Other paradigms: growth rate constants and tumor burden determined using computed tomography data correlate strongly with the overall survival of patients with renal cell carcinoma. Cancer J. 2009;15:441-447. [PMID: 19826366 DOI: 10.1097/ppo.0b013e3181be1b90]

A comparison of statistical methods for animal oncology studies

In pre-clinical oncology studies, tumor-bearing animals are treated and observed over a period of time in order to measure and compare the efficacy of one or more cancer-intervention therapies along with a placebo/standard of care group. A data analysis is typically carried out by modeling and comparing tumor volumes, functions of tumor volumes, or survival. Data analysis on tumor volumes is complicated because animals under observation may be euthanized prior to the end of the study for one or more reasons, such as when an animal's tumor volume exceeds an upper threshold. In such a case, the tumor volume is missing not-at-random for the time remaining in the study. To work around the non-random missingness issue, several statistical methods have been proposed in the literature, including the rate of change in log tumor volume and partial area under the curve. In this work, an examination and comparison of the test size and statistical power of these and other popular methods for the analysis of tumor volume data is performed through realistic Monte Carlo computer simulations. The performance, advantages, and drawbacks of popular statistical methods for animal oncology studies are reported. The recommended methods are applied to a real data set.

Novel biomarkers in NSCLC: Radiomic analysis, kinetic analysis, and circulating tumor DNA

Current radiographic methods of measuring treatment response for patients with nonsmall cell lung cancer have significant limitations. Recently, new modalities using standard of care images or minimally invasive blood-based DNA tests have gained interest as methods of evaluating treatment response. This article highlights three emerging modalities: radiomic analysis, kinetic analysis and serum-based measurement of circulating tumor DNA, with a focus on the clinical evidence supporting these methods. Additionally, we discuss the possibility of combining these modalities to develop a robust biomarker with strong correlation to clinically meaningful outcomes that could impact clinical trial design and patient care. At Last, we focus on how these methods specifically apply to a Veteran population.

AML/Normal Progenitor Balance Instead of Total Tumor Load (MRD) Accounts for Prognostic Impact of Flowcytometric Residual Disease in AML

Measurable residual disease (MRD) in AML, assessed by multicolor flow cytometry, is an important prognostic factor. Progenitors are key populations in defining MRD, and cases of MRD involving these progenitors are calculated as percentage of WBC and referred to as white blood cell MRD (WBC-MRD). Two main compartments of WBC-MRD can be defined: (1) the AML part of the total primitive/progenitor (CD34+, CD117+, CD133+) compartment (referred to as primitive marker MRD; PM-MRD) and (2) the total progenitor compartment (% of WBC, referred to as PM%), which is the main quantitative determinant of WBC-MRD. Both are related as follows: WBC-MRD = PM-MRD × PM%. We explored the relative contribution of each parameter to the prognostic impact. In the HOVON/SAKK study H102 (300 patients), based on two objectively assessed cut-off points (2.34% and 10%), PM-MRD was found to offer an independent prognostic parameter that was able to identify three patient groups with different prognoses with larger discriminative power than WBC-MRD. In line with this, the PM% parameter itself showed no prognostic impact, implying that the prognostic impact of WBC-MRD results from the PM-MRD parameter it contains. Moreover, the presence of the PM% parameter in WBC-MRD may cause WBC-MRD false positivity and WBC-MRD false negativity. For the latter, at present, it is clinically relevant that PM-MRD ≥ 10% identifies a patient sub-group with a poor prognosis that is currently classified as good prognosis MRDnegative using the European LeukemiaNet 0.1% consensus MRD cut-off value. These observations suggest that residual disease analysis using PM-MRD should be conducted.

Tumor Growth Rate Estimates Are Independently Predictive of Therapy Response and Survival in Recurrent High-Grade Serous Ovarian Cancer Patients

Simple Summary

While latest evidence suggests that some patients with recurrent high-grade serous ovarian cancer may profit from reinduction with platinum-based chemotherapy regimens, the selection of patients who are likely to respond remains difficult. The present study therefore aimed to adapt a mathematical model, which used frequently available laboratory values to estimate growth rates of recurring tumors as an objectifiable surrogate of both therapy response and patient survival. After clinical validation, the model may help to personalize treatment strategies and thereby increase survival of affected patients.

Abstract

This study aimed to assess the predictive value of tumor growth rate estimates based on serial cancer antigen-125 (CA-125) levels on therapy response and survival of patients with recurrent high-grade serous ovarian cancer (HGSOC). In total, 301 consecutive patients with advanced HGSOC (exploratory cohort: n = 155, treated at the Medical University of Vienna; external validation cohort: n = 146, from the Ovarian Cancer Therapy–Innovative Models Prolong Survival (OCTIPS) consortium) were enrolled. Tumor growth estimates were obtained using a validated two-phase equation model involving serial CA-125 levels, and their predictive value with respect to treatment response to the next chemotherapy and the prognostic value with respect to disease-specific survival and overall survival were assessed. Tumor growth estimates were an independent predictor for response to second-line chemotherapy and an independent prognostic factor for second-line chemotherapy use in both univariate and multivariable analyses, outperforming both the predictive (second line: p = 0.003, HR 5.19 [1.73–15.58] vs. p = 0.453, HR 1.95 [0.34–11.17]) and prognostic values (second line: p = 0.042, HR 1.53 [1.02–2.31] vs. p = 0.331, HR 1.39 [0.71–2.27]) of a therapy-free interval (TFI) < 6 months. Tumor growth estimates were a predictive factor for response to third- and fourth-line chemotherapy and a prognostic factor for third- and fourth-line chemotherapy use in the univariate analysis. The CA-125-derived tumor growth rate estimate may be a quantifiable and easily assessable surrogate to TFI in treatment decision making for patients with recurrent HGSOC.

Novel Tumor Growth Rate Analysis in the Randomized CLARINET Study Establishes the Efficacy of Lanreotide Depot/Autogel 120 mg with Prolonged Administration in Indolent Neuroendocrine Tumors

Introduction

Tumor quantity while receiving cancer therapy is the sum of simultaneous regression of treatment‐sensitive and growth of treatment‐resistant fractions at constant rates. Exponential rate constants for tumor regression/decay (d) and growth (g) can be estimated. Previous studies established g as a biomarker for overall survival; g increases after treatment cessation, can estimate doubling times, and can assess treatment effectiveness in small cohorts by benchmarking to large reference data sets. Using this approach, we analyzed data from the clinical trial CLARINET, evaluating lanreotide depot/autogel 120 mg/4 weeks (LAN) for treatment of neuroendocrine tumors (NETs).

Methods and Materials

Computed tomography imaging data from 97 LAN‐ and 101 placebo‐treated patients from CLARINET were analyzed to estimate g and d.

Results

Data from 92% of LAN‐ and 94% of placebo‐treated patients could be fit to one of the equations to derive g and d (p < .001 in most data sets). LAN‐treated patients demonstrated significantly slower g than placebo recipients (p = .00315), a difference of 389 days in doubling times. No significant difference was observed in d. Over periods of LAN administration up to 700 days, g did not change appreciably. Simulated analysis with g as the endpoint showed a sample size of 48 sufficient to detect a difference in median g with 80% power.

Conclusion

Although treatment of NETs with LAN can affect tumor shrinkage, LAN primarily slows tumor growth rather than accelerates tumor regression. Evidence of LAN efficacy across tumors was identified. The growth‐retarding effect achieved with LAN was sustained for a prolonged period of time.

Implications for Practice

The only curative treatment for neuroendocrine tumors (NETs) is surgical resection; however, because of frequent late diagnosis, this is often impossible. Because of this, treatment of NETs is challenging and often aims to reduce tumor burden and delay progression. A novel method of analysis was used to examine data from the CLARINET trial, confirming lanreotide depot/autogel is effective at slowing tumor growth and extending progression‐free survival. By providing the expected rate and doubling time of tumor growth early in the course of treatment, this method of analysis has the potential to guide physicians in their management of patients with NETs.

Treatment of neuroendocrine tumors is challenging, mainly aiming to reduce tumor burden and delay disease progression. This article reports on the kinetics of tumor growth using a novel method of analysis and data from the CLARINET study.

Enhanced Detection of Treatment Effects on Metastatic Colorectal Cancer with Volumetric CT Measurements for Tumor Burden Growth Rate Evaluation

PURPOSE

Mathematical models combined with new imaging technologies could improve clinical oncology studies. To improve detection of therapeutic effect in patients with cancer, we assessed volumetric measurement of target lesions to estimate the rates of exponential tumor growth and regression as treatment is administered.

EXPERIMENTAL DESIGN

Two completed phase III trials were studied (988 patients) of aflibercept or panitumumab added to standard chemotherapy for advanced colorectal cancer. Retrospectively, radiologists performed semiautomated measurements of all metastatic lesions on CT images. Using exponential growth modeling, tumor regression (d) and growth (g) rates were estimated for each patient's unidimensional and volumetric measurements.

RESULTS

Exponential growth modeling of volumetric measurements detected different empiric mechanisms of effect for each drug: panitumumab marginally augmented the decay rate [tumor half-life; d [IQR]: 36.5 days (56.3, 29.0)] of chemotherapy [d: 44.5 days (67.2, 32.1), two-sided Wilcoxon P = 0.016], whereas aflibercept more significantly slowed the growth rate [doubling time; g = 300.8 days (154.0, 572.3)] compared with chemotherapy alone [g = 155.9 days (82.2, 347.0), P ≤ 0.0001]. An association of g with overall survival (OS) was observed. Simulating clinical trials using volumetric or unidimensional tumor measurements, fewer patients were required to detect a treatment effect using a volumetric measurement-based strategy (32-60 patients) than for unidimensional measurement-based strategies (124-184 patients).

CONCLUSIONS

Combined tumor volume measurement and estimation of tumor regression and growth rate has potential to enhance assessment of treatment effects in clinical studies of colorectal cancer that would not be achieved with conventional, RECIST-based unidimensional measurements.

The Evolving Role of Metastasectomy for Patients with Metastatic Renal Cell Carcinoma

Surgical metastasectomy continues to be utilized for patients with solitary or low-volume metastatic renal cell carcinoma (mRCC). Although few high-quality data are available to evaluate outcomes, local treatment is recommended when feasible because it may allow a subset of patients to delay or avoid systemic treatments. With the development of improved mRCC therapies, utilization of metastasectomy has increased because most patients have incomplete responses to systemic treatment of their metastases. This review discusses the rationale and history of metastasectomy, trends in utilization, prognostic factors for patient selection, site-specific considerations, alternatives for nonsurgical local treatment, and risk of morbidity associated with metastasectomy.

Isolated Pancreatic Metastases of Renal Cell Carcinoma-A Paradigm of a Seed and Soil Mechanism: A Literature Analysis of 1,034 Observations

Previously documented arguments, in favor of the suspected impact of a seed and soil mechanism, in the development and progression of isolated pancreatic metastasis of renal cell carcinomas (isPM) are: (1) uniform and independent from the side of the primary tumor distribution of isPM within the pancreas and, (2) the similar survival rates for singular and multiple isPM. In addition, the present study adds new arguments that further confirm the importance of an seed and soil mechanism in isPM: (1) Within the singular isPM, the size of the metastasis does not affect the overall survival; (2) Within the group of multiple isPMs, the overall survival does not depend on the number of metastases; (3) For synchronous and metachronous isPM, survival rates are also not different, and (4) Within the group of metachronous isPM there is also no correlation between the overall survival and interval until metastases occurs. This unusual ineffectiveness of otherwise known risk factors of solid cancers can be explained plausibly by the hypothesis of a very selective seed and soil mechanism in isPM. It only allows embolized renal carcinoma cells in the pancreas to complete all steps required to grow into clinically manifest metastases. In all other organs, on the other hand, the body is able to eliminate the embolized tumor cells or at least put them into a dormant state for many years. This minimizes the risk of occult micrometastases in distant organs, which could later—after isPM treatment—grow into clinically manifest metastases, so that the prognosis of the isPM is only determined by an adequate therapy of the pancreatic foci, and prognostic factors, such as total tumor burden or interval until the occurrence of the isPM remain ineffective.

Impact of tumour size measurement inter-operator variability on model-based drug effect evaluation

Purpose

During oncology clinical trials, tumour size (TS) measurements are commonly used to monitor disease progression and to assess drug efficacy. We explored inter-operator variability within a subset of a phase III clinical trial conducted from August 1995 to February 1997 and its impact on drug effect evaluation using a tumour growth inhibition model.

Methods

One hundred twenty lesions were measured twice at each time point; once at the hospital and once at the centralised centre. A visual analysis was performed to identify trends within the profiles over time. Linear regression and relative error ratios were used to explore the inter-operator variability of raw TS measurements and model-based estimates.

Results

While correlation between patient-level estimates of drug effect was poor (r² = 0.28), variability between the study-level estimates was much less affected (9%).

Conclusions

The global evaluation of drug effect using modelling approaches might not be affected by inter-operator variability. However, the exploration of covariates for drug effect and the characterisation of an exposure–tumour shrinkage relationship seems limited by the high measurement variability that translates to a poor correlation of individual drug effect estimates. This might be addressed by the use of more precise computer-aided measurement methods.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04049-5) contains supplementary material, which is available to authorized users.

Observations on Solitary Versus Multiple Isolated Pancreatic Metastases of Renal Cell Carcinoma: Another Indication of a Seed and Soil Mechanism?

Isolated pancreas metastases are a rare type of metastasis of renal cell carcinoma, characterized by the presence of pancreatic metastases, while all other organs remain unaffected. In a previous study, we determined arguments from the literature which (a) indicate a systemic-haematogenic metastasis route (uniform distribution of the metastases across the pancreas and independence of the metastatic localization in the pancreas of the side of the renal carcinoma); and (b) postulate a high impact of a seed and soil mechanism (SSM) on isolated pancreatic metastasis of renal cell carcinoma (isPM) as an explanation for exclusive pancreatic metastases, despite a systemic haematogenous tumor cell embolization. The objective of the study presented was to search for further arguments in favor of an SSM with isPM. For that purpose, the factor's histology, grading, and singular/multiple pancreas metastases were analyzed on the basis of 814 observations published up to 2018. While histology and grading allowed for no conclusions regarding the importance of an SSM, the comparison of singular/multiple pancreas metastases produced arguments in favor of an SSM: 1. The multiple pancreas metastases observed in 38.1% prove that multiple tumor cell embolisms occur with isPM, the exclusive "maturation" of which in the pancreas requires an SSM; 2. The survival rates (SVR), which are consistent with singular and multiple pancreas metastases (despite the higher total tumor load with the latter), prove that the metastasized tumor cells are not able to survive in all other organs because of an SSM, which results in identical SVR when the pancreatic foci are treated adequately.

On the relationship between tumour growth rate and survival in non-small cell lung cancer

A recurrent question within oncology drug development is predicting phase III outcome for a new treatment using early clinical data. One approach to tackle this problem has been to derive metrics from mathematical models that describe tumour size dynamics termed re-growth rate and time to tumour re-growth. They have shown to be strong predictors of overall survival in numerous studies but there is debate about how these metrics are derived and if they are more predictive than empirical end-points. This work explores the issues raised in using model-derived metric as predictors for survival analyses. Re-growth rate and time to tumour re-growth were calculated for three large clinical studies by forward and reverse alignment. The latter involves re-aligning patients to their time of progression. Hence, it accounts for the time taken to estimate re-growth rate and time to tumour re-growth but also assesses if these predictors correlate to survival from the time of progression. I found that neither re-growth rate nor time to tumour re-growth correlated to survival using reverse alignment. This suggests that the dynamics of tumours up until disease progression has no relationship to survival post progression. For prediction of a phase III trial I found the metrics performed no better than empirical end-points. These results highlight that care must be taken when relating dynamics of tumour imaging to survival and that bench-marking new approaches to existing ones is essential.

Imaging Response of Antiangiogenic and Immune-Oncology Drugs in Metastatic Renal Cell Carcinoma (mRCC): Current Status and Future Challenges

This report aims to review criteria which have been proposed for treatment evaluation in mRCC under anti-angiogenic and immune-oncologic therapies and discuss future challenges for imagers. RECIST criteria seem to only partially reflect the clinical benefit derived from anti-angiogenic drugs in mRCC. New methods of analysis propose to better evaluate response to these drugs, including a new threshold for size criteria (-10%), attenuation (Choi and modified Choi criteria), functional imaging techniques (perfusion CT, ultrasound or MRI), and new PET radiotracers. Imaging of progression is one of the main future challenges facing imagers. It is progression and not response that will trigger changes in therapy, therefore it is tumour progression that should be identified by imaging techniques to guide the oncologist on the most appropriate time to change therapy. Yet little is known on dynamics of tumour progression, and much data still needs to be accrued to understand it. Finally, as immunotherapies develop, flare or pseudo-progression phenomena are observed. Studies need to be performed to determine whether imaging can distinguish between patients undergoing pseudo-progression for which therapy should be continued, or true progression for which the treatment must be changed.

Translating new data to the daily practice in second line treatment of renal cell carcinoma: The role of tumor growth rate

The therapeutic options for patients with metastatic renal cell carcinoma (mRCC) have completely changed during the last ten years. With the sequential use of targeted therapies, median overall survival has increased in daily practice and now it is not uncommon to see patients surviving kidney cancer for more than four to five years. Once treatment fails with the first line targeted therapy, head to head comparisons have shown that cabozantinib, nivolumab and the combination of lenvatinib plus everolimus are more effective than everolimus alone and that axitinib is more active than sorafenib. Unfortunately, it is very unlikely that we will ever have prospective data comparing the activity of axitinib, cabozantinib, lenvatinib or nivolumab. It is frustrating to observe the lack of biomarkers that we have in this field, thus there is no firm recommendation about the optimal sequence of treatment in the second line. In the absence of reliable biomarkers, there are several clinical endpoints that can help physicians to make decisions for an individual patient, such as the tumor burden, the expected response rate and the time to achieve the response to each agent, the prior response to the agent administered, the toxicity profile of the different compounds and patient preference. Here, we propose the introduction of the tumor-growth rate (TGR) during first-line treatment as a new tool to be used to select the second line strategy in mRCC. The rapidness of TGR before the onset of the treatment reflects the variability between patients in terms of tumor growth kinetics and it could be a surrogate marker of tumor aggressiveness that may guide treatment decisions.

Optimizing clinical benefit with targeted treatment in mRCC: "Tumor growth rate" as an alternative clinical endpoint

Tumor growth rate (TGR), usually defined as the ratio between the slope of tumor growth before the initiation of treatment and the slope of tumor growth during treatment, between the nadir and disease progression, is a measure of the rate at which tumor volume increases over time. In patients with metastatic renal cell carcinoma (mRCC), TGR has emerged as a reliable alternative parameter to allow a quantitative and dynamic evaluation of tumor response. This review presents evidence on the correlation between TGR and treatment outcomes and discusses the potential role of this tool within the treatment scenario of mRCC. Current evidence, albeit of retrospective nature, suggests that TGR might represent a useful tool to assess whether treatment is altering the course of the disease, and has shown to be significantly associated with progression-free survival and overall survival. Therefore, TGR may represent a valuable endpoint for clinical trials evaluating new molecularly targeted therapies. Most importantly, incorporation of TGR in the assessment of individual patients undergoing targeted therapies may help clinicians decide if a given agent is no longer able to control disease growth and whether continuing therapy beyond RECIST progression may still produce clinical benefit.

The pre-operative rate of growth of colorectal metastases in patients selected for liver resection does not influence post-operative disease-free survival

AIMS

To assess the potential association between the change in diameter of colorectal liver metastases between pre-operative imaging and liver resection and disease-free survival in patients who do not receive pre-operative liver-directed chemotherapy.

MATERIALS AND METHODS

Analysis of a prospectively maintained database of patients undergoing liver resection for colorectal liver metastases between 2005 and 2012 was undertaken. Change in tumour size was assessed by comparing the maximum tumour diameter at radiological diagnosis determined by imaging and the maximum tumour diameter measured at examination of the resected specimen in 157 patients.

RESULTS

The median interval from first scan to surgery was 99 days and the median increase in tumour diameter in this interval was 38%, equivalent to a tumour doubling time (DT) of 47 days. Tumour DT prior to liver resection was longer in patients with T1 primary tumours (119 days) than T2-4 tumours (44 days) and shorter in patients undergoing repeat surgery for intra-hepatic recurrence (33 days) than before primary resection (49 days). The median disease-free survival of the whole cohort was 1.57 years (0.2-7.3) and multivariate analysis revealed no association between tumour DT prior to surgery and disease-free survival.

CONCLUSIONS

The rate of growth of colorectal liver metastases prior to surgery should not be used as a prognostic factor when considering the role of resection.

Therapies with diverse mechanisms of action kill cells by a similar exponential process in advanced cancers

Successful cancer treatments are generally defined as those that decrease tumor quantity. In many cases, this decrease occurs exponentially, with deviations from a strict exponential being attributed to a growing fraction of drug-resistant cells. Deviations from an exponential decrease in tumor quantity can also be expected if drugs have a nonuniform spatial distribution inside the tumor, for example, because of interstitial pressure inside the tumor. Here, we examine theoretically different models of cell killing and analyze data from clinical trials based on these models. We show that the best description of clinical outcomes is by first-order kinetics with exponential decrease of tumor quantity. We analyzed the total tumor quantity in a diverse group of clinical trials with various cancers during the administration of different classes of anticancer agents and in all cases observed that the models that best fit the data describe the decrease of the sensitive tumor fraction exponentially. The exponential decrease suggests that all drug-sensitive cancer cells have a single rate-limiting step on the path to cell death. If there are intermediate steps in the path to cell death, they are not rate limiting in the observational time scale utilized in clinical trials--tumor restaging at 6- to 8-week intervals. On shorter time scales, there might be intermediate steps, but the rate-limiting step is the same. Our analysis, thus, points to a common pathway to cell death for cancer cells in patients. See all articles in this Cancer Research section, "Physics in Cancer Research."

Tumor growth rate provides useful information to evaluate sorafenib and everolimus treatment in metastatic renal cell carcinoma patients: an integrated analysis of the TARGET and RECORD phase 3 trial data

BACKGROUND

Response Evaluation Criteria in Solid Tumors (RECIST) criteria may not be sufficient to evaluate the response of targeted therapies in metastatic renal cell carcinoma (mRCC). The tumor growth rate (TGR) incorporates the time between evaluations and may be adequate.

OBJECTIVE

To determine how TGR is modified along the treatment sequence and is associated with outcome in mRCC patients.

DESIGN, SETTING, AND PARTICIPANTS

Medical records from all patients prospectively treated at Gustave Roussy (IGR) in the Treatment Approaches in Renal Cancer Global Evaluation Trial (TARGET) (sorafenib vs placebo, n=84) and the RECORD (everolimus vs placebo, n=43) phase 3 trials were analyzed. TGR was computed across clinically relevant periods: BEFORE treatment introduction (wash-out), UNDER (first cycle), at PROGRESSION (last cycle) and AFTER treatment discontinuation (washout). The association between TGR and outcome (overall survival [OS] and progression-free survival [PFS]) was computed in the entire TARGET cohort (n=903).

INTERVENTION

Sorafenib, everolimus, or placebo.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

TGR, RECIST, OS, and PFS rates.

RESULTS AND LIMITATIONS

Although nearly all the patients (IGR) were classified as stable disease (RECIST) after the first cycle, the great majority of the patients exhibited a decrease in TGR UNDER compared with BEFORE (sorafenib: p<0.00001; everolimus: p<0.00001). In sorafenib-treated but not in everolimus-treated patients (IGR), TGR at PROGRESSION (last cycle) was still lower than TGR BEFORE (washout) (p=0.012), while TGR AFTER progression (washout) was higher than TGR at PROGRESSION (last cycle) (p=0.0012). Higher TGR (first cycle) was associated with worse PFS (hazard ratio [HR]: 3.61; 95% confidence interval [CI], 2.45-5.34) and worse OS (HR: 4.69; 95% CI, 1.54-14.39), independently from the Motzer score and from the treatment arm in the entire TARGET cohort.

CONCLUSIONS

Computing TGR in mRCC patients is simple and provides clinically useful information for mRCC patients: (1) TGR is independently associated with prognosis (PFS, OS), (2) TGR allows for a subtle and quantitative characterization of drug activity at the first evaluation, and (3) TGR reveals clear drug-specific profiles at progression.

Modeling tumor growth kinetics after treatment with pazopanib or placebo in patients with renal cell carcinoma

PURPOSE

The purpose of this study is to characterize tumor growth kinetics in patients with renal cell carcinoma (RCC) after treatment with pazopanib or placebo and to identify predictive patient-specific covariates.

METHODS

Different tumor growth models that included patient-specific covariates were fit to tumor growth data from Phase 2 (n = 220) and Phase 3 (n = 423) clinical trials using nonlinear mixed-effects modeling. Logistic regression was used to determine whether individual model parameters or covariates were related to occurrence of new lesions.

RESULTS

A modified Wang model that included a quadratic growth term and a mixture model adequately described the data. Patients in Group 1 (93 %) showed treatment-dependent tumor shrinkage followed by treatment-independent regrowth. Patients in Group 2 (7 %) showed treatment-independent tumor shrinkage that did not regrow. In Group 1, pazopanib 800 mg increased the tumor shrinkage rate by 267 % compared to placebo. Baseline tumor size was dependent on baseline hemoglobin, baseline lactate dehydrogenase, study, and prior nephrectomy. Logistic regression analysis showed that prior radiotherapy, baseline tumor size, tumor shrinkage rate, tumor regrowth rate, study, and treatment (P < 0.01 for all) were all important predictors of new lesions. Patients treated with placebo were approximately twice as likely to develop new lesions than patients treated with pazopanib.

CONCLUSIONS

Mathematical modeling of tumor growth kinetics can quantify the effect of anticancer therapies. Pazopanib 800 mg was shown to be an effective treatment for RCC that increased the tumor shrinkage rate by 267 % compared with placebo and reduced the likelihood of developing new lesions.

Tumour burden is an independent prognostic factor in metastatic renal cell carcinoma

Study Type--Prognosis (cohort series) Level of Evidence 2b. What's known on the subject? and What does the study add? In the literature, few studies have evaluated the role of tumour burden (TB) in metastatic real cell carcinoma (mRCC), even though it has been considered as important in localized tumours. In metastatic patients the role of TB is uncertain because it was analyzed in chemotherapy treated patients or using a partial evaluation of TB. This study, first reports the independent prognostic and predictive role of TB in mRCC patients treated with targeted agents in prospective clinical trials. TB is able to predict prognosis independently to localization of metastases and prognostic class defined by MSKCC criteria, moreover it is strictly related to patient's performance status.

OBJECTIVE

• To investigate the possible prognostic role of baseline tumour burden (TB) in terms of progression-free survival (PFS) and overall survival (OS), in patients with metastatic renal cell carcinoma (mRCC).

PATIENTS AND METHODS

• A homogenous group of patients with mRCC enrolled in second-line trials post-cytokine treatment were selected for the present analysis. • The Response Evaluation Criteria in Solid Tumors (the sum of the longest unidimensional diameter of each target lesion) were used to assess TB. • The PFS and OS rates were estimated using the Kaplan-Meier method and compared across the groups using the log-rank test. • The association between TB and PFS or OS was evaluated using a Cox proportional hazards model. Multivariable analyses were adjusted for other prognostic variables: the Memorial Sloan Kettering Cancer Centre (MSKCC) risk class and treatment.

RESULTS

• A total of 124 patients were included in the final analysis. Of these, 66% received sorafenib or sunitinib and 34% received placebo. The median follow-up was 80.1 month. • TB was directly related to PFS and OS and these associations remained significant after adjusting for modified MSKCC risk class and treatment,. • Each 1-cm increase in TB increased the risk of progression by 4.5% (hazard ratio [HR]: 1.05; 95% confidence interval [CI] 1.02-1.07; P < 0.001) and the risk of death by 5% (HR: 1.05; 95% CI 1.03-1.08; P < 0.001).

CONCLUSIONS

• TB is easy to calculate from standard computed tomography and significantly relates to OS in patients with mRCC. • We report for the first time the independent prognostic role of baseline TB in multivariate analysis. •  We believe that this information could be translated into clinical practice.

Analyzing the pivotal trial that compared sunitinib and IFN-α in renal cell carcinoma, using a method that assesses tumor regression and growth

PURPOSE

We applied a method that analyzes tumor response, quantifying the rates of tumor growth (g) and regression (d), using tumor measurements obtained while patients receive therapy. We used data from the phase III trial comparing sunitinib and IFN-α in metastatic renal cell carcinoma (mRCC) patients.

METHODS

The analysis used an equation that extracts d and g.

RESULTS

For sunitinib, overall survival (OS) was strongly correlated with log g (Rsq = 0.44, P < 0.0001); much less with log d (Rsq = 0.04; P = 0.0002). The median g of tumors in these patients (0.00082 per days; log g = -3.09) was about half that (P < 0.001) of tumors in patients receiving IFN-α (0.0015 per day; log g = -2.81). With IFN-α, the OS/log g correlation (Rsq = 0.14) was weaker. Values of g from measurements obtained by study investigators or central review were highly correlated (Rsq = 0.80). No advantage resulted in including data from central review in regressions. Furthermore, g can be estimated accurately four months before treatment discontinuation. Extrapolating g in a model that incorporates survival generates the hypothesis that g increased after discontinuation of sunitinib but did not accelerate.

CONCLUSIONS

In patients with mRCC, sunitinib reduced tumor growth rate, g, more than did IFN-α. Correlating g with OS confirms earlier analyses suggesting g may be an important clinical trial endpoint, to be explored prospectively and in individual patients.

The impact of tumor burden characteristics in patients with metastatic renal cell carcinoma treated with sunitinib

BACKGROUND

An important goal of noncurative therapy for metastatic renal cell carcinoma (mRCC) is tumor burden (TB) control. However, to the authors' knowledge, the impact of TB characteristics on clinical outcome has not been studied in patients with mRCC who were treated with vascular endothelial growth factor-targeted therapy.

METHODS

Patients with clear cell mRCC who were treated with sunitinib between June 2004 and October 2007 were retrospectively identified. Computed tomography scans were re-reviewed from baseline, at the time of maximal TB shrinkage (TS) while receiving sunitinib, and at the time of progressive disease (PD). Measurements were recorded as per Response Evaluation Criteria In Solid Tumors (RECIST).

RESULTS

A total of 69 patients were identified. The majority (54%) were classified as being of favorable risk using Cleveland Clinic Foundation Tyrosine Kinase Inhibitor (CCF TKI) risk group criteria. All patients underwent prior nephrectomy and 77% received prior systemic therapy. There were a median of 8 metastatic deposits across all organs (range, 1-27 deposits). The median TB at the initiation of therapy was 14.0 cm (range, 3.0 cm-42.2 cm). On multivariable analysis, baseline characteristics of disease confined to above the diaphragm (P = .03) and a total TB <13 cm (P = .09) were found to be independent positive predictors of progression-free survival. A+ baseline, total number of metastases <10 (P < .001) and TB above the diaphragm <6.5 cm (P = .05) were found to be independent positive predictors of overall survival (OS). Increased TS while receiving sunitinib was found to be significantly associated with OS (P < .001). At the time of PD, tumor location and pattern of disease progression were not found to be associated with survival as measured from the date of PD. However, total TB (P = .003) and total number of metastatic deposits (≤12 vs >12; P < .001) were found to be significant predictors of survival after PD.

CONCLUSIONS

The results of the current study indicate that TB characteristics are associated with clinical outcome in patients with mRCC who are treated with sunitinib.