Causal mediation analysis for longitudinal data with exogenous exposure

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation.

A randomised non-comparative phase II trial of cixutumumab (IMC-A12) or ramucirumab (IMC-1121B) plus mitoxantrone and prednisone in men with metastatic docetaxel-pretreated castration-resistant prostate cancer

BACKGROUND

Cixutumumab, a human monoclonal antibody (HuMAb), targets the insulin-like growth factor receptor. Ramucirumab is a recombinant HuMAb that binds to vascular endothelial growth factor receptor-2. A non-comparative randomised phase II study evaluated cixutumumab or ramucirumab plus mitoxantrone and prednisone (MP) in metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Men with progressive mCRPC during or after docetaxel therapy received mitoxantrone 12 mg/m(2) on day 1 and prednisone 5mg twice daily and were randomised 1:1 to receive either cixutumumab or ramucirumab 6 mg/kg intravenously weekly in a 21-day cycle. Primary end-point was composite progression-free survival (cPFS). Secondary end-points included safety, response, radiographic progression-free survival (PFS) and overall survival (OS). Sample size was based on a 50% increase in median cPFS from 2.6 (MP) to 3.9 months (either combination).

RESULTS

132 men were treated (66 per arm). Median cPFS was 4.1 months (95% confidence interval (CI), 2.2-5.6) for cixutumumab and 6.7 months (95% CI, 4.5-8.3) for ramucirumab. Median time to radiographic progression was 7.5 months for cixutumumab and 10.2 months for ramucirumab, with a median OS of 10.8 and 13.0 months, respectively. Fatigue was the most frequent adverse event (AE). Incidence of most non-haematologic grade 3-4 AEs was <10% on both arms. Grade 3 cardiac dysfunction occurred in 7.6% of patients on ramucirumab.

CONCLUSION

Combinations of cixutumumab or ramucirumab plus MP were feasible and associated with moderate toxicities in docetaxel-pretreated men with mCRPC. Of the two regimens, the ramucirumab regimen is worthy of further testing based on the observed cPFS relative to the historical control.

Ramucirumab versus placebo as second-line treatment in patients with advanced hepatocellular carcinoma following first-line therapy with sorafenib (REACH): a randomised, double-blind, multicentre, phase 3 trial

BACKGROUND

VEGF and VEGF receptor-2-mediated angiogenesis contribute to hepatocellular carcinoma pathogenesis. Ramucirumab is a recombinant IgG1 monoclonal antibody and VEGF receptor-2 antagonist. We aimed to assess the safety and efficacy of ramucirumab in advanced hepatocellular carcinoma following first-line therapy with sorafenib.

METHODS

In this randomised, placebo-controlled, double-blind, multicentre, phase 3 trial (REACH), patients were enrolled from 154 centres in 27 countries. Eligible patients were aged 18 years or older, had hepatocellular carcinoma with Barcelona Clinic Liver Cancer stage C disease or stage B disease that was refractory or not amenable to locoregional therapy, had Child-Pugh A liver disease, an Eastern Cooperative Oncology Group performance status of 0 or 1, had previously received sorafenib (stopped because of progression or intolerance), and had adequate haematological and biochemical parameters. Patients were randomly assigned (1:1) to receive intravenous ramucirumab (8 mg/kg) or placebo every 2 weeks, plus best supportive care, until disease progression, unacceptable toxicity, or death. Randomisation was stratified by geographic region and cause of liver disease with a stratified permuted block method. Patients, medical staff, investigators, and the funder were masked to treatment assignment. The primary endpoint was overall survival in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT01140347.

FINDINGS

Between Nov 4, 2010, and April 18, 2013, 565 patients were enrolled, of whom 283 were assigned to ramucirumab and 282 were assigned to placebo. Median overall survival for the ramucirumab group was 9·2 months (95% CI 8·0-10·6) versus 7·6 months (6·0-9·3) for the placebo group (HR 0·87 [95% CI 0·72-1·05]; p=0·14). Grade 3 or greater adverse events occurring in 5% or more of patients in either treatment group were ascites (13 [5%] of 277 patients treated with ramucirumab vs 11 [4%] of 276 patients treated with placebo), hypertension (34 [12%] vs ten [4%]), asthenia (14 [5%] vs five [2%]), malignant neoplasm progression (18 [6%] vs 11 [4%]), increased aspartate aminotransferase concentration (15 [5%] vs 23 [8%]), thrombocytopenia (13 [5%] vs one [<1%]), hyperbilirubinaemia (three [1%] vs 13 [5%]), and increased blood bilirubin (five [2%] vs 14 [5%]). The most frequently reported (≥1%) treatment-emergent serious adverse event of any grade or grade 3 or more was malignant neoplasm progression.

INTERPRETATION

Second-line treatment with ramucirumab did not significantly improve survival over placebo in patients with advanced hepatocellular carcinoma. No new safety signals were noted in eligible patients and the safety profile is manageable.

FUNDING

Eli Lilly and Co.

Phase I study of every 2- or 3-week dosing of ramucirumab, a human immunoglobulin G1 monoclonal antibody targeting the vascular endothelial growth factor receptor-2 in patients with advanced solid tumors

BACKGROUND

Ramucirumab is a fully human immunoglobulin G1 monoclonal antibody receptor antagonist designed to block the ligand-binding site of vascular endothelial growth factor receptor-2 (VEGFR-2). An initial phase I study evaluated ramucirumab administered weekly in advanced cancer patients. This phase I study of ramucirumab [administered every 2 or 3 weeks (Q2W or Q3W)] examined safety, maximum tolerated dose, pharmacokinetics, immunogenicity, antitumor activity, and pharmacodynamics.

PATIENTS AND METHODS

Patients with advanced solid malignancies were treated with escalating doses of ramucirumab i.v. over 1 h. Blood was sampled for pharmacokinetics studies throughout treatment; levels of circulating vascular endothelial growth factor-A (VEGF-A) and soluble VEGF receptors (R)-1 and -2 were assessed.

RESULTS

Twenty-five patients were treated with ramucirumab: 13 with 6, 8, or 10 mg/kg Q2W, and 12 with 15 or 20 mg/kg Q3W. The median treatment duration was 12 weeks (range 2-81). No dose-limiting toxicities were observed. The most frequently reported adverse events (AEs) included proteinuria and hypertension (n = 6 each), and diarrhea, fatigue and headache (n = 4 each). Treatment-related grade 3/4 AEs were: two grade 3 hypertension (10 and 20 mg/kg), one each grade 3 vomiting, fatigue (20 mg/kg), atrial flutter (15 mg/kg), and one each grade 4 duodenal ulcer hemorrhage (6 mg/kg) and grade 4 pneumothorax (20 mg/kg). Pharmacokinetic analysis revealed low clearance and half-life of ∼110-160 h. Analysis of serum biomarkers indicated considerable patient-to-patient variability, but trends toward elevated VEGF-A and a transient decline in soluble VEGFR-2. Fifteen patients (60%) had best response of stable disease, with a median duration of 13 months (range 2-18 months) in tumor types including colorectal, renal, liver, and neuroendocrine cancers.

CONCLUSION

Ramucirumab was well tolerated. Study results led to recommended phase II doses of 8 mg/kg Q2W and 10 mg/kg Q3W. Prolonged stable disease was observed, suggesting ramucirumab efficacy in various solid tumors.

CLINICALTRIALSGOV

NCT00786383.

Safety, tolerability, and pharmacokinetics of single and multiple doses of intravenous cixutumumab (IMC-A12), an inhibitor of the insulin-like growth factor-I receptor, administered weekly or every 2 weeks in patients with advanced solid tumors

BACKGROUND

Type 1 insulin-like growth factor receptor (IGF-IR) signaling is often dysregulated in cancer. Cixutumumab, a fully human IgG1 monoclonal antibody, blocks IGF-IR and inhibits downstream signaling. The current study determined the recommended dose, safety, and pharmacokinetic (PK) profile of weekly or every-2-week dosing of cixutumumab.

PATIENTS AND METHODS

Two open-label, multicenter phase I studies evaluated weekly (3-15 mg/kg) or every-2-weeks (6-15 mg/kg) dosing of cixutumumab in patients with advanced solid tumors. Serial blood samples for PK were collected up to 168-336 h (day 8-15) following the first administration of cixutumumab. Efficacy was evaluated as best overall tumor response.

RESULTS

A total of 24 and 16 patients were enrolled in the weekly and every-2-week dosing studies, respectively. Treatment-emergent adverse events (≥10%) included hyperglycemia, fatigue, anemia, nausea, and vomiting. Severe adverse events (AE) were infrequent; one serious AE (grade 3 electrocardiogram QT prolongation) was deemed possibly cixutumumab-related (10 mg/kg every-2-weeks). One death occurred due to disease progression (6 mg/kg weekly cohort). Maximum serum concentrations increased with dose. A maximum tolerated dose was not identified; pre-determined target serum minimum concentrations (60 μg/mL) were achieved with ≥6 mg/kg weekly and ≥10 mg/kg every-2-week dosing. Cixutumumab terminal elimination half-life is approximately a week (individual range, t1/2 = 4.58-9.33 days based upon 10 mg/kg every 2 weeks). Overall, stable disease was achieved in 25% of all patients.

CONCLUSIONS

Cixutumumab was associated with favorable safety and PK profiles. A dosing regimen of 10 mg/kg every 2 weeks was recommended for subsequent disease-focused clinical trials.

Ramucirumab plus paclitaxel versus placebo plus paclitaxel in patients with previously treated advanced gastric or gastro-oesophageal junction adenocarcinoma (RAINBOW): a double-blind, randomised phase 3 trial

BACKGROUND

VEGFR-2 has a role in gastric cancer pathogenesis and progression. We assessed whether ramucirumab, a monoclonal antibody VEGFR-2 antagonist, in combination with paclitaxel would increase overall survival in patients previously treated for advanced gastric cancer compared with placebo plus paclitaxel.

METHODS

This randomised, placebo-controlled, double-blind, phase 3 trial was done at 170 centres in 27 countries in North and South America, Europe, Asia, and Australia. Patients aged 18 years or older with advanced gastric or gastro-oesophageal junction adenocarcinoma and disease progression on or within 4 months after first-line chemotherapy (platinum plus fluoropyrimidine with or without an anthracycline) were randomly assigned with a centralised interactive voice or web-response system in a 1:1 ratio to receive ramucirumab 8 mg/kg or placebo intravenously on days 1 and 15, plus paclitaxel 80 mg/m(2) intravenously on days 1, 8, and 15 of a 28-day cycle. A permuted block randomisation, stratified by geographic region, time to progression on first-line therapy, and disease measurability, was used. The primary endpoint was overall survival. Efficacy analysis was by intention to treat, and safety analysis included all patients who received at least one treatment with study drug. This trial is registered with ClinicalTrials.gov, number NCT01170663, and has been completed; patients who are still receiving treatment are in the extension phase.

FINDINGS

Between Dec 23, 2010, and Sept 23, 2012, 665 patients were randomly assigned to treatment-330 to ramucirumab plus paclitaxel and 335 to placebo plus paclitaxel. Overall survival was significantly longer in the ramucirumab plus paclitaxel group than in the placebo plus paclitaxel group (median 9·6 months [95% CI 8·5-10·8] vs 7·4 months [95% CI 6·3-8·4], hazard ratio 0·807 [95% CI 0·678-0·962]; p=0·017). Grade 3 or higher adverse events that occurred in more than 5% of patients in the ramucirumab plus paclitaxel group versus placebo plus paclitaxel included neutropenia (133 [41%] of 327 vs 62 [19%] of 329), leucopenia (57 [17%] vs 22 [7%]), hypertension (46 [14%] vs eight [2%]), fatigue (39 [12%] vs 18 [5%]), anaemia (30 [9%] vs 34 [10%]), and abdominal pain (20 [6%] vs 11 [3%]). The incidence of grade 3 or higher febrile neutropenia was low in both groups (ten [3%] vs eight [2%]).

INTERPRETATION

The combination of ramucirumab with paclitaxel significantly increases overall survival compared with placebo plus paclitaxel, and could be regarded as a new standard second-line treatment for patients with advanced gastric cancer.

FUNDING

Eli Lilly and Company.

A phase II study of ramucirumab (IMC-1121B) in the treatment of persistent or recurrent epithelial ovarian, fallopian tube or primary peritoneal carcinoma

OBJECTIVE

Vascular endothelial growth factor (VEGF) receptor-mediated signaling contributes to ovarian cancer pathogenesis. Elevated VEGF expression is associated with poor clinical outcomes. We investigated ramucirumab, a fully human anti-VEGFR-2 antibody, in patients with persistent or recurrent epithelial ovarian, fallopian tube, or primary peritoneal carcinoma. Primary endpoints were progression-free survival at 6 months (PFS-6) and confirmed objective response rate (ORR).

METHODS

Women who received ≥ 1 platinum-based chemotherapeutic regimen and had a platinum-free interval of <12 months with measurable disease were eligible. Patients received 8 mg/kg ramucirumab intravenously every 2 weeks.

RESULTS

Sixty patients were treated; one patient remained on study as of September 2013. The median age was 62 years (range: 27-80), and median number of prior regimens was 3. Forty-five (75%) patients had platinum refractory/resistant disease. Thirty-nine patients (65.0%) had serous tumors. PFS-6 was 25.0% (n=15/60, 95% CI: 14.7-37.9%). Best overall response was: partial response 5.0% (n=3/60), stable disease 56.7% (n=34/60), and progressive disease 33.3% (n=20/60). The most common treatment-emergent adverse events possibly related to study drug were headache (65.0%; 10.0% Grade ≥ 3), fatigue (56.7%; 3.3% Grade ≥ 3), diarrhea (28.3%; 1.7% Grade ≥ 3), hypertension (25.0%; 3.3% Grade ≥ 3), and nausea (20.0%; no Grade ≥ 3). Two patients experienced intestinal perforations (3.3% Grade ≥ 3). Pharmacodynamic analyses revealed changes in several circulating VEGF proteins following initial ramucirumab infusion, including increased VEGF-A, PlGF and decreased sVEGFR-2.

CONCLUSIONS

Although antitumor activity was observed, the predetermined efficacy endpoints were not met.

A phase 2 randomised study of ramucirumab (IMC-1121B) with or without dacarbazine in patients with metastatic melanoma

BACKGROUND

To evaluate the efficacy and safety of ramucirumab (IMC-1121B; LY3009806), a fully human monoclonal antibody targeting the vascular endothelial growth factor receptor-2, alone and in combination with dacarbazine in chemotherapy-naïve patients with metastatic melanoma (MM).

METHODS

Eligible patients received ramucirumab (10mg/kg) + dacarbazine (1000 mg/m(2)) (Arm A) or ramucirumab only (10mg/kg) (Arm B) every 3 weeks. The primary end-point was progression-free survival (PFS); secondary end-points included overall survival (OS), overall response and safety.

FINDINGS

Of 106 randomised patients, 102 received study treatment (Arm A, N=52; Arm B, N=50). Baseline characteristics were similar in both arms. Median PFS was 2.6 months (Arm A) and 1.7 months (Arm B); median 6-month PFS rates were 30.7% and 17.9% and 12-month PFS rates were 23.7% and 15.6%, respectively. In Arm A, 9 (17.3%) patients had partial response (PR) and 19 (36.5%), stable disease (SD); PR and SD in Arm B were 2 (4.0%) and 21 (42.0%), respectively. Median OS was 8.7 months in Arm A and 11.1 months in Arm B. Patients in both arms tolerated the treatment with limited Grade 3/4 toxicities.

INTERPRETATION

Ramucirumab alone or in combination with dacarbazine was associated with an acceptable safety profile in patients with MM. Although the study was not powered for comparison between treatment arms, PFS appeared greater with combination therapy. Sustained disease control was observed on both study arm.

A phase 2, single-arm study of ramucirumab in patients with metastatic renal cell carcinoma with disease progression on or intolerance to tyrosine kinase inhibitor therapy

BACKGROUND

Multitargeted tyrosine kinase inhibitors (TKIs) have antitumor activity in metastatic renal cell carcinoma (mRCC). Resistance to these agents develops frequently, and their use is often limited by intolerance. Ramucirumab is a recombinant human monoclonal antibody directed against human vascular endothelial growth factor receptor-2. For this study, the authors investigated the clinical efficacy and safety of ramucirumab in patients with TKI-resistant/intolerant mRCC.

METHODS

In this single-arm phase 2 trial, patients received ramucirumab 8 mg/kg every 2 weeks until they developed disease progression or intolerable toxicity. The primary endpoint was the best objective response rate (ORR); additional endpoints included the disease control rate (DCR), progression-free survival (PFS), the median duration of overall response, and safety.

RESULTS

Thirty-nine patients with RCC received ramucirumab monotherapy. Prior TKI therapy included sunitinib (59% of patients), sunitinib and sorafenib (30.8% of patients), and sorafenib (10.3% of patients). The ORR was 5.1% (95% confidence interval [CI], 0.6%-17.3%). The 12-week DCR was 64.1% (95% CI, 47.2%-78.8%). The median PFS was 7.1 months (95% CI, 4.1-9.7 months), and the median overall survival was 24.8 months (95% CI, 18.9-32.6 months). Grade 3 or higher adverse events that occurred in ≥5% of patients included grade 3 hypertension (7.7%) and proteinuria (5.1%). There was 1 on-study death from multiorgan failure.

CONCLUSIONS

Although the study did not meet its primary endpoint of ≥15% ORR, ramucirumab was associated with evidence of antitumor activity in patients with TKI-resistant/intolerant mRCC. Ramucirumab was safe and well tolerated.

An open-label phase II study evaluating the safety and efficacy of ramucirumab combined with mFOLFOX-6 as first-line therapy for metastatic colorectal cancer

BACKGROUND

Vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR-2) are believed to mediate angiogenesis in colorectal cancer (CRC). Ramucirumab (RAM; IMC-1121B) is a human IgG1 monoclonal antibody that inhibits VEGF ligand binding to VEGFR-2, inhibiting VEGFR-2 activation and signaling.

METHODS

Patients with metastatic CRC, Eastern Cooperative Oncology Group performance status 0-1, and adequate organ function who had not received chemotherapy for metastatic disease received RAM and the modified FOLFOX-6 regimen every 2 weeks. Endpoints included progression-free survival (PFS), objective response rate, overall survival, and safety. The sample size was based on a potentially improved median PFS from 8 months to 11 months.

RESULTS

Forty-eight patients received therapy. Median PFS was 11.5 months (95% confidence interval [CI]: 8.6-13.1 months). The objective response rate was 58.3% (95% CI: 43.21-72.39). The disease control rate (complete or partial response plus stable disease) was 93.8% (95% CI: 82.8-98.7). Median overall survival was 20.4 months (95% CI: 18.5-25.1 months). The most frequent grade 3-4 adverse events included neutropenia (grade 3: 33.3%; grade 4: 8.3%), hypertension (grade 3: 16.7%), and neuropathy (grade 3: 12.5%). Two patients died during the study due to myocardial infarction and cardiopulmonary arrest.

CONCLUSION

RAM may enhance the efficacy of modified FOLFOX-6 chemotherapy with an acceptable safety profile in metastatic CRC.

Ramucirumab monotherapy for previously treated advanced gastric or gastro-oesophageal junction adenocarcinoma (REGARD): an international, randomised, multicentre, placebo-controlled, phase 3 trial

BACKGROUND

Vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2)-mediated signalling and angiogenesis can contribute to the pathogenesis and progression of gastric cancer. We aimed to assess whether ramucirumab, a monoclonal antibody VEGFR-2 antagonist, prolonged survival in patients with advanced gastric cancer.

METHODS

We did an international, randomised, double-blind, placebo-controlled, phase 3 trial between Oct 6, 2009, and Jan 26, 2012, at 119 centres in 29 countries in North America, Central and South America, Europe, Asia, Australia, and Africa. Patients aged 24-87 years with advanced gastric or gastro-oesophageal junction adenocarcinoma and disease progression after first-line platinum-containing or fluoropyrimidine-containing chemotherapy were randomly assigned (2:1), via a central interactive voice-response system, to receive best supportive care plus either ramucirumab 8 mg/kg or placebo, intravenously once every 2 weeks. The study sponsor, participants, and investigators were masked to treatment assignment. The primary endpoint was overall survival. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00917384.

FINDINGS

355 patients were assigned to receive ramucirumab (n=238) or placebo (n=117). Median overall survival was 5·2 months (IQR 2·3-9·9) in patients in the ramucirumab group and 3·8 months (1·7-7·1) in those in the placebo group (hazard ratio [HR] 0·776, 95% CI 0·603-0·998; p=0·047). The survival benefit with ramucirumab remained unchanged after multivariable adjustment for other prognostic factors (multivariable HR 0·774, 0·605-0·991; p=0·042). Rates of hypertension were higher in the ramucirumab group than in the placebo group (38 [16%] vs nine [8%]), whereas rates of other adverse events were mostly similar between groups (223 [94%] vs 101 [88%]). Five (2%) deaths in the ramucirumab group and two (2%) in the placebo group were considered to be related to study drug.

INTERPRETATION

Ramucirumab is the first biological treatment given as a single drug that has survival benefits in patients with advanced gastric or gastro-oesophageal junction adenocarcinoma progressing after first-line chemotherapy. Our findings validate VEGFR-2 signalling as an important therapeutic target in advanced gastric cancer.

FUNDING

ImClone Systems.

A phase II and biomarker study of ramucirumab, a human monoclonal antibody targeting the VEGF receptor-2, as first-line monotherapy in patients with advanced hepatocellular cancer

PURPOSE

To assess the efficacy and safety of the anti-VEGF receptor-2 (VEGFR-2) antibody ramucirumab as first-line therapy in patients with advanced hepatocellular carcinoma and explore potential circulating biomarkers.

EXPERIMENTAL DESIGN

Adults with advanced hepatocellular carcinoma and no prior systemic treatment received ramucirumab 8 mg/kg every two weeks until disease progression or limiting toxicity. The primary endpoint was progression-free survival (PFS); secondary endpoints included objective response rate (ORR) and overall survival (OS). Circulating biomarkers were evaluated before and after ramucirumab treatment in a subset of patients.

RESULTS

Forty-two patients received ramucirumab. Median PFS was 4.0 months [95% confidence interval (CI), 2.6-5.7], ORR was 9.5% (95% CI, 2.7-22.6; 4/42 patients had a partial response), and median OS was 12.0 months (95% CI, 6.1-19.7). For patients with Barcelona Clinic Liver Cancer (BCLC) stage C disease, median OS was 4.4 months (95% CI, 0.5-9.0) for patients with Child-Pugh B cirrhosis versus 18.0 months (95% CI, 6.1-23.5) for patients with Child-Pugh A cirrhosis. Treatment-related grade ≥ 3 toxicities included hypertension (14%), gastrointestinal hemorrhage and infusion-related reactions (7% each), and fatigue (5%). There was one treatment-related death (gastrointestinal hemorrhage). After treatment with ramucirumab, there was an increase in serum VEGF and placental growth factor (PlGF) and a transient decrease in soluble VEGFR-2.

CONCLUSION

Ramucirumab monotherapy may confer anticancer activity in advanced hepatocellular carcinoma with an acceptable safety profile. Exploratory biomarker studies showed changes in circulating VEGF, PlGF, and sVEGFR-2 that are consistent with those seen with other anti-VEGF agents.

REGARD: A phase III, randomized, double-blinded trial of ramucirumab and best supportive care (BSC) versus placebo and BSC in the treatment of metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma following disease progression on first-line platinum- and/or fluoropyrimidine-containing combination therapy

LBA5

Background: VEGF and VEGF receptor-2 mediated signaling and angiogenesis may contribute to gastric cancer pathogenesis. Ramucirumab (RAM; IMC-1121B) is a fully human IgG1 monoclonal antibody targeting VEGF-receptor 2. We conducted a placebo-controlled, double-blind, phase III international trial to evaluate the safety and efficacy of RAM in pts with metastatic gastric or GEJ adenocarcinoma progressing on first-line platinum- and/or fluoropyrimidine containing combination therapy. Methods: Pts were randomized 2:1 to receive RAM (8 mg/kg IV) plus BSC or placebo (PL) plus BSC every 2 weeks (wks) until disease progression, unacceptable toxicity, or death. Eligible patients had disease progression within 4 months (m) after 1st-line therapy for metastatic disease or within 6 m after adjuvant therapy. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), 12-wk PFS rate, overall response rate (ORR) and safety. Results: From 10/09 to 01/12, 355 pts were randomized (RAM: 238; PL: 117). Baseline characteristics were well balanced between arms. The Hazard Ratio (HR) for OS was 0.776 (95% CI, 0.603-0.998; p = 0.0473). Median OS was 5.2 m for RAM and 3.8 m for PL. The HR for PFS was 0.483 (95% CI, 0.376-0.620; p < 0.0001). Median PFS was 2.1 m for RAM and 1.3 m for PL. 12-wk PFS was 40% for RAM and 16% for PL. ORR was 3.4% for RAM and 2.6% for PL. Disease control rate was 49% for RAM and 23% for PL (p < 0.0001). Use of anti-cancer therapy post-study: 32% RAM; 39% PL. The most frequent of grade ≥ 3 adverse events (AEs) were: hypertension (7.2% RAM; 2.6% PL), anemia (6.4% RAM; 7.8% PL), abdominal pain (5.1% RAM; 2.6% PL), ascites (4.2% RAM; 4.3% PL), fatigue (4.2% RAM; 3.5% PL), decreased appetite (3.4% RAM; 3.5% PL) and hyponatremia (3.4% RAM; 0.9% PL). Conclusions: Ramucirumab conferred a statistically significant benefit in OS and PFS compared to PL in metastatic gastric or GEJ adenocarcinoma following progression on 1st-line therapy with an acceptable safety profile. Clinical trial information: NCT00917384.

Blockade of insulin-like growth factor type-1 receptor with cixutumumab (IMC-A12): a novel approach to treatment for multiple cancers

Insulin-like growth factor type-1 receptor (IGF-1R) plays a central role in cell proliferation and survival and is overexpressed in many tumor types. Notably, IGF-1R-mediated signaling confers resistance to diverse cytotoxic, hormonal, and biologic agents, suggesting that therapies targeting IGF-1R may be effective against a broad range of human malignancies. Cixutumumab (IMC-A12; ImClone Systems) is a fully human immunoglobulin G1 (IgG1) monoclonal antibody that specifically inhibits IGF-1R signaling. Binding of cixutumumab to IGF-1R results in receptor internalization and degradation. Because cixutumumab is an IgG1 monoclonal antibody, it may induce additional cytotoxicity via immune effector mechanisms such as antibody-dependent cellular cytotoxicity. In preclinical studies, cixutumumab monotherapy resulted in growth inhibition of multiple experimental cancers. Moreover, cixutumumab safely enhanced the tumor growth inhibitory and cytotoxic effects of a broad range of chemotherapeutics, and modulated the action of agents that target hormone receptors and signal transduction, which may have implications for cancer therapy. Herein, we review published preclinical and clinical data for cixutumumab and provide a comprehensive overview of selected clinical studies.

Randomized phase II study of docetaxel with or without ramucirumab (IMC-1121B) or icrucumab (IMC-18F1) in patients with urothelial transitional cell carcinoma (TCC) following progression on first-line platinum-based therapy

TPS4675^

Background: The vascular endothelial growth factor (VEGF) pathway may play an important role in the pathogenesis of bladder cancer. Two antibodies (ramucirumab or icrucumab) in combination with docetaxel are being tested in this clinical study. Ramucirumab is a fully human IgG1 monoclonal antibody (MAb) that specifically binds with high affinity to VEGF receptor-2 (VEGFR-2), thereby blocking the interaction of VEGF ligands. Ramucirumab inhibits VEGF-mediated proliferation of human endothelial cells and migration of human leukemia cells. Icrucumab is a fully human IgG1 MAb that specifically binds with high affinity to VEGFR-1 and blocks the binding of VEGF-A, VEGF-B, and placental growth factor (PlGF) to the receptor, thereby inhibiting subsequent signaling. Blockage of VEGFR-1 and VEGFR-2 by antibodies demonstrates antiangiogenic and antitumor activity and prevents dissemination and growth of lung metastases in several tumor xenograft models. Methods: This study includes patients (pts) with TCC with progressive disease after prior platinum-based therapy. Pts are randomized equally to 1 of 3 open-label treatments given on a 21-day cycle: docetaxel (75 mg/m2) on Day 1 (Arm A); docetaxel on Day 1 and ramucirumab (10 mg/kg) on Day 1 (Arm B); or docetaxel on Day 1 and icrucumab (12 mg/kg) on Days 1 and 8 (Arm C). Randomization is stratified by the absence/presence of visceral metastases and receipt of prior antiangiogenic therapy. The primary endpoint is progression-free survival (PFS). Secondary outcome measures include response rate and duration of response, overall survival, and pharmacodynamic markers, including circulating levels of PlGF, VEGF-A, VEGF-B, soluble VEGFR-1, and soluble VEGFR-2. Exploratory analyses of VEGF, VEGFR-1, and VEGFR-2 genetic polymorphisms will be performed. As of 12 January 2012, approximately 20% of 138 planned pts were randomized in the US and Canada. The sample size will allow differentiation of an expected increase in median PFS from 3.0 months to 4.5 months with a one-sided alpha of 0.1 and a power of 71%. ClinicalTrials.gov identifier: NCT01282463.

A phase II, open-label, multicenter study of IMC-1121B (ramucirumab; RAM) monotherapy in the treatment of persistent or recurrent epithelial ovarian (EOC), fallopian tube (FTC), or primary peritoneal (PPC) carcinoma (CP12-0711/NCT00721162)

5012

Background: VEGF receptor-mediated-signaling contributes to ovarian cancer pathogenesis. Elevated VEGF expression and serum levels are associated with poor clinical outcomes. We investigated RAM, a fully human VEGFR-2 antagonist antibody, in patients (pts) with persistent or recurrent EOC/FTC/PPC. Methods: Adult women with EOC/FTC/PPC who had completed ≥1 platinum (P)-based chemotherapeutic (ct) regimen and had a P-free interval (PFI) of <12 months (m), progression on, or persistent disease after P-based therapy were eligible. Any number of prior ct regimens was allowed. ECOG PS 0-1 and adequate organ function were required. Pts received 8 mg/kg RAM IV every 2 weeks. Primary endpoints were progression-free survival at 6m (PFS-6) and confirmed objective response rate (ORR) by RECIST 1.0. Results: 60 pts were treated; 1 remains on study as of Dec 2011. Median age was 62 years (range 27-80). Median number of prior regimens was 3 (range 1– 14). 51 pts (85%) received ≥ 2 prior regimens; 25 pts (42%) received >3 prior regimens. 45 pts (75%) were P resistant or refractory, with 65% (39 pts) serous tumors. PFS-6: 34.2% (95% CI: 21.7% – 47%). Best overall response: 3 PR (5%), 34 SD (57%), 20 PD (33%) and 3 not evaluable (5%). Median duration of PR: 5.6m (3.7, 5.6, 17.5); median PFS: 3.5m (95% CI: 2.3 – 5.3). Median OS: 11.1m (95% CI: 8.3 – 17.0). No unexpected toxicities were observed. Grade (G) 3 adverse events (AEs) observed in >5% of pts were: headache (10%) and fatigue (8%). No G4 AEs were observed in >5% of pts. 5 deaths occurred on RAM or within 30 days of discontinuation; 4 due to PD, and 1 due to intestinal perforation. 1 G4 bowel perforation and one G4 colo-vaginal fistula were noted. All 3 cases of perforation/fistula occurred in the setting of progressive, large-volume disease. Correlative biomarker studies are ongoing to identify patients most likely to benefit. Conclusions: Ramucirumab was reasonably tolerated and demonstrated single-agent activity in persistent or recurrent ovarian carcinoma, with approximately one-third of patients progression free at 6 months.

A phase II randomized study of cixutumumab (IMC-A12: CIX) or ramucirumab (IMC‐1121B: RAM) plus mitoxantrone (M) and prednisone (P) in patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC) following disease progression (PD) on docetaxel (DCT) therapy

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Background: Vascular endothelial growth factor (VEGF)-mediated angiogenesis and insulin-like growth factor (IGF-IR)-mediated signaling contribute to mCRPC growth. CIX and RAM are fully human IgG1 human monoclonal antibodies targeting IGF‐IR and VEGF receptor-2 (VEGFR-2) respectively. We investigated the safety and efficacy of CIX or RAM in combination with M + P in mCRPC pts with PD on DCT.

Methods: Eligible pts had mCRPC and PD during/within 120 days of DCT, ECOG PS 0-2, PSA ≥ 2 ng/mL, and adequate organ function. All pts received M 12 mg/m2 IV every 3 weeks (w) + P 5 mg PO BID for up to 12 cycles and were randomized to either CIX 6 mg/kg or RAM 6 mg/kg IV q w. Tumor assessments were after the first 3 cycles and then q6w. Primary endpoint was composite progression-free survival (cPFS: either RECIST PD, bone scan PD or new skeletal events). Other endpoints included safety, response and overall survival (OS). Sample size was based on a targeted 50% increase in median (mdn) cPFS from 2.6 months (m) to 3.9 m.

Results: 132 pts were treated; 66 each to CIX or RAM. Mdn age and baseline PSA was 65 yr and 129 ng/mL for pts treated with CIX and 68 yr and 111 ng/mL for RAM. Involvement of sites other than bone was CIX: 79% and RAM: 70%. The most frequent Grade ≥3 related adverse events for CIX/M/P: fatigue 17%, leukopenia 12%, and neutropenia 8%, and for RAM/M/P: leukopenia 8%, neutropenia 8% and hypertension 8%. Left ventricular dysfunction/CHF: 12% for CIX (0% G3) and 23% for RAM (8% G3). Mdn number of Rx cycles were 5 for CIX and 6 for RAM. Mdn follow-up was 22.7 m for CIX and 21.8 m for RAM. PSA response was 18.4% (8.8-32% 95% CI) on CIX and 22.0% (11.5-36% 95% CI) on RAM. Mdn cPFS and OS were 4.1 m (3.0-5.6 m 95% CI) and 10.8 m (6.5-13.0 m 95% CI) for CIX and 6.7 m (4.5-8.3 m 95% CI) and 13.0 m (9.5-16.0 m 95% CI) for RAM.

Conclusions: CIX/M/P and RAM/M/P were reasonably tolerated and achieved the primary endpoint. Preliminary cPFS and OS of RAM/M/P appear encouraging; sustained disease control was observed in pts on both rx arms. Correlation of serum markers of IGF and VEGF activity with clinical endpoints is planned.

A phase II, open-label study evaluating the safety and efficacy of ramucirumab combined with mFOLFOX-6 as first-line therapy in patients (pts) with metastatic colorectal cancer (mCRC): CP12-0709/NCT00862784

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Background: Vascular endothelial growth factor (VEGF) and the VEGF receptor-2 (VEGFR-2) are overexpressed in CRC and mediate angiogenesis. Ramucirumab (RAM; IMC-1121B) is a fully human IgG1 MAb that inhibits binding of VEGF ligands to VEGFR-2 and inhibits VEGFR-2 activation and signaling. In preclinical CRC models VEGFR-2 inhibition confers antitumor activity. RAM was administered with mFOLFOX-6 as 1st-line therapy (rx) in mCRC.

Methods: Eligible pts had mCRC with no prior chemo Rx (prior adjuvant rx was allowed), at least 1 measurable target lesion by RECIST v1.0, ECOG PS 0-1, and adequate organ function. Pts received RAM (8 mg/kg IV on D1), oxaliplatin (85 mg/m² IV on D1), folinic acid (400 mg/m² IV on D1), fluorouracil (5-FU, 400 mg/m² bolus followed by 2400 mg/m² continuous infusion over 46 hours on D1). Rx cycles were q2w and tumor assessments were q8w. Endpoints included progression-free survival (PFS), objective response rate (ORR), overall survival (OS), safety, and pharmacokinetics/immunogenicity. Sample size was based on an improved median (medn) PFS from 8 to 11 months (m).

Results: 48 pts received therapy. All were white; 25 M/23 F; median age 60.5 y. ECOG PS was 0/1 in 30/18 pts. 42 pts (88%) had metastatic disease, with liver (79%) and lung (35%) as most frequent sites. 13 (27%) pts had liver-only mCRC. The most frequently observed RAM-related adverse events (AEs) included hypertension 46% (15% Grade [G] ≥3); diarrhea 31% (2% G≥3); and nausea and infusion-related reactions, each 19% (0% G≥3). 2 pts died on study due to acute MI or cardiopulmonary arrest. Medn PFS was 11.5 m (9-13 m 95% CI) with 1-yr PFS of 48% (32-62% 95% CI). ORR: 67% (52-80% 95% CI); disease control rate (DCR: CR+PR+SD): 94% (83-99% 95% CI; 5 pts had CR, 27 had PR and 13 had SD). Medn duration of response was 11.0 m (7-12 m 95% CI). One-year OS was 85% (72-93% 95% CI). As of 4/15/2011, 2 pts continued to receive rx, 20 had died and 28 (58.3%) remained alive.

Conclusions: RAM combined with mFOLFOX-6 was reasonably tolerated in pts with mCRC. Median PFS exceeds 11 m. PFS, ORR, and DCR are encouraging and favor investigation of this regimen and of RAM in mCRC.

Vascular endothelial growth factor receptor-1 in human cancer: concise review and rationale for development of IMC-18F1 (Human antibody targeting vascular endothelial growth factor receptor-1)

The human vascular endothelial growth factor receptor-1 (VEGFR-1, or Flt-1) is widely expressed in normal and pathologic tissue and contributes to the pathogenesis of both neoplastic and inflammatory diseases. In human cancer, VEGFR-1 mediated signaling is responsible for both direct tumor activation and angiogenesis. VEGFR-1 mediated activation of nonmalignant supporting cells, particularly stromal, dendritic, hematopoietic cells, and macrophages, is also likely important for cancer pathogenesis. VEGFR-1 is also hypothesized to enable the development of cancer metastases by means of activation and premetastatic localization in distant organs of bone marrow-derived hematopoietic progenitor cells, which express VEGFR-1. IMC-18F1 is a fully human IgG(1) antibody that binds to VEGFR-1 and has been associated with the inhibition of cancer growth in multiple in vitro and human tumor xenograft models. The preliminary results of phase 1 investigations have also indicated a favorable safety profile for IMC-18F1 at doses that confer antibody concentrations that are associated with relevant antitumor activity in preclinical models.

Rationale for the development of IMC-3G3, a fully human immunoglobulin G subclass 1 monoclonal antibody targeting the platelet-derived growth factor receptor alpha

A large body of evidence suggests that the platelet-derived growth factor (PDGF) family and associated receptors are potential targets in oncology therapeutic development because of their critical roles in the proliferation and survival of various cancers and in the regulation and growth of the tumor stroma and blood vessels. Several small molecules that nonspecifically target the PDGF signaling axis are in current use or development as anticancer therapies. However, for the majority of these agents, PDGF and its receptors are neither the primary targets nor the principal mediators of anticancer activity. IMC-3G3, a fully human monoclonal antibody of the immunoglobulin G subclass 1, specifically binds to the human PDGF receptor alpha (PDGFRalpha) with high affinity and blocks PDGF ligand binding and PDGFRalpha activation. The results of preclinical studies and the frequent expression of PDGFRalpha in many types of cancer and in cancer-associated stroma support a rationale for the clinical development of IMC-3G3. Currently, IMC-3G3 is being evaluated in early clinical development for patients with several types of solid malignancies.

Anti-transforming growth factor beta receptor II antibody has therapeutic efficacy against primary tumor growth and metastasis through multieffects on cancer, stroma, and immune cells

PURPOSE

Transforming growth factor beta (TGFbeta) is a pleiotropic cytokine that affects tumor growth, metastasis, stroma, and immune response. We investigated the therapeutic efficacy of anti-TGFbeta receptor II (TGFbeta RII) antibody in controlling metastasis and tumor growth as well as enhancing antitumor immunity in preclinical tumor models.

EXPERIMENTAL DESIGN

We generated neutralizing antibodies to TGFbeta RII and assessed the antibody effects on cancer, stroma, and immune cells in vitro. The efficacy and mechanism of action of the antibody as monotherapy and in combination with chemotherapy in suppression of primary tumor growth and metastasis were evaluated in several tumor models.

RESULTS

Anti-TGFbeta RII antibody blocked TGFbeta RII binding to TGFbeta 1, 2, and 3, and attenuated the TGFbeta-mediated activation of downstream Smad2 kinase, invasion of cancer cells, motility of endothelial and fibroblast cells, and induction of immunosuppressive cells. Treatment with the antibody significantly suppressed primary tumor growth and metastasis and enhanced natural killer and CTL activity in tumor-bearing mice. Immunohistochemistry analysis showed cancer cell apoptosis and massive necrosis, and increased tumor-infiltrating T effector cells and decreased tumor-infiltrating Gr-1+ myeloid cells in the antibody-treated tumors. Fluorescence-activated cell sorting analysis indicated the significant reduction of peripheral Gr-1+/CD11b+ myeloid cells in treated animals. Concomitant treatment with the cytotoxic agent cyclophosphamide resulted in a significantly increased antitumor efficacy against primary tumor growth and metastasis.

CONCLUSIONS

These preclinical data provide a foundation to support using anti-TGFbeta RII antibody as a therapeutic agent for TGFbeta RII-dependent cancer with metastatic capacity.