RE:GenemanFound this and it suggests the PFS and DCR may be of more interest that ORR. Good for ONC, as the data look even better when dismissing ORR.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3237237/
Advantages and disadvantages of major endpoints
Overall survival
In view of its objective measurement and the unquestionable benefit derived by patients, OS has been historically considered the most important endpoint in medical oncology14. The US Food and Drug Administration considers OS as a direct measure of treatment benefit; according to that agency, OS is usually the preferred endpoint when studies can be conducted to adequately assess survival9. However, OS is increasingly an elusive endpoint, mostly because it may be confounded by the use of treatments administered to patients after participation in a given trial, including post-progression cross-over to the experimental arm4. As a result, many randomized trials in breast cancer are underpowered to detect significant OS differences; notably, only approximately 7 per cent of recent phase III trials in advanced breast cancer have used OS as their primary endpoint10. Nevertheless, nearly 20 per cent of such trials demonstrated a significant survival improvement, most frequently in association with an accompanying gain in PFS/TTP and in trials involving patients in second- and third-line therapies10. From a strictly methodological standpoint, it is arguable that the extent to which survival gain in those trials - especially in the first line - was due to trial therapy is unknown, given the effect of post-trial interventions. As a corollary to the prior statement, the expectation of OS gain in trials for which PFS was the primary endpoint may be elusive.
PFS and TTP
Efficacy endpoints based on tumour assessments have been increasingly used in drug development, and both have been accepted as markers of clinical benefit for drug approval11,15,16. For regulatory purposes, PFS seems preferable to TTP in so far as it captures fatal toxicities11. PFS is an attractive endpoint because it is available earlier than OS, is less likely than OS to be influenced by competing causes of death, and is not influenced by treatments administered after progression in a given trial. On the other hand, PFS is subject to measurement error and bias. Measurement error may stem from inconsistent use of definitions and standards among investigators17, whereas bias may results from unblinded ascertainment of progression and from the fact that the date at which progression is confirmed radiographically is a proxy for the true progression date, which lies somewhere within two successive assessments18. This overestimation of PFS does not raise serious methodological issues in randomized trials in which the same evaluation schedule is used for all arms, but may compromise comparisons across trials if different schedules have been used.
ORR
As stated previously, ORR is a frequent endpoint in phase III trials on advanced breast cancer. However, there are known limitations of ORR as an indicator of treatment benefit in oncology19, and patients with breast cancer and stable disease after therapy may also accrue benefit. In advanced, hormone-receptor-positive breast cancer, for example, the clinical benefit rate is often used because the survival experience of patients with stable disease after hormone therapy is commonly similar to that of patients with an objective response20. Indeed, the same has been found on occasion for patients treated with chemotherapy21. Thus, ORR is probably weaker than PFS as an efficacy parameter in advanced breast cancer, despite the fact that observing a response to treatment may be the only reliable indicator of treatment benefit in individual patients with cancer22.