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 to determine the safety, pharmacokinetics and pharmacodynamics of a dual VEGFR and FGFR inhibitor, brivanib, in patients with advanced or metastatic solid tumors.

BACKGROUND: This study was designed to determine the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of brivanib in patients with advanced/metastatic solid tumors. PATIENTS AND METHODS: Ninety patients enrolled in this two-part, phase I open-label study of oral brivanib alaninate. The primary objectives of this study were (in part A) dose-limiting toxicity, maximum tolerated dose (MTD) and the lowest biologically active dose level and (in part B) the optimal dose/dose range. The secondary objectives of this study were preliminary evidence of antitumor activity, PK and PD. RESULTS: Across part A (open-label dose escalation and MTD) and part B (open-label dose optimization), 68 patients received brivanib alaninate. Brivanib demonstrated a manageable toxicity profile at doses of 180-800 mg. Most toxic effects were mild. Systemic exposure of the active moiety brivanib increased linearly ≤1000 mg/day. The MTD was 800 mg/day. Forty-four patients were treated at the MTD: 20 with 800 mg continuously, 11 with 800 mg intermittently and 13 with 400 mg b.i.d. doses. Partial responses were confirmed in two patients receiving brivanib ≥600 mg. Dynamic contrast-enhanced magnetic resonance imaging demonstrated statistically significant decreases in parameters reflecting tumor vascularity and permeability after multiple doses in the 800-mg continuous q.d. and 400-mg b.i.d. dose cohorts. CONCLUSION: In patients with advanced/metastatic cancer, brivanib demonstrates promising antiangiogenic and antitumor activity and manageable toxicity at doses ≤800 mg orally q.d., the recommended phase II study dose.

Effect of CpG methylation on isotype and magnitude of antibody responses to influenza hemagglutinin-expressing plasmid.

We previously showed that intramuscular saline DNA immunizations favor the development of an IgG2a-dominant Th1 immune response, whereas gene gun DNA immunizations stimulate the production of an IgG1-dominant Th2 immune response. Several studies have implicated immunostimulatory CpG sequences as the causative factor in the development of Th1 immune responses to saline DNA immunization. To determine whether the Th1 cytokine-inducing properties of CpG sequences in plasmid DNA (pDNA) were responsible for the induction of a Th1 immune response, in vitro methylated and untreated (nonmethylated) hemagglutinin-expressing pDNA were compared for immunogenicity. Methylation abrogated the immunostimulatory activity of pDNA for cultured splenocytes and significantly reduced antigen expression. However, methylation of pDNA was not associated with a change from the induction of IgG2a to IgG1. After immunization with the methylated plasmid, the magnitude of the immune response was reduced. However, the decline in the total antibody response matched the decline in antigen expression. The dose of DNA or the presence of lipopolysaccharide in pDNA likewise did not affect the preferential development of an IgG2a antibody response. Our findings reveal that high levels of CpG sequences are not required for raising IgG2a-predominant, Thl-biased immune responses to intramuscular injections of hemagglutinin-expressing DNA.

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.

DNA vaccines: vector design, delivery, and antigen presentation.

Inoculations with antigen-expressing plasmid DNAs (DNA vaccines) in the production of protective immune responses. Since the initial development of DNA vaccines more than 5 years ago, major strides have been made in the design of efficient vaccine vectors and in the process of vaccine delivery. However, many questions remain regarding the mechanism of cellular transfection and in the development of immune responses. This review addresses functional aspects of DNA vaccines, including vector design and delivery, as well as cellular transfection and antigen presentation.

DNA immunization for influenza virus: studies using hemagglutinin- and nucleoprotein-expressing DNAs.

DNA-based immunizations have been used to analyze the ability of DNA-expressed hemagglutinin (HA) and nucleoprotein (NP) to protect BALB/c mice against a homologous influenza virus, A/PR/8/34 (H1N1), challenge. The HA DNA, but not the NP DNA, protected mice against the lethal viral challenge. For the HA DNA, single gene gun inoculations of 0.04 microg and boosted inoculations of 0.004 microg of DNA raised complete protection. For the NP DNA, boosted gene gun immunizations of 0.4 microg of DNA and boosted intradermal or intramuscular injections of 50 microg of DNA failed to protect. The protection elicited by the HA DNA vaccine correlated with the titers of neutralizing antibody.

Different T helper cell types and antibody isotypes generated by saline and gene gun DNA immunization.

Several routes and methods of DNA immunization have been shown to generate Ab, Th cells, and CTL responses. However, few studies have directly compared the immune responses generated by different routes and methods of DNA immunization. Utilizing an influenza hemagglutinin (H1)-expressing plasmid, we compared the immune response produced by saline injection of DNA into skin or muscle, and gene gun immunization of skin or muscle. We found that saline-DNA immunization raised a predominantly Th1 response with mostly IgG2a anti-H1 Ab, while gene gun DNA immunization produced a predominantly Th2 response with mostly IgG1 anti-H1 Abs. These distinct types of immune responses were generated by the method, not the route, of DNA immunization. The initial immunization established the Th cell-type of the immune response. The Th cell-type did not change with further DNA immunizations by the same or the alternate method, or after a viral challenge. The ability to generate different Th types was not due to differences in the doses of DNA used in saline and gene gun DNA immunization. These findings have important implications for vaccine design and studies of the mechanism of Th cell differentiation.

Familial hypothyroidism caused by a nonsense mutation in the thyroid-stimulating hormone beta-subunit gene.

Hereditary hypothyroidism caused by thyroid-stimulating hormone (TSH) deficiency is a rare autosomal recessive disease. Affected individuals show symptoms of severe mental and growth retardation that can be prevented by early administration of exogenous thyroid hormone. In this paper, we describe two related Greek families with three children affected by congenital TSH-deficient hypothyroidism. Sequence analysis of the TSH beta-subunit gene (TSHB) showed that the mutation responsible for the hypothyroidism in these families is a nonsense mutation in exon 2. This mutation is a G-to-T transversion at nucleotide 94 that destroys the only TaqI site in the TSHB-coding region and gives rise to a novel 8.5-kb TaqI fragment. Restriction analysis showed that the three affected children are homozygous for the 8.5-kb allele and that the four parents and two unaffected children are heterozygous. This mutation gives rise to a truncated peptide which includes only the first 11 of 118 amino acids of the mature TSHB peptide.