The impressive progress recently observed in adult cancers through the introduction of new drugs has not yet been translated to adolescents between 12 and 17 years of age. Currently adolescents are grouped with children, so their access to new, effective drugs already available for adults is delayed because paediatric drug development starts late relative to adult programmes. Moreover, specific early phase trials designed exclusively for adolescents in rare diseases recruit poorly, even if conducted internationally. Evidence has shown that adolescents demonstrate similar toxicity profiles, maximum tolerated doses and pharmacokinetic parameters to adults. Although they may have specific vulnerabilities and their interests should be protected, they are, in many countries in Europe, entitled to provide informed consent themselves. There are no insurmountable scientific, medical, or regulatory barriers to their participation in Phase-I to III adult trials. Based on a review of the literature, the multi-stakeholder platform ACCELERATE, with representatives from academia, patient/parent advocacy groups, regulatory agencies and pharmaceutical companies, proposes the inclusion of adolescents in adult Phase-I to III trials of cancer drugs targeting a relevant disease or mechanism of action, without requiring preceding specific paediatric trials. The trials, however, should be delivered in age-appropriate clinical care settings by clinicians with adolescent trial expertise. Joint adolescent-adult trials will not exclude adolescents from participating in paediatric trials, as these approaches are complementary. This strategy is considered to be safe, rational, efficient and would provide more clinical trial options and accelerate drug development for adolescents with cancer.