Session (CTI)

While the oncology therapeutic landscape continues to evolve to address unmet clinical needs, the increasing complexity of treatment pathways—marked by uncertainty around appropriate comparators, the need for rapid drug development, and novel mechanisms of action—has led to the use of unconventional trial designs such as basket or multicohort studies. These designs, although necessary to accelerate patient access and account for the unknowns of emerging therapies (e.g., optimal dosing, combination vs. monotherapy, treatment schedules), often lack clear or widely accepted comparators and generate limited long-term data. Such constraints can pose significant challenges for health technology assessment (HTA) bodies, particularly when trial data are immature, affected by treatment switching, or unable to demonstrate curative potential—offering instead only delayed progression, recurrence, or relapse. Together, these issues complicate survival extrapolation, a key component of economic evaluations used to inform reimbursement decisions. This panel will explore methodological challenges and opportunities in survival extrapolation within the HTA context, focusing on three interrelated themes: (i) basket trials, (ii) treatment switching, and (iii) use of external evidence. Hugo Pedder will open the session with an HTA example illustrating real-world challenges. Arthur Allignol will explore survival extrapolation in basket trials, focusing on small, diverse subgroups and lack of comparators, and will discuss methods for borrowing strength and addressing exchangeability. Min-Hua Jen will present a case study using external evidence—historical or real-world data—to improve extrapolation amid treatment switching, applying time-acceleration in a Bayesian framework without relying on covariate matching. Ash Bullement will share findings from a neutral comparison of external evidence-based methods, highlighting trade-offs, justification, and the importance of context in HTA submissions. The session will conclude with a panel discussion and audience Q&A, offering practical insights for HTA stakeholders, statisticians, health economists, and regulatory affairs professionals navigating today’s oncology evidence landscape.