Polyamines in cancer: integrating organismal metabolism and antitumour immunity.

The natural mammalian polyamines putrescine, spermidine and spermine are essential for both normal and neoplastic cell function and replication. Dysregulation of metabolism of polyamines and their requirements is common in many cancers. Both clinical and experimental depletion of polyamines have demonstrated their metabolism to be a rational target for therapy; however, the mechanisms through which polyamines can establish a tumour-permissive microenvironment are only now emerging. Recent data indicate that polyamines can play a major role in regulating the antitumour immune response, thus likely contributing to the existence of immunologically 'cold' tumours that do not respond to immune checkpoint blockade. Additionally, the interplay between the microbiota and associated tissues creates a tumour microenvironment in which polyamine metabolism, content and function can all be dramatically altered on the basis of microbiota composition, dietary polyamine availability and tissue response to its surrounding microenvironment. The goal of this Perspective is to introduce the reader to the many ways in which polyamines, polyamine metabolism, the microbiota and the diet interconnect to establish a tumour microenvironment that facilitates the initiation and progression of cancer. It also details ways in which polyamine metabolism and function can be successfully targeted for therapeutic benefit, including specifically enhancing the antitumour immune response.

Multicenter study of decitabine administered daily for 5 days every 4 weeks to adults with myelodysplastic syndromes: the alternative dosing for outpatient treatment (ADOPT) trial.

PURPOSE: Decitabine, a DNA-targeted hypomethylating agent, is approved by the United States Food and Drug Administration for treatment of patients with myelodysplastic syndromes (MDS) on a schedule of 15 mg/m(2) administered via intravenous (IV) infusion every 8 hours for 3 days. This study assessed the efficacy and safety of an alternative dosing regimen administered on an outpatient basis in academic and community-based practices. PATIENTS AND METHODS: Patients were treated with decitabine 20 mg/m(2) by IV infusion daily for 5 consecutive days every 4 weeks. Eligible patients were > or = 18 years of age and had MDS (de novo or secondary) of any French-American-British (FAB) subtype and an International Prognostic Scoring System (IPSS) score > or = 0.5. The primary end point was the overall response rate (ORR) by International Working Group (IWG 2006) criteria; secondary end points included cytogenetic responses, hematologic improvement (HI), response duration, survival, and safety. RESULTS: Ninety-nine patients were enrolled; the ORR was 32% (17 complete responses [CR] plus 15 marrow CRs [mCRs]), and the overall improvement rate was 51%, which included 18% HI. Similar response rates were observed in all FAB subtypes and IPSS risk categories. Among patients who improved, 82% demonstrated responses by the end of cycle 2. Among 33 patients assessable for a cytogenetic response, 17 (52%) experienced cytogenetic CR (n = 11) or partial response (n = 6). CONCLUSION: Decitabine given on a 5-day schedule provided meaningful clinical benefit for patients with MDS, with more than half demonstrating improvement. This suggests that decitabine can be administered in an outpatient setting with comparable efficacy and safety to the United States Food and Drug Administration-approved inpatient regimen.

Palonosetron plus dexamethasone for prevention of chemotherapy-induced nausea and vomiting in patients receiving multiple-day cisplatin chemotherapy for germ cell cancer.

GOALS OF WORK: The aims of this study were to assess the safety and antiemetic efficacy of multiple-day dosing of palonosetron plus dexamethasone in patients receiving highly emetogenic multiple-day cisplatin-based chemotherapy for germ cell tumors. MATERIALS AND METHODS: Forty-one men undergoing 5-day cisplatin-based chemotherapy for testicular cancer received palonosetron 0.25 mg IV once daily 30 min before chemotherapy on days 1, 3, and 5 plus IV dexamethasone 20 mg before chemotherapy on days 1 and 2, and 8 mg PO bid on days 6 and 7 and 4 mg bid on day 8. Safety and efficacy were assessed in 24-h intervals for 9 days. Efficacy endpoints included emesis, intensity of nausea and its interference with patient functioning, and rescue antiemetic use. A subset of patients (n = 11) was studied for electrocardiograph effects and pharmacokinetic evaluation. MAIN RESULTS: This multiple-day antiemetic regimen was safe, with headache and constipation the most common treatment-related adverse events, mostly mild. Neither adverse events nor electrocardiographic changes appeared to increase in frequency, duration, or intensity over time despite a 1.42-fold systemic accumulation of palonosetron with repeated doses. The majority of patients had no emesis at any time throughout days 1-5 (51%) or days 6-9 (83%), had no moderate-to-severe nausea, and did not require rescue medication. Most patients reported that nausea had no significant effect on daily functioning on days 1-4 (72%) and days 5-9 (85%). CONCLUSIONS: Palonosetron on days 1, 3, and 5, along with a regimen of dexamethasone, was safe and well tolerated and effectively controlled both nausea and emesis in patients undergoing 5-day cisplatin-based chemotherapy for testicular cancer.

Pharmacokinetics of palonosetron in combination with aprepitant in healthy volunteers.

BACKGROUND: Palonosetron is a second-generation 5-HT(3) receptor antagonist with a prolonged duration of action and higher receptor binding affinity than first-generation agents (ondansetron, granisetron, and dolasetron). Aprepitant is a selective antagonist of substance P/neurokinin 1 that augments the benefit of 5-HT(3) receptor antagonists in the prevention of chemotherapy-induced nausea and vomiting. METHODS: This randomized, open-label, two-way, crossover trial was designed to evaluate the effect of oral aprepitant on the pharmacokinetics and safety of a single intravenous (IV) dose of palonosetron in 12 healthy subjects. Treatment A consisted of a single IV bolus dose of palonosetron 0.25mg on day 1. Treatment B added oral aprepitant 125 mg on day 1 (30 minutes prior to palonosetron) and 80 mg on days 2 and 3. Blood for pharmacokinetic evaluations was collected through 168 hours after palonosetron administration on days 1 and 15; safety was monitored through day 22. RESULTS: Mean plasma concentration-time plots for palonosetron were virtually identical for palonosetron administered alone or with concomitant aprepitant. The ratio of geometric least-square mean values (with:without aprepitant) for C(max) was 98.6% (90% confidence interval [CI]: 61.8-157%), and for AUC(0-infinity) the ratio was 101% (90% CI: 85.6-119%). With and without aprepitant coadministration, respectively, mean plasma elimination half-life was 40 hours and 43 hours (difference: -3.0 hours; p = 0.348), mean total body clearance was 130 mL/min and 136 mL/min (difference: -5.6 mL/min; p = 0.735), and mean volume of distribution at steady-state was 410.9 L and 442.3 L (difference: -31.4 L; p = 0.463). Palonosetron alone and the palonosetron/aprepitant regimen were well tolerated. CONCLUSION: These results indicate no significant differences in pharmacokinetic parameters for palonosetron between the two treatments, and suggest that palonosetron can be safely coadministered with aprepitant with no alterations in the expected safety profile and no dosage adjustment necessary.

Evaluation of safety and pharmacokinetics of consecutive multiple-day dosing of palonosetron in healthy subjects.

This study evaluated the safety and pharmacokinetics of consecutive multiple-day dosing of palonosetron. Sixteen healthy subjects received an intravenous bolus dose of palonosetron 0.25 mg (n = 12) or placebo (n = 4) daily for 3 consecutive days. Safety was evaluated throughout the study. Serial plasma samples were collected on days 1 and 3 for pharmacokinetic determinations. Three days of dosing with palonosetron 0.25 mg was safe and well tolerated. There were no clinically significant changes from baseline in laboratory values, vital signs, physical examinations, or electrocardiogram intervals. Plasma palonosetron concentrations declined in a biphasic manner, measurable up to 168 hours after dosing on day 3. Mean terminal phase elimination half-life after day 3 dosing was 42.8 hours. The 2.1-fold accumulation of palonosetron in plasma following 3 daily doses was predictable based on elimination half-life of approximately 40 hours, and the maximum plasma concentration remained below the maximum plasma concentration previously observed after a single, well-tolerated 0.75 mg intravenous bolus dose of palonosetron.