Measurement of piperacillin plasma concentrations in cancer patients with suspected infection

Background

Piperacillin (PIP) in combination with tazobactam is commonly used for anti-infective treatment in cancer patients. PIP exerts a time-dependent killing. Thus, the maintenance of plasma concentrations above a pre-defined target concentration for a pre-defined time may be relevant for optimal efficacy. It is assumed that PIP-plasma concentrations above the clinical breakpoint of the target pathogen [Pseudomonas aeruginosa, clinical breakpoint at minimal inhibitory concentration (MIC) 16 mg/L] should be reached for 100% of the dosing interval or >4xMIC (64 mg/L) for 50% of the dosing interval. Whereas studies in the intensive-care setting have shown underdosing in patients with sepsis, little is known about PIP-plasma concentrations in cancer patients.

Methods

Data of 56 cancer patients who received piperacillin/tazobactam (PIP/TAZ, 4.5 g three times daily) as empiric therapy for suspected infection were analysed at baseline and 4 h after the infusion.

Results

Median trough concentrations in steady state [median 3 days (IQR 3–5) after start of PIP/TAZ] were 4.6 mg/L (95% CI 0.3–136.3) and median PIP-plasma concentrations 4 h after infusion were 46.2 mg/L (95% CI 10.1–285.6). A second evaluation 5 days (IQR 4–7) after start of PIP/TAZ confirmed these results: trough concentrations were 2.7 mg/L (95% CI 0.5–6.3), concentrations after 4 h 28.0 mg/L (95% CI 1.7–47.3). A good renal function was associated with lower plasma concentrations (r = ?0.388, p < 0.003). Detailed pharmacokinetic measurements in six patients showed low maximum plasma concentration (median 165 mg/L) and a rapid decline of plasma concentrations (median plasma half time 1.38 h).

Conclusion

In conclusion, piperacillin plasma concentrations in cancer patients are below target levels warranting prospective trials to investigate therapeutic drug monitoring.

     

Imatinib in myeloid/lymphoid neoplasms with eosinophilia and rearrangement of <Emphasis Type="Italic">PDGFRB</Emphasis> in chronic or blast phase

We evaluated clinical characteristics and outcome on imatinib of 22 patients with myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRB. Median age was 49 years (range 20–80), 91% were male. Fifteen different PDGFRB fusion genes were identified. Eosinophilia was absent in 4/19 (21%) cases and only 11/19 (58%) cases had eosinophils ≥1.5×10⁹/L. On imatinib, 17/17 (100%) patients in chronic phase achieved complete hematologic remission after median 2 months (range 0–13)?. Complete cytogenetic remission and/or complete molecular remission by RT-PCR were achieved in 12/13 (92%) and 12/14 patients (86%) after median 10 (range 3–34) and 19 months (range 7–110), respectively. In patients with blast phase (myeloid, n = 2; lymphoid, n = 3), treatment included combinations of imatinib (n = 5), intensive chemotherapy (n = 3), and/or allogeneic stem cell transplantation (n = 3). All 3 transplanted patients (complex karyotype, n = 2) experienced early relapse. Initially, patients were treated with imatinib 400 mg/day (n = 15) or 100 mg/day (n = 7), the dose was reduced from 400 mg/day to 100 mg/day during follow-up in 9 patients. After a median treatment of 71 months (range 1–135), the 5-year survival rate was 83%; 4/22 (18%) patients died (chronic phase; n = 2; blast phase, n = 2) due to progression (n = 3) or comorbidity while in remission (n = 1). Of note, 3/4 patients had a complex karyotype. In summary, the most important characteristics of myeloid/lymphoid neoplasms with rearrangement of PDGFRB include (a) male predominance, (b) frequent lack of hypereosinophilia, (c) presentation in chronic or blast phase, (d) rapid responses and long-term remission on low-dose imatinib, and (e) possible adverse prognostic impact of a complex karyotype.     

Dasatinib in imatinib‐resistant or ‐intolerant chronic‐phase,chronic myeloid leukemia patients: 7‐year follow‐up of study CA180‐034

Dasatinib was approved at 100 mg once daily for imatinib‐resistant or ‐intolerant patients with chronic myeloid leukemia (CML) in chronic phase, based on results of the phase 3 CA180‐034 (NCT00123474) study. Here we present the final 7‐year analysis of this pivotal study, the longest follow‐up to date of any second‐generation BCR–ABL1 tyrosine kinase inhibitor (TKI). Patients (n = 670) with imatinib‐resistant or ‐intolerant CML in chronic phase received dasatinib. Nineteen percent of patients continued on study treatment, with a greater proportion in the 100 mg once daily arm remaining on therapy. Seven‐year rates for major molecular response (MMR), progression‐free survival (PFS), and overall survival (OS) were similar across doses; MMR, PFS, and OS results were 46, 42, and 65% at 100 mg once daily, respectively. Improved PFS and OS rates were reported in patients who achieved BCR–ABL1 ≤10% at 3 and 6 months. No new safety signals were identified. The incidence of drug‐related pleural effusion was 28% at 100 mg once daily and 35% at the other three dose groups. Incidence of drug‐related pulmonary hypertension and pulmonary arterial hypertension remained low (≤3% across all doses). Arterial ischemic events occurred in ≤4% of patients across all doses. These data support the long‐term efficacy and well‐established safety profile of dasatinib for patients with imatinib‐resistant or ‐intolerant CML in chronic phase. Am. J. Hematol. 91:869–874, 2016. © 2016 Wiley Periodicals, Inc.     

Metabolism of dynorphin A(1-13)

Dynorphin A(1-13), a tridecapeptide of the endogenous opioid peptides, has modest effects in reducing mild opiate withdrawal in humans. Previous studies revealed that dynorphin also potentiates the analgesic effect of morphine in morphine-tolerant rats and mice. The therapeutic potential of dynorphin A(1-13) is limited due to extensive metabolism by human metabolic enzymes resulting in an in vivo half-life of less than one minute. Chemical modifications of dynorphin A(1-13), such as N-methylation of Tyr1 and amidation of the C-terminus have been shown to be effective in protecting against the proteolytic enzymes in human plasma. This article is a general review of the metabolism of dynorphin A(1-13) in human plasma and CSF.     

Identification of Stabilized Dynorphin Derivatives for Suppressing Tolerance in Morphine-Dependent Rats

PURPOSE: Modulatory actions on morphine-induced effects, such as tolerance and withdrawal, have been noted for dynorphin A(1-13) [Dyn A(1-13)] and similar peptides. These are currently of limited therapeutic potential due to extensive metabolism by human metabolic enzymes resulting in a half-life of less than 1 min in human plasma. The purpose of this study was to identify stabilized dynorphin A (Dyn A) derivatives, to determine their metabolic routes in human plasma, and to assess whether the pharmacodynamic activity is retained. METHODS: The stability of peptides in human plasma was tested using in vitro metabolism studies with and without enzyme inhibitors. Identification of the generated metabolites was performed by mass spectrometry after high performance liquid chromatography (HPLC) separation. The in vivo activity of a stabilized dynorphin was tested by tail-flick assay in morphine-tolerant rats. RESULTS: Though amidation of the Dyn A(1-13) was able to stop the majority of C-terminal degradation, metabolism of Dyn A(1-10) amide continued by captopril sensitive enzymes, suggesting that Dyn A(1-13) amide is a better candidate for additional stabilization. Two Dyn A(1-13) amide derivatives further stabilized at the N-terminal end, [D-Tyr1]-Dyn A(1-13) amide and [N-Met-Tyr1]-Dyn A(1-13) amide, showed half-lives in plasma of 70 and 130 min, respectively. The most stable derivative [N-Met-Tyr1]-Dyn A(1-13) amide was tested successfully for retention of the pharmacological activity in modulating antinociceptive activity. CONCLUSIONS: [N-Met-Tyr1]-Dyn A(1-13) amide showed significant stability and antinociceptive activity in the tail-flick test, thus pointing to the clinical potential of this derivative in the management of pain as well as its potential activity in suppressing opiate tolerance and withdrawal.     

Capecitabine in combination with mitomycin C in patients with gastrointestinal cancer: results of an extended multicentre phase-I trial

The aim of this study was to determine the dose-limiting toxicity (DLT) and establish the recommended dose for mitomycin C added every 3 weeks to the standard combination dose of capecitabine. Cohorts of at least three patients with pretreated gastrointestinal carcinoma received capecitabine 1000 mg m(-2) orally twice daily on days 1-14 plus i.v. bolus mitomycin C on day 1 at doses of 4, 6, 8 or 10 mg m(-2) (corresponding to dose levels I-IV). Cycles were repeated every 3 weeks. Two treatment cycles were considered for the evaluation of DLTs. Of the 53 patients enrolled, the majority had colorectal (n=27) or gastric (n=14) cancers. Patients had received a median of two lines of prior chemotherapy (34% with >/=3 lines and 87% with prior 5-FU-based therapy). At the recommended dose level (IV, n=30), grade 3 adverse events during cycles 1 and 2 were: anaemia (10%); leukopenia (3%); thrombocytopenia (3%); stomatitis/mucositis (3%); hand-foot syndrome (3%). Two patients experienced DLTs (mucositis, n=1; neutropenic fever, n=1), but there were no grade 4 events. The median dose intensity for capecitabine and mitomycin C was 100% during cycles 1 and 2 and only four patients required postponement of therapy. Of the 43 patients evaluable for efficacy, seven achieved partial and minor remissions (16%; 95% CI, 5-28%), and 12 patients (28%) had stable disease. The favourable safety profile and promising activity of the capecitabine/mitomycin C combination, even in heavily pretreated patients, warrant further evaluation in patients with advanced colorectal and gastric cancers.