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Background It has been suggested that the results from fragile trials are less likely to translate into benefit in routine clinical practice. Methods We searched the Food and Drug Administration (FDA) archives to identify drug approvals for solid organ malignancies between 2010 and 2019. We calculated the Fragility Index (FI) supporting each approval, using methods to account for time‐to‐event. We compared FI and trial and approval characteristics using Mann‐Whitney U and Kruskal‐Wallis test. Using logistic regression, we examined study characteristics associated with withdrawal of consent or lost to follow‐up (WCLFU) exceeding the calculated FI. Results The median FI among 125 included studies was 23 (range 1–322). The FI was ≤10 in 35 studies (28%), 11–20 in 21 (17%), and >20 in 69 (55%). The median FI/Nexp was 7.7% (range 0.1–51.7%). The median FI was significantly lower among approvals processed through the accelerated vs regular pathway (5.5 vs 25, p = 0.001), but there was no difference in median FI/Nexp. The WCLFU exceeded FI in 42% of studies. Overall survival endpoints were more likely to have a WCLFU exceeding FI (OR 3.16, p = 0.003). WCLFU exceeding FI was also associated with a lesser magnitude of effect (median HR 0.69 vs 0.55, p FI. Conclusion The median FI among all trials was 23, and WCLFU exceeded FI in 42%. Comparative trials in solid tumors supporting approval through the accelerated pathway are more fragile compared to trials approved through the regular pathway, an observation likely explained by a lower sample size in the experimental arm., Trials in solid tumors supporting accelerated approval are more fragile compared to regular approvals. This finding supports the need for post‐marketing trials or real‐world analyses to ensure the benefit observed in clinical trials is robust and reproducible.

Background The clinical benefit and pricing of breakthrough-designated cancer drugs are uncertain. This study compares the magnitude of the clinical benefit and monthly price of new and supplemental breakthrough-designated and non-breakthrough-designated cancer drug approvals. Methods A cross-sectional cohort comprised approvals of cancer drugs for solid tumors from July 2012 to December 2017. For each indication, the clinical benefit from the pivotal trials was scored via validated frameworks: the American Society of Clinical Oncology Value Framework (ASCO-VF), the American Society of Clinical Oncology Cancer Research Committee (ASCO-CRC), the European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS), and the National Comprehensive Cancer Network (NCCN) Evidence Blocks. A high clinical benefit was defined as scores ≥ 45 for the ASCO-VF, overall survival gains ≥ 2.5 months or progression-free survival gains ≥ 3 months for all cancer types for the ASCO-CRC criteria, a grade of A or B for trials of curative intent and a grade of 4 or 5 for trials of noncurative intent for the ESMO-MCBS, and scores of 4 and 5 and a combined score ≥ 16 for the NCCN Evidence Blocks. Monthly Medicare drug prices were calculated with Medicare prices and DrugAbacus. Results This study identified 106 trials supporting approval of 52 drugs for 96 indications. Forty percent of these indications received the breakthrough designation. Among the included trials, 33 (43%), 46 (73%), 35 (34%), and 67 (69%) met the thresholds established by the ASCO-VF, ASCO-CRC, ESMO-MCBS, and NCCN, respectively. In the metastatic setting, there were higher odds of clinically meaningful grades in trials supporting breakthrough drugs with the ASCO-VF (odds ratio [OR], 3.69; P = .022) and the NCCN Evidence Blocks (OR, 5.80; P = .003) but not with the ASCO-CRC (OR, 3.54; P = .11) or version 1.1 (v1.1) of the ESMO-MCBS (OR, 1.22; P = .70). The median costs of breakthrough therapy drugs were significantly higher than those of nonbreakthrough therapies (P = .001). Conclusions In advanced solid cancers, drugs that received the breakthrough therapy designation were more likely than nonbreakthrough therapy drugs to be scored as providing a high clinical benefit with the ASCO-VF and the NCCN Evidence Blocks but not with the ESMO-MCBS v1.1 or the ASCO-CRC scale.