Tumor growth inhibition modeling to support the starting dose for dacomitinib.

Dacomitinib is a second-generation, irreversible EGFR tyrosine kinase inhibitor for first-line treatment of patients with metastatic non-small cell lung cancer and EGFR-activating mutations. A high rate of dose reductions in the pivotal trial led to an observed inverse exposure-response (ER) relationship with the primary end points. Three ER models were developed to determine if the starting dose from the pivotal trial, 45 mg once daily (q.d.) dose, is appropriate: a longitudinal logistic regression model for adverse event-related dose changes, a Claret tumor growth inhibition (TGI) model, and a Cox model for progression-free survival (PFS) based on the TGI model predictions. This analysis included 266 patients taking dacomitinib with a starting dose of 45 mg (N = 250) or 30 mg (N = 16) q.d. The ER relationships with the time-varying exposure metrics, most recent maximum plasma concentration (Cmax ) and average concentration (Cavg ) from the first dose, were established for the dose reduction and TGI models, respectively. The TGI model characterized the tumor inhibition over time with constant growth rate (kL  = 0.0012 years-1 ) and highly variable kill rate (kD  = 1.002 years-1 /[µg/L]θcavg , coefficient of variation [CV] = 89%) and drug resistance (λ = 14.47 years-1 , CV = 96%) leading to prolonged tumor shrinkage. The ER relationship was characterized using an exposure parameter with a power parameterization (θcavg = 0.454, p < 0.0001). The Cox model found that baseline tumor size (p = 0.0166) and week 8 tumor shrinkage rate (p = 0.0726) were the best predictors of PFS. Simulations of dose reductions and drug interruptions on tumor shrinkage over time showed greater and more prolonged tumor shrinkage with a starting dose of 45 mg q.d.

Worldwide Prevalence of Epidermal Growth Factor Receptor Mutations in Non-Small Cell Lung Cancer: A Meta-Analysis.

BACKGROUND: Identification of variable epidermal growth factor receptor (EGFR) gene mutations in non-small cell lung cancer (NSCLC) is important for the selection of appropriate targeted therapies. This meta-analysis was conducted to provide a worldwide overview of EGFR mutation and submutation (specifically exon 19 deletions, exon 21 L858R substitutions, and others) prevalence, and identify important covariates that influence EGFR mutation status in patients with advanced NSCLC to address this clinical data gap. METHODS: Embase® and MEDLINE® in Ovid were searched for studies published between 2004 and 2019 with cohorts of ≥ 50 adults with EGFR mutations, focusing on stage III/IV NSCLC (≤ 20% of patients with stage I/II NSCLC). Linear mixed-effects models were fitted to EGFR mutation endpoints using logistic transformation (logit), assuming a binomial distribution. The model included terms for an intercept reflecting European studies and further additive terms for other continents. EGFR submutations examined were exon 19 deletions, exon 21 L858R substitutions, and others. RESULTS: Of 3969 abstracts screened, 57 studies were included in the overall EGFR mutation analysis and 74 were included in the submutation analysis relative to the overall EGFR mutation population (Europe, n = 12; Asia, n = 51; North America, n = 5; Central America, n = 1; South America, n = 1; Oceania, n = 1; Global, n = 3). The final overall EGFR mutations model estimated Asian and European prevalence of 49.1% and 12.8%, respectively, and included an additive covariate for the proportion of male patients in a study. There were no significant covariates in the submutation analyses. Most submutations were actionable: exon 19 deletions (49.2% [Asia]; 48.4% [Europe]); exon 21 L858R substitutions (41.1% [Asia]; 29.9% [Europe]). CONCLUSIONS: Although EGFR mutation prevalence was higher in Asian than Western countries, data support worldwide testing for EGFR overall and submutations to inform appropriate targeted treatment decisions.

Evaluation of the Effect of Proton Pump Inhibitors on the Efficacy of Dacomitinib and Gefitinib in Patients with Advanced Non-Small Cell Lung Cancer and EGFR-Activating Mutations.

INTRODUCTION: Dacomitinib and gefitinib are irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) indicated for the first-line treatment of patients with advanced non-small cell lung cancer (NSCLC) and EGFR-activating mutations. Pharmacokinetic (PK) studies in healthy volunteers suggested that acid-reducing drugs such as proton pump inhibitors (PPI) decreased dacomitinib and gefitinib exposure by limiting the pH-dependent absorption. This analysis retrospectively evaluates the effect of concomitant PPI use on dacomitinib exposure and on progression-free survival (PFS) and overall survival (OS) in patients treated with dacomitinib 45 mg QD or gefitinib 250 mg QD in a 1:1 randomized phase 3 study (ARCHER 1050). METHODS: The analysis grouped all patients (n = 452) treated in each arm of the study as non-PPI users, PPI users, or extensive PPI users. PFS and OS data were presented by Kaplan-Meier plots and analyzed using Cox proportional hazards models. Dacomitinib exposure was compared using a linear mixed-effects model. RESULTS: Results showed that dacomitinib PFS and OS did not differ significantly when comparing PPI users (N = 59) to non-PPI users (N = 152), while extensive PPI users (N = 24) had shorter PFS [hazard ratio (HR): 1.94, p = 0.011] and OS (HR: 1.77, p = 0.027) when compared to non-PPI users. For patients treated with gefitinib, PFS did not differ significantly when comparing PPI users (N = 51) and extensive PPI users (N = 19) to non-PPI users (N = 159); however, both PPI users (HR: 1.65, p = 0.007) and extensive PPI users (HR: 1.70, p = 0.050) had shorter OS when compared to non-PPI users. Further analysis by adjusting potential confounders indicated no statistically significant differences in PFS or OS between any PPI user vs. non-PPI user groups in the dacomitinib and gefitinib arms. PPI use did not appear to affect dacomitinib exposure. CONCLUSION: In conclusion, PPI use in patients with NSCLC likely has minimal impact on dacomitinib or gefitinib efficacy despite decreased absorption of these drugs observed in PK studies. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT01774721.

Augmenting the randomized controlled trial with real-world data to aid clinical decision making in metastatic renal cell carcinoma: a systematic review and meta-analysis.

Aim: To evaluate how efficacy outcomes from real-world data (RWD) can support those from randomized controlled trials (RCTs), in the context of first-line tyrosine kinase inhibitor treatment of metastatic renal cell carcinoma. Patients & methods: PubMed, Ovid, MEDLINE and EMBASE were searched for RCTs and RWD studies with ≥50 adult patients per arm published in 2000-2017. Outcome measures were median progression-free survival, median overall survival and objective response rate. Results: A total of 13 RCTs and 22 RWD studies met eligibility criteria; 31, 28 and 25 studies, respectively, reported median progression-free survival, median overall survival and objective response rate. Summary outcome measures were similar in RWD and RCTs. Conclusion: RWD validates efficacy-based outcomes from RCTs and may provide supportive evidence to inform clinical decisions.

Sunitinib for Metastatic Renal Cell Carcinoma: A Systematic Review and Meta-Analysis of Real-World and Clinical Trials Data.

BACKGROUND: Randomized controlled trials (RCTs) have stringent inclusion criteria and may not fully represent patients seen in everyday clinical practice. Real-world data (RWD) can provide supportive evidence for the effectiveness of medical interventions in more heterogeneous populations than RCTs. Sunitinib is a widely used first-line treatment for patients with metastatic renal cell carcinoma (mRCC). OBJECTIVE: This is the first comprehensive meta-analysis to evaluate the efficacy of sunitinib using the novel approach of combining RCTs and RWD. METHODS: RCTs and RWD studies published between 2000 and 2017 were identified from PubMed, Ovid, MEDLINE, and EMBASE. Eligible studies contained a cohort of ≥ 50 adult patients with mRCC receiving first-line sunitinib treatment. The meta-analysis combined RWD and RCT treatment groups, adjusting for data type (RCT or RWD). Recorded outcomes were median progression-free survival (mPFS), median overall survival (mOS), and objective response rate (ORR). Publication bias was assessed via review of funnel plots for each outcome measure. A random effects model to account for study heterogeneity was applied to each endpoint. Sensitivity analyses evaluated the robustness of the overall estimates. RESULTS: Of the 3611 studies identified through medical database searches, 22 (15 RWD studies, 7 RCTs) met eligibility criteria and were analyzed. mPFS (18 studies), mOS (19 studies), and ORR (15 studies) were reported for aggregate measures based on 4815, 5321, and 4183 patients, respectively. Reported mPFS (RWD, 7.5-11.0 months; RCTs, 5.6-15.1 months) and ORR data (RWD, 14.0-34.6%; RCTs, 18.8-46.9%) were consistent with the overall confidence estimates (95% confidence interval [CI]) of 9.3 (8.6-10.2) months and 27.9% (24.2-32.0), respectively. Reported mOS showed greater variation in RWD (6.8-33.2 months) compared with RCTs (21.8-31.5 months), with an overall confidence estimate (95% CI) of 23.0 (19.2-27.6) months. Inspection of funnel plots and sensitivity analyses indicated that there was no publication bias for any efficacy endpoint. Sensitivity analyses showed no evidence of lack of robustness for mPFS, mOS, or ORR. Interpretation of these results is limited by differences in trial design, cohort characteristics, and missing data. CONCLUSIONS: This novel, comprehensive meta-analysis validates sunitinib as an effective first-line treatment for patients with mRCC in both RCTs and everyday clinical practice. The methodology provides a framework for future analyses combining data from RCTs and RWD.

Clinical implications of an analysis of pharmacokinetics of crizotinib coadministered with dexamethasone in patients with non-small cell lung cancer.

PURPOSE: Dexamethasone is a systemic corticosteroid and a known cytochrome P450 (CYP)3A inducer. Crizotinib is a selective tyrosine kinase inhibitor of ALK, ROS1, and MET and a substrate of CYP3A. This post hoc analysis characterized the use of concomitant CYP3A inducers with crizotinib and estimated the effect of dexamethasone use on crizotinib pharmacokinetics at steady state. METHODS: This analysis used data from four clinical studies (PROFILE 1001, 1005, 1007, and 1014) including 1690 patients with non-small cell lung cancer with ALK or ROS1 rearrangements treated with crizotinib at 250 mg twice daily. Frequency and reasons for use of concomitant CYP3A inducers, including dexamethasone, with crizotinib were characterized. Multiple steady-state trough concentrations (Ctrough,ss) of crizotinib were measured for each patient. A linear mixed-effects model was used for within-patient comparison of crizotinib Ctrough,ss between dosing of crizotinib alone and crizotinib coadministered with dexamethasone consecutively for ≥ 21 days. RESULTS: Dexamethasone was the most commonly used CYP3A inducer (30.4%). A total of 15 patients had crizotinib Ctrough,ss for both crizotinib dosing with and without dexamethasone. The adjusted geometric mean ratio of crizotinib Ctrough,ss following coadministration with dexamethasone relative to crizotinib without dexamethasone, as a percentage, was 98.2% (90% confidence interval, 79.1-122.0%). CONCLUSIONS: Crizotinib plasma exposure following coadministration with dexamethasone was similar to that when crizotinib was administered without dexamethasone, indicating dexamethasone has no effect on crizotinib exposure or efficacy. Other CYP3A inducers with similar potency would likewise have no clinically relevant effect on crizotinib exposure.

Clinical toxicity of antibody drug conjugates: a meta-analysis of payloads.

Background Antibody drug conjugates (ADCs) utilize a monoclonal antibody to deliver a cytotoxic payload specifically to tumor cells, limiting exposure to healthy tissues. Major clinical toxicities of ADCs include hematologic, hepatic, neurologic, and ophthalmic events, which are often dose-limiting. These events may be off-target effects caused by premature release of payload in circulation. A meta-analysis was performed to summarize key clinical safety data for ADCs by payload, and data permitting, establish a dose-response model for toxicity incidence as a function of payload, dose/regimen, and cancer type. Methods A literature search was performed to identify and extract data from clinical ADC studies. Toxicity incidence and severity were collected by treatment arm for anemia, neutropenia, thrombocytopenia, leukopenia, hepatic toxicity, peripheral neuropathy, and ocular toxicity. Exploratory plots, descriptive summaries, and logistic regression modelling were used to explore Grade ≥ 3 (G3/4) toxicities and assess the impact of covariates, including cancer type and dose/regimen. Results The dataset contained 70 publications; quantitative analysis included 43 studies with G3/4 toxicity information reported for the endpoints above. G3/4 anemia, neutropenia and peripheral neuropathy were consistently reported for MMAE ADCs, thrombocytopenia and hepatic toxicity for DM1, and ocular toxicity for MMAF. Safety profiles of MMAE, DM1, and DM4 ADCs differed between solid and hematologic cancers. Conclusions Published ADC clinical data is limited by non-uniform reporting for toxicity and lack of dosing information, limiting the ability to develop quantitative models relating toxicity to exposure. However, the current analysis suggests that key G3/4 toxicities of ADCs in the clinic are likely off-target and related to payload.

Clinical Implications of the Pharmacokinetics of Crizotinib in Populations of Patients with Non-Small Cell Lung Cancer.

PURPOSE: We assessed the effect of baseline patient demographic and disease characteristics on the crizotinib pharmacokinetic parameters oral clearance (CL/F), volume of distribution (V2/F), and area under the curve at steady state (AUCss) following multiple crizotinib 250-mg twice-daily dosing in patients with ALK-positive cancer. EXPERIMENTAL DESIGN: A pharmacokinetic model was fit to data from 1,214 patients. We identified statistically significant covariates (P ≤ 0.001) by evaluating their effects on CL/F and V2/F and estimated their magnitudes. RESULTS: Age, Eastern Cooperative Oncology Group performance status, aspartate aminotransferase (AST) levels, albumin levels, and smoking status had no effect on CL/F or V2/F. Statistically significant covariates were Asian race and female sex for CL/F and V2/F and body weight, creatinine clearance (CLcr), and total bilirubin for CL/F only. The model predicted that CL/F would be 9% lower or higher in a 40-kg or a 100-kg patient, respectively; 16% lower in patients with CLcr 30 mL/minute; 23% lower in Asians; and 11% lower in females than the reference patient (65-kg non-Asian male; baseline CLcr, 91.6 mL/minute; total bilirubin, 0.41 mg/dL). The effect of total bilirubin on CL/F was small. V2/F was 23% lower in Asians than non-Asians and females than males. Effects of all significant covariates on AUCss were not predicted to be clinically relevant. CONCLUSIONS: Crizotinib at a 250-mg twice-daily starting dose appears to be appropriate for all patients irrespective of age, sex, race, body weight, mild or moderate renal impairment, or hepatic function (in the range evaluated: bilirubin ≤ 2.1 mg/dL or AST ≤124 U/L). Clin Cancer Res; 22(23); 5722-8. ©2016 AACR.

Population pharmacokinetics of pegaptanib sodium (Macugen(®)) in patients with diabetic macular edema.

OBJECTIVE: Population pharmacokinetic modeling of pegaptanib was undertaken to determine influence of renal function on apparent clearance. METHODS: In a randomized, double-masked multicenter trial, intravitreal pegaptanib (0.3, 1.0, or 3.0 mg/eye) was administered in patients with diabetic macular edema every 6 weeks for 12-30 weeks. A one-compartment model with first-order absorption, distribution volume, and clearance was used to characterize the pegaptanib plasma concentration-time profile. RESULTS: In 58 patients, increases in area under the concentration-time curve (AUC) to end of the dosing interval (AUC0-tau) and maximum concentration with repeat doses were <6%, indicating minimal plasma accumulation. Sex and race did not have clinically significant effects on pegaptanib exposure. In the final model, the AUC extrapolated to infinite time and maximum concentration increased by ≥50% in older patients (aged >68 years) relative to younger patients due to decreases in creatinine clearance (CRCL), a significant predictor of clearance. Pegaptanib clearance was reduced by 29% when CRCL decreased by 50%. The change in exposure with CRCL (range, 0-190 mL/minute) was < 10-fold with 0.3-3.0 mg doses. CONCLUSION: While pegaptanib clearance and AUC were significantly influenced by CRCL, the predicted exposure in patients with renal insufficiency or renal failure shows no evidence that a dose adjustment is warranted, given the tenfold margin of safety observed over the dose range of 0.3-3.0 mg.

A model-based dose-response meta-analysis of ocular hypotensive agents as a drug development tool to evaluate new therapies in glaucoma.

PURPOSE: To characterize dose and response for intraocular pressure (IOP) reduction and incidence of hyperemia using a model-based meta-analysis of IOP-lowering monotherapy studies to evaluate new ocular antihypertensive therapies for glaucoma. METHODS: Published randomized controlled trials, regulatory documents, and sponsor reports of IOP-lowering monotherapies were used to develop dose-response models to characterize efficacy (IOP change from baseline) and safety (incidence of hyperemia) profiles. RESULTS: The meta-analysis for efficacy included 31 trials with 6,516 patients receiving bimatoprost, latanoprost, travoprost, timolol, or placebo. Estimated IOP reduction with placebo was -2.01 mmHg. Maximal IOP reduction was similar among the prostaglandin analogs (estimate, -6.27 mmHg; baseline, 25 mmHg). Estimated median effective IOP-lowering dose (ED50) was 0.002%, 0.00098%, and 0.00063% daily with bimatoprost, latanoprost, and travoprost, respectively. The hyperemia (safety) analysis included 25 trials with 6,244 patients. Typical maximal estimated difference between drug and placebo was 43%, and estimated ED50 of 0.011%, 0.014%, and 0.0015% daily for bimatoprost, latanoprost, and travoprost, respectively. Latanoprost treatment was predicted to incur the lowest rate of hyperemia of the prostaglandins, for equivalent IOP reduction. CONCLUSIONS: Model-based meta-analyses for IOP reduction and incidence of hyperemia among prostaglandin analogs are well described by maximal efficacy models and can provide a useful methodology for evaluating glaucoma therapies.

Integrating disease progression models, non-clinical pharmacokinetic data and treatment response endpoints to optimize intravitreal dosing regimens.

OBJECTIVE: To rapidly identify patients who will ultimately respond to 1 year of therapy, and optimize their inter dose interval. MATERIALS AND METHODS: An intravitreal (IVT) ophthalmic dosing paradigm was designed based on clinical efficacy, nonclinical pharmacokinetics (PK), and disease progression modeling. Relevant non-clinical PK models were used to extrapolate IVT drug concentrations to patients. RESULTS: Modeling predicted that > 80% of patients who would respond to 1 year of IVT treatment with an improvement in best-corrected visual acuity (BCVA) could be identified after the first 2 doses of treatment. These 2 initial doses produced ~ 75% of the maximum improvement in BCVA attainable. Moreover, the models also predicted those patients who responded after 1 year of treatment may tolerate an extension of the inter dose interval to 12 weeks without significant deterioration of BCVA. In contrast, > 70% of responsive patients who did not respond to 1 year of treatment showed inadequate responses after 2 doses. CONCLUSIONS: These models use data from 2 doses to identify those patients likely to benefit after 1 year of treatment, and thereafter can lengthen their inter dose interval without deleterious effects. This method identifies potential treatment responders early, and lengthens the inter dose interval during long-term administration while allowing non-responders to pursue alternative therapies earlier, thereby minimizing risk to the patient.

Population pharmacokinetics of pegaptanib in patients with neovascular, age-related macular degeneration.

The anti-vascular endothelial growth factor (VEGF) aptamer pegaptanib is eliminated primarily by renal clearance. Because renal function declines with age, pegaptanib exposure in patients with age-related macular degeneration (AMD) may increase. Therefore, a population pharmacokinetic (PK) analysis of pegaptanib was undertaken in Western and Asian AMD patients to determine the influence of renal function on apparent pegaptanib clearance (CL). Pegaptanib (0.3-3 mg per eye) was administered every 4 to 6 weeks to 262 AMD patients in 4 studies. Pegaptanib exposures (area under the concentration-time curve [AUC] and maximum plasma concentration) after 8 doses were similar to exposures following the first dose, consistent with the absence of plasma accumulation. A 1-compartment model parameterized in terms of the absorption rate constant, apparent volume of distribution, and CL was used to describe the pegaptanib plasma concentration data. Creatinine clearance (CLCR), body weight (WT), and age influenced pegaptanib PK. Decreasing CLCR from 70 to 30 mL/min doubled AUC. After adjustment for CLCR, WT, and age, the model predicted no race differences in CL or AUC. Given that the therapeutic 0.3 mg per eye dose of pegaptanib results in exposures one-tenth of those observed following the well-tolerated 3-mg dose, these results suggest that no dose adjustment is warranted for AMD patients with moderate renal insufficiency (CLCR >30 mL/min).

Validation of the Health-Related Productivity Questionnaire Diary (HRPQ-D) on a sample of patients with infectious mononucleosis: results from a phase 1 multicenter clinical trial.

The objective of this work was to assess the performance of the newly developed Health-Related Productivity Questionniare-Diary (HRPQ-D). Patients completed the HRPQ-D daily for 1-week periods during weeks 1, 2, 4, and 8 of a clinical trial for infectious mononucleosis. Productivity data were collected on a daily basis in terms of absenteeism, presenteeism, and combined lost productivity for three work venues (work outside home, housework, and classes/homework). These were then correlated with patient symptom scores. Symptom scores were positively correlated with lost work hours because of absenteeism and combined lost productivity scores. However, negative correlations were observed between symptom scores and the lost work hours due to presenteeism. The HRPQ-D demonstrated good construct validity, making it a useful tool for determining productivity levels across different work venues within clinical trial or survey research applications.

Pharmacokinetics and renal effects of cidofovir with a reduced dose of probenecid in HIV-infected patients with cytomegalovirus retinitis.

To reduce possible nephrotoxicity, intravenous prehydration with normal saline and administration of probenecid must be used with each infusing of the antiviral cidofovir. The recommended standard-dose probenecid (SDP) regimen is 2 g at 3 hours before cidofovir, then 1 g at 2 and 8 hours after cidofovir (total 4 g). A new regimen of reduced-dose probenecid (RDP), 2 g at 1 hour before cidofovir without additional probenecid administrations after infusion (total 2 g), was compared with SDP using a randomized, open-label, parallel design. A single dose of cidofovir (5 mg/kg) was given as a 1-hour infusion after saline prehydration to 24 HIV-infected patients (11 males, 13 females) with cytomegalovirus retinitis and good renal function. Blood was sampled for 48 hours and urine for 24 hours after the start of the cidofovir infusion. Cidofovir pharmacokinetics did not differ significantly between groups. Average key pharmacokinetic parameters (Cmax, tmax, lambda z, AUC0-infinity, Vss, CL, CLR, fe, ER) for RDP differed by less than 17% from SDP and were consistent with previously reported SDP data. Renal function parameters, other safety endpoints, and adverse events were similar between the groups. Therefore, the reduced-dose regimen of probenecid provided renal protection after a single dose of cidofovir and did not alter the pharmacokinetics of cidofovir in patients with moderately good renal function. Although the overall pharmacokinetic results do not show a significant difference in cidofovir exposure with the new probenecid regimen, the main issue of safety of the new dose regimen, both relating to renal toxicity and probenecid-related adverse events, is not adequately addressed in a small study.