Systemic Pharmacokinetics, Safety, and Preliminary Efficacy of Topical AhR Agonist Tapinarof: Results of a Phase 1 Study

Tapinarof cream is a novel topical nonsteroidal agent that represents a unique class of anti-inflammatory molecules targeting the aryl hydrocarbon receptor. Study 201851 was an open-label, 2-cohort sequential study that assessed the systemic pharmacokinetics, safety, and efficacy of tapinarof in adults with moderate to severe atopic dermatitis. A total of 11 participants were enrolled: 5 received 2% cream, and 6 received 1% cream. Tapinarof was systemically absorbed, and measurable amounts were detected in both cohorts. Generally, plasma exposure was greater with the 2% cream and decreased from day 1 to day 21. Median T_max ranged from 1 to 4 hours. Preliminary efficacy results were similar between the 1% and 2% concentrations, with the 1% cream showing better tolerability based on 3 subjects in the 2% cohort who discontinued treatment because of systemic AEs. The efficacy and safety of 1% tapinarof support results of previous positive studies that used a different formulation. However, conclusions in the present study are limited because of the open-label design and small number of participants. The 1% cream was selected as the concentration for use in future studies because of its lower AE incidence and efficacy comparable to the 2% cream.

A randomized, double-blind, placebo-controlled trial of camicinal in Parkinson's disease

Background: Delayed gastric emptying may impair l‐dopa absorption, contributing to motor fluctuations. We evaluated the effect of camicinal (GSK962040), a gastroprokinetic, on the absorption of l‐dopa and symptoms of PD.

Methods: Phase II, double‐blind, placebo‐controlled trial. Participants were randomized to receive camicinal 50 mg once‐daily (n = 38) or placebo (n = 20) for 7 to 9 days.

Results:l‐dopa exposure was similar with coadministration of camicinal compared to placebo. Median time to maximum l‐dopa concentration was reduced, indicating more rapid absorption of l‐dopa. Camicinal resulted in significant reduction in OFF time (–2.31 hours; 95% confidence interval: –3.71, –0.90), significant increase in ON time (+1.88 hours; 95% confidence interval: 0.28, 3.48) per day, and significant decrease in mean total MDS‐UPDRS score (–12.5; 95% confidence interval: –19.67, ‐5.29). Camicinal treatment was generally well tolerated.

Conclusions: PD symptom improvement with camicinal occurred in parallel with more rapid absorption of l‐dopa. This study provides evidence of an improvement of the motor response to l‐dopa in people with PD treated with camicinal 50 mg once‐daily compared with placebo, which will require further evaluation. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

A first in human study of SB-743921, a kinesin spindle protein inhibitor, to determine pharmacokinetics, biologic effects and establish a recommended phase II dose

PURPOSE

To determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), safety, pharmacokinetics, and pharmacodynamics of SB-743921 when administered as a 1-h infusion every 21 days to patients with advanced solid tumors or relapsed/refractory lymphoma.

METHODS

Patients who failed prior standard therapy or those without any standard options were eligible. Forty-four patients were enrolled using an initial accelerated dose-escalation phase followed by a standard dose-escalation phase. An additional 20 patients were enrolled at the recommended phase II dose to obtain additional safety and pharmacokinetic data. The doses evaluated ranged from 2 to 8 mg/m(2). The pharmacokinetics of SB-743921 was evaluated at 19 time-points over 48 h following during administration during cycle 1. Toxicity was assessed by the NCI Common Terminology Criteria version 3.0. Response evaluation was performed every 6 weeks.

RESULTS

The most common and consistent DLT was neutropenia. Other DLTs observed included hypophosphatemia, pulmonary emboli, SVC syndrome, transaminitis, hyponatremia, and hyperbilirubinemia. The MTD of SB-743921 as a 1-h infusion every 21 days was established as 4 mg/m(2). The maximum plasma concentration and area under the plasma concentration time curve appeared to increase proportionally to dose. One durable objective response was seen in a patient with metastatic cholangiocarcinoma who was on treatment 11 months and 6 patients had stable disease for over four cycles.

CONCLUSIONS

The recommended phase II dose of SB-743921 on this specific schedule of a 1-h infusion every 3 weeks is 4 mg/m(2). The promising efficacy and lack of severe toxicities in this study warrant the continued development of SB-743921.

Southwest Oncology Group phase II study of ispinesib in androgen-independent prostate cancer previously treated with taxanes

PURPOSE

The mitotic spindle has proven to be an effective therapeutic target in antineoplastic efforts. In this study, we sought to assess the efficacy of ispinesib, a mitotic kinesin spindle protein (KSP) inhibitor in androgen-independent prostate cancer progressing after docetaxel.

PATIENTS AND METHODS

Patients were treated with ispinesib 18 mg/m2 every 21 days and assessed for prostate-specific antigen (PSA) and measurable disease response at regular intervals. Kinesin spindle protein expression in archival tumors, population ispinesib pharmacokinetics, and pharmacodynamic assessments of circulating lymphocytes were included.

RESULTS

The study was terminated after first stage because no responses were seen in the first 21 patients. Median duration of PSA or clinical progression-free survival was 9 weeks. Plasma concentrations of ispinesib were comparable with those observed in previous phase I investigations. Immunohistochemical analysis of archival tumor specimens did not demonstrate significant KSP expression in most of the prostate cancer cases studied. Pharmacodynamic assessments of circulating lymphocytes from patients receiving ispinesib showed an absence of monopolar spindle formation, as would be expected if the drug were having its expected effects.

CONCLUSION

Ispinesib was inactive in this study of patients with androgen-independent, and largely docetaxelresistant, prostate cancer. The lack of efficacy might be explained by the low expression of the drug target seen in prostate cancer, whereas not detecting monopolar spindles in circulating lymphocytes with drug treatment likely reflects the lack of dividing cells in peripheral blood.

Phase II study of ispinesib in recurrent or metastatic squamous cell carcinoma of the head and neck

Ispinesib (SB-715992) inhibits the mitotic kinesin spindle protein (KSP), a novel target for anticancer therapy. A phase II study was conducted to examine the efficacy of ispinesib in recurrent or metastatic head and neck squamous cell carcinoma (RMHNSC). Patients with up to one prior line of chemotherapy for RMHNSC were treated with ispinesib 18 mg/m2 IV over 1 hour every 21 days. Twenty-one patients were enrolled onto this study with a target stage I sample size of 19. Of 20 evaluable patients, no objective responses were seen and stable disease > 2 cycles was observed in five patients (25%). The median time to progression was 1.4 (95% CI 1.3-2.3) months, median survival was 3.5 (95% CI 2.8-7.8) months, and 1 year overall survival was 20% (95% CI 8.3-48.1%). The most frequent attributable grades III-V adverse events were neutropenia (60% of patients) and leukopenia (55%). The pharmacokinetic profile was consistent with results from phase I studies. Archival tissues (n = 14) demonstrated low to moderate KSP expression by immunohistochemistry. In addition, no pharmacodynamic changes were observed in peripheral blood mononuclear cells. We detected no antitumor activity of ispinesib in RMHNSC on this dosing schedule.

In vitro-in vivo correlation of hepatobiliary drug clearance in humans

The biliary clearance (Cl(biliary)) of three compounds was estimated using sandwich-cultured human hepatocytes (SCHH) and compared with Cl(biliary) values measured in vivo. Tc-99m sestamibi (MIBI) Cl(biliary) was determined in seven healthy volunteers using an oroenteric catheter to aspirate duodenal secretions, and gamma scintigraphy to determine gallbladder contraction; this technique was used previously to determine Tc-99m mebrofenin (MEB) and piperacillin (PIP) in vivo Cl(biliary). In vitro Cl(biliary) of MEB, MIBI, and PIP was quantified in SCHH as the ratio of mass excreted into bile canaliculi and area under the blood concentration-time curve (AUC) in medium. MIBI Cl(biliary) in vivo was 5.5+/-1.2 mL/min/kg (mean+/-SD). The rank order of Cl(biliary) predicted from SCHH corresponded well with the in vivo Cl(biliary) values in mL/min/kg for MEB (7.44 vs 16.1), MIBI (1.20 vs 5.51), and PIP (0.028 vs 0.032). In conclusion, the methods developed allowed for reproducible quantification of Cl(biliary) of drugs in healthy humans and prediction of Cl(biliary) from in vitro data.

Determination of the biliary excretion of piperacillin in humans using a novel method

AIM

To evaluate the applicability of a novel method to determine the biliary excretion of piperacillin.

METHODS

Healthy volunteers were administered piperacillin i.v. Duodenal aspirates were collected via a custom-made oroenteric catheter; blood and urine also were collected. Gallbladder ejection fraction (EF) was determined by gamma scintigraphy and pharmacokinetic parameters were calculated using noncompartmental analysis.

RESULTS

The fraction of the piperacillin dose excreted unchanged into bile was 1.1 +/- 0.3% (biliary clearance corrected for EF was 0.032 +/- 0.008 ml min(-1) kg(-1)).

CONCLUSIONS

This methodology can be used to determine reliably the biliary clearance of drugs that are excreted only marginally into bile. Normalization of biliary clearance for EF significantly reduces intersubject variability of this parameter.