Off-label despite high-level evidence: a clinical practice review of commonly used off-patent cancer medicines

INTRODUCTION

Off-label use of medicines is generally discouraged. However, several off-patent, low-cost cancer medicines remain off-label for indications in which they are commonly used in daily practice, supported by high-level evidence based on results of phase III clinical trials. This discrepancy may generate prescription and reimbursement obstacles as well as impaired access to established therapies.

METHODS

A list of cancer medicines that remain off-label in specific indications despite the presence of high-level evidence was generated and subjected to European Society for Medical Oncology (ESMO) expert peer review to assess for accountability of reasonableness. These medicines were then surveyed on approval procedures and workflow impact. The most illustrative examples of these medicines were reviewed by experts from the European Medicines Agency to ascertain the apparent robustness of the supporting phase III trial evidence from a regulatory perspective.

RESULTS

A total of 47 ESMO experts reviewed 17 cancer medicines commonly used off-label in six disease groups. Overall, high levels of agreement were recorded on the off-label status and the high quality of data supporting the efficacy in the off-label indications, often achieving high ESMO-Magnitude of Clinical Benefit Scale (ESMO-MCBS) scores. When prescribing these medicines, 51% of the reviewers had to implement a time-consuming process associated with additional workload, in the presence of litigation risks and patient anxiety. Finally, the informal regulatory expert review identified only 2 out of 18 (11%) studies with significant limitations that would be difficult to overcome in the context of a potential marketing authorisation application without additional studies.

CONCLUSIONS

We highlight the common use of off-patent essential cancer medicines in indications that remain off-label despite solid supporting data as well as generate evidence on the adverse impact on patient access and clinic workflows. In the current regulatory framework, incentives to promote the extension of indications of off-patent cancer medicines are needed for all stakeholders.

Plasma ctDNA RAS status selects patients for anti-EGFR treatment rechallenge in metastatic colorectal cancer: a meta-analysis

BACKGROUND

Recently one randomized trial and several phase II studies underscored that patients with metastatic colorectal cancer who progressed after an initial clinical benefit from anti-epidermal growth factor receptor (EGFR) treatment may further benefit from rechallenge with anti-EGFR therapy. Testing circulating tumor DNA (ctDNA) RAS status prior to anti-EGFR rechallenge seems a promising non-invasive method to predict and monitor response to anti-EGFR readministration.

AIM

To assess the capability of liquid biopsy ctDNA in exploring RAS status and in predicting outcome of metastatic colorectal cancer patients treated with anti-EGFR monoclonal antibody rechallenge.

MATERIALS AND METHODS

Systematic review of literature and meta-analysis of the available evidence.

RESULTS

Data from four studies involving 117 patients were available. All patients harbored RAS wild type tumors and derived benefit from first line anti-EGFR therapy. Of these, 65 underwent plasma ctDNA before anti-EGFR treatment rechallenge and were eligible for analyses: 35 patients had RAS wild type ctDNA, and 30 RAS mutated, indicating that 46% of patients underwent RAS status conversion after primary anti-EGFR therapy. Anti-EGFR rechallenge among patients with plasma ctDNA RAS wild type status was associated with a consistent benefit in progression free survival (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.22-0.70; p = 0.001; I² = 0) and overall survival (HR 0.37, 95% CI 0.16-0.85; p = 0.02; I² = 74%) when compared to its use among patients with plasma ctDNA RAS mutation. Patients with plasma ctDNA RAS wild type profile also performed statistically better in term of disease control rate, risk for disease progression at 3 and 6 months, and risk for death at 6 and 12 months.

CONCLUSION

RAS status assessment continues to be useful in predicting benefit for anti-EGFR treatment.

Biases in study design, implementation, and data analysis that distort the appraisal of clinical benefit and ESMO-Magnitude of Clinical Benefit Scale (ESMO-MCBS) scoring

Background

The European Society for Medical Oncology-Magnitude of Clinical Benefit Scale (ESMO-MCBS) is a validated, widely used tool developed to score the clinical benefit from cancer medicines reported in clinical trials. ESMO-MCBS scores assume valid research methodologies and quality trial implementation. Studies incorporating flawed design, implementation, or data analysis may generate outcomes that exaggerate true benefit and are not generalisable. Failure to either indicate or penalise studies with bias undermines the intention and diminishes the integrity of ESMO-MCBS scores. This review aimed to evaluate the adequacy of the ESMO-MCBS to address bias generated by flawed design, implementation, or data analysis and identify shortcomings in need of amendment.

Methods

As part of a refinement of the ESMO-MCBS, we reviewed trial design, implementation, and data analysis issues that could bias the results. For each issue of concern, we reviewed the ESMO-MCBS v1.1 approach against standards derived from Helsinki guidelines for ethical human research and guidelines from the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, the Food and Drugs Administration, the European Medicines Agency, and European Network for Health Technology Assessment.

Results

Six design, two implementation, and two data analysis and interpretation issues were evaluated and in three, the ESMO-MCBS provided adequate protections. Seven shortcomings in the ability of the ESMO-MCBS to identify and address bias were identified. These related to (i) evaluation of the control arm, (ii) crossover issues, (iii) criteria for non-inferiority, (iv) substandard post-progression treatment, (v) post hoc subgroup findings based on biomarkers, (vi) informative censoring, and (vii) publication bias against quality-of-life data.

Conclusion

Interpretation of the ESMO-MCBS scores requires critical appraisal of trials to understand caveats in trial design, implementation, and data analysis that may have biased results and conclusions. These will be addressed in future iterations of the ESMO-MCBS.

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We reviewed trial design, implementation, and data analysis issues that could bias the results of trials.

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These issues could skew the results of ESMO-MCBS scores.

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Six design, two implementation, and two analysis issues were reviewed, and seven shortcomings were identified.

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These issues will be addressed in future versions of the MCBS scale.

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Interpretation of MCBS scores requires critical appraisal of trials.