There are unmet needs in evaluating treatment response of hepatocellular carcinoma in research protocols. Early predictors, such as imaging biomarkers, could allow for earlier judgment of treatment effect. Currently RECIST is the most widely accepted criterion in clinical trials. A modified RECIST (mRECIST) criterion was developed to take into account the unique imaging characteristics of HCC lesions. Much discussion has occurred regarding linear measurements and their appropriateness for evaluating change in tumor burden over time. The simplicity of currently accepted criteria differs with the increasing sophistication of imaging techniques. Tumor volume change on 3D imaging can provide insight into actual action of treatment rather than an estimate of action as shown by linear and bi-dimensional measurements. It was the aim of this study to determine whether linear, bi-dimensional, and volumetric percent changes of HCC lesions, in both the arterial and portal venous phases, are significantly comparable. 27 HCC lesions (identified on 25 subjects) were measured at two timepoints by each method on 3D GRE MRI scans in both phases. Percent change was calculated per lesion for each measurement type in both the arterial and portal venous phases. Signed rank tests, paired t tests, and comparison of change tests were run to evaluate the data. Significant differences between the percent changes of linear measurements versus volumetric measurements were observed using a Wilcoxon signed-rank test which showed p = 0.0000. A simple correlation assessment showed positive correlations for all measurements, with the lowest being correlations 0.8679 for the arterial linear percent change versus the arterial volumetric percent change and 0.8434 for the portal venous linear percent change versus the portal venous volumetric percent change. Differences between percent changes of linear versus bi-dimensional measurements and bi-dimensional versus volumetric measurements were significant as well (Linear versus bi-dimensional p = 0.0001, bi-dimensional versus volumetric p = 0.0004). To conclude, the differences in the percent changes when comparing the measurement types are statistically significant, particularly when comparing linear and volumetric measurements. Establishing a reproducible volumetric criterion could lead to improvements in the implementation of clinical trials.

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Background: Drugs targeting angiogenic pathway remain the mainstay of treatment for metastatic renal cell carcinoma (mRCC). Tyrosine Kinase Inhibitors (TKI) as Sunitinib, Pazopanib as single agents and humanised monoclonal antibody bevacizumab (Bev) in combination with Interferon- α2a (IFN) have established as the first-line therapy for mRCC. Despite improvements in treatment, there are multiple questions which remain unanswered. In the combination of Bev and IFN, the respective role of each drug and whether any additional anti-angiogenic activity is gained by adding IFN to Bev remains unknown. As the clinical benefit obtained with these cytostatic agents does not always correlate with the conventional response assessment techniques as RECIST, it is necessary to reconsider the methods by which we assess benefit from these therapies. In this thesis, I report three studies aiming to answer these questions. Methods: With the clinical trial reported here, I explore whether Bev induced changes in vascular parameters measured by Dynamic Contrast Enhanced MRI (DCE-MRI) is significantly enhanced by the addition of IFN. In a phase II, randomised, open labelled, multicentre trial, treatment naïve mRCC patients were randomised to receive Bev on its own or in combination with a low dose (3MU) or standard dose (9MU) IFN. DCE-MRI was used to assess the changes in vascularity with the primary endpoint being, changes in transfer coefficient (Ktrans) after six weeks of treatment. I also report two retrospective imaging-based studies, using contrast-enhanced CT scans, performed to improve the methodology of response assessment for these antiangiogenic therapeutics. Here I explore the use of a) combining changes in size and arterial phase contrast enhancement measured using CT scan and b) changes in CT texture as methods of therapeutic response assessment in mRCC patients treated with TKI. Results: With the phase 2 clinical trial, we faced significant difficulty in recruitment as a result of restrictions in access to treatment in NHS, other competing studies and restrictions proposed by the DCE-MRI inclusion criteria. With slow recruitment, an unplanned analysis was performed after 21 patients were recruited. Analysis of primary endpoint showed no trend in the difference between arms with no correlation found between change in Ktrans and addition of IFN to bevacizumab. Effect size analysis performed due to the small numbers recruited failed to show any significance in the observed difference in Ktrans. Change in Ktrans and Kep may identify a group of patients likely to have PFS > 6 months, but this observation needs to evaluation in a larger sample size. Measuring size and change in arterial phase enhancement retrospectively using CT, a new criterion "modified" Choi, which prerequisite a combination of a decrease in arterial phase density by 15% and a decrease in size by 10% for response was proposed. Response assessment was measured with RECIST, Choi and modified Choi individually in 20 evaluable patients retrospectively and clinical benefit compared with Kaplan-Meier statistics and Log-Rank test. Response assessment as defined by the modified Choi criteria successfully identified patients who received clinical benefit from the treatment. Time to progression (TTP) was 448 days for the partial response and 89 days for stable disease as per the new criteria which were statistically significant with a p-value of 0.002. The second retrospective analysis explored the textural changes in enhanced CT scan. Performed in collaboration with researchers from Brighton University who developed the software algorithm used to assess changes in entropy and uniformity, 87 metastases from 39 patients with mRCC were analysed at baseline and after two cycles of TKI treatment. Textural parameters and response assessment criteria were correlated with TTP. After two cycles of TKI, the decrease in tumour entropy was 3%-45%, and increase in uniformity was 5%-21%. At a threshold change of -2% with uniformity, on a coarse scale of 2.5, the textural change was able to separate responders from non-responders. With Kaplan-Meier analysis comparing all four criteria, the percentage change in uniformity was statistically more significant than for RECIST, Choi, and Modified Choi criteria. Cox regression analysis showed that texture uniformity was an independent predictor of time to progression. Discussion: With the studies reported here, I was able to demonstrate the importance of improving the methodology in assessment of therapeutic response to targeted anti-angiogenic therapy in metastatic renal cell carcinoma. Even though the clinical trial, terminated early due to slow recruitment, did not reach its primary endpoint, changes in other vascular parameters as Kep combined with changes Ktrans showed tendency towards identifying a group of patients who derived clinical benefit of >6months with these therapies. This is particularly exciting as given the vascular stabilisation effect proposed for bevacizumab, the effusion parameter Kep may be a better tool in assessing response rather than Ktrans and warrants further assessment in a larger cohort. Modified choi criterion and textural analysis are two important methodological improvements in response assessment of cytostatic anti-angiogenic therapy. In the analyses reported here, both techniques have shown superiority over RECIST in response assessment and differentiating mRCC patients who is likely to gain clinical benefit by TKI therapy. Validation of these criteria on a larger patient cohort is important. As these criterions are assessed on standard enhanced CT scans, incorporating these criteria, especially modified choi criterion, as part of standard CT assessment could be performed and will provide a real world validation. Retrospective assessment using larger cohort of patients from previous phase 3 trials or inclusion of these parameters prospectively in phase 3 trials would also help us in evaluating these modalities further.