Statistical controversies in clinical research: should schedules of tumor size assessments be changed?

BACKGROUND: Time to progression (TTP) is often used as a primary end point in phase II clinical trials. Since the actual date of nadir and progression is never known, most calculated TTP are overestimated. This study evaluates the imprecision on the estimate of TTP under two hypothetical tumor kinetic settings and various assessment schedules. DESIGN: A two-component tumor growth model was used to account for treatment effect assuming exponential decay for tumor shrinkage and linear growth for progression. Evolution of tumor burden (TB) was modelized according to two scenarios using either a cytotoxic or a cytostatic agent and several assessment schedules. TB, nadir, progression and TTP were simulated for each visit schedule. RESULTS: For cytotoxic agents, our model predicted response at 1.5 weeks, a TB at nadir of 40.2 mm (starting from 100 mm) occurring at 6.7 weeks and true progression at 11.2 weeks with a TB of 48.2 mm. For cytostatic agents, our model predicted no response, a TB at nadir of 77 mm occurring at 9.2 weeks and true progression at 19.4 weeks with a TB of 92 mm. Depending on the assessment schedule, estimated TTP was increased from 0.8 to 36.8 weeks and from 0.6 to 28.6 weeks when compared with the true TTP and varied from 5.2% to 298% and from 1.66 to 109.58% when compared with the true TB at progression for cytotoxic and cytostatic agents, respectively. Our model further shows that for cytotoxic agents, evaluation of TB every 6 weeks is optimal to capture the true nadir, the time to nadir, the true progression and the true TTP, whereas for cytostatic agents, this evaluation is optimal every 10 weeks. CONCLUSIONS: Our results emphasize the importance to estimate the effects of tested drugs on tumor shrinkage before design any phase II clinical trials to choose optimal TB evaluation's timing.

How to report toxicity associated with targeted therapies?

BACKGROUND: In the era of personalized medicine, molecularly targeted therapies (MTT) have modified the outcome of some cancer types. The price of tumor control needs to be balanced with toxicity since these new therapies are administered continuously for several months or sometimes for several years. For cytotoxic drugs, the incidence of adverse event (AE) was traditionally reported as frequency and intensity. This simple measure is not sufficient to capture the recurrent nature and duration of AE. This paper presents two methods to better describe the toxicity burden across the time: prevalence and Q-TWiST. PATIENTS AND METHODS: Limitation of worst-grade method and advantages of prevalence and Q-TWiST in the analysis of toxicity were illustrated using data from a phase II trial and a hypothetically simulated clinical trial. RESULTS: Prevalence integrates the recurrent nature of AE. Using prevalence, it is possible to obtain a time profile of AE. Q-TWiST method evaluates the weighted time spent in each health state and also considers the recurrent nature of side-effects in order to assess the 'risk-benefit' ratio of a treatment. When interpreting Q-TWiST results, it is necessary to take into account overall survival and progression-free survival and to define a clinically relevant difference according to the setting. CONCLUSION: The two methods presented here capture different effects. They are helpful for physicians in their treatment choice (balance benefit risk), to counsel patients and to optimize supportive care. In order to ensure consistency and provide critical information required for medical decision-making, it is important to encourage the use of alternative statistical methods in the analysis of toxicities associated with MTT. CLINICAL TRIAL: NCT00541008.

Sorafenib in patients with locally advanced and metastatic chordomas: a phase II trial of the French Sarcoma Group (GSF/GETO).

BACKGROUND: There is no consensual treatment of locally advanced or metastatic chordomas. PATIENTS AND METHODS: We conducted a multicenter, open-label, uncontrolled phase II trial of sorafenib (800 mg/day). The primary end point was the 9-month progression-free rate according to RECIST 1.1. All patients had documented progressive disease at the time of study entry. RESULTS: Twenty-seven patients were enrolled between May 2011 and January 2014. The median age was 64 (range, 30-86) years. There were 17 men and 10 women. Twelve patients had been previously treated with chemotherapy and molecularly targeted agents. The maximum toxicity grade per patient was grade 3 in 21 cases (77.8%) and grade 4 in 4 cases (14.8%). Sorafenib provided an intent-to-treat best objective response of 1/27 [3.7%; 95% confidence interval (CI) 0.1% to 19.0%], a 9-month progression-free rate of 73.0% (95% CI 46.1-88.0) and a 12-month overall survival rate of 86.5% (95% CI 55.8-96.5). Survival curves were similar in pretreated and not pretreated patients. DISCUSSION: Additional clinical trials further exploring sorafenib as a treatment of locally advanced or metastatic chordomas are warranted.

A dose-escalating phase I of imatinib mesylate with fixed dose of metronomic cyclophosphamide in targeted solid tumours.

BACKGROUND: Preclinical findings suggest that imatinib mesylate (IM) and metronomic cyclophosphamide (MC) combination provides synergistic antiangiogenic activity on both pericytes and endothelial cells. METHODS: We have designed a 3+3 dose-escalating phase I trial with a fixed dose of MC (50 mg two times daily) plus IM (400 mg per day; 300 and 400 mg two times daily). Enrolled patients had IM- and sutininib-refractory advanced gastrointestinal stromal tumours (GIST) (n=17), chordoma (n=7) and mucosal melanoma (n=2). Dose-limiting toxicities were monitored for the first 6 weeks. Progression-free survival (PFS) and response assessment are based on RECIST 1.0 guidelines. Pharmacokinetics of IM were measured before and after exposure to MC. RESULTS: No dose-limiting toxicity was observed. Fourteen patients of the expanded cohort received 400 mg two times daily of IM with MC. Apart from a case of possibly related acute leukaemia occurring after 4 years of treatment, we did not see unexpected toxicity. No drug-drug pharmacokinetic interaction was observed. There was no objective response. We have observed long-lasting stable disease in chordoma patients (median PFS=10.2 months; range, 4.2-18+) and short-term stable disease in heavily GIST pretreated patients (median PFS=2.3 months; range, 2.1-6.6). CONCLUSION: This combination is feasible and may warrant further exploration in refractory GIST or chordoma patients.

Complication-related removal of totally implantable venous access port systems: Does the interval between placement and first use and the neutropenia-inducing potential of chemotherapy regimens influence their incidence? A four-year prospective study of 4045 patients.

BACKGROUND: Totally implantable venous access port systems are widely used in oncology, with frequent complications that sometimes necessitate device removal. The aim of this study is to investigate the impact of the time interval between port placement and initiation of chemotherapy and the neutropenia-inducing potential of the chemotherapy administered upon complication-related port removal. PATIENTS AND METHODS: Between January 2010 and December 2013, 4045 consecutive patients were included in this observational, single-center prospective study. The chemotherapy regimens were classified as having a low (<10%), intermediate (10-20%), or high (>20%) risk for inducing neutropenia. RESULTS: The overall removal rate due to complications was 7.2%. Among them, port-related infection (2.5%) and port expulsion (1%) were the most frequent. The interval between port insertion and its first use was shown to be a predictive factor for complication-related removal rates. A cut-off of 6 days was statistically significant (p = 0.008), as the removal rate for complications was 9.4% when this interval was 0-5 days and 5.7% when it was ≥6 days. Another factor associated with port complication rate was the neutropenia-inducing potential of the chemotherapy regimens used, with removal for complications involved in 5.5% of low-risk regimens versus 9.4% for the intermediate- and high-risk regimens (p = 0.003). CONCLUSION: An interval of 6 days between placement and first use of the port reduces the removal rate from complications. The intermediate- and high-risk for neutropenia chemotherapy regimens are related to higher port removal rates from complications than low-risk regimens.