A Relative Bioavailability, Bioequivalence, and Food Effect Study of Niraparib Tablets in Patients with Advanced Solid Tumors

PURPOSE

The poly (ADP-ribose) polymerase inhibitor niraparib is indicated as maintenance treatment in patients with certain subtypes of advanced ovarian cancer, and is being investigated in patients with other solid tumors. Niraparib is available in 100-mg capsules with a starting dosage of 200 or 300 mg/d. This study assessed the relative bioavailability (BA) and bioequivalence (BE) between a 1 × 300-mg tablet relative to 3 × 100-mg niraparib capsules. In addition, the food effect (FE) of a high-fat meal on the pharmacokinetic (PK) properties of tablet-formulated niraparib was investigated.

METHODS

This was a US-based, 3-stage, open-label, multicenter, single-crossover, randomized-sequence study. Enrolled patients were 18 years and older, with histologically or cytologically confirmed advanced solid tumors (metastatic or local) and disease progression despite standard therapy. Patients were randomly assigned 1:1 to receive niraparib 1 × 300-mg tablet or 3 × 100-mg capsules in the BA and BE stages or 1 × 300-mg tablet in a fasted or fed (high-fat meal) state in the FE stage. Across all study stages, PK parameters were assessed for 7 days after each dose (tablet or capsule) or prandial state (fasted or fed). In the BA stage, patients crossed over to the other treatment after a 7-day washout period, which was extended to 14 days in the BE and FE stages. Tolerability was assessed for patients who received any amount of niraparib.

FINDINGS

The BA-, BE-, and FE-evaluable populations comprised 23, 108, and 19 patients, respectively, who completed both treatment periods in each study stage, had sufficient concentration data to accurately estimate PK parameters without niraparib carryover, and did not experience disqualifying events. PK parameters were similar after dosing with tablet or capsule formulations; the 90% CIs of the geometric least square means for Cmax, AUC0-t, and AUC0-∞ were within the 0.80 to 1.25 BE limits. In the FE stage, Cmax, AUC0-t, and AUC0-∞ were 11%, 32%, and 28% higher, respectively, in the fed versus fasted state. The safety population included 29, 168, and 28 patients in the BA, BE, and FE stages, respectively, who received niraparib. No new safety signals were identified.

IMPLICATIONS

Niraparib tablets were found to be bioequivalent to capsules. A modest (≤32%) FE was observed with a high-fat meal, but was not considered to be clinically meaningful, given niraparib's PK variability.

CLINICALTRIALS

gov identifier: NCT03329001. (Clin Ther. 2024;46:XXX-XXX) © 2024 Elsevier HS Journals, Inc.

An Integrated Analysis of Dostarlimab Immunogenicity

Monoclonal antibodies that block the interaction between programmed cell death 1 (PD-1) and its ligand (PD-L1) have revolutionized cancer immunotherapy. However, immunogenic responses to these new therapies—such as the development of antidrug antibodies (ADAs) and neutralizing antibodies (NAbs)—may represent a significant challenge to both efficacy and safety in some patients. Dostarlimab (TSR-042) is an approved, humanized, anti-PD-1 monoclonal antibody that has shown efficacy in multiple solid tumor types. Here, we report the results of an immunogenicity analysis of dostarlimab monotherapy in patients enrolled in the GARNET trial, a multicenter, open-label, single-arm phase 1 study. Overall, 477 of 478 patients (99.8%) were included in the analysis of dostarlimab antibody prevalence, and 349 out of 478 enrolled patients (73.0%) were evaluable for treatment-emergent antibodies to dostarlimab. The incidence of treatment-emergent ADAs was 2.5% at the recommended therapeutic dose (500 mg Q3W for the first 4 doses, 1000 mg Q6W until discontinuation), which is comparable to other anti-PD-(L)1 drugs. NAbs were detected in only 1.3% of patients. In the small percentage of patients who developed ADAs, there was no evidence of altered efficacy or safety of dostarlimab at the recommended dosing regimen. These findings demonstrated that treatment with dostarlimab was associated with a low risk of eliciting clinically meaningful ADAs over the course of this study, and dostarlimab is already approved by health authorities.

Estimating postprandial glucose fluxes using hierarchical Bayes modelling

A new stochastic computational method was developed to estimate the endogenous glucose production, the meal-related glucose appearance rate (R(a meal)), and the glucose disposal (R(d)) during the meal tolerance test. A prior probability distribution was adopted which assumes smooth glucose fluxes with individualized smoothness level within the context of a Bayes hierarchical model. The new method was contrasted with the maximum likelihood method using data collected in 18 subjects with type 2 diabetes who ingested a mixed meal containing [U-¹³C]glucose. Primed [6,6-²H₂]glucose was infused in a manner that mimicked the expected endogenous glucose production. The mean endogenous glucose production, R(a meal), and R(d) calculated by the new method and maximum likelihood method were nearly identical. However, the maximum likelihood gave constant, nonphysiological postprandial endogenous glucose production in two subjects whilst the new method gave plausible estimates of endogenous glucose production in all subjects. Additionally, the two methods were compared using a simulated triple-tracer experiment in 12 virtual subjects. The accuracy of the estimates of the endogenous glucose production and R(a meal) profiles was similar [root mean square error (RMSE) 1.0±0.3 vs. 1.4±0.7 μmol/kg/min for EGP and 2.6±1.0 vs. 2.9±0.9 μmol/kg/min for R(a meal); new method vs. maximum likelihood method; P=NS, paired t-test]. The accuracy of R(d) estimates was significantly increased by the new method (RMSE 5.3±1.9 vs. 4.2±1.3; new method vs. ML method; P<0.01, paired t-test). We conclude that the new method increases plausibility of the endogenous glucose production and improves accuracy of glucose disposal compared to the maximum likelihood method.

Insulin pharmacokinetics following dosing with Technosphere insulin in subjects with chronic obstructive pulmonary disease

OBJECTIVES

Insulin exposure after inhalation has been reported to be altered significantly in subjects with chronic obstructive pulmonary disease (COPD). In this study, the rate and extent of insulin exposure was compared in healthy volunteers and subjects with COPD following administration of Technosphere * Insulin (TI), a dry powder insulin formulation for pulmonary delivery.

METHODS

Insulin pharmacokinetics were evaluated in an open-label, single-dose, hyperinsulinemic-euglycemic glucose clamp study in 19 nondiabetic, nonsmoking healthy subjects (mean age [±SD] = 50.9 ± 14.1 years, body mass index = 29.1 ± 3.5 kg/m(2), forced expiratory volume in 1 second (FEV(1)) = 3.52 ± 1.02 L) and 17 nondiabetic subjects with mild-to-moderate COPD (mean age = 60.0 ± 9.0 years, body mass index = 28.5 ± 5 kg/m(2), FEV(1) = 2.56 ± 0.83 L). Subjects received a single 30-U dose of TI. Serial blood samples were obtained for insulin and C-peptide determination through 480 min after dosing. Insulin concentrations were adjusted for endogenous insulin by C-peptide correction; pharmacokinetic parameters were estimated using the corrected values.

RESULTS

For the COPD and non-COPD groups, respectively, mean peak insulin (C(max)) was 34.7 µU/mL and 39.5 µU/mL (p = 0.29), median t(max) was 15 and 12 min (p = 0.24), and mean insulin exposure from time 0 to 240 min (AUC(0-240)) was 2037 µU/mL · min and 2279 µU/mL · min (p = 0.47). Cough was the most common respiratory adverse event observed. One instance of hypoglycemia was reported and was attributed to trial procedure.

CONCLUSIONS

The rapid insulin absorption and the resulting insulin pharmacokinetic profile following TI inhalation were not significantly altered in the mild-to-moderate COPD population studied; however, long-term safety and efficacy of TI have not been established in patients with mild or moderate COPD. Longer-term experience is needed to fully characterize the effects of COPD on insulin PK following TI administration.

Pharmacokinetic characterization of the novel pulmonary delivery excipient fumaryl diketopiperazine

BACKGROUND

Technosphere® [Bis-3,6(4-fumarylaminobutyl)-2,5-diketopiperazine (FDKP)] microparticles, the integral component of the Technosphere inhalation system, deliver drugs to the deep lung and have been used to administer insulin and glucagon-like peptide-1 via inhalation in clinical studies. Three studies were conducted to characterize FDKP pharmacokinetics, including assessments in subjects with diabetic nephropathy (DNP), in subjects with chronic liver disease (CLD), and in healthy subjects.

METHODS

An open-label, nonrandomized, two-period, fixed-sequence crossover absorption, distribution, metabolism, and excretion (ADME) study was conducted in six healthy nonsmoking men who received single intravenous and oral doses of [(14)C]FDKP solution, with serial sampling of blood, urine, feces, and expired air. Additionally, two single-dose, open-label, parallel-design studies with 20 mg of inhaled FDKP were conducted in (1) 12 diabetic subjects with normal renal function and 24 DNP subjects and (2) 12 healthy subjects and 21 CLD subjects.

RESULTS

In the ADME study, >95% of the intravenous dose and <3% of the oral dose were recovered in urine, with no evidence of metabolism. No significant pharmacokinetic differences were observed between healthy subjects and CLD subjects [geometric mean (% coefficient of variation) area under the curve from time 0 to 480 minutes (AUC(0-480)): 26,710 (34.8) and 31,477 (28.8) ng/ml·min, respectively]. Maximum observed drug concentration (C(max)) and AUC(0-480) were higher in DNP subjects than in subjects with normal renal function [C(max): 159.9 (59.4) ng/ml versus 147.0 (44.3) ng/ml; AUC(0-480): 36,869 (47.2) ng/ml·min versus 30,474 (31.8) ng/ml·min]. None of the differences observed were considered clinically significant.

CONCLUSIONS

Fumaryl diketopiperazine is predominantly cleared unchanged by the kidney with essentially no oral bioavailability. Technosphere is a safe delivery vehicle for medications administered via inhalation.

Pharmacokinetics and linear exposure of AFRESA compared with the subcutaneous injection of regular human insulin

AIM

AFRESA [Technosphere Insulin (TI); MannKind Corporation, Valencia, CA], a dry powder preparation of regular human insulin (RHI), utilizes a novel and versatile drug carrier platform that enables pulmonary administration of medications typically administered by injection. The aim of this study was to compare the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of three different inhaled doses of TI with those of subcutaneous (s.c.) RHI.

METHODS

This randomized, open-label, four-way crossover study of 11 healthy, non-smoking volunteers evaluated PK and PD profiles following single inhalations of 25, 50 or 100 U TI and 10 IU RHI administered subcutaneously using a euglycaemic clamp technique.

RESULTS

Following inhalation of TI, peak insulin concentrations (C(max)) were achieved approximately 2 h earlier than with RHI (12-17 min for TI vs. 134 min for RHI). Area under the insulin concentration-time curve (AUC) and insulin C(max) values increased with increasing TI dose. Insulin exposure, as measured by AUC, was found to be linear over the dose range studied. Compared with s.c. RHI, TI at doses of 25, 50 and 100 U showed a relative bioavailability of 25, 23 and 21%, respectively. The maximum bioeffect, as measured by the glucose infusion rate, occurred approximately 2 h earlier for all three TI doses (42, 50 and 58 min, respectively) than for s.c. RHI (171 min). No treatment-related adverse events were reported with TI.

CONCLUSION

TI is an inhaled insulin with a more rapid absorption and a more rapid elimination than subcutaneously administered RHI, resulting in a quick onset and short duration of action. Insulin exposure following TI administration was found to be linear over the dose range of 25-100 U.