Erdafitinib in patients with advanced solid tumours with FGFR alterations (RAGNAR): an international, single-arm, phase 2 study

BACKGROUND

FGFR alterations are reported across various malignancies and might act as oncogenic drivers in multiple histologies. Erdafitinib is an oral, selective pan-FGFR tyrosine kinase inhibitor with activity in FGFR-altered advanced urothelial carcinoma. We aimed to evaluate the safety and activity of erdafitinib in previously treated patients with FGFR-altered advanced solid tumours.

METHODS

The single-arm, phase 2 RAGNAR study was conducted at 156 investigative centres (hospitals or oncology practices that are qualified oncology study centres) across 15 countries. The study consisted of four cohorts based on tumour histology and patient age; the results reported in this Article are for the primary cohort of the study, defined as the Broad Panel Cohort, which was histology-agnostic. We recruited patients aged 12 years or older with advanced or metastatic tumours of any histology (except urothelial cancer) with predefined FGFR1-4 alterations (mutations or fusions according to local or central testing). Eligible patients had disease progression on at least one previous line of systemic therapy and no alternative standard therapy available to them, and an Eastern Cooperative Oncology Group performance status of 0-1 (or equivalent for adolescents aged 12-17 years). Patients received once-daily oral erdafitinib (8 mg/day with provision for pharmacodynamically guided up-titration to 9 mg/day) on a continuous 21-day cycle until disease progression or intolerable toxicity. The primary endpoint was objective response rate by independent review committee according to Response Evaluation Criteria In Solid Tumors (RECIST), version 1.1, or Response Assessment In Neuro-Oncology (RANO). The primary analysis was conducted on the treated population of the Broad Panel Cohort. This ongoing study is registered with ClinicalTrials.gov, number NCT04083976.

FINDINGS

Patients were recruited between Dec 5, 2019, and Feb 15, 2022. Of 217 patients treated with erdafitinib, 97 (45%) patients were female and 120 (55%) were male. The data cutoff was Aug 15, 2022. At a median follow-up of 17·9 months (IQR 13·6-23·9), an objective response was observed in 64 (30% [95% CI 24-36]) of 217 patients across 16 distinct tumour types. The most common grade 3 or higher treatment-emergent adverse events related to erdafitinib were stomatitis (25 [12%]), palmar-plantar erythrodysaesthesia syndrome (12 [6%]), and hyperphosphataemia (11 [5%]). The most commonly occurring serious treatment-related adverse events (grade 3 or higher) were stomatitis in four (2%) patients and diarrhoea in two (1%). There were no treatment-related deaths.

INTERPRETATION

RAGNAR results show clinical benefit for erdafitinib in the tumour-agnostic setting in patients with advanced solid tumours with susceptible FGFR alterations who have exhausted other treatment options. These results support the continued development of FGFR inhibitors in patients with advanced solid tumours.

FUNDING

Janssen Research & Development.

Erdafitinib in pediatric patients with advanced solid tumors with fibroblast growth factor receptor (FGFR) gene alterations: RAGNAR study pediatric cohort

TPS10058

Background: FGFR gene alterations have been observed in pediatric patients with cancers and represent potentially targetable genomic variants. Gliomas (high- and low-grade) and soft tissue sarcomas are among the pediatric solid tumors that may harbor FGFR alterations. Erdafitinib is a selective pan-FGFR inhibitor approved in patients with locally advanced or metastatic urothelial carcinoma with susceptible FGFR2/3 alterations. RAGNAR (NCT04083976) is an ongoing single-arm, open-label, phase 2 histology-agnostic study investigating the efficacy and safety of erdafitinib in patients with advanced solid tumors exhibiting FGFR alterations after failure of standard systemic therapies. Here we describe the pediatric study cohort. Methods: The pediatric cohort (n = 26, planned) includes patients (≥ 6- < 18 y) with advanced solid tumors (measurable disease per RECIST v.1.1 or RANO [brain tumors]) with FGFR mutations, gene fusions, or internal tandem duplication (patients with FGFR amplification are not eligible) identified via local test reports or central molecular testing. Eligible patients will have received ≥ 1 lines of prior systemic therapy, have exhausted or be unable to tolerate standard-of-care therapies, and have documented disease progression and measurable disease. In addition, up to 6 patients in this cohort will be allowed to be treatment naive. Children and adolescents will be treated with oral erdafitinib, allowing pharmacodynamically guided uptitration based on serum phosphate levels to maximize efficacy. Treatment will continue until progressive disease. The primary end point is overall response rate (ORR) assessed by an independent review committee. Secondary efficacy end points include ORR assessed by the investigator, duration of response, disease control rate, clinical benefit rate, progression-free survival, and overall survival. Other secondary end points are pharmacokinetic exposure parameters, incidence/severity of adverse events, and change from baseline in patient-reported health status. End-of-treatment visit will occur 30 days after the last dose of erdafitinib. A follow-up phase will continue until death, withdrawal of consent, loss to follow-up, or end of study. As of January 2022, 3 patients have been enrolled. Clinical trial information: NCT04083976.

Tumor agnostic efficacy and safety of erdafitinib in patients (pts) with advanced solid tumors with prespecified fibroblast growth factor receptor alterations (FGFRalt) in RAGNAR: Interim analysis (IA) results

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Background: Erdafitinib (erda) is an oral selective pan-FGFR tyrosine kinase inhibitor approved to treat locally advanced or metastatic urothelial carcinoma (UC) in adults with susceptible FGFR3/2alt who have progressed during or after ≥ 1 line of platinum containing chemotherapy . FGFRalt are observed across a wide range of malignancies and may function as oncogenic drivers independent of the underlying tumor type. RAGNAR (NCT04083976) is an ongoing phase 2 open label, single arm tumor agnostic trial investigating the efficacy and safety of erda in pretreated adult and pediatric pts with advanced solid tumors and FGFRalt. Here, we report results from a planned IA of RAGNAR. Methods: Pts aged ≥ 6 y with advanced or metastatic solid tumors of any histology (except UC) with predefined FGFR1-4alt (mutations/fusions based on local/central test) and documented disease progression on ≥ 1 prior line of systemic therapy (tx) and no alternative standard tx received oral erda until disease progression or intolerable toxicity. The primary end point is objective response rate (ORR) by independent review committee (IRC). Secondary end points include investigator assessed ORR, duration of response (DOR), disease control rate (DCR), clinical benefit rate (CBR), PFS, OS, and treatment emergent adverse events (TEAEs). Results: As of the IA data cutoff, 178 pts were treated (median age 56.5 y [range 12-79], median 2 prior systemic tx). Only 9.0% of pts responded to last line of tx prior to study entry. ORR by IRC was 29.2% (95% CI, 22.7-36.5). Investigator assessed ORR was 26.4% (95% CI, 20.1-33.5). Responses were observed in 14 distinct tumor types, including gliomas, thoracic, gastrointestinal, gynecological, and rare tumors (Table). ORR in pts with FGFR mutations vs fusions was comparable (26.8% vs 27.0%, respectively). Median DOR, PFS, and OS were 7.1 mo (95% CI, 5.5-9.3), 5.2 mo (95% CI, 4.0-5.6), and 10.9 mo (95% CI, 7.9-14.3), respectively; DCR was 75.3% and CBR was 48.9%. All pts experienced TEAEs, including 69.1% with grade ≥ 3. Treatment-related serious TEAEs occurred in 7.3% of pts. Conclusions: RAGNAR data show, for the first time, evidence of efficacy for erda in heavily pretreated pts with a variety of hard to treat advanced FGFR+ malignancies, including glioblastoma, pancreatic, and salivary gland cancers. Safety was consistent with the known erda safety profile. Clinical trial information: NCT04083976. [Table: see text]

A translational model-based approach to inform the choice of the dose in phase 1 oncology trials: the case study of erdafitinib

PURPOSE

Erdafitinib (JNJ-42756493, BALVERSA) is a tyrosine kinase inhibitor indicated for the treatment of advanced urothelial carcinoma. In this work, a translational model-based approach to inform the choice of the doses in phase 1 trials is illustrated.

METHODS

A pharmacokinetic (PK) model was developed to describe the time course of erdafitinib plasma concentrations in mice and rats. Data from multiple xenograft studies in mice and rats were analyzed using the Simeoni tumor growth inhibition (TGI) model. The model parameters were used to derive a range of erdafitinib exposures that might inform the choice of the doses in oncology phase 1 trials. Conversion of exposures to doses was based on preliminary PK assessments from the first-in human (FIH) study.

RESULTS

A one-compartment PK disposition model, with linear absorption and dose-dependent clearance, adequately described the PK data in both mice and rats via an allometric scaling approach. The TGI model was able to describe tumor growth dynamics, providing quantitative measurements of erdafitinib antitumor potency in mice and rats. Based on these estimates, ranges of efficacious unbound concentration were identified for erdafitinib in mice (0.642-5.364 μg/L) and rats (0.782-2.565 μg/L). Based on the FIH data, it was possible to transpose exposures into doses and doses of above 4 mg/day provided erdafitinib exposures associated with significant TGI in animals. The findings were in agreement with the results of the FIH trial, in which the first hints of clinical activities were observed at 6 mg.

CONCLUSION

The successful modeling exercise of erdafitinib preclinical data showed how translational PK-PD modeling might be a tool to help to inform the choice of the doses in FIH studies.

Erdafitinib's effect on serum phosphate justifies its pharmacodynamically guided dosing in patients with cancer

A population pharmacokinetic (PK)–pharmacodynamic (PD) model was developed using data from 345 patients with cancer. The population PK‐PD model evaluated the effect of erdafitinib total and free plasma concentrations on serum phosphate concentrations after once‐daily oral continuous (0.5–12 mg) and intermittent (10–12 mg for 7 days on/7 days off) dosing, and investigated the potential covariates affecting erdafitinib‐related changes in serum phosphate levels. Phosphate is used as a biomarker for erdafitinib's efficacy and safety: increases in serum phosphate were observed after dosing with erdafitinib, which were associated with fibroblast growth factor receptor target engagement via inhibition of renal fibroblast growth factor 23–mediated signaling. PK‐PD model‐based simulations were performed to assess the approved PD‐guided dosing algorithm of erdafitinib (8 mg once‐daily continuous dosing, with up‐titration to 9 mg based on phosphate levels [<5.5 mg/dl] and tolerability at 14–21 days of treatment). The serum phosphate concentrations increased after the first dose and reached near maximal level after 14 days of continuous treatment. Serum phosphate increased with erdafitinib free drug concentrations: doubling the free concentration resulted in a 1.8‐fold increase in drug‐related phosphate changes. Dose adjustment after at least 14 days of dosing was supported by achievement of >95% maximal serum phosphate concentration. The peak‐to‐trough fluctuation within a dosing interval was limited for serum phosphate concentrations (5.68–5.65 mg/dl on Day 14), supporting phosphate monitoring at any time relative to dosing. Baseline phosphate was higher in women, otherwise, none of the investigated covariate–parameter relationships were considered clinically relevant. Simulations suggest that the starting dose of 8‐mg with up‐titration to 9‐mg on Days 14–21 maximized the number of patients within the target serum phosphate concentrations (5.5–7 mg/dl) while limiting the number of treatment interruptions. The findings from the PK‐PD model provided a detailed understanding of the erdafitinib concentration‐related phosphate changes over time, which supports erdafitinib's dosing algorithm.

Population Pharmacokinetics of Total and Free Erdafitinib in Adult Healthy Volunteers and Cancer Patients: Analysis of Phase 1 and Phase 2 Studies

A population pharmacokinetic (PK) model was developed using data pooled from 6 clinical studies (3 in healthy volunteers and 3 in cancer patients) to characterize total and free plasma concentrations of erdafitinib following single- and multiple-dose administration, to understand clinically relevant covariates, and to quantify the inter- and intraindividual variability in erdafitinib PK. An open, linear, 3-compartment disposition model with first-order absorption and a lag time was used to describe the PK profile of total and free erdafitinib plasma concentrations. The PK of erdafitinib were linear and time independent. After oral administration, erdafitinib was rapidly absorbed, with a time to maximum concentration between 2 and 4 hours. In patients, erdafitinib total apparent oral clearance was 0.200 L/h (median free fraction = 0.24%), and the effective terminal half-life of total drug was 76.4 hours. Interindividual variability in PK parameters was moderate for oral clearance and central volume of distribution, and large for absorption rate and peripheral volume of distribution. Sex and renal function were significant covariates on free oral clearance, while weight, sex, and α₁ -acid-glycoprotein were significant on oral central volume of distribution. Age, race, and mild hepatic impairment were not significant covariates of erdafitinib exposure. Given that the magnitude of the covariate effects were within 25% of reference values and that the recommended dosing regimen of erdafitinib comprises individual dose up-titrations and reductions based on presence or absence of toxicities, the clinical relevance of the investigated covariates is expected to be limited, and no dose adjustments are warranted.

Erdafitinib in Locally Advanced or Metastatic Urothelial Carcinoma

BACKGROUND

Alterations in the gene encoding fibroblast growth factor receptor (FGFR) are common in urothelial carcinoma and may be associated with lower sensitivity to immune interventions. Erdafitinib, a tyrosine kinase inhibitor of FGFR1-4, has shown antitumor activity in preclinical models and in a phase 1 study involving patients with FGFR alterations.

METHODS

In this open-label, phase 2 study, we enrolled patients who had locally advanced and unresectable or metastatic urothelial carcinoma with prespecified FGFR alterations. All the patients had a history of disease progression during or after at least one course of chemotherapy or within 12 months after neoadjuvant or adjuvant chemotherapy. Prior immunotherapy was allowed. We initially randomly assigned the patients to receive erdafitinib in either an intermittent or a continuous regimen in the dose-selection phase of the study. On the basis of an interim analysis, the starting dose was set at 8 mg per day in a continuous regimen (selected-regimen group), with provision for a pharmacodynamically guided dose escalation to 9 mg. The primary end point was the objective response rate. Key secondary end points included progression-free survival, duration of response, and overall survival.

RESULTS

A total of 99 patients in the selected-regimen group received a median of five cycles of erdafitinib. Of these patients, 43% had received at least two previous courses of treatment, 79% had visceral metastases, and 53% had a creatinine clearance of less than 60 ml per minute. The rate of confirmed response to erdafitinib therapy was 40% (3% with a complete response and 37% with a partial response). Among the 22 patients who had undergone previous immunotherapy, the confirmed response rate was 59%. The median duration of progression-free survival was 5.5 months, and the median duration of overall survival was 13.8 months. Treatment-related adverse events of grade 3 or higher, which were managed mainly by dose adjustments, were reported in 46% of the patients; 13% of the patients discontinued treatment because of adverse events. There were no treatment-related deaths.

CONCLUSIONS

The use of erdafitinib was associated with an objective tumor response in 40% of previously treated patients who had locally advanced and unresectable or metastatic urothelial carcinoma with FGFR alterations. Treatment-related grade 3 or higher adverse events were reported in nearly half the patients. (Funded by Janssen Research and Development; BLC2001 ClinicalTrials.gov number, NCT02365597.).

Immune network for viral hepatitis B: Topological representation

The liver is a well-known immunotolerogenic environment, which provides the adequate setting for liver infectious pathogens persistence such as the hepatitis B virus (HBV). Consequently, HBV infection can derive in the development of chronic disease in a proportion of the patients. If this situation persists in time, chronic hepatitis B (CHB) would end in cirrhosis, hepatocellular carcinoma and eventually, the death of the patient. It is thought that this immunotolerogenic environment is the result of complex interactions between different elements of the immune system and the viral biology. Therefore, the purpose of this work is to unravel the mechanisms implied in the development of CHB and to design a tool able to help in the study of adequate therapies. Firstly, a conceptual framework with the main components of the immune system and viral dynamics was constructed providing an overall insight on the pathways and interactions implied in this disease. Secondly, a review of the literature was performed in a modular fashion: (i) viral dynamics, (ii) innate immune response, (iii) humoral and (iv) cellular adaptive immune responses and (v) tolerogenic aspects. Finally, the information collected was integrated into a single topological representation that could serve as the plan for the systems pharmacology model architecture. This representation can be considered as the previous unavoidable step to the construction of a quantitative model that could assist in biomarker and target identification, drug design and development, dosing optimization and disease progression analysis.

Erdafitinib (ERDA; JNJ-42756493), a pan-fibroblast growth factor receptor (FGFR) inhibitor, in patients (pts) with metastatic or unresectable urothelial carcinoma (mUC) and FGFR alterations (FGFRa): Phase 2 continuous versus intermittent dosing

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Background: Although immune checkpoint inhibitors (ICI) have improved outcomes in some pts with platinum-resistant mUC, many pts (eg, pts with TCGA luminal 1 tumors, many of whom are FGFRa) may not benefit. ERDA, a pan-FGFR (1-4) inhibitor, demonstrated promising phase 1 activity: 11 partial responses among 24 FGFRa mUC pts. We report efficacy and safety of ERDA in the ongoing global open-label phase 2 study BLC2001 (NCT02365597). Methods: Pts had measurable mUC with specific FGFR2/ FGFR3 mutations or translocations per central lab Janssen assay, ECOG 0-2, and were chemorefractory (progressed during/following ≥ 1 line of prior systemic chemo or ≤ 12 mos of [neo]adjuvant chemo). Cisplatin-ineligible, chemo-naïve pts, and prior ICI treatment were allowed. Pts were randomized 1:1 to 28-d cycles of oral 6 mg/d continuous dosing (6 C) or 10 mg/d intermittent 7 d on/7 d off dosing (10 I) ERDA; the dose was further uptitrated if no significant treatment-related adverse events (TRAEs) were observed. The primary end point was ORR. Results: 78 pts received 6 C and 33 pts received 10 I (10 I cohort stopped early) ERDA. 31 pts in 6 C arm were further uptitrated. Across arms, 50% had ≥ 2 prior lines of therapy; 93% were chemorefractory. Confirmed ORRs (RECIST 1.1) were 35% and 24%, and disease control rates (CR+PR+SD) were 74% and 73% in the 6 C and 10 I arms, respectively. Adverse events (AEs) were manageable, and there were no treatment-related deaths (Table). Treatment is ongoing in 10 pts. Conclusions: ERDA (6 C or 10 I) has promising efficacy and tolerability in pts with FGFRa mUC. Based on these results and ERDA pharmacometric modeling, dosing was optimized at 8 mg/d (continuous), and this cohort is ongoing. Phase 3 study is planned. Clinical trial information: NCT02365597. [Table: see text]

Phase I Dose-Escalation Study of JNJ-42756493, an Oral Pan–Fibroblast Growth Factor Receptor Inhibitor, in Patients With Advanced Solid Tumors

Purpose

JNJ-42756493 is an orally administered pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor. This first-in-human study evaluates the safety, pharmacokinetics, and pharmacodynamics and defines the recommended phase II dose (RP2D) of JNJ-42756493.

Patients and Methods

Eligible patients with advanced solid tumors received escalating doses of JNJ-42756493 from 0.5 to 12 mg administered continuously daily or JNJ-42756493 10 or 12 mg administered intermittently (7 days on/7 days off).

Results

Sixty-five patients were enrolled. The most common treatment-emergent adverse events included hyperphosphatemia (65%), asthenia (55%), dry mouth (45%), nail toxicity (35%), constipation (34%), decreased appetite (32%), and dysgeusia (31%). Twenty-seven patients (42%) experienced grade ≥ 3 treatment-emergent adverse events, and one dose-limiting toxicity of grade 3 ALT elevation was observed at 12 mg daily. Maximum-tolerated dose was not defined. Nine milligrams daily was considered as the initial RP2D; however, tolerability was improved with intermittent schedules, and 10 mg administered on a 7-days-on/7-days-off schedule was considered the final RP2D. Pharmacokinetics were linear, dose proportional, and predictable, with a half-life of 50 to 60 hours. Dose-dependent elevations in serum phosphate, a manifestation of pharmacodynamic effect, occurred in all patients starting at 4 mg daily. Among 23 response-evaluable patients with tumor FGFR pathway alterations, four confirmed responses and one unconfirmed partial response were observed in patients with glioblastoma and urothelial and endometrial cancer (all with FGFR2 or FGFR3 translocations); 16 patients had stable disease.

Conclusion

JNJ-42756493 administered at 10 mg on a 7-days-on/7-days-off schedule achieved exposures at which clinical responses were observed, demonstrated pharmacodynamic biomarker activity, and had a manageable safety profile.

The association between body composition and toxicities from the combination of Doxil and trabectedin in patients with advanced relapsed ovarian cancer

Emerging research suggests that body composition can predict toxicity of certain chemotherapeutic agents. We used data from a clinical study to investigate associations between body composition and combined DOXIL (pegylated liposomal doxorubicin; PLD) and trabectedin (Yondelis) treatment, an effective treatment for ovarian cancer that shows high interpatient variation in toxicity profile. Patients (n = 74) participating in a phase III randomized trial of relapsed advanced ovarian cancer receiving PLD (30 mg/m2) and trabectedin (1.1 mg/m2) were included. Muscle tissue was measured by analysis of computerized tomography images, and an extrapolation of muscle and adipose tissue to lean body mass (LBM) and fat mass (FM) were employed. Toxicity profile after cycle 1 was used and graded according to the National Cancer Institute Common Toxicity Criteria (version 3). Patients presented with a wide range of body composition. In overweight and obese patients (body mass index (BMI) ≥ 25 kg/m2, n = 48) toxicity was more prevalent in those with lower BMI (p = 0.028) and a lower FM (n = 43, p = 0.034). Although LBM alone was not predictive of toxicity, a lower FM/LBM ratio was the most powerful variable associated with toxicity (p = 0.006). A different pattern emerged among normal weight patients (n = 26) where toxicity was rare among patients with smaller BMI (<21 kg/m2). A clear association between both FM and LBM (primarily driven by FM) in explaining PLD plus trabectedin toxicity emerged, but only in individuals with excess body weight, with a lower ratio predicting higher exposure and risk for toxicity.

Population pharmacokinetic analysis of abiraterone acetate in healthy volunteers and chemotherapy-naive and chemotherapy-pretreated metastatic castration-resistant prostate cancer patients

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Background: Abiraterone acetate (AA) is an effective therapy for patients with metastatic castration-resistant prostate cancer (mCRPC). AA is metabolized to abiraterone, an androgen biosynthesis inhibitor. We performed population pharmacokinetic (PK) analyses to estimate PK parameters after a 1,000 mg/d oral dose of AA in patients with mCRPC with and without prior chemotherapy and after a one-time 1,000 mg dose in healthy volunteers, to determine consistency between groups. Methods: Studies included in analysis: COU-AA-302 (pre-chemotherapy mCRPC); COU-AA-301 and COU-AA-006 (post-docetaxel mCRPC); and COU-AA-008, COU-AA-009, and COU-AA-014 (healthy subjects). A total of 4,627 plasma concentrations from 360 subjects were analyzed using nonlinear mixed-effects modeling. Results: A two-compartment model with three-transit compartments following sequential zero-first order kinetics was used to characterize the systemic absorption of abiraterone. Absorption-related parameters were affected by food intake. Abiraterone PK was characterized by an extensive apparent clearance, which was lower in patients with mCRPC (1505 L/h) compared with healthy subjects (2240 L/h), and by large apparent central (5630 L) and peripheral volumes of distribution (17,400 L). PK of abiraterone was similar in chemotherapy-naïve and chemotherapy-pretreated patients and was characterized by a relatively high between- and within-subject variability (eg, between-subject coefficient of variation [CV%] for relative bioavailability in the clinical studies was 61.1% and the CV% for within-subject variability was 71.3%). No factors other than food intake and patient-healthy volunteer status impacted PK. Conclusions: Based on this population PK model, the recommended 1,000 mg/d dose of AA results in similar abiraterone exposure for patients with mCRPC regardless of prior chemotherapy status. The food effect on absorption-related parameters in this analysis confirms current dosing instructions for AA. Clinical trial information: NCT00638690, NCT00887198.

Relationship between abiraterone exposure, prostate-specific antigen (PSA) kinetics, and overall survival (OS) in patients with metastatic castration-resistant prostate cancer (mCRPC)

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Background: Abiraterone, the active metabolite of abiraterone acetate (AA), is an effective androgen biosynthesis inhibitor for patients with metastatic castration-resistant prostate cancer (mCRPC). We conducted a sequential exposure-biomarker-survival modeling analysis to explore the relationship between prostate-specific antigen (PSA) kinetics and overall survival (OS) and to establish the exposure response for PSA kinetics and OS in chemotherapy-naïve and -pretreated patients with mCRPC following AA administration. Methods: The exposure-PSA-survival modeling framework was based on two phase III studies, COU-AA-301 (chemotherapy-pretreated, N = 1184) and COU-AA-302 (chemotherapy-naïve, N = 1081), and included a mixed-effects tumor growth inhibition (TGI) model to describe PSA dynamics in response to AA and a Cox proportional hazards survival model to evaluate the relationship between relative risk of death and PSA dynamic end points. Results: The TGI model best described the longitudinal PSA dynamics following AA treatment. Abiraterone exposure significantly increased PSA decay rate (maximum effect of 2.72, p < 0.0001). The estimated concentration for 50% of the maximum effect (EC50) was 4.75 ng/mL. The abiraterone effect on PSA kinetics was similar in chemotherapy-naïve and -pretreated subjects, and approximately 90% of subjects had a steady-state concentration greater than the EC50. All model-predicted PSA metrics were strongly associated with OS in both populations; model-based post-treatment PSA doubling time showed the strongest association (hazard ratios approximately 0.9 in both populations). Simulations showed that the modeling framework could accurately predict the survival outcome for both studies. Conclusions: The analysis revealed a similar effect of abiraterone on PSA kinetics and association between PSA kinetics and OS in chemotherapy-naïve and -pretreated subjects, providing additional evidence for surrogacy of PSA kinetics and the use of PSA end points to indicate clinical benefit of abiraterone in subjects with mCRPC regardless of prior chemotherapy. Furthermore, the study confirmed that the recommended 1,000 mg/d dose of AA leads to adequate clinical exposure above the effective level. Clinical trial information: NCT00638690, NCT00887198.

Population pharmacokinetics and pharmacodynamics of rivaroxaban in patients with acute coronary syndromes

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Population pharmacokinetics and pharmacodynamics of rivaroxaban have been characterized in healthy subjects and in patients with total venous thromboembolism, deep vein thrombosis or atrial fibrillation.

WHAT THIS STUDY ADDS

• This article is the first description of the population pharmacokinetics (PK) and pharmacodynamics (PD) of rivaroxaban in patients with acute coronary syndrome (ACS). It is the largest population pharmacokinetic and pharmacodynamic study on rivaroxaban conducted to date (n= 2290). The PK and PK-PD relationship of rivaroxaban in patients with ACS were similar to those in other patient populations. In addition, model-based simulations showed that the influence of renal function and age on the exposure to rivaroxaban in the ACS population were similar to the findings from Phase 1 special population studies. These findings suggest that rivaroxaban has highly predictable PK-PD and may provide a consistent anticoagulant effect across the studied patient populations, which allows an accurate prediction of the dose to control anticoagulation optimally.

AIMS

The aim of this analysis was to use a population approach to facilitate the understanding of the pharmacokinetics and pharmacodynamics of rivaroxaban in patients with acute coronary syndrome (ACS) and to evaluate the influence of patient covariates on the exposure of rivaroxaban in patients with ACS. METHODS A population pharmacokinetic model was developed using pharmacokinetic samples from 2290 patients in Anti-Xa Therapy to Lower Cardiovascular Events in Addition to Standard Therapy in Subjects with Acute Coronary Syndrome Thrombolysis in Myocardial Infarction 46. The relationship between pharmacokinetics and the primary pharmacodynamic end point, prothrombin time, was evaluated.

RESULTS

The pharmacokinetics of rivaroxaban in patients with ACS was adequately described by an oral one-compartment model. The estimated absorption rate, apparent clearance and volume of distribution were 1.24 h(-1) (interindividual variability, 139%), 6.48 l h(-1) (31%) and 57.9 l (10%), respectively. Simulations indicate that the influences of renal function, age and bodyweight on exposure in ACS patients are consistent with the findings in previous Phase 1 studies. Rivaroxaban plasma concentrations exhibit a close-to-linear relationship with prothrombin time in the ACS population, with little interindividual variability. The estimated pharmacokinetic and pharmacodynamic parameters for the ACS patients were comparable to those for venous thromboembolism prevention, deep vein thrombosis and atrial fibrillation patients.

CONCLUSIONS

The similarity in pharmacokinetics/pharmacodynamics of rivaroxaban among different patient populations and the low interindividual variability in the exposure-prothrombin time relationship indicate that the anticoagulant effect of rivaroxaban is highly predictable and consistent across all the patient populations studied.

Population pharmacokinetics of tapentadol immediate release (IR) in healthy subjects and patients with moderate or severe pain

BACKGROUND

Tapentadol is a new, centrally active analgesic agent with two modes of action--mu opioid receptor agonism and norepinephrine reuptake inhibition--and the immediate-release (IR) formulation is approved in the US for the relief of moderate to severe acute pain. The aims of this analysis were to develop a population pharmacokinetic model to facilitate the understanding of the pharmacokinetics of tapentadol IR in healthy subjects and patients following single and multiple dosing, and to identify covariates that might explain variability in exposure following oral administration.

METHODS

The analysis included pooled data from 11,385 serum pharmacokinetic samples from 1827 healthy subjects and patients with moderate to severe pain. Population pharmacokinetic modelling was conducted using nonlinear mixed-effects modelling (NONMEM) software to estimate population pharmacokinetic parameters and the influence of the subjects' demographic characteristics, clinical laboratory chemistry values and disease status on these parameters. Simulations were performed to assess the clinical relevance of the covariate effects on tapentadol exposure.

RESULTS

A two-compartment model with zero-order release followed by first-order absorption and first-order elimination best described the pharmacokinetics of tapentadol IR following oral administration. The interindividual variability (coefficient of variation) in apparent oral clearance (CL/F) and the apparent central volume of distribution after oral administration were 30% and 29%, respectively. An additive error model was used to describe the residual variability in the log-transformed data, and the standard deviation values were 0.308 and 0.314 for intensively and sparsely sampled data, respectively. Covariate analysis showed that sex, age, bodyweight, race, body fat, hepatic function (using total bilirubin and total protein as surrogate markers), health status and creatinine clearance were statistically significant factors influencing the pharmacokinetics of tapentadol. Total bilirubin was a particularly important factor that influenced CL/F, which decreased by more than 60% in subjects with total bilirubin greater than 50 micromol/L.

CONCLUSIONS

The population pharmacokinetic model for tapentadol IR identified the relationship between pharmacokinetic parameters and a wide range of covariates. The simulations of tapentadol exposure with identified, statistically significant covariates demonstrated that only hepatic function (as characterized by total bilirubin and total protein) may be considered a clinically relevant factor that warrants dose adjustment. None of the other covariates are of clinical relevance, nor do they necessitate dose adjustment.

Modeling the effectiveness of paliperidone ER and olanzapine in schizophrenia: meta-analysis of 3 randomized, controlled clinical trials

The time course of Positive and Negative Syndrome Scale (PANSS) scores in adult schizophrenia patients was modeled, and the effectiveness of paliperidone extended-release tablets (paliperidone ER) and olanzapine was quantified. Data from 3 randomized, double-blind phase III studies were used. Patients received paliperidone ER (3, 6, 9, 12, or 15 mg), olanzapine 10 mg, or matched placebo once daily for 6 consecutive weeks. An indirect response model implemented using a nonlinear mixed effects approach described the time course of the PANSS. Deterioration rate was modeled as a function of baseline PANSS score, placebo, and drug effects, and the dropout effect. An exponential decrease of the placebo response was also implemented. Paliperidone ER and olanzapine treatment were characterized by a long-lasting drug effect (13%), with a larger but short-lasting placebo effect (40%) and a notable dropout rate. The covariate exploration failed to identify any clinically relevant factors. The nonparametric bootstrap analysis confirmed the acceptable precision of parameter estimates. The visual predictive check supported the model's adequacy to reproduce observed PANSS time courses. The population model describes the time course of PANSS scores in schizophrenia patients and is appropriate for use in clinical trial simulation activities.

Mechanism-based Pharmacokinetic/Pharmacodynamic Meta-analysis of Trabectedin (ET-743, Yondelis) Induced Neutropenia

Myelosuppression was found to be one of the main toxicities of trabectedin (ET-743, Yondelis) during phase I/II studies. Our objective was to develop a pharmacokinetic-pharmacodynamic (PK/PD) model that describes the time course of the absolute neutrophil counts (ANCs) in cancer patients receiving trabectedin. Data from 699 patients who received intravenous trabectedin as monotherapy (dose range: 0.006-1.8 mg/m2) as a 1-, 3-, or 24-h infusion every 21 days; 1- or 3-h infusion on days 1, 8, and 15 every 28 days; or a 1-h infusion daily for 5 consecutive days every 21 days were used to develop (N=405; ANCs=7,291) and validate (N=294; ANCs=5,029) the model. The PK/PD model comprised a trabectedin-sensitive progenitor cell compartment, linked to the peripheral blood compartment, through three transition compartments representing the maturation chain in the bone marrow. To capture the rebound effect due to endogenous growth factors, the model included a feedback mechanism. The model estimated three system-related parameters: ANC at baseline (Circ0), mean transit time in bone marrow (MTT), and a feedback parameter (gamma). A first-order process quantified by the rate constant k(e0) described the trabectedin concentrations at the effect compartment (C(e)), which were assumed to reduce the proliferation rate and/or to increase the killing rate of the progenitor cells according to the function alphaC(e)beta. The model was qualified and simulations were undertaken to evaluate the neutropenia schedule dependency and the effects of selected covariates. NONMEM software was used to perform the modeling and simulation analyses. For a typical man of 70 kg, the mean values (between-subject variability; %) of the Circ0, MTT, gamma, k(e0), alpha, and beta were estimated to be 4.46 x 10(9)/l (37.9%), 4.0 days (37.5%), 0.218 (41.8%), 2.09 h(-1) (77.9%), 2.00 l/microg (85.1%), and 1.26, respectively. Although in women, k(e0) was reduced by 29% and a 25% increase in body weight resulted in a 12.6% reduction in the beta parameter, the clinical relevance of these effects is limited. The model evaluation procedure indicated accurate prediction of the observed incidence of neutropenia grades 3 and 4 across the dosing regimens evaluated. Simulations indicated that trabectedin dose and interdose interval, but not infusion duration, are the main determinants of the neutropenia severity. The model-predicted time course of the ANC and its variability confirmed that neutropenia is reversible, of short duration, and non-cumulative. The extent and time course of neutropenia following six different dosing regimens of trabectedin were well predicted by the semiphysiological PK/PD model.

Mechanism-based PKPD model for hepatoprotective effect of dexamethasone on transient transaminitis after trabectedin (ET- 743) treatment

2545

Background: Reversible transient elevations in transaminases have been observed after trabectedin (T) administration, despite no alteration in plasma PK. A PKPD model was developed to evaluate the time course of ALT elevation, tolerance development, and covariate effects following different dosing schedules in cancer subjects. Methods: T was administered to 711 subjects as monotherapy (dose range: 0.024 - 1.8 mg/m2) as 1-, 3-, or 24-hr infusions every 21 days; 1- or 3-hr infusions on days 1, 8, and 15 every 28 days; or 1-hr infusions daily for 5 consecutive days every 21 days. Population PKPD modeling was performed with covariate evaluation [dexamethasone use (469/711 pt), ECOG PS scores (89.7% pts = 1), and BW (36–122 kg)] on PD parameters, followed by model validation. Simulations assessed the influence of dosing regimen and selected covariates on the time course of ALT and the effectiveness of the dose reduction strategy. Results: A precursor-dependent PKPD model described the temporal relationship between ALT elevation and T concentrations, where the transfer process of ALT from hepatocytes to plasma is stimulated by trabectedin plasma concentration. Overall, 66% of subjects had transaminitis. Mean predicted (%SEM) baseline ALT (ALTo) and T1/2 in plasma were 33 (5.5) U/L and 1.4 days, respectively. The magnitude of the T stimulation on the ALT transfer rate from hepatocytes to plasma was 11.2% per 100 pg/mL of trabectedin plasma concentration. Dexamethasone decreased the rate of T-induced ALT release from hepatocyte by 63% (p<0.001). Model validation results showed good concordance with the observed incidence of grade 3/4 toxicity. Simulations showed that severity of ALT elevation was dose- and schedule-dependent. The dose reduction strategy decreased the incidence of grade =3 toxicity by 13% and 39% following 2 and 4 cycles of therapy, respectively. Conclusions: A PKPD model quantifying the hepatoprotective effect of dexamethasone on transient and reversible transaminitis after T treatment has been developed. The model predicts that co-administration of dexamethasone and the suggested dose reduction strategy will enhance the safe use of T in the clinic.

No significant financial relationships to disclose.

Population Pharmacokinetic Meta-Analysis of Trabectedin (ET-743,??Yondelis??) in Cancer Patients

OBJECTIVE

To characterise the population pharmacokinetics of trabectedin (ET-743, Yondelis(R)) in cancer patients.

METHODS

A total of 603 patients (945 cycles) receiving intravenous trabectedin as monotherapy at doses ranging from 0.024 to 1.8 mg/m(2) and given as a 1-, 3- or 24-hour infusion every 21 days; a 1- or 3-hour infusion on days 1, 8 and 15 of a 28-day cycle; or a 1-hour infusion daily for 5 consecutive days every 21 days were included in the analysis. An open four-compartment pharmacokinetic model with linear elimination, linear and nonlinear distribution to the deep and shallow peripheral compartments, respectively, and a catenary compartment off the shallow compartment was developed to best describe the index dataset using NONMEM V software. The effect of selected patient covariates on trabectedin pharmacokinetics was investigated. Model evaluation was performed using goodness-of-fit plots and relative error measurements for the test dataset. Simulations were undertaken to evaluate covariate effects on trabectedin pharmacokinetics.

RESULTS

The mean (SD) trabectedin elimination half-life was approximately 180 (61.4) hours. Plasma accumulation was limited when trabectedin was given every 3 weeks. Systemic clearance (31.5 L/h, coefficient of variation 51%) was 19.2% higher in patients receiving concomitant dexamethasone. The typical values of the volume of distribution at steady state for male and female patients were 6070L and 5240L, respectively. Within the range studied, age, body size variables, AST, ALT, alkaline phosphatase, lactate dehydrogenase, total bilirubin, creatinine clearance, albumin, total protein, Eastern Cooperative Oncology Group performance status and presence of liver metastases were not statistically related to trabectedin pharmacokinetic parameters. The pharmacokinetic parameters of trabectedin were consistent across the infusion durations and dose regimens evaluated.

CONCLUSIONS

The integration of trabectedin pharmacokinetic data demonstrated linear elimination, dose-proportionality up to 1.8 mg/m(2) and time-independent pharmacokinetics. The pharmacokinetic impact of dexamethasone and sex covariates is probably limited given the moderate to large interindividual pharmacokinetic variability of trabectedin. The antiemetic and hepatoprotective effects are still a valid rationale to recommend dexamethasone as a supportive treatment for trabectedin.

Semi-physiological pharmacokinetic/pharmacodynamic (PKPD) model for trabectedin-induced neutropenia

9575

Background: Neutropenia was the trabectedin (T) dose limiting toxicity in phase I studies. The objective of the present study was to develop a semi-physiological PKPD model that describes the time course of the absolute neutrophil counts (ANC) in cancer subjects receiving trabectedin. Methods: A total of 704 subjects receiving intravenous T as monotherapy (dose range: 0.024 - 1.8 mg/m2) as a 1, 3 or 24 hr infusion every 21 days; 1 or 3 hr infusion on day 1, 8, 15 every 28 days; or a 1 hr infusion daily for 5 consecutive days every 21 days were used to develop (N=405, ANC=7253) and validate (N=299, ANC=4977) the model. The model comprised of a trabectedin-sensitive progenitor cell compartment, linked to the peripheral blood compartment, through three transition compartments representing the maturation chain in the bone marrow. To capture the rebound effect due to endogenous growth factors, the model included a feedback mechanism. The model estimated three system-related parameters: ANC at baseline (ANC0), mean transit time in bone marrow (MTT), and a feedback parameter. T concentrations at the effect compartment were assumed to reduce the proliferation rate and/or to increase the killing rate of the progenitor cells according to a sigmoid-EMax function. Model evaluation was examined using goodness of fit plots, relative error measurements, and posterior predictive checks. Computer simulations were undertaken to evaluate the neutropenia schedule dependency. Results: The mean (between subject variability, %) of the ANC0, MTT, T potency were estimated to be 4.4 × 109/L (39%), 3.99 days (40%), and 15.6 μg/L (58%), respectively. The feedback parameter, EMax and Hill coefficient were estimated to be 0.198, 154 and 1.48. Model validation procedure evidenced accurate prediction of the incidence of grade 3/4 neutropenia. Simulations indicated that T dose and interdose interval, but not infusion duration, are the main determinants of the neutropenia severity. The model predicted time course of the ANC confirmed that neutropenia is reversible, short-lasting, and non-cumulative. Conclusions: The extent and time course of neutropenia following five different dosing regimens of T were well predicted by the semi-physiological PKPD model.

[Table: see text]

Population pharmacokinetics of trabectedin (ET-743) in subjects with cancer

2030

Background: Trabectedin (T) is a DNA minor-groove intercalating agent. The objective of this study is to characterize the population pharmacokinetics of T in cancer subjects. Methods: A total of 603 subjects (945 cycles) receiving intravenous T as monotherapy at doses ranging from 0.024 to 1.8 mg/m2 and given as 1, 3 or 24 hrs infusion every 21 days; 3 hrs infusion on day 1, 8, 15 every 28 days; or 1 hr infusion daily for 5 consecutive days every 21 days were included in the analysis. An open four-compartment pharmacokinetic model with linear elimination, linear and non-linear distribution to the deep and shallow peripheral compartments, respectively, and a catenary compartment off the shallow compartment was developed to best describe a total of 4251 concentrations from 274 subjects (Index Dataset) using NONMEM V. The effect of selected covariates on T pharmacokinetics was investigated. Model was evaluated using goodness of fit plots and relative error measurements for 2362 concentrations from 329 subjects (Test Dataset). Computer simulations were undertaken to evaluate the covariate effects on T pharmacokinetics. Results: Mean (SD) of T terminal half-life was ≈180 (61.4) h. Plasma accumulation was limited when T was given every three weeks. Systemic clearance, 31.5 L/h (CV = 51%), was 19.2% higher in subjects receiving concomitant dexamethasone. Typical values of volume of distribution at steady-state for males and females were 6070 L and 5240 L, respectively. Age, body size variables, AST, ALT, LDH, creatinine clearance, albumin, total protein and presence of liver metastases were not related to T pharmacokinetics. No difference in model parameters was observed for the infusion durations evaluated. T AUC and Cmax were dose proportional for each schedule evaluated and consistent across cancer types. Conclusions: The integration of phase I/II pharmacokinetic data demonstrated T linear elimination, dose-proportionality up to 1800 μg/m2, and time-independent pharmacokinetics. Given the moderate to large interindividual variability in T pharmacokinetics, the clinical relevance of dexamethasone and gender covariates is probably limited since a substantial overlap in simulated concentration-time profiles was observed.

[Table: see text]