Composite event-free-survival as an endpoint in oncology drug evaluation: Review and guidance perspectives from the Haute Autorité de Santé (HAS)

BACKGROUND

The use of right-censored composite endpoints, such as progression-free survival, has been questioned in haemato-oncology trials due to potential bias in estimated treatment effect. This may impact the accuracy of health technology evaluations. We hypothesized that there is heterogeneity and potential sources of bias in the reporting of composite endpoints to health technology assessment (HTA) bodies.

METHODS

We reviewed the submissions for reimbursement of oncology drugs in 2021 and 2022 that used a composite endpoint in the pivotal trial, after appraisal by the French HTA body. The retrieved information included the clinical study report, protocol, and statistical analysis plan submitted by the industry. All events of the composite endpoint and all causes of censored observations were measured. The design characteristics and treatment effect estimates were recorded.

FINDINGS

Seventy-six submissions were selected, including seven without a right-censored endpoint and four evaluating associations, resulting in 65 analysed records: 17 for haematological and 48 for solid tumours. Out these 65 submissions, 47 (72·3%) used a randomized controlled design, and 18 (27·7%) a non-comparative design. The most frequently used composite endpoint was progression-free survival, used in 54 (83·1%) of the submissions. Censoring was possibly informative in 51 (92·7%) cases, mostly due to the onset of new treatment (44/51, 86·3%) and/or discontinuation of follow-up (33/51, 64·7%). In contrast, 38 (58·5%) trials reported a quantification of censored observations, with only 12/51 (23·5%) quantifying the informative ones. The estimated treatment effect on the composite outcome increased with the amount of censoring, suggesting a higher benefit of the drug, but remained below that on survival with poor evidence of surrogacy (R-squared=0·23).

INTERPRETATION

Clinical study reports should be improved in terms of reporting censoring, while stakeholders should be aware of this potential source of bias. At a minimum, sensitivity analysis that ignores intercurrent events should be requested.

Importance of collateral circulation of bowel in urologic surgery

As urologic surgery becomes more extensive planned or inadvertent compromise of the vascular supply of the bowel becomes more likely. Familiarity with the normal anatomy of the vascular supply of the large and small intestines must, therefore, be part of every urologist's fund of knowledge. With an appreciation of the critical areas of collateral circulation conclusions can be drawn as to which arteries can and cannot be ligated safely. Intraoperative Doppler flow studies may help the surgeon to evaluate whether collateral supply is adequate to maintain bowel viability. In certain marginal situations hydration and postoperative treatment with antibiotics may be helpful.