Measures of response: RECIST, WHO, and new alternatives

Risks and benefits associated with novel phase 1 oncology trial designs

BACKGROUND

Although aggressive dose escalation strategies were designed to improve the risk-benefit profile of phase 1 oncology trials, they have not been adequately studied. The prevalence of several novel trial designs and their association with a variety of clinical endpoints was evaluated.

METHODS

A review of the literature was performed to identify phase 1 oncology studies of cytotoxic agents published from 2002 through 2004.

RESULTS

Of 955 phase 1 oncology articles initially identified, 149 studies, comprising 4532 patients, were analyzed. Only 34% of studies utilized aggressive dose escalation schemes, 22% permitted intrapatient dose escalation, and only 28% enrolled fewer than 3 patients to any dose level. Studies that allowed intrapatient dose escalation or used fewer than 3 patients per dose were not associated with different rates of response or toxicity, nor did they increase the number of patients who received the recommended phase 2 dose. However, aggressive dose escalations were associated with increased rates of both hematologic (17% vs 10%) and nonhematologic (17% vs 13%) toxicity with similar response rates. Only studies that used conservative dose escalation designs and those that studied U.S. Food and Drug Administration (FDA)-approved agents required fewer patients to complete a trial. Trials of FDA-approved agents were also associated with higher response rates than trials of non-FDA-approved agents (10% vs 2%), without an increased risk of toxicity.

CONCLUSIONS

Several novel aggressive design strategies intended to improve the risk-benefit profile of phase 1 oncology trials are not associated with improved clinical outcome, and may be harmful in certain instances.

Diffusion magnetic resonance imaging: a biomarker for treatment response in oncology

Imaging of response to oncology treatments, either on clinical protocol or as part of standard practice, is a complicated process that has evolved during the last 10 years due to the improvement of existing imaging technologies and the introduction of newer modalities. Diffusion magnetic resonance imaging is a technique that measures the mobility of water within tissues and, as such, may function as a surrogate marker for both tissue cellularity and response to treatment that occur earlier than usual measures of tumor response. This review highlights the development of this technique and the state of current clinical understanding of its utility.

Assessment of tumor response on MR imaging after locoregional therapy

Assessment of tumor response after locoregional therapies is important in determining treatment success and in guiding future therapy. Magnetic resonance imaging plays an important role in evaluating treatment response to new therapies directed toward hepatic lesion treatment. The traditional and accepted criteria to determine tumor response in oncology, namely the Response Evaluation Criteria in Solid Tumors (RECIST) and the European Association for the Study of the Liver (EASL) criteria, use decrease in tumor size and lesion enhancement as an indicator of successful therapy. A more recent evaluation method is the Apparent Diffusion Coefficient (ADC) measured by diffusion-weighted MR imaging. Diffusion-weighted MR imaging and ADC values map the thermally induced motion of water molecules in tissues and thereby are able to provide insight into tumor microstructure. In this article we discuss the role of MR imaging in assessing treatment response after various locoregional therapies. We describe the role of tumor size and lesion enhancement as well as ADC mapping. We also discuss the magnetic resonance imaging findings after radiofrequency ablation (RFA), transarterial chemoembolization (TACE) and radioembolization.