Table 2.
Predictors of Trial Primary Endpoint Success
| Trial Factor | Proportion of Successful Trials (%)† | p-value* | |
|---|---|---|---|
| Total enrollment, median (IQR) | Trial Success | 573 patients (372 – 828) | p=0.82 |
| Trial Failure | 584 patients (331 – 877) | ||
| Industry funding of trial | Yes | 118/219 (53.9%) | p=0.08 |
| No | 5/16 (31.3%) | ||
| Cooperative group trial | Yes | 11/36 (30.6%) | p=0.004 |
| No | 112/199 (56.3%) | ||
| Disease site | Breast | 24/38 (63.2%) | p=0.23 |
| Gastrointestinal | 27/49 (55.1%) | ||
| Genitourinary | 16/34 (47.1%) | ||
| Thoracic | 28/66 (42.4%) | ||
| Other | 28/48 (58.3%) | ||
| Molecular profile restrictiona | Yes | 22/26 (84.6%) | p<0.0001 |
| No | 101/209 (48.3%) | ||
| Systemic therapyb | Targeted therapy | 100/183 (54.6%) | p=0.14 |
| Cytotoxic chemotherapy | 21/49 (42.9%) | ||
| Treatment order | First-line therapy | 57/121 (47.1%) | p=0.10 |
| Second-line or higher therapy | 66/114 (57.9%) | ||
| Single-agent or combinationc | Single-agent | 60/93 (64.5%) | p=0.002 |
| Combination | 61/139 (43.9%) | ||
| Trial PEP | PFS | 89/133 (66.9%) | p<0.0001 |
| OS | 34/102 (33.3%) | ||
| PFS assessmentd | Investigator-assessed | 34/42 (81.0%) | p=0.09 |
| Independent review | 38/58 (65.5%) | ||
| Co-primary endpointe | Yes | 12/18 (66.7%) | p=0.21 |
| No | 111/217 (51.2%) | ||
Proportion of trials where the PEP was met (trial success) over total number of trials per trial factor.
p-value reflects Pearson’s Chi-squared test p-values comparing trial success versus trial failure for all trial characteristics except total enrollment, for which the Mann-Whitney U-test p-value is provided.
Molecular profile restriction refers to those trials that selected for patients with specific tumor-related mutations. This includes trials selecting for patients with EGFR mutation, ALK fusion, BRAF mutation, and similar.
Systemic therapy interventions were divided into targeted therapies (including monoclonal antibodies, small molecule inhibitors, and similar) and cytotoxic chemotherapy; 3 trials (1 PFS PEP and 2 OS PEP) investigated either a purely surgical or nuclear medicine question and were not included in this analysis.
Studies tested either a single-agent intervention (“Single-agent”) or in combination with other oncotherapeutics (“Combination”); 3 trials (1 PFS PEP and 2 OS PEP) investigated either a purely surgical or nuclear medicine question and were not included in this analysis.
PFS assessment (investigator-assessed versus independent central review) provided for trials with PFS as PEP; 33 trials did not specify independent or investigator PFS assessment.
Trials which had a co-primary OS and PFS endpoint were designated as PFS primary endpoint trials.
Abbreviations: %, percentage of trials; IQR, interquartile range; PEP, primary endpoint; PFS, progression-free survival; OS, overall survival.