An assessment of a biosensor system for the quantification of microcystins in freshwater cyanobacterial blooms

Microcystin-producing cyanobacterial blooms are a global issue threatening drinking water supplies and recreation on lakes and beaches. Direct measurement of microcystins is the only way to ensure waters have concentrations below guideline concentrations; however, analyzing water for microcystins takes several hours to days to obtain data. We tested LightDeck Diagnostics' bead beater cell lysis and two versions of the quantification system designed to give microcystin concentrations within 20 min and compared it to the standard freeze-thaw cycle lysis method and ELISA quantification. The bead beater lyser was only 30 % effective at extracting microcystins compared to freeze-thaw. When considering freeze-thaw samples analyzed in 2021, there was good agreement between ELISA and LightDeck version 2 (n = 152; R2 = 0.868), but the LightDeck slightly underestimated microcystins (slope of 0.862). However, we found poor relationships between LightDeck version 2 and ELISA in 2022 (n = 49, slopes 0.60 to 1.6; R2 < 0.6) and LightDeck version 1 (slope = 1.77 but also a high number of less than quantifiable concentrations). After the quantification issues are resolved, combining the LightDeck system with an already-proven rapid lysis method (such as microwaving) will allow beach managers and water treatment operators to make quicker, well-informed decisions.

Abstract OT1-1-03: A phase 3 randomized, double-blind trial comparing PF-05280014 + paclitaxel vs. trastuzumab + paclitaxel for treatment of HER2+ metastatic breast cancer patients

Background: PF05280014 is being developed as a potential biosimilar to trastuzumab. PF-05280014 demonstrated similarity to trastuzumab in nonclinical evaluations. In a Phase I trial in healthy volunteers, PF-05280014 pharmacokinetic characteristics and safety profile were shown to be similar to those of trastuzumab. The goal of this Phase 3 trial is to demonstrate that the efficacy and safety of PF-05280014 + paclitaxel are similar to those of trastuzumab sourced from the EU (trastuzumab-EU) + paclitaxel in women with HER2-positive metastatic breast cancer.

Trial design: In this randomized, double-blind trial, patients will be randomized 1:1 into 2 arms: PF-05280014 + paclitaxel and trastuzumab-EU + paclitaxel. Randomization will be stratified by prior adjuvant trastuzumab exposure and estrogen receptor status. The order of infusion will be PF-05280014 or trastuzumab (4 mg/kg in Cycle 1; 2 mg/kg thereafter over 90 min) first followed by paclitaxel (80 mg/m2).

Eligibility: Female patients, aged ≥18 y with confirmed HER-2 overexpressing metastatic breast cancer, ≥1measurable lesion (RECIST), Eastern Cooperative Oncology Group status 0–2, normal left ventricular ejection fraction, and normal laboratory values are eligible. Key exclusion criteria are prior systemic therapy for metastatic disease, prior cumulative dose of anthracyclines &gt;400 mg/m2, and major surgery, radiotherapy or investigational agents within 4 weeks. All subjects must provide informed consent.

Aims: The primary objective is to demonstrate the similarity in objective response rate (ORR) of PF-05280014 + paclitaxel treatment to that of trastuzumab-EU + paclitaxel. Secondary objectives include evaluating 1-year progression-free survival, safety, pharmacokinetics, and immunogenicity of these combination treatments.

Statistical methods: This study tests whether the ORR of PF-05280014 is similar to that of trastuzumab-EU, using a margin of 13%, i.e., 5% alpha for non-inferiority. Assuming 60% ORR in both arms, 600 patients (300/arm) will be needed to achieve 90% power. Assuming 10% attrition, a total of 660 patients will be randomized. The intent-to-treat (ITT) population is defined as all subjects who are randomized to receive treatment. The per-protocol population is defined as all subjects who are randomized to and receive treatment and do not have any major protocol violations and will be used for evaluation efficacy endpoints.

Accrual: The target accrual of this global trial is 660 patients.

Contact information: For further information, please contact the Director, Clinical Trials Disclosure Group, Pfizer Inc. (marla.brickman@pfizer.com).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-1-03.

Abstract OT1-1-05: A Phase I pharmacokinetics trial comparing PF-05280014 and trastuzumab in healthy volunteers (REFLECTIONS B327-01)

Background: Trastuzumab is a humanized recombinant monoclonal antibody that selectively binds the extracellular domain of human epidermal growth factor receptor 2 (HER2) and is approved for treatment of breast and gastric cancers. PF05280014 is being developed as a potential biosimilar to trastuzumab. In nonclinical evaluations, PF-05280014 has an identical amino acid sequence to trastuzumab and similar physicochemical and in vitro functional properties. The goal of this phase I trial is to demonstrate the pharmacokinetic similarity of PF-05280014 to trastuzumab sourced from both the United States (trastuzumab-US) and European Union (trastuzumab-EU).

Trial design: In this double-blind, parallel group, single dose trial, subjects will be randomized 1:1:1 into 3 arms: PF-05280014; trastuzumab-US, and trastuzumab-EU (NCT01603264).

Eligibility: Healthy male volunteers, 18–55 years of age with normal left ventricular ejection fraction are eligible. Multiple exclusion criteria common to Phase 1 trials are in effect. All subjects must provide informed consent.

Aims: The primary objectives are to demonstrate the pharmacokinetic similarity of PF-05280014 to trastuzumab-US and trastuzumab-EU. Secondary objectives include evaluating the safety, tolerability, and immunogenicity of PF-05280014 compared with US-licensed and EU-approved trastuzumab products.

Statistical methods: Pharmacokinetic similarity will be demonstrated if the 90% confidence interval of the ratio of the area under the concentration-versus-time curve from time 0 to the last time point with quantifiable concentration (AUCT) and maximum concentration (Cmax) of PF-05280014 to both trastuzumab-US and trastuzumab-EU are within 80%–125%. At least 93 subjects, 31/arm, will be needed to provide &gt;81% power to demonstrate pharmacokinetic similarity for all comparisons. The planned enrolment is 105 subjects to account for subjects who may not complete the full follow-up period. The intent-to-treat (ITT) population is defined as all subjects who are randomized to receive treatment. The modified ITT population is defined as all subjects who are randomized and receive at least one dose of treatment and will be used to assess safety, tolerability, and immunogenicity. The per-protocol population is defined as all subjects who are randomized to and receive treatment and do not have any major protocol violations and will be used for the primary evaluation of pharmacokinetic parameters.

Accrual: The target accrual is 105 subjects; present accrual is 17subjects.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT1-1-05.

The effects of gastric pH and food on the pharmacokinetics of a new oral cephalosporin, cefpodoxime proxetil

The effects of alteration of gastric pH and food on the pharmacokinetics of 200 mg doses of cefpodoxime proxetil tablets were studied in two separate randomized, open label, crossover studies in healthy subjects. In the pH study (n = 17 subjects), there was a lead-in period done under fasting conditions, followed by randomization to a four-way crossover of pentagastrin (6 micrograms/kg, subcutaneously), ranitidine (150 mg orally, 10 and 2 hours before dosing with the antibiotic), sodium bicarbonate (12.6 gm), or aluminum hydroxide (120 cc). Gastric pH was determined by nasogastric aspirates before and 10 minutes after the intervention, just before the antibiotic was given. Peak plasma concentrations (Cmax) and area under plasma concentration-time curve (AUC) were highest in fasting and pentagastrin periods and were 35% to 50% lower for all of the other periods (p less than 0.0001). Gastric pH and Cmax and AUC were inversely related (r = 0.66 and r = 0.62; p less than 0.0001 for both). In the food study (n = 16 subjects), there were two lead-in periods, one done while subjects were fasting and one while they were normal diet, followed by randomization to a four-way crossover of either high or low protein diets, or high or low fat diets. There were six meals in each diet. Dosing with the antibiotic was done at the midpoint of the fourth meal. Cmax and AUC were 22% to 34% higher for all diets than for the fasting period (p less than 0.0001), whereas the time to Cmax was unchanged. These studies demonstrated that absorption of cefpodoxime proxetil is best at low gastric pH or in the presence of food, which suggests that the role of gastrointestinal function on the pharmacokinetic profile is complex.

Porcine immunoglobulin transfer after prepartum treatment with selenium or vitamin E

Responses to prepartum injection of sows with Se and vitamin E (E) were evaluated by determining immunoglobulin (IgA, IgM, IgG) levels in the colostrum and serum of the sows and the serum of their offspring. Fifty-four sows (40 multiparous, 14 primiparous) receiving diets adequate in E and Se according to current NRC (1988) standards were randomly allotted to four treatment groups in which a single i.m. injection of saline (controls), 5 mg of Se, 1,000 IU of E, or both Se and E were given on d 100 of gestation. Sows were bled prior to and 7 d after injection, at farrowing and on d 14 and 28 of lactation. Colostral samples were collected at the initiation of farrowing. Pigs were bled 20 h postpartum and at 14 and 28 d of age. Major immunoglobulin changes in the serum of the sows due to treatment were not seen prior to parturition. Injections of Se and(or) E resulted in higher colostral IgM levels (8.4, 10.7, 9.8 and 9.6 mg/ml, respectively), but only the response from Se was significant (P less than .05). Concentrations of colostral IgA or IgG were not affected by treatment (P greater than .30). Compared with controls, all three treatments increased (P less than .10) IgM concentrations in serum from pigs at birth (28.3, 33.3, 36.0 and 33.5 mg/ml, respectively), whereas IgA and IgG concentrations were not affected (P greater than .30).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of addition of yeast culture supplement to diets of lactating cows on ruminal fermentation and microbial populations

Six ruminally fistulated Holstein cows were utilized in a randomized block design to examine effects of yeast culture supplement on ruminal metabolism and apparent digestibility. Cows were fed a diet of 40% corn silage and 60% concentrate (DM basis). Treatments were control (supplement without yeast cells) and yeast culture supplement. Treatment periods were 6 wk. Ruminal pH, ammonia, molar proportions of acetate and isovalerate, and acetate: propionate ratio were lower and molar proportions of propionate and valerate higher in cows receiving yeast. The concentration of anaerobic bacteria tended to be higher and cellulolytic bacteria concentrations were greater in cows fed yeast than in cows receiving control diet. Supplemental yeast did not affect molar proportions of isobutyrate or butyrate, total VFA, or viable yeast concentrations in ruminal fluid. Ruminal liquid dilution rate and total tract apparent digestibilities were not different between treatments. Rate of disappearance of cellulose in vitro was lower in cows receiving yeast. Less variation in ammonia concentrations and microbial numbers suggest that ruminal fermentation was more stable in cows receiving yeast culture supplement.

The effect of oral zindotrine (MDL-257), a bronchial smooth muscle relaxant, on histamine airways responsiveness in asymptomatic asthmatics

We evaluated the efficacy of an oral dosage form of the investigational smooth muscle relaxant, zindotrine, a novel pyridazine derivative, in counteracting histamine-induced bronchospasm in a group of 12 non-medicated asymptomatic asthmatics. Histamine inhalation challenges were performed before (control) and 45, 150, and 300 minutes after zindotrine (200 and 300 mg), or the corresponding dose of placebo was administered orally in a randomized, double-blind crossover fashion. When compared to the control state, the 300-mg zindotrine dose markedly lowered histamine airway responsiveness as indicated by a significant (P less than .01) increase in the inhaled histamine dose necessary to provoke a 20% decrease in the forced expired volume in one second (PD20FEV1) 45 minutes after drug administration. The PD20FEV1 then decreased linearly over time but remained higher than the control PD20FEV1 value (P less than .05) during the entire observation period. The 200-mg zindotrine dose failed to affect the PD20FEV1. Our data indicate that orally administered zindotrine lowers airways responsiveness to inhaled histamine in asymptomatic asthmatics in a dose-dependent and time-dependent fashion.

Changes in LH pulse frequency and amplitude in intact mares during the transition into the breeding season

Two groups of mares were exposed to an abrupt, artificial increase or a natural increase in daylength. In both groups, mean LH pulse frequency increased with time of year and was accompanied by a reciprocal decrease in LH pulse amplitude. A non-pulsatile pattern of LH secretion was observed in some mares sampled close to the day of ovulation. Maximum mean LH pulse frequency and the onset of the breeding season occurred earlier in those mares exposed to an abrupt artificial increase in daylength. In blood samples collected frequently, mean serum LH concentrations increased in relation to time of year. However, during 60 days before ovulation, when LH pulse frequency increased, mean daily serum LH values only increased on Day -3 before ovulation. The magnitude of the periovulatory LH rise was greater before the second than the first ovulation of the breeding season. These results support the hypothesis that, in the mare, a photoperiod-induced seasonal alteration in LH pulse frequency and/or amplitude may play a role in the onset of the breeding season.

Effects of diet concentrate level and sodium bicarbonate on site and extent of forage fiber digestion in the gastrointestinal tract of wethers

Four adult wethers (45 kg) with permanent ruminal and abomasal cannulae were used in a repeated measures Latin-square arrangement of treatments to quantitate the effects of diet concentrate level and sodium bicarbonate (NaHCO3) on site and extent of forage fiber digestion in the gastrointestinal tract. Experimental diets consisted of Kentucky-31 tall fescue hay, soybean meal and a semi-purified concentrate mixture in ratios of 95:5:0, 76:4:20, 57:3:40 and 38:2:60; NaHCO3 represented 0 or 7.5% of the concentrate mixture. Ruminal digestion (% of intake) of neutral detergent fiber (NDF) and hemicellulose decreased linearly (P less than .05), whereas acid detergent fiber (ADF) digestion responded in a cubic (P less than .05) fashion to increasing concentrate level; NaHCO3 improved ruminal digestion of NDF (P less than .10) and ADF (P less than .05), but not hemicellulose. Post-ruminal digestion (% of rumen non-degraded) of NDF and ADF tended to increase, whereas hemicellulose digestion responded in a cubic (P less than .05) fashion to increasing concentrate level; NaHCO3 decreased (P less than .05) post-ruminal digestion of all fiber fractions. Total tract digestion of NDF and ADF showed a cubic (P less than .05) response, whereas hemicellulose digestion responded in a quadratic (P less than .05) fashion to increasing concentrate level; NaHCO3 had no effect on total tract digestion of any fiber fraction. Correlations of ruminal hemicellulose digestion with mean pH (r = .33; P = .07) and minimum pH (r = .30; P = .09) were attained in a 24-h feeding cycle.(ABSTRACT TRUNCATED AT 250 WORDS)