A glycosylated recombinant human granulocyte colony stimulating factor produced in a novel protein production system (AVI-014) in healthy subjects: a first-in human, single dose, controlled study.

BACKGROUND: AVI-014 is an egg white-derived, recombinant, human granulocyte colony-stimulating factor (G-CSF). This healthy volunteer study is the first human investigation of AVI-014. METHODS: 24 male and female subjects received a single subcutaneous injection of AVI-014 at 4 or 8 mcg/kg. 16 control subjects received 4 or 8 mcg/kg of filgrastim (Neupogen, Amgen) in a partially blinded, parallel fashion. RESULTS: The Geometric Mean Ratio (GMR) (90% CI) of 4 mcg/kg AVI-014/filgrastim AUC(0-72 hr) was 1.00 (0.76, 1.31) and Cmax was 0.86 (0.66, 1.13). At the 8 mcg/kg dose, the AUC(0-72) GMR was 0.89 (0.69, 1.14) and Cmax was 0.76 (0.58, 0.98). A priori pharmacokinetic bioequivalence was defined as the 90% CI of the GMR bounded by 0.8-1.25. Both the white blood cell and absolute neutrophil count area under the % increase curve AUC(0-9 days) and Cmax (maximal % increase from baseline)GMR at 4 and 8 mcg/kg fell within the 0.5-2.0 a priori bound set for pharmacodynamic bioequivalence. The CD 34+ % increase curve AUC(0-9 days) and Cmax GMR for both doses was approximately 1, but 90% confidence intervals were large due to inherent variance, and this measure did not meet pharmacodynamic bioequivalence. AVI-014 demonstrated a side effect profile similar to that of filgrastim. CONCLUSION: AVI-014 has safety, pharmacokinetic, and pharmacodynamic properties comparable to filgrastim at an equal dose in healthy volunteers. These findings support further investigation in AVI-014.

Analysis of expansion of myeloid progenitors in mice to identify leukemic susceptibility genes.

The myeloid progenitor cell compartment (MPC) exhibits pronounced expansion in human myeloid leukemias. It is becoming more apparent that progression of myelodysplastic syndromes and myeloproliferative diseases to acute myelogenous leukemia is the result of defects in progenitor cell maturation. The MPC of bone marrow was analyzed in mice using a cell culture assay for measuring the relative frequency of proliferative myeloid progenitors. Response to the cytokines SCF, IL-3, and GM-CSF was determined by this assay for the leukemic mouse strain BXH-2 and ten other inbred mouse strains. Significant differences were found to exist among ten inbred mouse strains in the nature of their MPC in bone marrow, indicating the presence of genetic polymorphisms responsible for the divergence. The SWR/J and FVB/J strains show consistently low frequencies of myeloid progenitors, while the DBA/2J and SJL/J inbred strains show consistently high frequencies of myeloid progenitors within the bone marrow compartment. In addition, in silico linkage disequilibrium analysis was conducted to identify possible chromosomal regions responsible for the phenotypic variation. Given the importance of this cell compartment in leukemia progression and the soon to be released genomic sequence of 15 mouse strains, these differences may provide a valuable tool for research into leukemia.

Radiation dose delivered to the proximal penis as a predictor of the risk of erectile dysfunction after three-dimensional conformal radiotherapy for localized prostate cancer.

PURPOSE/OBJECTIVE: In this study, we evaluated in a serial manner whether radiation dose to the bulb of the penis is predictive of erectile dysfunction, ejaculatory difficulty (EJ), and overall satisfaction with sex life (quality of life) by using serial validated self-administered questionnaires. METHODS AND MATERIALS: Twenty-nine potent men with AJCC Stage II prostate cancer treated with three-dimensional conformal radiation therapy alone to a median dose 72.0 Gy (range: 66.6-79.2 Gy) were evaluated by determining the doses received by the penile bulb. The penile bulb was delineated volumetrically, and the dose-volume histogram was obtained on each patient. RESULTS: The median follow-up time was 35 months (range, 16-43 months). We found that for D(30), D(45), D(60), and D(75) (doses to a percent volume of PB: 30%, 45%, 60%, and 75%), higher than the corresponding median dose (defined as high-dose group) correlated with an increased risk of impotence (erectile dysfunction firmness score = 0) (odds ratio [OR] = 7.5, p = 0.02; OR = 7.5, p = 0.02; OR = 8.6, p = 0.008; and OR = 6.9, p = 0.015, respectively). Similarly, for EJD D(30), D(45), D(60), and D(75), doses higher than the corresponding median ones correlated with worsening ejaculatory function score (EJ = 0 or 1) (OR = 8, p = 0.013; OR = 8, p = 0.013; OR = 9.2, p = 0.015; and OR = 8, p = 0.026, respectively). For quality of life, low (< or =median dose) dose groups of patients improve over time, whereas high-dose groups of patients worsen. CONCLUSIONS: This study supports the existence of a penile bulb dose-volume relationship underlying the development of radiation-induced erectile dysfunction. Our data may guide the use of inverse treatment planning to maximize the probability of maintaining sexual potency after radiation therapy.

Analysis of reciprocal congenic lines reveals the C3H/HeJ genome to be highly resistant to ApcMin intestinal tumorigenesis.

Genetic background affects polyp development in the Multiple intestinal neoplasia (Apc(Min)) mouse model. The Modifier of Min 1 (Mom1) locus accounts for approximately 50% of the variation in polyp multiplicity. We generated reciprocal congenic lines, such that the recipient C57BL/6J (B6) strain carries a donor C3H/HeJ (C3H) Mom1 allele, and the recipient C3H strain carries a donor B6 Mom1 allele. Hybrid progeny from congenic females mated to B6 Apc(Min/+) males were analyzed. A single C3H Mom1 locus on the B6 background reduced small intestinal polyp numbers by 50% and colon polyp incidence by 66% compared to their susceptible B6 Mom1(S/S)Apc(Min/+) siblings. These findings show that the C3H genome contains a resistant Mom1(R) locus. The reciprocal congenic line, which carries the susceptible B6 Mom1(S) locus on the C3H background, reduced small intestinal polyp numbers by 80% and colon polyp incidence by 95% compared to B6 Mom1(S/S)Apc(Min/+) mice. These data demonstrate that unidentified modifiers in the C3H strain can suppress intestinal polyp multiplicity in Apc(Min/+) mice, and act in the absence of a resistant Mom1(R) locus.

Exposure-dependent inhibition of intestinal and hepatic CYP3A4 in vivo by grapefruit juice.

Consumption of typical quantities of grapefruit juice (GFJ) increases the oral bioavailability of several CYP3A4 substrates without affecting their elimination, consistent with selective inhibition of intestinal but not hepatic CYP3A4. However, increases in the AUCs of CYP3A4 substrates recently associated with the consumption of large amounts of GFJ were similar to those observed with potent inhibitors of hepatic CYP3A4. The current study compared the effects of consuming large quantities and more typical amounts of GFJ on the activity of hepatic and intestinal cytochrome P450 3A4 in vivo, employing the erythromycin breath test (EBT) and oral midazolam pharmacokinetics. This was a two-phase, randomized, placebo-controlled crossover study, with each phase conducted with a separate panel of subjects. In Phase I, 8 male volunteers were randomized to the order of receiving one glass (240 mL) of water (placebo) or double-strength (DS) GFJ tid for 2 days and then 90, 60, and 30 minutes prior to administration of probe drugs on the 3rd day. In Phase II, 16 male volunteers were randomized to the order of receiving one glass of (1) single-strength (SS) GFJ, (2) DS GFJ, and (3) water (placebo). All treatments were administered in a fasted state. There was at least a 7-day washout period between treatments. Probe drugs, administered 30 minutes or 1 hour following each treatment in Phase I or II, respectively, consisted of oral midazolam (2 mg) coadministered with IV [14G N-methyl] erythromycin (0.03 mg). The EBT was performed 20 minutes following erythromycin administration. Blood was collected during the 24 hours following probe drug administration for the analysis of midazolam pharmacokinetics. In Phase I, consumption of one glass of DS GFJ tid for 3 days increased the Cmax of midazolam 3-fold, the AUC 6-fold, and the t1/2 2-fold and decreased the amount of exhaled 14CO2 in all 8 subjects, with a mean decrease in EBT of 18%. In Phase II, consumption of one glass of DS GFJ significantly increased the AUC and Cmax of midazolam approximately 2-fold without a significant effect on the t1/2 of midazolam or the EBT. The effects of consuming one glass of SS GFJ on midazolam pharmacokinetics and the EBT were not significantly different from those of one glass of DS GFJ. It was concluded that consumption of one glass of DS GFJ tid for 3 days significantly increased the AUC, Cmax, and t1/2 of midazolam and reduced EBT values, reflecting inhibition of both hepatic and intestinal CYP3A4. In contrast, consumption of one glass of SS or DS GFJ increased midazolam AUC and Cmax, with little effect on the midazolam t1/2 and EBT values, reflecting preferential inhibition of intestinal CYP3A4. Alterations of midazolam AUC and Cmax induced by nine glasses of DS GFJ were significantly greater than those produced by one glass of SS or DS GFJ. These data suggest that GFJ inhibits intestinal and hepatic CYP3A4 in an exposure-dependent fashion and that patients taking medications that are CYP3A4 substrates are at risk for developing drug-related adverse events if they consume large amounts of grapefruit juice.

The CAST/Ei strain confers significant protection against Apc(Min) intestinal polyps, independent of the resistant modifier of Min 1 (Mom1) locus.

Intestinal adenoma development in Apc(Min) mice is influenced by genetic background. We generated a congenic line between the CAST and B6 inbred strains to study the effects of a resistant CAST background in the absence of a major modifier locus, Modifier of Min 1 (Mom1(R)). Progeny from a CAST.B6 Mom1(R/S) x B6 Apc(Min/+) intercross were 110 or 200 days of age and screened for intestinal polyps. There was a significant decrease (P < 0.0001) in polyp multiplicity and size in CASTB6F1 Mom1(R/S), Apc(Min/+) and CASTB6F1 Mom1(S/S), Apc(Min/+) progeny compared with B6 Mom1(S/S), Apc(Min/+) controls. A complete absence of colon polyps was observed in all mice heterozygous for the CAST background. These results demonstrate that the CAST strain carries dominant modifier loci, in addition to Mom1(R), that dramatically reduce polyp burden in the small intestine and eliminate polyp burden in the colon of Apc(Min) mice.