This study was presented at the 2019 International Congress on Targeted Anticancer Therapies (TAT) in Paris, France, from February 25-27, 2019. Dr Jun Sato of the National Cancer Center Hospital, Japan is the lead author of this study.1

Results from a retrospective study evaluating the focus of early-phase clinical trials of investigational drug candidates in oncology conducted from 1991 to 2015 showed a sharp decline in the proportion of phase I clinical trials focusing on common cancers (ie, lung or colorectal cancers), with a corresponding increase in the proportion of uncommon cancers being investigated in these early trials over the same time period.1

According to a press announcement from the European Society of Medical Oncology, “the 1991-2015 timespan chosen for the analysis coincides with a revolution in cancer therapy, driven by the development of molecularly targeted anticancer drugs and application of comprehensive molecular profiling techniques for patient selection in clinical trials. Initially, from 1990s to early 2000s, scientists used these advances to investigate large cancer populations with frequent genomic mutations, but over time, the focus of genomic-driven clinical trials has shifted to less common mutations and rarer tumor types.”1

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This study included 866 published phase 1 trials conducted worldwide between 1991 and 2015 that evaluated novel cancer drug candidates in over 29,000 patients.  The major finding was that the percentage of phase 1 trials in which patients with either lung or colorectal cancer comprised at least 50% of study enrollment declined from 46.3% in 1991-1995 to 16.7% in 2011-2015. Although the absolute number of these clinical trials increased over the 1991-2015 period, there was a much larger increase in the number of phase 1 trials focusing on patients with rare cancers. Furthermore, this trend was observed when trials from different geographic areas were considered separately.

Importantly, although these results reflect an increased focus on more uncommon types of cancer, such as biliary tract cancers, they do not imply that interest in investigating potential new therapies in subpopulations of patients with lung or colorectal cancer is waning. “Common cancers like lung adenocarcinomas are now classified into multiple, rarer subtypes based on genomic markers,” said Dr Rodrigo Dienstmann of the Oncology Data Science unit at the Vall d’Hebron Institute of Oncology, Barcelona, Spain.

Moreover, it was noted that the period from 1991 to 2015 does not fully capture phase 1 studies investigating immunotherapy, particularly in the setting of lung cancer. 

“Across all cancer types, what we are seeing is more and more phase 1 trials, reflecting the latest waves of innovation,” concluded Dr Markus Joerger, who is responsible for the phase 1 unit at the St Gallen Cancer Centre, Switzerland.


  1. European Society for Medical Oncology. Rare cancers a growing focus of early-stage clinical trials [press release]. Accessed February 25, 2019.