To maximize the odds of success of a novel drug development program, we must understand the PK, safety profile, and PD potential of the chemical as soon as possible. The program's early (and cheapest) stages must address the most pressing concerns.The earlier in the process that uncertainty is resolved (e.g. by proper risk inference and quantification, careful in vitro and in vivo experiments, modeling and simulation), the better the chances of making subsequent correct developmental decisions—whether to end unsafe or futile compounds or move forward with truly promising compounds.In this setting, biostatisticians give a different and valuable perspective, as they are schooled to assess uncertainty. Preclinical, research, quality, natural history, and clinical trial design and analysis all require rethinking within the specific limitations of a genetic therapy study. Hence, this skill set is in significant demand in the GTx sector. Pharmacometricians, who are physiologically based mathematical modeling specialists and have extra abilities complementing statistical knowledge and expertise, are equally vital players. To manage complex drug development challenges, the two functions, biostatistics and pharmacometry, are increasingly working jointly. Based on our recent experience in this sector, the development of gene therapy drugs presents unique quantitative issues and potential, and collaboration among biostatisticians, pharmacometricians, and other quantitative scientists in this field can produce synergistic results.Because of GTx's unique character and the inherent high level of uncertainty associated with these treatments, incorporating a biostatistician and pharmacometric as early as practical in the GTx development process is crucial.It is vital that multi-domain practitioners—academic, industrial, and regulatory—work together to set standards and best practices and communicate scientific and technological viewpoints from their various groups to support innovation in quantitative drug development of GTx products. Gene therapies have the potential to provide highly focused breakthrough one-time treatment to individuals with considerable unmet medical needs, eliminate the need for maintenance drug schemes, and reduce the danger of off-target side effects. Developing gene therapy is exceedingly complex and unexpected. Quantitative groups will be critical to the success of future gene therapy programs and must approach drug development in this space as fully integrated strategic partners in cross-functional drug development teams, sharing information and learning throughout the preclinical, manufacturing, early design, and late product planning lifecycles. For quantitative teams working on gene therapy research, experience in epidemiological methodologies, bioinformatics, clinical pharmacology, classical experiment design, rare disease clinical trial design, and a deep grasp of the biology underpinning these medicines will be critical skill areas.