Pazopanib Exposure Relationship with Clinical Efficacy and Safety in the Adjuvant Treatment of Advanced Renal Cell Carcinoma

Impact of bariatric surgery on oral anticancer drugs: an analysis of real-world data

PURPOSE

The number of patients with bariatric surgery who receive oral anticancer drugs is rising. Bariatric surgery may affect the absorption of oral anticancer drugs. Strikingly, no specific drug dosing recommendations are available. We aim to provide practical recommendations on the application of oral anticancer drugs in patients who underwent bariatric surgery.

METHODS

Patients with any kind of bariatric surgery were extracted retrospectively in a comprehensive cancer center. In addition, a flowchart was proposed to assess the risk of inadequate exposure to oral anticancer drugs in patients who underwent bariatric surgery. Subsequently, the flowchart was evaluated retrospectively using routine Therapeutic drug monitoring (TDM) samples.

RESULTS

In our analysis, 571 cancer patients (0.4% of 140.000 treated or referred patients) had previous bariatric surgery. Of these patients, 78 unique patients received 152 oral anticancer drugs equaling an overall number of 30 unique drugs. The 30 different prescribed oral anticancer drugs were categorized as low risk (13%), medium risk (67%), and high risk (20%) of underdosing. TDM plasma samples of 25 patients (82 samples) were available, of which 21 samples post-bariatric surgery (25%) were below the target value.

CONCLUSIONS

The proposed flowchart can support optimizing the treatment with orally administered anticancer drugs in patients who underwent bariatric surgery. We recommend performing TDM in drugs that belong to BCS classes II, III, or IV. If more risk factors are present in BCS classes II or IV, a priori switches to other drugs may be advised. In specific cases, higher dosages can be provided from the start (e.g., tamoxifen).

Evaluating the Clinical Impact and Feasibility of Therapeutic Drug Monitoring of Pazopanib in a Real-World Soft-Tissue Sarcoma Cohort

INTRODUCTION AND OBJECTIVE

Pazopanib is registered for metastatic renal cell carcinoma and soft-tissue sarcoma (STS). Its variable pharmacokinetic (PK) characteristics and narrow therapeutic range provide a strong rationale for therapeutic drug monitoring (TDM). Prior studies have defined target levels of drug exposure (≥ 20.5 mg/L) linked to prolonged progression-free survival (PFS), but the added value of using TDM remains unclear. This study investigates the effect of TDM of pazopanib in patients with STS on survival outcomes and dose-limiting toxicities (DLTs) and evaluates the feasibility of TDM-guided dosing.

METHODS

A TDM-guided cohort was compared to a non-TDM-guided cohort for PFS, overall survival (OS) and DLTs. PK samples were available from all patients, though not acted upon in the non-TDM-guided cohort. We evaluated the feasibility of TDM by comparing the proportion of underdosed patients in our TDM cohort with data from previous publications.

RESULTS

A total of 122 STS patients were included in the TDM-guided cohort (n = 95) and non-TDM-guided cohort (n = 27). The average exposure in the overall population was 30.5 mg/L and was similar in both groups. Median PFS and OS did not differ between the TDM-guided cohort and non-TDM-guided cohort (respectively 5.5 vs 4.4 months, p = 0.3, and 12.6 vs 10.1 months, p = 0.8). Slightly more patients in the non-TDM-guided cohort experienced DLTs (54%) compared to the TDM-guided cohort (44%). The proportion of underdosed patients (13.3%) was halved compared to historical data (26.7%).

CONCLUSION

TDM reduced the proportion of patients with subtherapeutic exposure levels by ~ 50%. Nonetheless, the added value of TDM for achieving target trough levels of ≥ 20.5 mg/L for pazopanib on survival outcomes could not be confirmed in STS patients.

Therapeutic Drug Monitoring of Pazopanib in Renal Cell Carcinoma and Soft Tissue Sarcoma: A Systematic Review

BACKGROUND

Pazopanib, an anti-angiogenic multitarget tyrosine kinase inhibitor, has been approved for the treatment of metastatic renal cell carcinoma and soft tissue sarcoma. However, its recommended dose does not always produce consistent outcomes, with some patients experiencing adverse effects or toxicity. This variability is due to differences in the systemic exposure to pazopanib. This review aimed to establish whether sufficient evidence exists for the routine or selective therapeutic drug monitoring of pazopanib in adult patients with approved indications.

METHODS

A systematic search of the PubMed and Web of Science databases using search terms related to pazopanib and therapeutic drug monitoring yielded 186 and 275 articles, respectively. Ten articles associated with treatment outcomes or toxicity due to drug exposure were selected for review.

RESULTS

The included studies were evaluated to determine the significance of the relationship between drug exposure/Ctrough and treatment outcomes and between drug exposure and toxicity. A relationship between exposure and treatment outcomes was observed in 5 studies, whereas the trend was nonsignificant in 4 studies. A relationship between exposure and toxicity was observed in 6 studies, whereas 2 studies did not find a significant relationship; significance was not reported in 3 studies.

CONCLUSIONS

Sufficient evidence supports the therapeutic drug monitoring of pazopanib in adult patients to improve its efficacy and/or safety in the approved indications.

Therapeutic Drug Monitoring for Tyrosine Kinase Inhibitors in Metastatic Renal Cell Carcinoma

Inter-individual variability in drug response pose significant challenges to treatment with tyrosine kinase inhibitors (TKIs) in patients with metastatic renal cell carcinoma (mRCC). TKIs meet traditional criteria for using therapeutic drug monitoring (TDM), but research is still limited. Understanding the role of TDM in individualizing treatment strategies could help optimize treatment. Here we review the state of knowledge of TDM for TKIs in mRCC treatment. A comprehensive literature review of original research studies focusing on TDM of TKIs in mRCC treatment, clinical in vivo studies reporting on pharmacokinetics-pharmacodynamics, therapeutic ranges, drug concentrations, dose adjustments, clinical outcomes, or other relevant aspects related to TDM. We reviewed studies involving human subjects published in peer-reviewed journals. A narrative synthesis approach was employed to summarize the findings. Key themes and trends related to TDM of TKIs in mRCC treatment were identified and synthesized to provide a comprehensive overview of the current state of knowledge. Our search yielded 25 articles. Most were observational. The most consistently reported association between plasma concentration and effect was pazopanib Ctrough >20 µg/mL, but this concentration was not significant across all studies. We found inconsistent evidence for sunitinib and cabozantinib. For axitinib, we found a clear exposure-response relationship, but research was too diverse to conclude on a therapeutic window to use for TDM. We found much heterogeneity between recommended time of measurement (minimum plasma concentration [Cmin], maximal plasma concentration [Cmax], area under the curve [AUC]) and large variation in plasma concentration associated with clinical outcomes, which makes it difficult to recommend specific concentration intervals based on 1 or more of these measurements. Results were more consistent with TKIs continuously administered. Further research is needed to elucidate the long-term impact of TDM to possibly establish standardized therapeutic intervals. Prospective studies are suggested. The application of TDM in TKI-combination therapy is warranted in future research.

Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Although kinase inhibitors (KI) frequently portray large interpatient variability, a 'one size fits all' regimen is still often used. In the meantime, relationships between exposure-response and exposure-toxicity have been established for several KIs, so this regimen could lead to unnecessary toxicity and suboptimal efficacy. Dose adjustments based on measured systemic pharmacokinetic levels-i.e., therapeutic drug monitoring (TDM)-could therefore improve treatment efficacy and reduce the incidence of toxicities. Therefore, the aim of this comprehensive review is to give an overview of the available evidence for TDM for the 77 FDA/EMA kinase inhibitors currently approved (as of July 1st, 2023) used in hematology and oncology. We elaborate on exposure-response and exposure-toxicity relationships for these kinase inhibitors and provide practical recommendations for TDM and discuss corresponding pharmacokinetic targets when possible.

Framework for Implementing Individualised Dosing of Anti-Cancer Drugs in Routine Care: Overcoming the Logistical Challenges

Precision medicine in oncology involves identifying the 'right drug', at the 'right dose', for the right person. Currently, many orally administered anti-cancer drugs, particularly kinase inhibitors (KIs), are prescribed at a standard fixed dose. Identifying the right dose remains one of the biggest challenges to optimal patient care. Recently the Precision Dosing Group established the Accurate Dosing of Anti-cancer Patient-centred Therapies (ADAPT) Program to address individualised dosing; thus, use existing anti-cancer drugs more safely and efficiently. In this paper, we outline our framework, based on the Medical Research Council (MRC) framework, with a simple 6-step process and strategies which have led to the successful implementation of the ADAPT program in South Australia. Implementation strategies in our 6-step process involve: (1) Evaluate the evidence and identify the cancer drugs: Literature review, shadowing other experts, establishing academic partnerships, adaptability/flexibility; (2) Establishment of analytical equipment for drug assays for clinical purposes: assessment for readiness, accreditation, feasibility, obtaining formal commitments, quality assurance to all stakeholders; (3) Clinical preparation and education: educational material, conducted educational meetings, involve opinion leaders, use of mass media, promote network weaving, conduct ongoing training; (4) Blood collection, sample preparation and analyses: goods received procedures, critical control points (transport time); (5) Interpret and release results with recommendations: facilitate the relay of clinical data to providers; (6) Clinical application: providing ongoing consultation, identify early adopters, identify, and prepare champions. These strategies were selected from the 73 implementation strategies outlined in the Expert Recommendations for Implementing Change (ERIC) study. The ADAPT program currently provides routine plasma concentrations for patients on several orally administered drugs in South Australia and is currently in its evaluation phase soon to be published. Our newly established framework could provide great potential and opportunities to advance individualised dosing of oral anti-cancer drugs in routine clinical care.

Therapeutic Drug Monitoring of Tyrosine Kinase Inhibitors in the Treatment of Advanced Renal Cancer

Seven tyrosine kinase inhibitor compounds with anti-angiogenic properties remain key drugs to treat advanced renal cell carcinoma. There is a strong rationale to develop therapeutic drug monitoring for these drugs. General considerations of such monitoring of the several groups of anticancer drugs are given, with a focus on oral therapy. Pharmacokinetics and the factors of inter- and intraindividual variabilities of these tyrosine kinase inhibitors are described together with an exhaustive presentation of their pharmacokinetic/pharmacodynamic relationships. The latter was observed in studies where every patient was treated with the same dose, and the results of several prospective studies based on dose individualization support the practice of increasing individual dosage in case of low observed plasma drug concentrations. Finally, the benefits and limits of therapeutic drug monitoring as a routine practice are discussed.

Therapeutic drug monitoring-based precision dosing of oral targeted therapies in oncology: a prospective multicenter study

BACKGROUND

Oral targeted therapies show a high pharmacokinetic (PK) interpatient variability. Even though exposure has been positively correlated with efficacy for many of these drugs, these are still dosed using a one-size-fits-all approach. Consequently, individuals have a high probability to be either underexposed or overexposed, potentially leading to suboptimal outcomes. Therapeutic drug monitoring, which is personalized dosing based on measured systemic drug concentrations, could address these problems.

PATIENTS AND METHODS

Patients were enrolled in this prospective multicenter study (www.trialregister.nl; NL6695) if they started treatment with one of the 24 participating oral targeted therapies. Primary outcome was to halve the proportion of underexposed patients, compared with historical data. PK sampling was carried out after 4, 8 and 12 weeks, and every 12 weeks thereafter. In case of Cmin below the predefined target and manageable toxicity, a pharmacokinetically guided intervention was proposed (i.e. checking compliance and drug-drug interactions, concomitant intake with food, splitting intake moments or dose increments).

RESULTS

In total, 600 patients were included of whom 426 patients are assessable for the primary outcome and 552 patients had ≥1 PK sample(s) available and were therefore assessable for the overall analyses. Pharmacokinetically guided dosing reduced the proportion of underexposed patients at the third PK measurement by 39.0% (95% confidence interval 28.0% to 49.0%) compared with historical data. At the third PK measurement, 110 out of 426 patients (25.8%) had a low exposure. In total, 294 patients (53.3%) had ≥1 PK sample(s) below the preset target at a certain time point during treatment. In 166 of these patients (56.5%), pharmacokinetically guided interventions were carried out, which were successful in 113 out of 152 assessable patients (74.3%).

CONCLUSIONS

Pharmacokinetically guided dose optimization of oral targeted therapies was feasible in clinical practice and reduced the proportion of underexposed patients considerably.

Dose Individualization of Oral Multi-Kinase Inhibitors for the Implementation of Therapeutic Drug Monitoring

Oral multi-kinase inhibitors have transformed the treatment landscape for various cancer types and provided significant improvements in clinical outcomes. These agents are mainly approved at fixed doses, but the large inter-individual variability in pharmacokinetics and pharmacodynamics (efficacy and safety) has been an unsolved clinical issue. For example, certain patients treated with oral multi-kinase inhibitors at standard doses have severe adverse effects and require dose reduction and discontinuation, yet other patients have a suboptimal response to these drugs. Consequently, optimizing the dosing of oral multi-kinase inhibitors is important to prevent over-dosing or under-dosing. To date, multiple studies on the exposure-efficacy/toxicity relationship of molecular targeted therapy have been attempted for the implementation of therapeutic drug monitoring (TDM) strategies. In this milieu, we recently conducted research on several multi-kinase inhibitors, such as sunitinib, pazopanib, sorafenib, and lenvatinib, with the aim to optimize their treatment efficacy using a pharmacokinetic/pharmacodynamic approach. Among them, sunitinib use is an example of successful TDM implementation. Sunitinib demonstrated a significant correlation between drug exposure and treatment efficacy or toxicities. As a result, TDM services for sunitinib has been covered by the National Health Insurance program in Japan since April 2018. Additionally, other multi-kinase targeted anticancer drugs have promising data regarding the exposure-efficacy/toxicity relationship, suggesting the possibility of personalization of drug dosage. In this review, we provide a comprehensive summary of the clinical evidence for dose individualization of multi-kinase inhibitors and discuss the utility of TDM of multi-kinase inhibitors, especially sunitinib, pazopanib, sorafenib, and lenvatinib.

Exposure-response analyses of cabozantinib in patients with metastatic renal cell cancer

Aim

In the registration trial, cabozantinib exposure ≥ 750 ng/mL correlated to improved tumor size reduction, response rate and progression free survival (PFS) in patients with metastatic renal cell cancer (mRCC). Because patients in routine care often differ from patients in clinical trials, we explored the cabozantinib exposure–response relationship in patients with mRCC treated in routine care.

Methods

Cabozantinib trough concentrations (C_min) were collected and average exposure was calculated per individual. Exposure–response analyses were performed using the earlier identified target of C_min > 750 ng/mL and median C_min. In addition, the effect of dose reductions on response was explored. PFS was used as measure of response.

Results

In total, 59 patients were included:10% were classified as favourable, 61% as intermediate and 29% as poor IMDC risk group, respectively. Median number of prior treatment lines was 2 (0–5). Starting dose was 60 mg in 46%, 40 mg in 42% and 20 mg in 12% of patients. Dose reductions were needed in 58% of patients. Median C_min was 572 ng/mL (IQR: 496–701). Only 17% of patients had an average C_min ≥ 750 ng/mL. Median PFS was 52 weeks (95% CI: 40–64). No improved PFS was observed for patients with C_min ≥ 750 ng/mL or ≥ 572 ng/ml. A longer PFS was observed for patients with a dose reduction vs. those without (65 vs. 31 weeks, p = .001). After incorporating known covariates (IMDC risk group and prior treatment lines (< 2 vs. ≥ 2)) in the multivariable analysis, the need for dose reduction remained significantly associated with improved PFS (HR 0.32, 95% CI:0.14–0.70, p = .004).

Conclusion

In these explorative analyses, no clear relationship between increased cabozantinib exposure and improved PFS was observed. Average cabozantinib exposure was below the previously proposed target in 83% of patients. Future studies should focus on validating the cabozantinib exposure required for long term efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09338-1.

Pharmacokinetics and therapeutic drug monitoring of anticancer protein/kinase inhibitors

Over the past two decades, protein/kinase inhibitors, as targeted therapies, raised in number and have become increasingly mainstream in the treatment of malignant diseases, thanks to the ease of oral administration and the minimal adverse drug reactions. These drugs have similar pharmacokinetic properties: a relatively good absorption and distribution, a strong hepatic metabolism, and a mainly biliary excretion. However, this pharmacokinetic and route of administration has the disadvantage of resulting in a large inter- and intra-individual variability. Despite this significant variability, these drugs are largely prescribed at the same initial dose for quite all patients (flat dose), even though this variability would require individualized adaptation for each patient and/or each new circumstance. Promptly after their commercialization, scientific teams have performed concentration measurements of several drugs and showed the existence of efficacy or toxicity thresholds. This has contributed to the development of therapeutic drug monitoring as one of the strategies to improve the response and reduce the adverse reactions of these drugs. There is still a need to determine precise thresholds for the remaining drugs and to evaluate the impact of TDM in therapeutic management. In order to determine the current state of the art, this article reviews indications, pharmacokinetics and TDM data for 49 marketed PKIs.

Precision Dosing of Targeted Therapies Is Ready for Prime Time

Fixed dosing of oral targeted therapies is inadequate in the era of precision medicine. Personalized dosing, based on pharmacokinetic (PK) exposure, known as therapeutic drug monitoring (TDM), is rational and supported by increasing evidence. The purpose of this perspective is to discuss whether randomized studies are needed to confirm the clinical value of precision dosing in oncology. PK-based dose adjustments are routinely made for many drugs and are recommended by health authorities, for example, for patients with renal impairment or for drug-drug interaction management strategies. Personalized dosing simply extrapolates this paradigm from selected patient populations to each individual patient with suboptimal exposure, irrespective of the underlying cause. If it has been demonstrated that exposure is related to a relevant clinical outcome, such as efficacy or toxicity, and that exposure can be optimized by PK-guided dosing, it could be logically assumed that PK-guided dosing would result in better treatment outcomes without the need for randomized confirmatory trials. We propose a path forward to demonstrate the clinical relevance of individualized dosing of molecularly-targeted anticancer drugs.

Intermittent versus continuous administration of pazopanib in progressive radioiodine refractory thyroid carcinoma: Final results of the randomised, multicenter, open-label phase II trial PAZOTHYR

INTRODUCTION

Multikinase inhibitor (MKI) treatments have shown efficacy in progressive radioiodine refractory thyroid cancers (RAIR-TC), but most patients experienced substantial adverse effects. This randomised multicentric study investigated intermittent versus continuous pazopanib administration.

PATIENTS AND METHODS

The PAZOTHYR study included RAIR-TC patients with progressive disease in the last 12 months, who may have received one prior MKI. RAIR-TC patients received pazopanib for 6 months, and patients with stable disease or tumour response were randomly assigned (1:1) to receive continuous (CP) or intermittent (IP) pazopanib until progression. The primary end-point was time to treatment failure (TTF) defined as the time from randomisation to permanent discontinuation of pazopanib, due to any cause. One hundred randomised patients were needed to demonstrate an increase from 50% (CP) to 70% (IP) (hazard ratio (HR) 0.515, 80% power) in the rate of patients still under treatment 6 months (6m-SuT) post-randomisation. Secondary end-points included the overall response rate (ORR), progression-free survival (PFS) under pazopanib and safety.

RESULTS

RAIR-TC patients (168) enrolled from June 18, 2013 to January 16, 2018, received 6-month pazopanib treatment and showed 35.6% (95% CI 28.2-43.6) best response rate and 89.4% (83.5-93.7) disease control rate. One hundred patients were randomised (IP:50; CP:50). With a median follow-up of 31.3 months, median TTF was not statistically different between arms (IP:14.7, 95% confidence interval (CI) 9.3-17.4; CP:11.9, 95% CI 7.5-15.6) months (HR 0.79, 0.49-1.27). 6m-SuT rates were similar (IP:80% 66.0-88.7%; CP:78% 63.8-87.2%). Median PFS under pazopanib were not statistically different (IP:5.7 4.8-7.8; CP: 9.2 7.3-11.1) months (HR 1.36, 0.88-2.12). Pazopanib-related adverse events grade 3-4 occurred in 36 (IP: 19, 38%; CP: 17, 34%) randomised patients. Seven pazopanib-related deaths occurred.

CONCLUSIONS

Intermittent administration of pazopanib did not demonstrate significant superiority in efficacy or tolerance compared with continuous treatment. An intermittent administration scheme cannot be recommended outside clinical trials. This study was registered with ClinicalTrial.gov, number NCT01813136.

Evaluating the utility of therapeutic drug monitoring in the clinical use of small molecule kinase inhibitors: a review of the literature

Introduction: Orally administered small molecule kinase inhibitors (KI) are a key class of targeted anti-cancer medicines that have contributed substantially to improved survival outcomes in patients with advanced disease. Since the introduction of KIs in 2001, there has been a building body of evidence that the benefit derived from these drugs may be further enhanced by individualizing dosing on the basis of concentration.Areas covered: This review considers the rationale for individualized KI dosing and the requirements for robust therapeutic drug monitoring (TDM). Current evidence supporting TDM-guided KI dosing is presented and critically evaluated, and finally potential approaches to address translational challenges for TDM-guided KI dosing and alternate approaches to support individualization of KI dosing are discussed.Expert opinion: Intuitively, the individualization of KI dosing through an approach such as TDM-guided dosing has great potential to enhance the effectiveness and tolerability of these drugs. However, based on current literature evidence it is unrealistic to propose that TDM-guided KI dosing should be routinely implemented into clinical practice.

ATLAS trial of adjuvant axitinib in patients with renal cell carcinoma: subgroup analyses with focus on axitinib dosing and racial groups

Background

The ATLAS trial, investigating adjuvant axitinib versus placebo in renal cell carcinoma (RCC), was stopped for futility at a preplanned interim analysis. We report subgroup outcome analyses by ethnicity, time on treatment, dose modification and toxicity.

Patients and methods

Patient demographics, baseline characteristics, treatment duration and exposure and safety were analysed for Asian versus non-Asian patients treated with axitinib versus placebo. Disease-free survival (DFS) was analysed by ethnicity, treatment duration (≥1 versus <1 year), dose modification and adverse event (AE) grade.

Results

No DFS benefit was observed for Asian {hazard ratio (HR) 0.883 [95% confidence interval (CI) 0.638-1.220]} or non-Asian [HR 0.828 (95% CI 0.490-1.400)] patients treated with axitinib or placebo. Fewer Asian versus non-Asian patients were in the highest-risk group in axitinib (51.9% versus 72.3%) or placebo (51.5% versus 66.0%) arm. Highest-risk patients in both subgroups had no DFS benefit with either treatment. More axitinib-treated Asian versus non-Asian patients had dose reductions due to AEs (58.8% versus 46.0%; P = 0.028). Asian patients experienced more nasopharyngitis but less fatigue or asthenia than non-Asians. Among Asian patients, proteinuria, hypothyroidism, nasopharyngitis, and hypertension were more common in Japanese patients than Korean patients and more common in Korean patients than Chinese patients. Patients receiving axitinib >1 year versus ≤1 year did not have different DFS: HR 0.572 (95% CI 0.247-1.327); P = 0.1874. Compared with patients on stable axitinib dose, DFS was longer in patients with dose reduction [HR 0.458 (95% CI 0.305-0.687); P = 0.0001], whereas DFS was not different in those with dose escalation [HR 1.936 (95% CI 0.937-3.997); P = 0.0685]. DFS was not different in patients experiencing grade ≥2 versus <2 AEs within 6 months of initiating axitinib: HR 0.885 (95% CI 0.419-1.869); P = 0.7488.

Conclusions

Asian versus non-Asian subgroup analysis revealed differences in AE experience and drug exposure. There were no DFS differences based on ethnicity or treatment duration, but axitinib dose reduction led to longer DFS.

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DFS analysis by Asian versus non-Asian did not indicate a DFS benefit over placebo for either subgroup.

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Asian patients had a lower median daily dose of axitinib and more frequent dose reductions versus non-Asian patients.

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Duration of axitinib treatment did not impact DFS in both Asian and non-Asian subgroups.

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Patients with dose reductions had longer DFS versus patients with stable dose or dose increase.

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There were notable differences in AEs between Asian and non-Asian patients and among Japanese, Korean and Chinese patients.

Adjuvant therapy in renal cell carcinoma: Current knowledges and future perspectives

While many patients with non-metastatic renal cell carcinoma (RCC) can be cured with surgery alone, upward of 40% of patients recur in a short delay, raising the question of additional perioperative treatments. To address this clinical need, multiple trials have investigated the addition of systemic therapy after surgery in localized or locally advanced RCC. However, adjuvant systemic therapies in the past decades have provided disappointing results with only one positive study of antiangiogenic treatments. Debatable clinical benefit of adjuvant antiangiogenic tyrosine kinase inhibitors (TKIs) therapy at cost of high adverse event profiles have paved the way for development of alternative perioperative strategies, such as immune checkpoint inhibitors (ICIs). Further investigation into combination therapies with immunotherapy, neoadjuvant approaches and patient selection will be key to determining optimal adjuvant therapy regimens to improve outcomes and increase cure rates for patients with non-metastatic RCC. In this review, we extensively present the strong and weakness of the five adjuvant antiangiogenic TKI trials, highlight the main differences and discuss about the reasons of failure. We also expose the current ongoing clinical trials in the perioperative setting and provide new insights concerning the evolving landscape of the management of non-metastatic RCC.

Therapeutic drug monitoring of oral targeted antineoplastic drugs

PURPOSE

This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed.

METHODS

A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted.

RESULTS

OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy.

CONCLUSION

Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.

New Insights into Adjuvant Therapy in Renal Cell Carcinoma: Is the Chapter of VEGF Inhibitors Definitely Closed?

Adjuvant therapy with antiangiogenic agents in locoregional renal cell carcinoma did not translate into a sufficient benefit and highlight the crucial role of patient selection. Ongoing clinical trials with immune-targeted agents hold great promise for this unmet clinical need.

Adjuvant therapy in renal cell carcinoma: is it the right strategy to inhibit VEGF?

Despite several clinical trials have assessed different agents in the adjuvant setting, renal cell carcinoma (RCC) still remains a disease orphan of an effective adjuvant treatment. In fact, systemic therapies targeting angiogenesis that have been observed to be effective in metastatic setting failed to show an improvement in terms of clinical outcomes when used ad adjuvant treatments. In this study, we performed a meta-analysis of 5 randomized clinical trials to assess the impact of tyrosine kinase inhibitors (TKIs) targeting angiogenesis after surgery: ASSURE, S-TRAC, PROTECT, ATLAS, SORCE. Among the 6,531 patients assessed, we confirmed the lack of efficacy of adjuvant treatments in terms of disease-free survival (DFS) (pooled-HR 0.93, 95% CI, 0.84–1.02, P=0.16) and overall survival (OS) (pooled-HR 0.98, 95% CI, 0.88–1.09, P=0.54). To the best of our knowledge, we still ignore why some treatments active in the metastatic setting do not show similar efficacy as adjuvant treatment. Exploring possible reasons of this apparently conflicting results is important as it may offer new insights that should be evaluated in next generation adjuvant trials. Immune checkpoint inhibitors (ICIs) have reported significant results—as monotherapy or in combinations with other anticancer agents—in metastatic setting, and the results of trials evaluating these agents in the adjuvant setting are awaited.

The Right Dose: From Phase I to Clinical Practice

To realize the full potential of promising new anticancer drugs, it is of paramount importance to administer them at the right dose. The aim of this educational article is to provide several opportunities to optimize anticancer drug dosing, focusing on oral targeted therapies. First, therapeutic drug monitoring can optimize exposure in individual patients, if the optimal concentration is known. This approach is of particular interest in regard to oral kinase inhibitors with high interindividual pharmacokinetic variability. If exposure is related to response, then therapeutic drug monitoring is potentially feasible, although the clinical utility of this approach has not yet been established. Other approaches to reduce variability include administration of more frequent, smaller doses and administration under optimal prandial conditions. However, for many drugs, the labeled dose has not been demonstrated to be the optimal dose; for such agents, the vast majority of patients may be receiving excessive doses, which results in excessive toxicity. Furthermore, administration of lower off-label doses may reduce both medical and financial toxicity. These strategies should be applied from registration studies to clinical practice, with the goal of better optimizing anticancer treatment.

Adjuvant Pazopanib Versus Placebo After Nephrectomy in Patients With Localized or Locally Advanced Renal Cell Carcinoma: Final Overall Survival Analysis of the Phase 3 PROTECT Trial

Most studies indicate no benefit of adjuvant therapy with VEGFR tyrosine kinase inhibitors in advanced renal cell carcinoma (RCC). PROTECT (NCT01235962) was a randomized, double-blind, placebo-controlled phase 3 study to evaluate adjuvant pazopanib in patients with locally advanced RCC at high risk of relapse after nephrectomy (pazopanib, n = 769; placebo, n = 769). The results of the primary analysis showed no difference in disease-free survival between pazopanib 600 mg and placebo. Here we report the final overall survival (OS) analysis (median follow-up: pazopanib, 76 mo, interquartile range [IQR] 66-84; placebo, 77 mo, IQR 69-85). There was no significant difference in OS between the pazopanib and placebo arms (hazard ratio 1.0, 95% confidence interval 0.80-1.26; nominal p > 0.9). OS was worse for patients with T4 disease compared to those with less advanced disease and was better for patients with body mass index (BMI) ≥30 kg/m² compared to those with lower BMI. OS was significantly better for patients who remained diseasefree at 2 yr after treatment compared with those who relapsed within 2 yr. These findings are consistent with the primary outcomes from PROTECT, indicating that adjuvant pazopanib does not confer a benefit in terms of OS for patients following resection of locally advanced RCC. PATIENT SUMMARY: In the randomized, double-blind, placebo-controlled phase 3 PROTECT study, overall survival was similar for patients with locally advanced renal cell carcinoma (RCC) at high risk of relapse after nephrectomy who received adjuvant therapy with pazopanib or placebo. Pazopanib is not recommended as adjuvant therapy following resection of locally advanced RCC. This trial is registered at Clinicaltrials.gov as NCT01235962.

Outcomes based on age in patients with metastatic renal cell carcinoma treated with first line targeted therapy or checkpoint immunotherapy: Older patients more prone to toxicity

OBJECTIVES

Older patients with metastatic renal cell carcinoma (mRCC) were underrepresented in pivotal trials.

MATERIALS AND METHODS

Consecutive patients with mRCC treated at Aarhus University Hospital with first line tyrosine kinase inhibitors (TKI), mTOR inhibitors, or checkpoint immunotherapy (CPI) were retrospectively analyzed in age-subgroups; ≥ 75, 65-74, and < 65 years, with overall survival (OS), time-to-treatment discontinuation (TTD), and progression-free survival (PFS) as endpoints. Hazards ratios were adjusted (aHR) for International Metastatic RCC Database Consortium (IMDC) risk factors, histology, and age.

RESULTS

Of 838 patients, 159 (19%) were ≥ 75 years, 324 (39%) 65-74 years, and 355 (42%) < 65 years. Treatments were TKI in 729 (87%) patients, mTOR in 43 (5%) and CPI in 67 (8%). Older patients ≥ 75 years compared with 65-74 years and < 65 years had lower toxicity-adjusted median doses of pazopanib, 300 mg vs. 400 mg vs. 600 mg, respectively, (p < 0.001), and sunitinib, 25 mg vs. 37.5 mg vs. 50 mg, respectively (p < 0.001); numerically fewer doses of CPI, median 2 vs. 5 vs. 5, respectively, (p = 0.2); a higher proportion had dose reduction/interruption, 76% vs. 55% vs. 41%, respectively, (p < 0.001); and shorter mean time to dose reduction/interruption, 0.5 months vs. 1.9 months vs. 3.4 months, respectively, (p < 0.001). After adjusting IMDC prognostic factors and histology in multivariate analyses, age did not impact OS (aHR 1.0; 95% CI 0.99-1.02, p = 0.2), TTD (aHR 1.0; 95% CI 0.99-1.01, p = 0.4) or PFS (aHR 1.0, 95% CI 0.99-1.01; p = 0.9).

CONCLUSION

Older patients with mRCC were more prone to toxicity; but age did not impact outcomes. Proactive dose modification/interruption and awareness may help to reduce toxicity while maintaining efficacy.

Pharmacokinetically guided dosing has the potential to improve real-world outcomes of pazopanib

It remains unclear whether therapeutic drug monitoring (TDM) of pazopanib improves treatment outcomes in routine clinical practice. We did a prospective cohort study to evaluate the benefits of TDM for pazopanib therapy in real-world practice. Among 25 patients with pharmacokinetically guided dosing, only 5 (20%, 95% confidence interval 6.8-40.7%) discontinued treatment because of adverse events. However, 5 (41.7%, 95% confidence interval 15.2-72.3%) of historical controls including 12 patients not receiving such a strategy experienced adverse events leading to early termination. PK-guided dosing significantly increased median time-to-treatment discontinuation (252 vs 74 days, P = .012) with reduced toxicity and improved overall survival (not reached vs 313 days, P = .002) relative to conventional dosing in the control group. In conclusion, PK-guided dose adaptation through the use of TDM has the potential to improve treatment outcomes of pazopanib in routine clinical practice, warranting larger, randomized studies.

Adjuvant therapy for high-risk renal cell carcinoma after nephrectomy how many trials are positive? Only one or more than one

Adjuvant treatment with VEGFR tyrosine kinase inhibitor in renal cell carcinoma after nephrectomy has been reported through four clinical trials: S-TRAC, ASSURE, PROTECT and ATLAS. Only S-TRAC has been significantly positive on primary endpoint DFS under sunitinib compared to placebo, whereas ASSURE, PROTECT and ATLAS did not show any gain under sunitinib, sorafenib, pazopanib or axitinib, respectively. Nevertheless, there are arguments for a trend for the impact of anti-angiogenic therapy on outcome of patients with high-risk renal cell carcinoma cancer following nephrectomy, allowing for a fair discussion with patients to decide for or against an adjuvant treatment.

Towards Rational Cancer Therapeutics: Optimizing Dosing, Delivery, Scheduling, and Combinations

The current trend to personalize anticancer therapies mostly relies on selecting the best drug or combination of drugs to achieve optimal efficacy in patients. In addition to the comprehensive genetic and molecular knowledge of each tumor before choosing the drugs to be given, there is probably much room left for improvement by further personalizing the very modes by which the drugs are given, once they have been carefully selected. In particular, shifting from standard dosing to tailored dosing should help in maintaining drug exposure levels in the right therapeutic window, thus ensuring that the efficacy/toxicity balance is optimal. This paper covers the current knowledge regarding pharmacokinetic/pharmacodynamic relationships of anticancer agents, from decades-old cytotoxics to the latest immune checkpoint inhibitors, the most frequent sources for long-neglected interpatient variability impacting on drug exposure levels, and what could be done to achieve real personalized medicine in oncology such as implementing therapeutic drug monitoring with adaptive dosing strategies or using model-driven modalities for personalized dosing and scheduling.

Characterizing Exposure-Response Relationship for Therapeutic Monoclonal Antibodies in Immuno-Oncology and Beyond: Challenges, Perspectives, and Prospects

Recent data from immuno-oncology clinical studies have shown the exposure-response (E-R) relationship for therapeutic monoclonal antibodies (mAbs) was often confounded by various factors due to the complex interplay of patient characteristics, disease, drug exposure, clearance, and treatment response and presented challenges in characterization and interpretation of E-R analysis. To tackle the challenges, exposure relationships for therapeutic mAbs in immuno-oncology and oncology are reviewed, and a general framework for an integrative understanding of E-R relationship is proposed. In this framework, baseline factors, drug exposure, and treatment response are envisioned to form an interconnected triangle, driving the E-R relationship and underlying three components that compose the apparent relationship: exposure-driven E-R, baseline-driven E-R, and response-driven E-R. Various strategies in data analysis and study design to decouple those components and mitigate the confounding effect are reviewed for their merits and limitations, and a potential roadmap for selection of these strategies is proposed. Specifically, exposure metrics based on a single-dose pharmacokinetic model can be used to mitigate response-driven E-R, while multivariable analysis and/or case control analysis of data obtained from multiple dose levels in a randomized study may be used to account for the baseline-driven E-R. In this context, the importance of collecting data from multiple dose levels, the role of prognostic factors and predictive factors, the potential utility of clearance at baseline and its change over time, and future directions are discussed.

Impact of concomitant acid suppressive therapy on pazopanib efficacy and dose reductions in patients with metastatic renal cell carcinoma

PURPOSE

The aim of this study was to investigate the impact of acid suppressive therapy on clinical efficacy and safety of pazopanib in patients with metastatic renal cell carcinoma (mRCC).

METHODS

A single-center retrospective study was carried out. Charts of mRCC patients who received pazopanib as first-line treatment were reviewed and concomitant use of proton pump inhibitors (PPI) and histamine 2 receptor antagonists (H2RA) was studied. Two groups of patients were identified, namely patients receiving PPI/H2RA and patients without acid suppressive therapy. Both groups were compared with regard to progression free survival (PFS), overall survival (OS), tumor response, and time to dose reduction of pazopanib.

RESULTS

Ninety-one patients were included. Median PFS was 8 months in the PPI/H2RA group vs. 7 months in the no PPI/H2RA group (hazard ratio (HR) 0.76 (95% confidence interval (CI) 0.42-1.35)), p = 0.35. Median OS was 27 months in the PPI/H2RA group vs. 23 months in the no PPI/H2RA group (HR 0.87 (95% CI 0.46-1.66)), p = 0.68. Mean tumor response was 17% (95% CI 8-25%) in the PPI/H2RA group vs. 11% (95% CI 0-21%) in the no PPI/H2RA group, p = 0.52. Median time to first dose reduction was 9 months in both subgroups (HR 1.25 (95% CI 0.65-2.39)), p = 0.51. Median time to second dose (< 600 mg) reduction was 17 months in the PPI/H2RA group vs. 7 months in the no PPI/H2RA group (HR 0.26 (95% CI 0.07-0.89)), p = 0.03.

CONCLUSION

In this limited patient series, no evidence of a negative impact of PPI/H2RA on clinical outcome and time to first dose reduction was observed. These results suggest that PPI/H2RA might be considered, when there is a clinical need, in patients treated with pazopanib for mRCC. However, a prospective study is warranted to confirm these results.

The adjuvant treatment of kidney cancer: a multidisciplinary outlook

Approximately 70% of cases of kidney cancer are localized or locally advanced at diagnosis. Among patients who undergo surgery for these cancers, 30-35% will eventually develop potentially fatal metachronous distant metastases. Effective adjuvant treatments are urgently needed to reduce the risk of recurrence of kidney cancer and of dying of metastatic disease. To date, almost all of the tested adjuvant agents have failed to demonstrate any benefit. Only two trials of an autologous renal tumour cell vaccine and of the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor sunitinib have shown positive results, but these have been criticized for methodological reasons and conflicting data, respectively. The results of two additional trials of targeted agents as adjuvant therapies have not yet been published. Novel immune checkpoint inhibitors are promising approaches to adjuvant therapy in kidney cancer, and a number of trials are now underway. An important component of the management of patients with kidney cancer, particularly those who undergo radical resection for localized renal cell carcinoma, is the preservation of kidney function to reduce morbidity and mortality. The optimal management of these patients therefore requires a multidisciplinary approach involving nephrologists, oncologists, urologists and pathologists.

Cost-Neutral Optimization of Pazopanib Exposure by Splitting Intake Moments: A Prospective Pharmacokinetic Study in Cancer Patients

BACKGROUND AND OBJECTIVE

Pazopanib is an oral tyrosine kinase inhibitor used in the treatment of renal cell carcinoma and soft-tissue sarcoma. At the approved dose of 800 mg once daily (QD), 16-20% of patients are being underdosed and at risk of decreased efficacy. This study aimed to show whether splitting intake moments, as a cost-neutral alternative to a dose increase, leads to an increased exposure.

METHODS

We performed a cross-over trial comparing the pharmacokinetics of pazopanib 800 mg QD with pazopanib 400 mg twice daily. Pharmacokinetic sampling was performed at steady-state for both dosing schedules.

RESULTS

Nine evaluable patients were included. At the 800 mg QD dosing schedule, median minimum plasma concentration (C_min), area under the concentration-time curve from 0 to 24 h (AUC_0-24h), and maximum plasma concentration (C_max) were 23.2 mg/L (interquartile range 18.5-27.6), 773 mg h/L (557-1009), and 40.6 mg/L (36.4-56.4) compared with 41.6 mg/L (30.5-55.8, p = 0.004), 942 mg h/L (885-1419, p = 0.027), and 50.2 mg/L (46.8-72.5, p = 0.074) at 400 mg twice daily. One patient experienced a grade 3 event (i.e., diarrhea).

CONCLUSIONS

This study demonstrates that splitting intake moments of pazopanib leads to a 79% increase in C_min, with acceptable tolerability. Therefore, this new dosing schedule offers a cost-neutral opportunity to optimize treatment in patients with low exposure.

CLINICAL TRIAL REGISTRATION

NL6137 ( http://www.trialregister.nl ).

Imatinib, sunitinib and pazopanib: From flat-fixed dosing towards a pharmacokinetically guided personalized dose

Tyrosine kinase inhibitors (TKIs) are anti‐cancer drugs that target tyrosine kinases, enzymes that are involved in multiple cellular processes. Currently, multiple oral TKIs have been introduced in the treatment of solid tumours, all administered in a fixed dose, although large interpatient pharmacokinetic (PK) variability is described. For imatinib, sunitinib and pazopanib exposure‐treatment outcome (efficacy and toxicity) relationships have been established and therapeutic windows have been defined, therefore dose optimization based on the measured blood concentration, called therapeutic drug monitoring (TDM), can be valuable in increasing efficacy and reducing the toxicity of these drugs.

In this review, an overview of the current knowledge on TDM guided individualized dosing of imatinib, sunitinib and pazopanib for the treatment of solid tumours is presented. We summarize preclinical and clinical data that have defined thresholds for efficacy and toxicity. Furthermore, PK models and factors that influence the PK of these drugs which partly explain the interpatient PK variability are summarized. Finally, pharmacological interventions that have been performed to optimize plasma concentrations are described. Based on current literature, we advise which methods should be used to optimize exposure to imatinib, sunitinib and pazopanib.

Major pitfalls of protein kinase inhibitors prescription: A review of their clinical pharmacology for daily use

Protein kinase inhibitors (PKI) are a growing class of anticancer agents. They are prescribed with flat doses, and their oral administration is associated with interindividual variability in exposure. Patients can be over- or underexposed, due to numerous factors. We reviewed key pharmacokinetic concepts and mechanisms by which PKIs prescription could be altered. Challenging situations that could lead to increased toxicity or to therapeutic failure are described and recommendation for clinicians are proposed. Finally, the interest of therapeutic drug monitoring and indications for its use in daily practice is discussed.

Clinical outcomes and toxicities of pazopanib administered orally in crushed form: Case reports and review of the literature

Cancer treatment has changed dramatically with the development of oral targeted therapies. Pazopanib, an oral VEGF tyrosine kinase inhibitor, is currently approved for advanced renal cell carcinoma, advanced soft tissue sarcoma, and is being studied for various tumor types. Due to the potential of increased exposure to pazopanib when crushed, pazopanib should be given as an intact whole tablet. Thus, in patients with difficulty swallowing medications or feeding tubes, pazopanib is usually not considered to be an option. Here, we describe two cases which show the administration of crushed pazopanib was feasible and had apparent clinical activity.

Long-term survival and prognostic factors for locally advanced renal cell carcinoma with renal vein tumor thrombus

BACKGROUND

Previous related studies have mainly focused on renal cell carcinoma (RCC) with venous tumor thrombus, specifically inferior vena cava tumor thrombus with renal vein tumor thrombus (RVTT). However, only a few studies have focused on postoperative long-term survival of RCC patients exclusively with RVTT. Our aim was to investigate the independent prognostic factors for locally advanced RCC with RVTT in China.

METHODS

Patients with locally advanced RCC with RVTT were enrolled for the study from January 2000 to December 2015. All patients underwent radical nephrectomy. Survival analysis was estimated using Kaplan-Meier. Univariable and multivariable survival analyses were performed using COX. Patients were divided into high-risk, middle-risk, and low-risk groups based on independent prognostic factors and then analyzed for survival.

RESULTS

One hundred twenty-eight consecutive patients (103 men & 25 women) were enrolled with a median age of 61 years. Thrombi were all graded 0 using the Mayo system, of which 23 were friable. None of the thrombi detached during surgery. 121 patients were successfully followed up, with a median follow-up period of 47 months. Median overall survival was 127 months (95%CI: 101-153). The 5-year and 10-year cancer-specific survival (CSS) rate was 67.9 and 57.0%. 59 patients had recurrence with median time of 40 months. Friable thrombus, paraneoplastic syndrome (PNS), modified Fuhrman grade 3/4 and perirenal fat invasion were independent prognostic factors (p < 0.05). The 5-year CSS for the Low-risk group (no factors) was 100%, Middle-risk group (1-2 factors) was 68.6%, while the High-risk group (3-4 factors) was 0%.

CONCLUSIONS

After radical surgery, RCC patients with RVTT had a relatively fair prognosis except for patients with friable thrombus, PNS, higher modified Fuhrman grade and perirenal fat invasion.

COMPARZ Post Hoc Analysis: Characterizing Pazopanib Responders With Advanced Renal Cell Carcinoma

This post hoc analysis of the COMPARZ study (pazopanib, n = 557; sunitinib, n = 553) supported similar efficacy of first-line pazopanib and first-line sunitinib treatment in advanced renal cell carcinoma. Patients who required dose modifications because of toxicity received higher cumulative doses with longer time of treatment and had significantly better objective response rate, progression-free survival, and overall survival than patients with minimal toxicity.

Relative Dose Intensity of Induction-Phase Pazopanib Treatment of Soft Tissue Sarcoma: Its Relationship with Prognoses of Pazopanib Responders

The approved standard dose of pazopanib is 800 mg per day, but the appropriate dose of pazopanib to treat soft tissue sarcoma (STS) patients in real-world practice is controversial. Of 124 STS patients treated with pazopanib, we retrospectively analyzed the cases of STS patients who achieved progression-free survival at 12 weeks by pazopanib treatment as pazopanib responders, and we evaluated their relative dose intensity (RDI) in the initial 12 weeks (12W-RDI). We enrolled 78 STS patients in the analyses as pazopanib responders, and 54 patients of the 78 pazopanib responders (69%) were able to maintain 12W-RDI ≥80%. In landmark analyses, patients with 12W-RDI of 80% ≥80% had significantly longer progression-free survival compared to those with 12W-RDI <80% (30.7 weeks vs. 22.0 weeks, hazard ratio [HR]: 0.56 [95%CI: 0.33–0.94], p = 0.026). The most frequently observed reasons of treatment interruption and/or dose reduction of pazopanib during the initial 12 weeks were anorexia and liver function disorders. Liver toxicity was the adverse event most frequently observed in the 12W-RDI <80% patients throughout the treatment periods. Based on our results, it appears that maintaining as high a dose intensity as possible that is tolerable—at least during the initial 12 weeks—is likely to be the better option in pazopanib treatment for STS patients.

Exploratory Investigation of Target Pazopanib Concentration Range for Patients With Renal Cell Carcinoma

BACKGROUND

Severe adverse events frequently occur in patients treated with pazopanib, necessitating dose reduction and discontinuation. However, information on the exposure-toxicity relationship is limited.

PATIENTS AND METHODS

For this retrospective and observational clinical study, we examined 27 patients with renal cell carcinoma treated with pazopanib and enrolled between October 2014 and March 2018. The primary goal was to evaluate the association between trough pazopanib concentration and occurrence of grade ≥ 3 toxicities, and secondarily, to estimate the association between trough pazopanib concentration and objective response rate.

RESULTS

Mean trough pazopanib concentration was significantly higher in the grade ≥ 3 toxicity group (n = 9) than in the grade ≤ 2 toxicity group (n = 18). Based on the receiver operating characteristic curve, the threshold value of trough pazopanib concentration for predicting grade ≥ 3 toxicities was 50.3 μg/mL (area under the curve, 0.85; 95% confidence interval, 0.70-0.99; P < .05). In the pazopanib < 20.5 μg/mL group (n = 3), no patient experienced an objective response. Objective response rates between patients with 20.5 to 50.3 μg/mL pazopanib (n = 11) and patients with ≥ 50.3 μg/mL (n = 13) were similar (45.5% vs. 46.2%).

CONCLUSION

From results of this study, the target trough pazopanib concentration range may be 20.5 to 50.3 μg/mL for patients with renal cell carcinoma.

Axitinib versus placebo as an adjuvant treatment of renal cell carcinoma: results from the phase III, randomized ATLAS trial

Background

The ATLAS trial compared axitinib versus placebo in patients with locoregional renal cell carcinoma (RCC) at risk of recurrence after nephrectomy.

Patients and methods

In a phase III, randomized, double-blind trial, patients had >50% clear-cell RCC, had undergone nephrectomy, and had no evidence of macroscopic residual or metastatic disease [independent review committee (IRC) confirmed]. The intent-to-treat population included all randomized patients [≥pT2 and/or N+, any Fuhrman grade (FG), Eastern Cooperative Oncology Group status 0/1]. Patients (stratified by risk group/country) received (1 : 1) oral twice-daily axitinib 5 mg or placebo for ≤3 years, with a 1-year minimum unless recurrence, occurrence of second primary malignancy, significant toxicity, or consent withdrawal. The primary end point was disease-free survival (DFS) per IRC. A prespecified DFS analysis in the highest-risk subpopulation (pT3, FG ≥ 3 or pT4 and/or N+, any T, any FG) was conducted.

Results

A total of 724 patients (363 versus 361, axitinib versus placebo) were randomized from 8 May 2012, to 1 July 2016. The trial was stopped due to futility at a preplanned interim analysis at 203 DFS events. There was no significant difference in DFS per IRC [hazard ratio (HR) = 0.870; 95% confidence interval (CI) : 0.660-1.147; P = 0.3211). In the highest-risk subpopulation, a 36% and 27% reduction in risk of a DFS event (HR; 95% CI) was observed per investigator (0.641; 0.468-0.879; P = 0.0051), and by IRC (0.735; 0.525-1.028; P = 0.0704), respectively. Overall survival data were not mature. Similar adverse events (AEs; 99% versus 92%) and serious AEs (19% versus 14%), but more grade 3/4 AEs (61% versus 30%) were reported for axitinib versus placebo.

Conclusions

ATLAS did not meet its primary end point; however, improvement in DFS per investigator was seen in the highest-risk subpopulation. No new safety signals were reported.

Trial registration number

NCT01599754.

Adjuvant therapy after nephrectomy for renal cell carcinoma

Adjuvant treatment with vascular endothelial growth factor receptor tyrosine kinase inhibitor in renal cell carcinoma after nephrectomy has been reported through three clinical trials: S-TRAC, ASSURE and PROTECT. Only S-TRAC has been significantly positive on primary end-point disease-free survival under sunitinib compared to placebo, whereas ASSURE and PROTECT did not show any gain under sunitinib, sorafenib or pazopanib. This short review presents the differences between the trials and provides hypotheses on why S-TRAC may have been positive.

Update on the biology and management of renal cell carcinoma

Renal cell cancer (RCC) (epithelial carcinoma of the kidney) represents 2%-4% of newly diagnosed adult tumors. Over the past 2 decades, RCC has been better characterized clinically and molecularly. It is a heterogeneous disease, with multiple subtypes, each with characteristic histology, genetics, molecular profiles, and biologic behavior. Tremendous heterogeneity has been identified with many distinct subtypes characterized. There are clinical questions to be addressed at every stage of this disease, and new targets being identified for therapeutic development. The unique characteristics of the clinical presentations of RCC have led to both questions and opportunities for improvement in management. Advances in targeted drug development and understanding of immunologic control of RCC are leading to a number of new clinical trials and regimens for advanced disease, with the goal of achieving long-term disease-free survival, as has been achieved in a proportion of such patients historically. RCC management is a promising area of ongoing clinical investigation.

Adjuvant Vascular Endothelial Growth Factor-targeted Therapy in Renal Cell Carcinoma: A Systematic Review and Pooled Analysis

CONTEXT

Contradictory data exist with regard to adjuvant vascular endothelial growth factor receptor (VEGFR)-targeted therapy in surgically managed patients for localized renal cell carcinoma (RCC).

OBJECTIVE

To systematically evaluate the current evidence regarding the therapeutic benefit (disease-free survival [DFS] and overall survival [OS]) and grade 3-4 adverse events (AEs) for adjuvant VEGFR-targeted therapy for resected localized RCC.

EVIDENCE ACQUISITION

A critical review of PubMed/Medline, Embase, and the Cochrane Library in January 2018 according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement was performed. We identified reports and reviewed them according to the Consolidated Standards of Reporting Trials and Standards for the Reporting of Diagnostic Accuracy Studies criteria. Of eight full-text articles that were eligible for inclusion, five studies (two of five were updated analyses) were retained in the final synthesis. Study characteristics were abstracted and the number needed to treat (NNT) per trial was estimated.

EVIDENCE SYNTHESIS

The three randomized controlled phase III trials included the following comparisons: sunitinib versus placebo or sorafenib versus placebo (Adjuvant Sorafenib or Sunitinib for Unfavorable Renal Carcinoma [ASSURE] study, n=1943), sunitinib versus placebo (S-TRAC, n=615), and pazopanib versus placebo (Pazopanib As Adjuvant Therapy in Localized/Locally Advanced RCC After Nephrectomy study, n=1135). The NNT ranged from 10 (S-TRAC) to 137 (ASSURE study). The pooled analysis showed that VEGFR-targeted therapy was not statistically significantly associated with improved DFS (hazard ratio [HRrandom]: 0.92, 95% confidence interval [CI]: 0.82-1.03, p=0.16) or OS (HRrandom: 0.98, 95% CI: 0.84-1.15, p=0.84) compared with the control group. The adjuvant therapy group experienced significantly higher odds of grade 3-4 AEs (ORrandom: 5.89, 95% CI: 4.85-7.15, p<0.001). In exploratory analyses focusing on patients who started on the full-dose regimen, DFS was improved in patients who received adjuvant therapy (HRrandom: 0.83, 95% CI: 0.73-0.95, p=0.005).

CONCLUSIONS

This pooled analysis of reported randomized trials did not reveal a statistically significant effect between adjuvant VEGFR-targeted therapy and improved DFS or OS in patients with intermediate/high-risk local or regional fully resected RCC. Improvement in DFS may be more likely with the use of full-dose regimens, pending further results. However, adjuvant treatment was associated with high-grade AEs.

PATIENT SUMMARY

Vascular endothelial growth factor receptor-targeted therapy after nephrectomy for localized kidney cancer is not associated with consistent improvements in delaying cancer recurrence or prolonging life and comes at the expense of potentially significant side effects.

Perioperative Therapy in Renal Cell Carcinoma: What Do We Know, What Have We Learned, What's Next?

Recent adjuvant vascular endothelial growth factor tyrosine kinase inhibitor trials in resected high-risk renal cell carcinoma that compared sunitinib, sorafenib, pazopanib, and axitinib with placebo controls have demonstrated mixed impact on disease-free survival, no improvement in overall survival, and, thus, controversy. Here, we discuss the results and conduct of these trials to provide new insight into the goals and strategies of treating resected renal cell cancer that is at high risk for recurrence. The potential for leveraging what we have learned from these trials to conduct successful contemporary adjuvant and perioperative immune checkpoint inhibition trials and future adjuvant trial design is discussed.