Sufficiency of Single-Arm Studies to Support Registration of Targeted Agents in Molecularly Selected Patients with Cancer: Lessons from the Clinical Development of Crizotinib

Do Early Phase Oncology Trials Predict Clinical Efficacy in Subsequent Biomarker-Enriched Phase III Randomized Trials?

BACKGROUND

Promising early phase trial results of biomarker-targeted therapies have occasionally led to regulatory approval.

OBJECTIVE

We examined if early phase trials were predictive of efficacy in randomized controlled trials (RCTs) with matching treatment settings.

PATIENTS AND METHODS

Cancer drug RCTs conducted between January 2006 and March 2021 were identified through Clinicaltrials.gov. Biomarker-enriched RCTs and associated matching early phase trials were included. Trial pairs were compared using objective response rate (ORR) and progression-free survival (PFS). We examined whether early phase trials results were associated with RCT results using logistic regression.

RESULTS

The search yielded 2157 unique RCTs and 27 RCTs pairing with early phase trials were included. Based on average difference of trial pairs, ORR was similar (1.6%; 95% confidence interval (CI) - 2.5 to 5.6, p = 0.50) and median PFS was higher in early phase trials (2.0 months; 95% CI 0.9-3.0, p < 0.05). On an individual pair basis, there was large variability in difference for ORR (range - 23.9 to 20.2%) and median PFS (range - 0.8 to 7.4 months). The probability of the RCT meeting its primary endpoint is 95% (95% prediction interval (PI) 72.8-99.3%) when the early phase trial ORR is 77.7%.

CONCLUSIONS

Overall, in early phase trials, ORR has minimal bias and median PFS appears to be slightly overestimated. Substantial variability between trials suggests early phase trial results may be inconsistent with subsequent RCT. Early phase trial results may be associated with RCTs meeting their primary endpoint when ORR is very high; however, caution must be exercised when using early phase trials as representative of RCTs.

High-grade glioma therapy: adding flexibility in trial design to improve patient outcomes

INTRODUCTION

Outcomes for patients with high grade gliomas have changed little over the past thirty years. This realization prompted renewed efforts to increase flexibility in the design and conduct of clinical brain tumor trials.

AREAS COVERED

This manuscript reviews the development of clinical trial methods, challenges and considerations of flexible clinical trial designs, approaches to improve identification and testing of active agents for high grade gliomas, and evaluation of their delivery to the central nervous system.

EXPERT OPINION

Flexibility can be introduced in clinical trials in several ways. Flexible designs tout smaller sample sizes, adaptive modifications, fewer control arms, and inclusion of multiple arms in one study. Unfortunately, modifications in study designs cannot address two challenges that are largely responsible for the lack of progress in treating high grade gliomas: 1) the identification of active pharmaceutical agents and 2) the delivery of these agents to brain tumor tissue in therapeutic concentrations. To improve the outcomes of patients with high grade gliomas efforts must be focused on the pre-clinical screening of drugs for activity, the ability of these agents to achieve therapeutic concentrations in non-enhancing tumors, and a willingness to introduce novel compounds in minimally pre-treated patient populations.

Response Rates and Durations of Response for Biomarker-Based Cancer Drugs in Nonrandomized Versus Randomized Trials

BACKGROUND

Many new targeted cancer drugs have received FDA approval based on durable responses in nonrandomized controlled trials (non-RCTs). The goal of this study was to evaluate whether the response rates (RRs) and durations of response (DoRs) of targeted cancer drugs observed in non-RCTs are consistent when these drugs are tested in RCTs.

METHODS

We used the FDA's Table of Pharmacogenomic Biomarkers in Drug Labeling to identify cancer drugs that were approved based on changes in biomarker endpoints through December 2017. We then identified the non-RCTs and RCTs for these drugs for the given indications and extracted the RRs and DoRs. We compared the RRs and median DoR in non-RCTs versus RCTs using the ratio of RRs and the ratio of DoRs, defined as the RRs (or DoRs) in non-RCTs divided by the RRs (or DoRs) in RCTs. The ratio of RRs or DoRs was pooled across the trial pairs using random-effects meta-analysis.

RESULTS

Of the 21 drug-indication pairs selected, both non-RCTs and RCTs were available for 19. The RRs and DoRs in non-RCTs were greater than those in RCTs in 63% and 87% of cases, respectively. The pooled ratio of RRs was 1.06 (95% CI, 0.95-1.20), and the pooled ratio of DoRs was 1.17 (95% CI, 1.03-1.33). RRs and DoRs derived from non-RCTs were also poor surrogates for overall survival derived from RCTs.

CONCLUSIONS

The RRs were not different between non-RCTs and RCTs of cancer drugs approved based on changes to a biomarker, but the DoRs in non-RCTs were significantly higher than in RCTs. Caution must be exercised when approving or prescribing targeted drugs based on data on durable responses derived from non-RCTs, because the responses could be overestimates and poor predictors of survival benefit.

Benchmarking single-arm studies against historical controls from non-small cell lung cancer trials - an empirical analysis of bias

Background: Recent trials of novel agents in 'rare' molecular subtypes of non-small cell lung cancer (NSCLC) have used single-arm trial designs and benchmarked outcomes against historical controls. We assessed the consistency of historical control outcomes using docetaxel data from published NSCLC randomized controlled trials (RCTs).Material and methods: Advanced NSCLC RCTs including a docetaxel monotherapy arm were included. Heterogeneity in tumor objective response rates (ORRs), progression-free survival (PFS) and overall survival (OS), and correlations between outcomes and year of trial commencement were assessed.Results: Among 63 trials (N = 10,633) conducted between 2000 and 2017, ORR ranged from 0% to 26% (I² = 76.1%, p_{heterogeneity} < .0001). Mean of the median PFS was 3.0 months (range: 1.4-6.4), 3-month PFS ranged from 25% to 85% (I² = 86.0%, p_{heterogeneity} < .0001). Mean of the median OS was 9.1 months (range: 4.7-22.9), 9-month OS ranged from 23% to 79% (I² = 83.0%, p_{heterogeneity} < .0001). Each later year of trial commencement was associated with 0.3% (p = .046), 0.5% (p = .11) and 0.9% (p = .001) improvement in ORR, 3-month PFS and 9-month OS rates, respectively.Conclusions: There was significant heterogeneity and an improving trend in docetaxel outcomes across trials conducted over 20 years. Benchmarking biomarker-targeted agents against historical controls may not be a valid approach to replace RCTs. Innovative study designs involving a concurrent control arm should be considered.

A Review of Perspectives on the Use of Randomization in Phase II Oncology Trials

Historically, phase II oncology trials assessed a treatment's efficacy by examining its tumor response rate in a single-arm trial. Then, approximately 25 years ago, certain statistical and pharmacological considerations ignited a debate around whether randomized designs should be used instead. Here, based on an extensive literature review, we review the arguments on either side of this debate. In particular, we describe the numerous factors that relate to the reliance of single-arm trials on historical control data and detail the trial scenarios in which there was general agreement on preferential utilization of single-arm or randomized design frameworks, such as the use of single-arm designs when investigating treatments for rare cancers. We then summarize the latest figures on phase II oncology trial design, contrasting current design choices against historical recommendations on best practice. Ultimately, we find several ways in which the design of recently completed phase II trials does not appear to align with said recommendations. For example, despite advice to the contrary, only 66.2% of the assessed trials that employed progression-free survival as a primary or coprimary outcome used a randomized comparative design. In addition, we identify that just 28.2% of the considered randomized comparative trials came to a positive conclusion as opposed to 72.7% of the single-arm trials. We conclude by describing a selection of important issues influencing contemporary design, framing this discourse in light of current trends in phase II, such as the increased use of biomarkers and recent interest in novel adaptive designs.

Routine thyroglobulin, neck ultrasound and physical examination in the routine follow up of patients with differentiated thyroid cancer-Where is the evidence?

PURPOSE

Patients with differentiated thyroid cancer (DTC) typically have a favourable prognosis and recurrence as late as 45 years after diagnosis has been reported. International clinical guidelines for monitoring recommend routine thyroglobulin, ultrasound and physical examination for the detection of recurrence. The aim of this review was to systematically review whether routine monitoring using thyroglobulin (Tg), neck ultrasound and physical examination for recurrence in differentiated thyroid cancer patients is effective in improving patient survival and/or quality of life.

METHODS

Primary studies were retrieved via a comprehensive search of three electronic bibliographic databases (PubMed, Web of Science Core Collection and Cochrane Library) without time restriction. Eligible studies must have reported on disease-free patients with DTC subject to long-term routine surveillance. The primary and secondary outcomes of interest were overall survival (or other survival parameters) and quality of life, respectively.

RESULTS

Literature searches yielded 5529 citations, which were screened by two reviewers. 241 full texts were retrieved. No randomised controlled trials or two-arm cohort studies on the effectiveness of any of the three specified interventions were identified. However, three 'single-arm' studies reporting long-term follow-up outcomes in patients undergoing regular surveillance were identified and appraised.

CONCLUSIONS

This review highlights a lack of empirical evidence to support current use of routine surveillance in DTC. Although early detection is possible, routine surveillance may lead to unnecessary intervention.

Co-expression of the recombined alcohol dehydrogenase and glucose dehydrogenase and cross-linked enzyme aggregates stabilization

As the key chiral precursor of Crizotinib (S)-1-(2,6-dichloro-3-fluorophenyl) phenethyl alcohol can be prepared from 1-(2,6-dichloro-3-fluorophenyl) acetophenone by the reductive coupling reactions of alcohol dehydrogenase (ADH) and glucose dehydrogenases (GDH). In this work the heterologous expression plasmids harbouring the encoding genes of ADH and GDH were constructed respectively and co-expressed in the same E. coli strain. After optimization, a co-cross-linked enzyme aggregates (co-CLEAs) of both ADH and GDH were prepared from crude enzyme extracts by cross-linking with the mass ratio of Tween 80, glutaraldehyde and total protein (0.6:1:2) which rendered immobilized biocatalysts that retained 81.90% (ADH) and 40.29% (GDH) activity retention. The ADH/GDH co-CLEAs show increased thermal stability and pH stability compared to both enzymes. The ADH/GDH co-CLEAs also show 80% (ADH) and 87% (GDH) residual activity after seven cycles of repeated use. These results make the ADH/GDH co-CLEAs a potential biocatalyst for the industrial preparation of (S)-1-(2,6-dichloro-3-fluorophenyl) phenethyl alcohol.