of a monopoly whereas in this study, HHI scores were generally < 20, demonstrating high variability and the lack of any consistent treatment strategy. There is a need to identify best treatment practices to ensure care for patients with receive care that is in accordance with treatment guidelines.

Heterochromatin Protein 1 Binding Protein 3 Expression as a Candidate Marker of Intrinsic 5-Fluorouracil Resistance

BACKGROUND

Despite receiving post-operative 5-fluorouracil (5-FU)-based chemotherapy, approximately 50% of patients with stage IIIC colon cancer experience recurrence. Currently, no molecular signature can predict response to 5-FU.

MATERIALS AND METHODS

Mouse models of colon cancer have been developed and characterized. Individual tumors in these mice can be longitudinally monitored and assessed to identify differences between those that are responsive and those that are resistant to therapy. Gene expression was analyzed in serial biopsies that were collected before and after treatment with 5-FU. Colon tumors had heterogeneous responses to treatment with 5-FU. Microarray analysis of pre-treatment biopsies revealed that Hp1bp3, a gene encoding heterochromatin protein 1 binding protein 3, was differentially expressed between sensitive and resistant tumors.

CONCLUSION

Using mouse models of human colorectal cancer, Hp1bp3 was identified as a candidate marker of intrinsic 5-FU resistance and may represent a potential biomarker for patient stratification or a target of clinical importance.

High-spatial and high-temporal resolution dynamic contrast-enhanced perfusion imaging of the liver with time-resolved three-dimensional radial MRI

PURPOSE

Detection, characterization, and monitoring the treatment of hepatocellular carcinomas (HCC) in patients with cirrhosis is challenging because of their variable and rapid arterial enhancement. Multiphase dynamic contrast-enhanced MRI is used clinically for HCC assessment; however, the method suffers from limited temporal resolution and difficulty in coordinating imaging and breath-hold timing within a narrow temporal window of interest. In this article, a volumetric, high-spatial resolution, and high-temporal resolution dynamic contrast-enhanced liver imaging method for improved detection and characterization of HCC is demonstrated.

METHODS

A time-resolved three-dimensional radial acquisition with iterative sensitivity-encoding reconstruction images the entire abdomen and thorax with high spatial and temporal resolution, using real-time three-dimensional fluoroscopy to match the breath hold to contrast arrival. The sequence was tested on 17 subjects, including eight patients with HCC or other hypervascular focal lesions.

RESULTS

This technique was successful in acquiring volumetric imaging of the entire liver with 2.1-mm isotropic spatial and true 4-s temporal resolution.

CONCLUSION

This technique may be suitable for detecting, characterizing, and monitoring the treatment of HCC. It also holds significant potential for perfusion modeling, which may provide a noninvasive means to rapidly determine the efficacy of chemotherapeutic agents in these tumors over the entire liver volume.

Randomized Phase II Trial of Gemcitabine Plus TH-302 Versus Gemcitabine in Patients With Advanced Pancreatic Cancer

PURPOSE

TH-302 is an investigational hypoxia-activated prodrug that releases the DNA alkylator bromo-isophosphoramide mustard in hypoxic settings. This phase II study (NCT01144455) evaluated gemcitabine plus TH-302 in patients with previously untreated, locally advanced or metastatic pancreatic cancer.

PATIENTS AND METHODS

Patients were randomly assigned 1:1:1 to gemcitabine (1,000 mg/m(2)), gemcitabine plus TH-302 240 mg/m(2) (G+T240), or gemcitabine plus TH-302 340 mg/m(2) (G+T340). Randomized crossover after progression on gemcitabine was allowed. The primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS), tumor response, CA 19-9 response, and safety.

RESULTS

Two hundred fourteen patients (77% with metastatic disease) were enrolled between June 2010 and July 2011. PFS was significantly longer with gemcitabine plus TH-302 (pooled combination arms) compared with gemcitabine alone (median PFS, 5.6 v 3.6 months, respectively; hazard ratio, 0.61; 95% CI, 0.43 to 0.87; P = .005; median PFS for metastatic disease, 5.1 v 3.4 months, respectively). Median PFS times for G+T240 and G+T340 were 5.6 and 6.0 months, respectively. Tumor response was 12%, 17%, and 26% in the gemcitabine, G+T240, and G+T340 arms, respectively (G+T340 v gemcitabine, P = .04). CA 19-9 decrease was greater with G+T340 versus gemcitabine (-5,398 v -549 U/mL, respectively; P = .008). Median OS times for gemcitabine, G+T240, and G+T340 were 6.9, 8.7, and 9.2 months, respectively (P = not significant). The most common adverse events (AEs) were fatigue, nausea, and peripheral edema (frequencies similar across arms). Skin and mucosal toxicities (2% grade 3) and myelosuppression (55% grade 3 or 4) were the most common TH-302-related AEs but were not associated with treatment discontinuation.

CONCLUSION

PFS, tumor response, and CA 19-9 response were significantly improved with G+TH-302. G+T340 is being investigated further in the phase III MAESTRO study (NCT01746979).

A multicenter phase 1 study of γ -secretase inhibitor RO4929097 in combination with capecitabine in refractory solid tumors

BACKGROUND

RO4929097 is an oral inhibitor of γ -secretase that results in Notch signaling inhibition. Prior work has demonstrated that Notch signaling inhibition enhances chemotherapy sensitivity of cancer cells. This phase I study was conducted to determine maximum tolerated dose (MTD), toxicities and efficacy of RO4929097 and capecitabine in advanced solid tumors.

METHODS

Patients with refractory solid tumors received capecitabine at a fixed dose of 1,000 mg/m(2) twice daily with escalating doses of RO4929097 on a 21-day cycle in a 3 + 3 design. Capecitabine was administered for 14 days and the RO49029097 once daily, 3 days per week, both for a 21 day cycle.

RESULTS

Thirty patients were treated on six dose levels (20 to 150 mg). The maximally tolerated dose was not reached. One dose limiting toxicity was observed at each level 3 through 6 (hypophosphatemia, fatigue, and nausea/vomiting). Three confirmed partial responses were observed: two patients with fluoropyrimide-refractory colon cancer and one patient with cervical cancer. Autoinduction of RO4929097 was demonstrated with increasing dose levels and duration.

CONCLUSIONS

The recommended phase 2 dose is capecitabine 1,000 mg/m(2) orally twice daily on days 1 through 14 with RO4929097 20 mg orally once daily on days 1-3, 8-10 and 15-17 with a 21 day cycle. Clinical benefit was observed in cervical and colon cancer. Autoinduction of RO4929097 was seen both with increasing cycle number and increasing dose. Plasma concentrations of RO4929097 were above those needed for Notch inhibition.

Abstract 2356: Characterization of molecular signatures predicting response to 5-FU based chemotherapy in mouse models of colorectal cancer

Background: Colorectal cancer (CRC) often arises from adenomatous polyps that progress to invasive cancer, but polyps can also remain static in size, regress, or resolve. Predicting which progress and which remain benign is difficult, since longitudinal analysis of individual polyps is impossible due to removal in humans. There are currently no molecular signatures that can identify adenomas that will eventually progress. In patients with stage II and III CRC , adjuvant chemotherapy on a 5-fluorouracil (5FU)-based regimen is considered following surgery. Despite receiving post-operative therapy, almost 50% of patients with stage III cancer recur. Again, there is no molecular signature that can predict response to 5FU. The purpose of this study was to identify gene expression differences in colon tumors using a mouse model. Individual tumors in mice can be monitored longitudinally throughout progression and treatment. Specifically, we aimed to: (1) develop and characterize a new mouse model of colon cancer; (2) identify differences in molecular progression prior to histopathologcial progression; and (3) identify a priori differences in gene expression between tumors that are resistant or sensitive to 5FU.

Methods: (SWRxB6)F1.ApcMin/+ (F1.Min) mice were treated with the inflammatory agent dextran sodium sulfate to induce tumors in the distal colon. Colonoscopy was used to identify, follow, and biopsy individual tumors. To best define chemotherapy response, only tumors that exhibited stasis for 4 weeks prior were treated with 5FU. Gene expression was analyzed from serial biopsies from pre- and post-treatment tumor using microarray and qPCR.

Results: Tumors in F1.Min mice exhibit growth, stasis, and spontaneous regression. A majority of tumors become static in size after an initial period of growth. Histological evaluation of tumors revealed that many tumors remained adenomas (71%), while some advanced to intramucosal carcinomas (23%) and adenocarcinomas (3%). Interestingly, 3 tumors that remained adenomas and 3 that progressed to intramucosal carcinomas displayed differential expression of 68 genes regardless of time point. Analysis of pre-5FU biopsies from 5 resistant tumors and 6 sensitive tumors revealed differential expression patterns of Hp1bp3 and Xpo7.

Conclusions: F1.Min mice develop tumors that can progress to invasive adenocarcinomas, and tumor response to treatment with chemotherapy can be followed in real time. Differential expression of genes with prognostic benefit can occur early and can be sustained throughout tumor development. Molecular determinants of 5FU sensitivity can be identified prior to treatment. Defining expression patterns that predict outcomes to chemotherapy in CRC might minimize the risk of undergoing ineffective chemotherapy and identify patients that may benefit from other treatment approaches in the adjuvant setting.

Citation Format: Jamie N. Hadac, Terrah J. Paul Olson, Alyssa A. Leystra, Dawn M. Albrecht, Linda Clipson, Ruth Sullivan, Michael A. Newton, Richard B. Halberg, William R. Schelman. Characterization of molecular signatures predicting response to 5-FU based chemotherapy in mouse models of colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2356. doi:10.1158/1538-7445.AM2014-2356

Quantitative hepatic perfusion modeling using DCE-MRI with sequential breathholds

PURPOSE

To develop and demonstrate the feasibility of a new formulation for quantitative perfusion modeling in the liver using interrupted DCE-MRI data acquired during multiple sequential breathholds.

MATERIALS AND METHODS

A new mathematical formulation to estimate quantitative perfusion parameters using interrupted data was developed. Using this method, we investigated whether a second degree-of-freedom in the tissue residue function (TRF) improves quality-of-fit criteria when applied to a dual-input single-compartment perfusion model. We subsequently estimated hepatic perfusion parameters using DCE-MRI data from 12 healthy volunteers and 9 cirrhotic patients with a history of hepatocellular carcinoma (HCC); and examined the utility of these estimates in differentiating between healthy liver, cirrhotic liver, and HCC.

RESULTS

Quality-of-fit criteria in all groups were improved using a Weibull TRF (2 degrees-of-freedom) versus an exponential TRF (1 degree-of-freedom), indicating nearer concordance of source DCE-MRI data with the Weibull model. Using the Weibull TRF, arterial fraction was greater in cirrhotic versus normal liver (39 ± 23% versus 15 ± 14%, P = 0.07). Mean transit time (20.6 ± 4.1 s versus 9.8 ± 3.5 s, P = 0.01) and arterial fraction (39 ± 23% versus 73 ± 14%, P = 0.04) were both significantly different between cirrhotic liver and HCC, while differences in total perfusion approached significance.

CONCLUSION

This work demonstrates the feasibility of estimating hepatic perfusion parameters using interrupted data acquired during sequential breathholds.

Dynamic tumor growth patterns in a novel murine model of colorectal cancer

Colorectal cancer often arises from adenomatous colonic polyps. Polyps can grow and progress to cancer, but may also remain static in size, regress, or resolve. Predicting which polyps progress and which remain benign is difficult. We developed a novel long-lived murine model of colorectal cancer with tumors that can be followed by colonoscopy. Our aim was to assess whether these tumors have similar growth patterns and histologic fates to human colorectal polyps to identify features to aid in risk stratification of colonic tumors. Long-lived Apc(Min/+) mice were treated with dextran sodium sulfate to promote colonic tumorigenesis. Tumor growth patterns were characterized by serial colonoscopy with biopsies obtained for immunohistochemistry and gene expression profiling. Tumors grew, remained static, regressed, or resolved over time with different relative frequencies. Newly developed tumors demonstrated higher rates of growth and resolution than more established tumors that tended to remain static in size. Colonic tumors were hyperplastic lesions (3%), adenomas (73%), intramucosal carcinomas (20%), or adenocarcinomas (3%). Interestingly, the level of β-catenin was higher in adenomas that became intratumoral carcinomas than those that failed to progress. In addition, differentially expressed genes between adenomas and intramucosal carcinomas were identified. This novel murine model of intestinal tumorigenesis develops colonic tumors that can be monitored by serial colonoscopy, mirror growth patterns seen in human colorectal polyps, and progress to colorectal cancer. Further characterization of cellular and molecular features is needed to determine which features can be used to risk-stratify polyps for progression to colorectal cancer and potentially guide prevention strategies.

A phase I study of vorinostat in combination with bortezomib in patients with advanced malignancies

BACKGROUND

A phase I study to assess the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetics (PK) and antitumor activity of vorinostat in combination with bortezomib in patients with advanced solid tumors.

METHODS

Patients received vorinostat orally once daily on days 1-14 and bortezomib intravenously on days 1, 4, 8 and 11 of a 21-day cycle. Starting dose (level 1) was vorinostat (400 mg) and bortezomib (0.7 mg/m(2)). Bortezomib dosing was increased using a standard phase I dose-escalation schema. PKs were evaluated during cycle 1.

RESULTS

Twenty-three patients received 57 cycles of treatment on four dose levels ranging from bortezomib 0.7 mg/m(2) to 1.5 mg/m(2). The MTD was established at vorinostat 400 mg daily and bortezomib 1.3 mg/m(2). DLTs consisted of grade 3 fatigue in three patients (1 mg/m(2),1.3 mg/m(2) and 1.5 mg/m(2)) and grade 3 hyponatremia in one patient (1.5 mg/m(2)). The most common grade 1/2 toxicities included nausea (60.9%), fatigue (34.8%), diaphoresis (34.8%), anorexia (30.4%) and constipation (26.1%). Objective partial responses were observed in one patient with NSCLC and in one patient with treatment-refractory soft tissue sarcoma. Bortezomib did not affect the PKs of vorinostat; however, the Cmax and AUC of the acid metabolite were significantly increased on day 2 compared with day 1.

CONCLUSIONS

This combination was generally well-tolerated at doses that achieved clinical benefit. The MTD was established at vorinostat 400 mg daily × 14 days and bortezomib 1.3 mg/m(2) on days 1, 4, 8 and 11 of a 21-day cycle.

A Phase I study of intermittently dosed vorinostat in combination with bortezomib in patients with advanced solid tumors

BACKGROUND

Accumulating evidence shows evidence of efficacy with the combination of vorinostat and bortezomib in solid tumors. We previously examined a once-daily continuous dosing schedule of vorinostat in combination with bortezomib which was well tolerated in cycles 1 and 2; however, there was concern regarding the tolerability through multiple cycles. This study was conducted to evaluate an intermittent dosing schedule of vorinostat with bortezomib.

METHODS

Vorinostat was initially administered orally twice daily on days 1-14 with bortezomib IV on days 1, 4, 8, and 11 of a 21 day cycle. Two DLTs (elevated ALT and fatigue) were observed at dose level 1, thus the protocol was amended to administer vorinostat intermittently twice daily on days 1-4 and 8-11.

RESULTS

29 patients were enrolled; 13 men and 16 women. Common cancer types included sarcoma, pancreatic, colorectal, GIST, and breast. The most common Grade 3-4 toxicities at any dose level included thrombocytopenia, fatigue, increased ALT, elevated INR, and diarrhea. DLTs in the intermittent dosing scheduled included thrombocytopenia and fatigue. The Cmax and AUC for the intermittent dosing regimen were similar to those observed in the daily dosing. In this heavily pretreated population, stable disease was observed in patients with sarcoma, colorectal adenocarcinoma and GIST.

CONCLUSIONS

The MTD was established at vorinostat 300 mg BID on days 1-4 and 8-11 and bortezomib 1.3 mg/m(2) IV on days 1, 4, 8, and 11 of a 21 day cycle. Tolerability was not improved with the intermittent dosing schedule of vorinostat when compared to continuous dosing.

Vorinostat in combination with bortezomib in patients with advanced malignancies directly alters transcription of target genes

INTRODUCTION

Vorinostat is a small molecule inhibitor of class I and II histone deacetylase enzymes which alters the expression of target genes including the cell cycle gene p21, leading to cell cycle arrest and apoptosis.

METHODS

Patients enrolled in a phase I trial were treated with vorinostat alone on day 1 and vorinostat and bortezomib in combination on day 9. Paired biopsies were obtained in eleven subjects. Blood samples were obtained on days 1 and 9 of cycle 1 prior to dosing and 2 and 6 h post-dosing in all 60 subjects. Gene expression of p21, HSP70, AKT, Nur77, ERB1, and ERB2 was evaluated in peripheral blood mononuclear cells and tissue samples. Chromatin immunoprecipitation of p21, HSP70, and Nur77 was also performed in biopsy samples.

RESULTS

In peripheral blood mononuclear cells, Nur77 was significantly and consistently decreased 2 h after vorinostat administration on both days 1 and 9, median ratio of gene expression relative to baseline of 0.69 with interquartile range 0.49-1.04 (p < 0.001); 0.28 (0.15-0.7) (p < 0.001), respectively, with more pronounced decrease on day 9, when patients received both vorinostat and bortezomib. p21, a downstream target of Nur77, was significantly decreased on day 9, 2 and 6 h after administration of vorinostat and bortezomib, 0.67 (0.41-1.03) (p < 0.01); 0.44 (0.25-1.3) (p < 0.01), respectively. The ChIP assay demonstrated a protein-DNA interaction, in this case interaction of Nur77, HSP70 and p21 with acetylated histone H3, at baseline and at day 9 after treatment with vorinostat in tissue biopsies in most patients.

CONCLUSION

Vorinostat inhibits Nur77 expression, which in turn may decrease p21 and AKT expression in PBMCs. The influence of vorinostat on target gene expression in tumor tissue was variable; however, most patients demonstrated interaction of acetylated H3 with Nur77, HSP70, and p21 which provides evidence of interaction with the transcriptionally active acetylated H3.

Final results of the phase I trial of niraparib (MK4827), a poly(ADP)ribose polymerase (PARP) inhibitor incorporating proof of concept biomarker studies and expansion cohorts involving BRCA1/2 mutation carriers, sporadic ovarian, and castration resistant prostate cancer (CRPC)

2513

Background: Niraparib(N) is an oral, potent PARP1/2 inhibitor that induces synthetic lethality in BRCA1/2 deficient tumors. PARP is also implicated in transcription regulated by the androgen receptor (AR) and rearranged ETS genes; key targets in CRPC. Methods: Dose-escalation was enriched for BRCA1/2mutation carriers (BRCA-MCs). Two MTD expansion cohorts were undertaken in patients (pts) with sporadic high grade serous ovarian cancer (HGSOC) and CRPC. In CRPC pts, archival tissue and circulating tumor cells (CTC) were analyzed for PTEN deletion and ETS gene rearrangements. Results: 100 pts [ovary (49), CRPC (23), breast (12) others (16)], received N at 10 dose levels: 30mg to 400mg daily (od), continuously. Grade (G) 4 thrombocytopenia was dose limiting at 400mg od; MTD was established at 300mg od. Drug-related toxicities were G1-2 reversible anemia (48%), fatigue (42%), nausea (42%), thrombocytopenia (35%), anorexia (27%), neutropenia (24%), constipation (23%), and vomiting (20%). PKs were dose proportional with a mean elimination t1/2of 40 hours. Peripheral blood mononuclear cells had >50% PARP inhibition from 80 mg od. gH2AX foci formation, a marker of DNA damage, was seen in CTCs. Antitumor activity occurred from 60mg od with RECIST and/or CA125 partial responses (PR) in 9/20 (45%) BRCA-MC ovarian cancer pts and 2/4 (50%) BRCA-MC breast cancer pts. Platinum-sensitive vs resistant BRCA-MC HGSOC response rate was 60% vs 33% with median time for responding pts of 429 and 340 days, respectively. In sporadic HGSOC, there were 2/3 PRs in platinum-sensitive pts, and 3/20 PRs plus 4/20 stable disease (SD) >16 weeks in platinum resistant pts. In CRPC, symptomatic benefit and SD >6 months (median 9 months) was seen in 9/21 (43%) pts treated at MTD. CTC declines of >30% (median 80%; range 36%-92%) were observed in 7/10 (70%) pts with evaluable CTC counts (≥5 cells/ 7.5mL blood). Conclusions: Niraparib was well tolerated and has promising antitumor activity in BRCA-MCs, sporadic HGSOC and CRPC. Clinical trial information: NCT0074902.

Abstract 2726: Tumor progression and treatment response characterization in a novel mouse model of colon cancer

Background: Colorectal cancer (CRC) is the second leading cause of cancer-related mortality in the U.S. Currently, patients with resected stage II and III disease are considered for adjuvant chemotherapy on a 5-fluorouracil (5FU)-based regimen. Despite receiving post-operative therapy, almost 50% of patients with stage III cancer recur. While 5FU-based chemotherapy has been in clinical use for many decades, there is no accurate predictor of chemotherapeutic response. Prior studies examining this question have been unsuccessful in establishing a clinically relevant predictive molecular signature due to various limitations, including in vitro analysis of cancer cell lines which do not fully recapitulate disease complexity and analysis of hetereogeneously treated human samples of various tumor types. The purpose of this study was to identify molecular differences in colon tumors that are resistant or sensitive to 5FU treatment using the laboratory mouse. Specifically, we aimed to (1) develop and characterize a new mouse model of colon cancer and (2) identify tumors differences in gene expression between tumors that are resistant or sensitive to 5FU.

Methods: Long-lived (SWRxB6)F1.ApcMin/+ (F1.Min) mice were treated with the inflammatory agent dextran sodium sulfate to promote tumors in the distal colon. Colonoscopy was used to identify and longitudinally follow and biopsy individual tumors. To better define chemotherapy response, only tumors that exhibited no detectable size changes over 4 weeks were biopsied and treated with 5FU. Mice were treated with 5FU and serial biopsies were collected.

Results: Tumors in the F1.min mouse exhibit multiple size changes including growth, stasis, and spontaneous regression. Notably, a majority of tumors become static in size after an initial period of growth. Histological evaluation of all tumors revealed that whereas many tumors remained adenomas (71%), some advanced to intramucosal carcinomas (23%) and adenocarcinomas (3%). 2/7 tumors remained static in size as measured by the ratio of tumor-to-lumen cross sectional area, indicative of resistance to 5FU. 3/7 tumors regressed (33.8%-66.0% reduction) which is indicative of sensitivity. Response characteristics could not be assessed in 2/7 tumors due to limited sensitivity in this imaging and measurement system.

Conclusions: F1.Min mice develop tumors that can progress to invasive adenocarcinomas and tumor response to treatment with chemotherapy agents can be followed in real time. More tumors will be treated and in the future will be analyzed for gene expression differences via RNA microarray to identify a molecular signature that may predict 5FU response/resistance. Defining expression patterns that predict outcomes to chemotherapy in CRC could minimize the risk of undergoing ineffective chemotherapy as well as identify patients that may benefit from other treatment approaches in the adjuvant setting.

Citation Format: Jamie N. Hadac, Terrah J. Paul Olson, Michael A. Newton, Gregory D. Kennedy, William R. Schelman, Richard B. Halberg. Tumor progression and treatment response characterization in a novel mouse model of colon cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2726. doi:10.1158/1538-7445.AM2013-2726

TH-302 plus gemcitabine (G+T) versus gemcitabine (G) in patients with previously untreated advanced pancreatic cancer (PAC)

325

Background: TH-302 is a hypoxia-targeted drug with a hypoxia-triggered 2-nitroimidazole component designed to release the DNA alkylator, bromo-isophosphoramide mustard (Br-IPM), when reduced in severe hypoxia. A randomized Phase 2B study (NCT01144455) was conducted to assess the benefit of G+T to standard dose G as first-line therapy of PAC. Methods: An open-label multi-center study of two dose levels of TH-302 (240 mg/m2 or 340 mg/m2) in combination with G versus G alone (randomized 1:1:1). G (1,000 mg/m2) and T were administered IV over 30-60 minutes on Days 1, 8 and 15 of a 28-day cycle. Patients on the G could crossover after progression and be randomized to a G+T arm. The primary efficacy endpoint was a comparison of PFS between the combination arms and G alone (80% power to detect 50% improvement in PFS with one-sided alpha of 10%). Overall survival (OS) was a secondary endpoint. Results: 214 pts were treated; 163 (76%) Stage IV and 51 (24%) Stage IIIB. Median age 65 (range 29-86); 126 M/88 F; 38% ECOG 0/62% ECOG 1. Receiving 6 or more cycles: 32% G; 45% G+T240; 55% G+T340. Median PFS was 3.6 mo in G vs 5.6 mo in G+T240 (p=0.06) and 6.0 mo in G+T340 (p=0.01). Median OS was 6.9 mo in G vs 8.7 in G+T240 (p=0.83) vs 9.2 mo in G+T340 (p=0.80). 6-mo OS was 57% in G vs 69% in G+T240 (p=0.12) and 73% in G+340 (p=0.04); 12-mo OS was 26% in G vs 37% in G+T240 (p=0.18) and 38% in G+340 (p=0.13). RECIST best response was 10% in G vs 17% in G+T240 and 26% in G+T340. 14 and 12 pts in G crossed over to T240 and T340, respectively. Median post crossover PFS was 1.8 mo in T240 vs 2.9 mo in T340 (p=0.13). Median post crossover OS was 2.6 mo in T240 vs 13.4 mo in T340 (p=0.01). AEs leading to discontinuation were: 16% G, 17% G+T240 and 12% G+T340. Rash (47% in G+T340) and stomatitis (42% in G+T340) were greater in combination, 3 pts Grd 3 rash. Grd 3/4 thrombocytopenia were 11% G, 39% G+T240 and 63% G+T340 and Grd 3/4 neutropenia were 31% G, 56% G+T240 and 60% G+T340. Conclusions: The combination of G plus TH-302 improved the PFS of G. Skin and mucosal toxicity and myelosuppression were the most common TH-302 related AEs with no increase in treatment discontinuation. A phase 3 study of TH-302 (340 mg/m2) in combination with G is planned with OS as the primary efficacy endpoint. Clinical trial information: NCT01144455.

A phase I study of sorafenib, oxaliplatin and 2 days of high dose capecitabine in advanced pancreatic and biliary tract cancer: a Wisconsin oncology network study

Chemotherapy has yielded minimal clinical benefit in pancreatic and biliary tract cancer. A high-dose, short course capecitabine schedule with oxaliplatin, has shown some efficacy with a lower incidence of palmar-plantar erythrodysesthesia. Achieving high exposures of the targeted agent sorafenib may be possible with this shorter schedule of capecitabine by avoiding dermatologic toxicity. All patients had pancreatic or biliary tract cancer. Patients in both cohorts received oxaliplatin 85 mg/m2 followed by capecitabine 2,250 mg/m2 PO every 8 h x 6 doses starting on days 1 and 15 of a 28 day cycle, or 2DOC (2 Day Oxaliplatin/Capecitabine). Cohort 1 used sorafenib 200 mg BID, and cohort 2 used sorafenib 400 mg BID. Sixteen patients were enrolled. Across all cycles the most common grade 1 or 2 adverse events were fatigue (10 pts), diarrhea (10 pts), nausea (9 pts), vomiting (8 pts), sensory neuropathy (8 pts), thrombocytopenia (7 pts), neutropenia (5 pts), and hand-foot syndrome (5 pts). Grade 3 toxicites included neutropenia, mucositis, fatigue, vomiting and diarrhea. Cohort 1 represented the MTD. Two partial responses were seen, one each in pancreatic and biliary tract cancers. The recommended phase II dose of sorafenib in combination with 2DOC is 200 mg BID. There were infrequent grade 3 toxicities, most evident with sorafenib at 400 mg BID.

A phase II study of capecitabine and lapatinib in advanced refractory colorectal adenocarcinoma: A Wisconsin Oncology Network study

BACKGROUND

Prognosis remains poor after progression on first-line chemotherapy for colorectal adenocarcinoma, and inactivation of the EGFR pathway with monoclonal antibodies is an effective treatment strategy in selected patients with metastatic disease. Lapatinib is an oral EGFR and HER-2 dual tyrosine kinase inhibitor that has not shown significant activity in metastatic colorectal cancer. However, lapatinib may act synergistically with capecitabine in anticancer effects.

METHODS

This was an open-label, non-randomized phase II study of lapatinib 1,250 mg orally daily and capecitabine 2,000 mg/m(2) by mouth split into twice-daily dosing for 14 days of a 21 days cycle. Inclusion criteria included metastatic or locally advanced adenocarcinoma of the colon or rectum with progression by RECIST on or within six months of receiving a fluoridopyrimidine-, oxaliplatin- or irinotecan-containing regimen. Prior EGFR monoclonal antibody was permitted. K-ras testing was not routinely performed and was not a part of the study protocol.

RESULTS

Twenty nine patients (16 M; 13 F) were enrolled in this study. There were no complete or partial responses. 41.4% of patients achieved stable disease as a best response. Median overall survival was 6.8 months, with a 1-year survival rate of 22%, and median progression-free survival was 2.1 months. The combination produced few grade 3 and no grade 4 toxicities. No grade 3 toxicity occurred in more than 10% of patients.

CONCLUSIONS

Although capecitabine and lapatinib is well tolerated, it is not an effective regimen in patients with refractory colorectal adenocarcinoma.

A phase II study of the histone deacetylase inhibitor panobinostat (LBH589) in low-grade neuroendocrine tumors

e14554

Background: Neuroendocrine tumors (NETs) are a diverse and rare group of neoplasms arising from the neuroendocrine system. The most common subtypes are pancreatic islet cell tumors and carcinoid tumors. Although they represent only 2% of all gastrointestinal malignancies, given their overall favorable prognosis, the prevalence is much higher. Histone deacetylase (HDAC) inhibitors have already been shown to suppress tumor growth and induce apoptosis in a variety of solid tumors in preclinical data. We have previously shown that in NET cells, HDAC inhibitors have resulted in increased Notch1 expression and subsequent inhibition of growth. Methods: A single arm phase II study was performed. Adult patients with histologically confirmed, metastatic, low-grade NETs and an ECOG performance status of ≤ 2 were treated with the oral HDAC inhibitor panobinostat 20 mg once daily three times per week. Treatment was continued until patients experienced unacceptable toxicities or disease progression. Results: 15 patients were accrued and 13 were evaluable for response (66.7% male, age range 40-80 years old (mean 59.4 years old), 66.7% carcinoid, 33.3% pancreatic NET). The median number of prior therapies was 1 (range 0-2) and no patient had previously received everolimus. The response rate was 0%. The stable disease rate was 92.3% as defined by stability seen on the first CT scan. Median progression-free survival was 11.8 months. The 1 year PFS was 42%. Thrombocytopenia and fatigue were the most common treatment-related grade 3 toxicities. There was one grade 4 toxicity of thrombocytopenia. The study was stopped early at the planned interim analysis based on lack of meaningful clinical efficacy outlined in the Simon two-stage design. Conclusions: The HDAC inhibitor panobinostat had infrequent grade 3 and 4 events in this patient population and resulted in a large percentage of subjects with disease control. The disease control rate, however, needs to be considered in the context of the typical slow growth rate of NETs. These data alone do not support continued evaluation of HDAC inhibitors in low-grade NETs. This study was supported by Novartis.

A phase I study of the gamma-secretase inhibitor RO4929097 and capecitabine in refractory solid tumors

3101

Background: RO4929097 is a oral inhibitor of gamma-secretase, which results in Notch signaling inhibition. Prior work has demonstrated that Notch-signaling inhibition enhances chemosensitivity of colon cancer cells. This study sought to combine RO4929097 with capecitabine (cape) and determine maximum tolerated dose (MTD), toxicities and efficacy. Preclinical and prior phase I work demonstrated possible autoinduction of RO4929097, so pharmacokinetic (PK) evaluation of RO4929097 and cape was planned. Methods: Adult patients with refractory solid tumors were eligible and received RO4929097 and cape at a fixed dose of 1000 mg/m2 BID with escalating doses of RO4929097 on a 21-day cycle according to a 3+3 design. Cape was administered for 14 days and the RO49029097 once daily, 3 days per week. RO4929097 plasma concentrations were evaluated by LC/MS/MS on days 3 and 10 of cycle 1, and PK parameters analyzed with WinNonLin version 5.2. Results: 4 dose levels have been completed (20, 30, 45 and 68 mg); 18 of 19 patients are evaluable for toxicity and PK data is available for 11 patients. One DLT has been observed (intolerable grade 2 fatigue) at 68 mg. There have been 2 confirmed partial responses: fluoropyrimide-refractory colon cancer (for 12 cycles) and cervical cancer (for 6 cycles). The half-life, Cmax and AUC of RO4929097 all significantly decreased on day 10 compared to day 3, with an increase in clearance for all doses. The half-life was significantly shorter in dose level 3 (p=0.0012) and dose level 4 (p=0.0126) compared to dose level 1. Conclusions: RO4929097 plus cape was well tolerated. Activity was seen in cervical and colon cancer. Autoinduction of RO4929097 was seen both with increasing cycle number and increasing dose. However, all plasma concentrations of RO4929097 were above those needed for Notch inhibition (1.9 ng/mL based on prior studies). Dose level 1 (cape 1000 mg/m2 BID and RO4929097 20 mg daily) is the recommended phase II dose. [Table: see text]

A phase I study of selumetinib (AZD6244/ARRY-142866) in combination with cetuximab (cet) in refractory solid tumors and KRAS mutant colorectal cancer (CRC)

3103

Background: KRAS mutations have been recognized as clinically important predictors of resistance to EGFR-directed therapies in CRC. Oncogenic activation of the RAS/RAF/MEK/ERK signaling cascade mediates proliferation independent of growth factor receptor signaling. We hypothesized that targeting MEK with selumetinib could overcome resistance to cet in KRAS mutant CRC. A phase I study (NCT01287130) was undertaken to determine the tolerability, and pharmacokinetic profiles of the combination of selumetinib and cet, with an expanded cohort in KRAS mutant CRC at the MTD dose to evaluate preliminary anti-tumor activity. Methods: In the dose escalation portion, patients (pts) with advanced solid tumors received fixed dose cet with escalating doses of selumetinib in cohorts of 3-6 pts. In the expansion cohort, 14 pts with KRAS mutant CRC were enrolled at the MTD level. Results: 15 pts (9 M, 6 F), average age of 60 (41-73) years were treated at 3 dose levels in the dose escalation cohort and 14 pts were treated in the expansion cohort. Pts had the following tumor types: CRC 73%, NSCLC 13%, and H&N 13%, and had received a median of 4 (1-8) prior lines of therapy. 33% (only CRC) had prior EGFR-directed therapies. ECOG PS 0 (40%), 1 (53%), 2 (7%). 13 of 15 pts were evaluable for tolerability and response. One DLT for grade 4 hypomagnesemia occurred, and no other grade 4 toxicities were seen. Grade 3 (20%) toxicities included; rash, hyponatremia, and headache. The most common cycle 1 grade 1 and 2 adverse events included acneiform rash (100%), fatigue (54%), nausea/vomiting, (54%), diarrhea (54%), dry skin (46%), fever (23%), and hypomagnesemia (15%). Most pts (60%) required no dose modifications. The MTD was established at selumetinib 75 mg PO BID and cet 250 mg/m2 weekly following a 400 mg/m2load. Best response included 2 PR in pts with CRC and SD in 4 pts (1 SCC of the tonsil, 1 NSCLC, and 2 CRC). Conclusions: The combination of selumetinib and cet is well tolerated, and preliminary anti-tumor activity was observed in multiple pts. Results of the KRAS mutant CRC expansion cohort will be presented.

First-time-in-human study of GSK923295, a novel antimitotic inhibitor of centromere-associated protein E (CENP-E), in patients with refractory cancer

PURPOSE

GSK923295 is an inhibitor of CENP-E, a key cellular protein important in the alignment of chromosomes during mitosis. This was a Phase I, open-label, first-time-in-human, dose-escalation study, to determine the maximum-tolerated dose (MTD), safety, and pharmacokinetics of GSK923295.

PATIENTS AND METHODS

Adult patients with previously treated solid tumors were enrolled in successive cohorts at GSK923295 doses ranging from 10 to 250 mg/m(2). GSK923295 was administered by a 1-h intravenous infusion, once weekly for three consecutive weeks, with treatment cycles repeated every 4 weeks.

RESULTS

A total of 39 patients were enrolled. The MTD for GSK923295 was determined to be 190 mg/m(2). Observed dose-limiting toxicities (all grade 3) were as follows: fatigue (n = 2, 5%), increased AST (n = 1, 2.5%), hypokalemia (n = 1, 2.5%), and hypoxia (n = 1, 2.5%). Across all doses, fatigue was the most commonly reported drug-related adverse event (n = 13; 33%). Gastrointestinal toxicities of diarrhea (n = 12, 31%), nausea (n = 8, 21%), and vomiting (n = 7, 18%) were generally mild. Frequency of neutropenia was low (13%). There were two reports of neuropathy and no reports of mucositis or alopecia. GSK923295 exhibited dose-proportional pharmacokinetics from 10 to 250 mg/m(2) and did not accumulate upon weekly administration. The mean terminal elimination half-life of GSK923295 was 9-11 h. One patient with urothelial carcinoma experienced a durable partial response at the 250 mg/m(2) dose level.

CONCLUSIONS

The novel CENP-E inhibitor, GSK923295, had dose-proportional pharmacokinetics and a low number of grade 3 or 4 adverse events. The observed incidence of myelosuppression and neuropathy was low. Further investigations may provide a more complete understanding of the potential for GSK923295 as an antiproliferative agent.

A pilot phase II study of valproic acid for treatment of low-grade neuroendocrine carcinoma

INTRODUCTION

Notch1 has been shown to be a tumor suppressor in neuroendocrine tumors (NETs). Previous in vitro studies in NET cell lines have also suggested that valproic acid (VPA), a histone deacetylase inhibitor, can induce Notch1 and that Notch1 activation correlates with a decrease in tumor markers for NETs. Thus, this study aimed to evaluate the role of VPA in treating NETs and to determine whether VPA induced the Notch signaling pathway signaling in vivo.

PATIENTS AND METHODS

Eight patients with low-grade NETs (carcinoid and pancreatic) were treated with 500 mg of oral VPA twice a day with dosing adjusted to maintain a goal VPA level between 50 and 100 μg/mL. All patients were followed for 12 months or until disease progression.

RESULTS

Notch1 signaling was absent in all tumors prior to treatment and was upregulated with VPA. One patient had an unconfirmed partial response and was noted to have a 40-fold increase in Notch1 mRNA levels. Four patients had stable disease as best response. Tumor markers improved in 5 out of 7 patients. Overall, treatment with VPA was well tolerated.

CONCLUSION

. VPA activates Notch1 signaling in vivo and may have a role in treating low-grade NETs.

A preclinical and clinical study of lithium in low-grade neuroendocrine tumors

BACKGROUND

Low-grade neuroendocrine tumors (NETs) respond poorly to chemotherapy; effective, less toxic therapies are needed. Glycogen synthase kinase (GSK)-3β has been shown to regulate growth and hormone production in NETs. Use of lithium chloride in murine models suppressed carcinoid cell growth, reduced GSK-3β levels, and reduced expression of chromogranin A. This study assessed the efficacy of lithium chloride in patients with NETs.

DESIGN

Eligible patients had low-grade NETs. A single-arm, open-label phase II design was used. Lithium was dosed at 300 mg orally three times daily, titrated to serum levels of 0.8-1.0 mmol/L. The primary endpoint was objective tumor response by the Response Evaluation Criteria in Solid Tumors. Secondary endpoints included overall survival, progression-free survival, GSK-3β phosphorylation, and toxicity.

RESULTS

Fifteen patients were enrolled between October 3, 2007 and July 17, 2008, six men and nine women. The median age was 58 years. Patient diagnoses were carcinoid tumor for eight patients, islet cell tumor for five patients, and two unknown primary sites. Eastern Cooperative Oncology Group performance status scores were 0 or 1. Two patients came off study because of side effects. The median progression-free survival interval was 4.50 months. There were no radiographic responses. Because of an early stopping rule requiring at least one objective response in the first 13 evaluable patients, the study was closed to further accrual. Patients had pre- and post-therapy biopsies.

CONCLUSIONS

Lithium chloride was ineffective at obtaining radiographic responses in our 13 patients who were treated as part of this study. Based on the pre- and post-treatment tumor biopsies, lithium did not potently inhibit GSK-3β at serum levels used to treat bipolar disorders.

Cytotoxic Evaluation of 3-Aminopyridine-2-Carboxaldehyde Thiosemicarbazone, 3-AP, in Peripheral Blood Lymphocytes of Patients with Refractory Solid Tumors using Electron Paramagnetic Resonance

PURPOSE: 3-AP (3-aminopyridine-2-carboxaldehyde thiosemicarbazone, 3-AP) is a metal chelator that potently inhibits the enzyme ribonucleotide reductase, RR, which plays a key role in cell division and tumor progression. A sub-unit of RR has a non-heme iron and a tyrosine free radical, which are required for the enzymatic reduction of ribonucleotides to deoxyribonucleotides. The objective of the study was to determine whether 3-AP affects its targeted action by measuring EPR signals formed either directly or indirectly from low molecular weight ferric-3-AP chelates. METHODS: Peripheral blood lymphocytes were collected from patients with refractory solid tumors at baseline and at 2, 4.5 and 22 hours after 3-AP administration. EPR spectra were used to identify signals from high-spin Fe-transferrin, high-spin heme and low-spin iron or copper ions. RESULTS: An increase in Fe-transferrin signal was observed, suggesting blockage of Fe uptake. It is hypothesized that formation of reactive oxygen species by FeT(2) or CuT damage transferrin or the transferrin receptor. An increase in heme signal was also observed, which is a probable source of cytochrome c release from the mitochondria and potential apoptosis. In addition, increased levels of Fe and Cu were identified. CONCLUSION: These results, which were consistent with our earlier study validating 3-AP-mediated signals by EPR, provide valuable insights into the in vivo mechanism of action of 3-AP.

A phase I study of zibotentan (ZD4054) in patients with metastatic, castrate-resistant prostate cancer

PURPOSE

To assess the maximum well-tolerated dose (MWTD), dose limiting toxicity (DLT), pharmacokinetics (PK) and pharmacodynamics of zibotentan, a novel specific endothelin-A receptor antagonist, in patients with metastatic prostate cancer.

METHODS

Patients with metastatic, castrate-resistant prostate cancer (CRPC) were treated with escalating doses of oral zibotentan (ZD4054) 10-200 mg once daily. The initial cohort received 28 daily doses (Period 1). Patients who had evidence of clinical benefit and who had not met any of the criteria for withdrawal were allowed to receive zibotentan at their current dose level until they no longer derived clinical benefit (Period 2). PK of zibotentan and changes in prostate-specific antigen and bone markers were also assessed.

RESULTS

Sixteen patients were evaluable for the safety and single-dose PK analyses. Eleven patients completed Period 1, and nine patients proceeded to Period 2. DLTs were encountered at 22.5 mg; one patient had grade 3 dyspnea and peripheral edema and a second patient had grade 3 headache and intraventricular hemorrhage. Enrollment was expanded at the 15 mg dose level to further determine the safety and tolerability of zibotentan. No DLTs were seen at 15 mg, and the most frequent adverse events were headache, peripheral edema, fatigue, nasal congestion and nausea.

CONCLUSIONS

The MWTD for zibotentan was 15 mg orally daily. The predominant adverse events observed were consistent with those reported for this class of drugs, and prolonged stable disease was noted in some patients. Phase III studies with zibotentan in men with metastatic CRPC are ongoing.

Dose-escalation study of fixed-dose rate gemcitabine combined with capecitabine in advanced solid malignancies

PURPOSE

To define dose limiting toxicities (DLTs) and the maximum tolerated dose (MTD) of capecitabine with fixed-dose rate (FDR) gemcitabine.

METHODS

Eligible adults (advanced solid tumor; performance status

RESULTS

Thirty patients (median age 59 years) were enrolled. The predominant grade >or=3 toxicity was myelosuppression, particularly neutropenia. At dose level 4 (1,000 mg/m(2) gemcitabine), two out of five evaluable patients had a DLT (grade 4 neutropenia >or=7 days). At dose level 3 (800 mg/m(2) gemcitabine), one patient had a DLT (grade 3 neutropenia >or=7 days) among six evaluable patients. Therefore, the MTD and recommended phase II dose was designated as capecitabine 500 mg/m(2) PO BID days 1-14 with 800 mg/m(2) FDR gemcitabine days 1 and 8 infused at 10 mg/m(2) per min on a 21-day cycle. Partial responses occurred in pretreated patients with esophageal, renal cell and bladder carcinomas.

CONCLUSIONS

This regimen was well tolerated and may deserve evaluation in advanced gastrointestinal and genitourinary carcinomas.

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Key Words

• capecitabine
• gemcitabine
• phase i
• fixed-dose rate

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MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Antineoplastic Combined Chemotherapy Protocols/administration & dosage
• Antineoplastic Combined Chemotherapy Protocols/adverse effects
• Antineoplastic Combined Chemotherapy Protocols/therapeutic use
• Capecitabine
• Cohort Studies
• Deoxycytidine/administration & dosage
• Deoxycytidine/analogs & derivatives
• Dose-Response Relationship, Drug
• Female
• Fluorouracil/administration & dosage
• Fluorouracil/analogs & derivatives
• Humans
• Male
• Maximum Tolerated Dose
• Middle Aged
• Neoplasms/drug therapy
• Neutropenia/chemically induced
• Treatment Outcome
• Gemcitabine

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Grants

• T32 CA009614 NCI NIH HHS
• T32 CA009614-17 NCI NIH HHS
• T32 CA009614-18 NCI NIH HHS

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Affiliation(s)

Steven Attia University of Wisconsin Paul P Carbone Comprehensive Cancer Center Madison, Madison, WI 53792, USA.
Sherry Morgan-Meadows
Kyle D Holen
Howard H Bailey
Jens C Eickhoff
William R Schelman
Anne M Traynor
Daniel L Mulkerin
Toby C Campbell
Thomas A McFarland
Michael S Huie
James F Cleary
Amye J Tevaarwerk
Dona B Alberti
George Wilding
Glenn Liu

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A phase I study of Triapine in combination with doxorubicin in patients with advanced solid tumors

PURPOSE

To assess the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetics and antitumor activity of Triapine administered in combination with doxorubicin.

STUDY DESIGN

Patients were treated with doxorubicin intravenously (IV) on day 1 and Triapine IV on days 1-4 of a 21-day cycle. The starting dose (level 1) was doxorubicin 60 mg/m(2) and Triapine 25 mg/m(2). PK analysis was performed at various time-points before and after treatment.

RESULTS

Twenty patients received a total of 49 courses of treatment on study. At dose level 2 (doxorubicin 60 mg/m(2), Triapine 45 mg/m(2)), two patients experienced DLTs (febrile neutropenia, grade 4 thrombocytopenia). An additional three patients were enrolled at dose level 1 without initial toxicity. Enrollment then resumed at dose level 2a with a decreased dose of doxorubicin (45 mg/m(2)) with Triapine 45 mg/m(2). The two patients enrolled on this level had two DLTs (diarrhea, CVA). Enrollment was planned to resume at dose level 1; however, the sixth patient enrolled to this cohort developed grade 5 heart failure (ejection fraction 20%, pretreatment EF 62%) after the second course. Thus, doxorubicin and Triapine were reduced to 45 and 25 mg/m(2), respectively (level 1a), prior to resuming enrollment at dose level 1, the MTD. The main drug-related toxicity was myelosuppression. Non-hematologic toxicities included mild-to-moderate fatigue, grade 3 diarrhea and grade 4 CVA. There was one treatment-related death due to heart failure. While no objective responses were observed, subjective evidence of clinical activity was observed in patients with refractory melanoma and prostate cancer.

CONCLUSIONS

Pretreated patients with advanced malignancies can tolerate the combination of Triapine and doxorubicin at doses that achieve subjective clinical benefit with the main treatment-related toxicities being myelosuppression and fatigue. The MTD was determined to be doxorubicin 60 mg/m(2) on day 1 and Triapine 25 mg/m(2) on days 1-4 of a 21-day cycle.

Electron paramagnetic resonance study of peripheral blood mononuclear cells from patients with refractory solid tumors treated with Triapine

The metal chelator Triapine, 3-aminopyridine-2-carboxaldehyde thiosemicarbazone, is a potent inhibitor of ribonucleotide reductase. EPR spectra consistent with signals from Fe-transferrin, heme, and low-spin iron or cupric ion were observed in peripheral blood mononuclear cells (PBMCs) obtained from patients treated with Triapine. One signal that is unequivocally identified is the signal for Fe-transferrin. It is hypothesized that Fe uptake is blocked by reactive oxygen species generated by FeT(2) or CuT that damage transferrin or transferrin receptor. A potential source for the increase in the heme signal is cytochrome c released from the mitochondria. These results provide valuable insight into the in vivo mechanism of action of Triapine.

Glutamate mediates cell death and increases the Bax to Bcl-2 ratio in a differentiated neuronal cell line

Excessive stimulation of the NMDA receptor by glutamate induces cell death and has been implicated in the development of several neurodegenerative diseases. While apoptosis plays a role in glutamate-mediated toxicity, the mechanisms underlying this process have yet to be completely determined. Recent evidence has shown that exposure to excitatory amino acids regulates the expression of the antiapoptotic protein, Bcl-2, and the proapoptotic protein, Bax, in neurons. Since it has been suggested that the ratio of Bax to Bcl-2 is an important determinant of neuronal survival, the reciprocal regulation of these Bcl-2 family proteins may play a role in the neurotoxicity mediated by glutamate. Here, we have used a differentiable neuronal cell line, N1E-115, to investigate the molecular properties of glutamate-induced cell death. Annexin V staining was used to determine apoptotic cell death between 0 and 5 days differentiation with DMSO/low serum. Immunoblot analysis was used to determine whether the expression of Bcl-2 or Bax was modulated during the differentiation process. Bcl-2 protein levels were increased during maturation while Bax expression remained unchanged. Maximum Bcl-2 expression was observed following 5 days of differentiation. Examination of Bcl-2 and Bax following glutamate treatment revealed that the expression of these proteins was inversely regulated. Exposure to glutamate (0.001-10 mM) for 20+/-2 h resulted in a dose-dependent decrease in cell survival (as measured by MTT analysis) that was maximal at 10 mM. These results further support the role of apoptosis in glutamate-mediated cell death. Furthermore, a significant decrease in Bcl-2 levels was observed at 1 mM and 10 mM glutamate (32.1%+/-4.8 and 33.7+/-12.8%, respectively) while a significant upregulation of Bax expression (88.2+/-17.9%) was observed at 10 mM glutamate. Interestingly, Bcl-2 and Bax levels in cells treated with glutamate from 12-24 h were not significantly different from those of control. Taken together, these findings provide additional evidence for the reciprocal regulation of Bcl-2 and Bax expression by glutamate and suggest that neuronal excitotoxicity may, in part, result from the inverse regulation of these proteins.

Angiotensin II attenuates NMDA receptor-mediated neuronal cell death and prevents the associated reduction in Bcl-2 expression

While angiotensin II (Ang II) plays a major role in the regulation of blood pressure, fluid homeostasis and neuroendocrine function, recent studies have also implicated the peptide hormone in cell growth, differentiation and apoptosis. In support of this, we have previously demonstrated that Ang II attenuates N-methyl-D-aspartate (NMDA) receptor signaling [Molec. Brain Res. 48 (1997) 197]. To further examine the modulatory role of Ang II on NMDA receptor function, we investigated the effect of angiotensin receptor (AT) activation on NMDA-mediated cell death and the accompanying decrease in Bcl-2 expression. The viability of differentiated N1E-115 and NG108-15 neuronal cell lines was reduced following exposure to NMDA in a dose-dependent manner. MTT analysis (mitochondrial integrity) revealed a decrease in cell survival of 49.4+/-12.3% in NG108 cells and 79.9+/-6.8% in N1E cells following treatment with 10 mM NMDA for 20 h. Cytotoxicity in N1E cells was inhibited by the noncompetitive NMDA receptor antagonist, MK-801. Further, NMDA receptor-mediated cell death in NG108 cells was attenuated by treatment with Ang II. The Ang II effect was inhibited by both AT1 and AT2 receptor antagonists, losartan and PD123319, respectively, suggesting that both receptor subtypes may play a role in the survival effect of Ang II. Since it has been shown that activation of NMDA receptors alters the expression of Bcl-2 family proteins, Western blot analysis was performed in N1E cells to determine whether Ang II alters the NMDA-induced changes in Bcl-2 expression. A concentration-dependent decrease of intracellular Bcl-2 protein levels was observed following treatment with NMDA, and this reduction was inhibited by MK801. Addition of Ang II suppressed the NMDA receptor-mediated reduction in Bcl-2. The Ang II effect on NMDA-mediated changes in Bcl-2 levels was blocked by PD123319, but was not significantly changed by losartan, suggesting AT2 receptor specificity. Taken together, these results suggest that Ang II attenuates NMDA receptor-mediated neurotoxicity and that this effect may be due, in part, to an alteration in Bcl-2 expression.

Angiotensin II type-2 (AT2) receptor-mediated inhibition of NMDA receptor signalling in neuronal cells

The N-methyl-D-aspartate (NMDA) receptor has been reported to be important in synaptic plasticity, neuronal development, normal brain function and neurologic disease. We have recently shown that PC12W cells, a subclone of rat pheochromocytoma PC12 cell line, release nitric oxide (NO), as measured by in vitro spin-trapping combined with electron paramagnetic resonance (EPR) spectroscopy, when challenged with NMDA [Norby, S.W., Weyhenmeyer, J.A. and Clarkson, R.B., Stimulation and inhibition of NO production in macrophages and neuronal cells as observed by spin trapping, Free Rad. Biol. Med., 22 (1997) 1-9]. In the present study, we provide immunochemical evidence for the expression of both the NMDAR1 and NMDAR2A/B receptor subunits in PC12W cells, that express only the angiotensin type-2 (AT2) receptor subtype, and in NG108-15 (NG108) cells, a murine neuroblastoma x glioma hybrid that expresses both the angiotensin type-1 (AT1) and AT2 receptor subtypes. We also show that treatment of PC12W cells with angiotensin (Ang II) decreases NMDA-induced NO release by 28.0 +/- 4.2%, and that this response can be attenuated by pre-treating the cells with the isoform-specific AT2 antagonist, PD 123319. Interestingly, there was no effect on cGMP accumulation in PC12W cells treated with NMDA. Similar experiments were carried out using NG108 cells since the binding properties and functional characteristics of their NMDA receptors have been previously described [Ohkuma, S., Katsura, M., Chen, D., Chen, S. and Kuriyama, K., Presence of N-methyl-D-aspartate (NMDA) receptors in neuroblastoma x glioma hybrid NG 108-15 cells-analysis using 45Ca2+ influx and [3H]MK-801 binding as functional measures, Mol. Brain Res. 22 (1994) 166-172]. Our results show that NG108 cells significantly increase cGMP levels when challenged with NMDA (21.2 +/- 5.0% over control levels), and that this response can be attenuated by the addition of angiotensin (57.1 +/- 6.2% of stimulated levels). The effect of angiotensin on NMDA-mediated changes in cGMP levels was blocked by the AT2 antagonist, PD 123319, but was not significantly changed by the addition of the AT1 antagonist, losartan. Further, Ang II action on NMDA signalling in NG108 cells was completely inhibited by the addition of both the AT1 and AT2 antagonists. Taken together, these results suggest that AngII inhibits NMDA-mediated NO and cGMP production through a mechanism involving the AT2 receptor subtype.