Phase I dose-escalation study to determine the safety, pharmacokinetics and pharmacodynamics of brivanib alaninate in combination with full-dose cetuximab in patients with advanced gastrointestinal malignancies who have failed prior therapy

Background:

The objectives of this phase I study were to determine the safety, pharmacokinetics (PK), pharmacodynamics and efficacy of brivanib combined with full-dose cetuximab in patients with advanced gastrointestinal malignancies.

Methods:

Patients with advanced gastrointestinal malignancies who had failed prior therapies received brivanib (320, 600 or 800 mg daily) plus cetuximab (400 mg m^–2 loading dose then 250 mg m^–2 weekly). Assessments included adverse events, PK, tumour response, 2[18F]fluoro-2-deoxyglucose positron-emitting tomography and K-Ras mutation analyses.

Results:

Toxicities observed were manageable; the most common treatment-related toxicities (>10% of patients) were fatigue, diarrhoea, anorexia, increase in aspartate aminotransferase and alanine aminotransferase, acneiform dermatitis, headache, mucosal inflammation, nausea, dry skin, vomiting, hypertension, pruritus, proteinuria and weight loss. Of 62 patients, 6 (9.7%) had objective radiographic partial responses, with an overall response rate of 10%. Median duration of response was 9.2 months; median progression-free survival was 3.9 months.

Conclusions:

The acceptable toxicity profile and efficacy of brivanib observed in this study were promising. These findings are being further evaluated in a phase III study of brivanib plus cetuximab vs cetuximab alone in patients previously treated with combination chemotherapy for K-Ras wild-type advanced metastatic colorectal cancer.

A phase I study of BMS-582664 (brivanib alaninate), an oral dual inhibitor of VEGFR and FGFR tyrosine kinases, in combination with full-dose cetuximab in patients (pts) with advanced gastrointestinal malignancies (AGM) who failed prior therapy

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Background: Brivanib is an oral prodrug of BMS-540215, a dual tyrosine kinase inhibitor of VEGFR and FGFR signaling. Prior studies have validated both VEGF and EGF signaling pathways as targets in AGM. The MTD of single-agent brivanib is 800 mg qd (ASCO #3051, 2006). Methods: An open-label Phase I dose-escalation study of brivanib in combination with cetuximab was conducted in pts with AGM who failed prior therapy. Brivanib was given po Day 1 and qd from Day 8, starting at 320 mg. Cetuximab was given IV Day 8 (400 mg/m2) then weekly (250 mg/m2). Dose escalation of brivanib continued to 800 mg qd, when an expansion cohort for pts with colorectal cancer (CRC) was opened for additional safety and efficacy. Fresh tissue and blood sampling for biomarker and pharmacokinetic (PK) analysis was performed. FDG-PET was obtained at Baseline X 2, Days 15 and 56. Tumor response (modified WHO) was evaluated q 8 weeks. Results: 18 pts (15 CRC, 2 esophageal, 1 other) were treated with 320, 600 or 800 mg qd of brivanib in combination with cetuximab for a median of 8 weeks (range 1 - 20+). A single DLT, bilateral pulmonary emboli, occurred at 320 mg qd. Few treatment-related AEs occurred across the 3 cohorts (Table). PK/biomarker data is pending. Available FDG-PET results from measurements in 8 pts with 2–3 target lesions showed good baseline reproducibility in SUVpeak, SUVmean and SUVmax, with intra-subject CV of 3.6%, 7.2% and 9.3%, respectively. Conclusions: Brivanib in combination with full-dose cetuximab was well tolerated at ≤800 mg qd and did not result in enhancement of cetuximab associated AEs. Pre-treatment FDG-PET is a highly reproducible imaging modality.

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Immune responses induced by gene gun or intramuscular injection of DNA vaccines that express immunogenic regions of the serine repeat antigen from Plasmodium falciparum

The liver- and blood-stage-expressed serine repeat antigen (SERA) of Plasmodium falciparum is a candidate protein for a human malaria vaccine. We compared the immune responses induced in mice immunized with SERA-expressing plasmid DNA vaccines delivered by intramuscular (i.m.) injection or delivered intradermally by Gene Gun immunization. Mice were immunized with a pcdna3 plasmid encoding the entire 47-kDa domain of SERA (amino acids 17 to 382) or the N-terminal domain (amino acids 17 to 110) of SERA. Minimal antibody responses were detected following DNA vaccination with the N-terminal domain of SERA, suggesting that the N-terminal domain alone is not highly immunogenic by this route of vaccine delivery. Immunization of mice by Gene Gun delivery of the 47-kDa domain of SERA elicited a significantly higher serum antibody titer to the antigen than immunization of mice by i.m. injection with the same plasmid did. The predominant isotype subclass of the antibodies elicited to the SERA protein following i.m. and Gene Gun immunizations with SERA plasmid DNA was immunoglobulin G1. Coimmunization of mice with SERA plasmid DNA and a plasmid expressing the hepatitis B surface antigen (pCMV-s) by the i.m. route resulted in higher anti-SERA titers than those generated in mice immunized with the SERA DNA plasmid alone. Vaccination with DNA may provide a viable alternative or may be used in conjunction with protein-based subunit vaccines to maximize the efficacy of a human malaria vaccine that includes immunogenic regions of the SERA protein.