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Mathematical modelling of parasite transmission systems can provide useful information about host parasite interactions and biology and parasite population dynamics. In addition good predictive models may assist in designing control programmes to reduce the burden of human and animal disease. Model building is only the first part of the process. These models then need to be confronted with data to obtain parameter estimates and the accuracy of these estimates has to be evaluated. Estimation of parasite densities is central to this. Parasite density estimates can include the proportion of hosts infected with parasites (prevalence) or estimates of the parasite biomass within the host population (abundance or intensity estimates). Parasite density estimation is often complicated by highly aggregated distributions of parasites within the hosts. This causes additional challenges when calculating transmission parameters. Using Echinococcus spp. as a model organism, this manuscript gives a brief overview of the types of descriptors of parasite densities, how to estimate them and on the use of these estimates in a transmission model.

Purpose: This study characterized the multiple-dose pharmacokinetics of vemurafenib 240-960 mg twice daily (bid) in BRAF mutation-positive metastatic melanoma patients, using the commercial formulation (240-mg microprecipitated bulk powder film-coated tablets). Methods: Melanoma patients ( N = 52) were randomly allocated to four vemurafenib dose cohorts (240, 480, 720, or 960 mg bid for 14 days). After the day 15 morning dose, doses were interrupted until day 22, at which point patients were restarted on vemurafenib. Serial pharmacokinetic samples were collected after the morning dose on days 1, 9, and 15; trough pharmacokinetic samples were collected on day 2. Results: Vemurafenib concentration increased with multiple doses to steady state at day 15; C, AUC, and AUC increased between 3.3- and 3.8-fold across the fourfold dose range tested. Statistical analysis indicated dose proportionality across the dose range of 240-960 mg bid. Day 15 mean accumulation ratios (ratio of AUC on day 15/AUC on day 1) ranged from ~19 to 25 across cohorts. At steady state, the peak-to-trough ratio for vemurafenib exhibited a relatively flat concentration-time profile throughout the bid dosing interval. During dose interruption (days 15-22), mean vemurafenib trough concentrations decreased to minimal levels; vemurafenib exhibited a mean terminal phase half-life of 31.5-38.4 h. Conclusions: Vemurafenib plasma concentration accumulates with multiple bid doses of 240 mg. Vemurafenib exposure (AUC and C) is dose proportional over the 240- to 960-mg bid dose range and exhibits constant drug levels over the bid dosing interval. [ABSTRACT FROM AUTHOR]

BACKGROUND: A subcutaneous formulation of trastuzumab has been developed, offering potential improvements in patient convenience and resource use compared with the standard intravenous infusion of the drug. We compared the pharmacokinetic profile, efficacy, and safety of the subcutaneous and intravenous formulations in patients with HER2-positive early breast cancer. METHODS: The HannaH study was a phase 3, randomised, international, open-label, trial in the (neo)adjuvant setting. Patients with HER2-positive, operable, locally advanced or inflammatory breast cancer were randomly assigned to eight cycles of neoadjuvant chemotherapy administered concurrently with trastuzumab every 3 weeks either intravenously (8 mg/kg loading dose, 6 mg/kg maintenance dose) or subcutaneously (fixed dose of 600 mg); 1:1 ratio. Chemotherapy consisted of four cycles of docetaxel (75 mg/m(2)) followed by four cycles of fluorouracil (500 mg/m(2)), epirubicin (75 mg/m(2)), and cyclophosphamide (500 mg/m(2)), every 3 weeks. After surgery, patients continued trastuzumab to complete 1 year of treatment. Coprimary endpoints were serum trough concentration (C(trough)) at pre-dose cycle 8 before surgery (non-inferiority margin for the ratio between groups of 0·80) and pathological complete response (pCR; non-inferiority margin for the difference between groups of -12·5%), analysed in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT00950300. FINDINGS: 299 patients were randomly assigned to receive intravenous trastuzumab and 297 to receive subcutaneous trastuzumab. The geometric mean presurgery C(trough) was 51·8 [mu]g/mL (coefficient of variation 52·5%) in the intravenous group and 69·0 [mu]g/mL (55·8%) in the subcutaneous group. The geometric mean ratio of C(trough) subcutaneous to C(trough) intravenous was 1·33 (90% CI 1·24-1·44). 107 (40·7%) of 263 patients in the intravenous group and 118 (45·4%) of 260 in the subcutaneous group achieved a pCR. The difference between groups in pCR was 4·7% (95% CI -4·0 to 13·4). Thus subcutaneous trastuzumab was non-inferior to intravenous trastuzumab for both coprimary endpoints. The incidence of grade 3-5 adverse events was similar between groups. The most common of these adverse events were neutropenia (99 [33·2%] of 298 patients in the intravenous group vs 86 [29·0%] of 297 in the subcutaneous group), leucopenia (17 [5·7%] vs 12 [4·0%]), and febrile neutropenia (10 [3·4%] vs 17 [5·7%]). However, more patients had serious adverse events in the subcutaneous group (62 [21%] of 297 patients) than in the intravenous group (37 [12%] of 298); the difference was mainly attributable to infections and infestations (24 [8·1%] in the subcutaneous group vs 13 [4·4%] in the intravenous group). Four adverse events led to death (one in the intravenous group and three in the subcutaneous group), all of which occurred during the neoadjuvant phase. Of these, two-both in the subcutaneous group-were deemed to be treatment related. INTERPRETATION: Subcutaneous trastuzumab, administered over about 5 min, has a pharmacokinetic profile and efficacy non-inferior to standard intravenous administration, with a similar safety profile to intravenous trastuzumab, and therefore offers a valid treatment alternative. FUNDING: F Hoffmann-La Roche. [ABSTRACT FROM AUTHOR]