One trial may be enough. One uninterpretable trial is not

Episode Summary

In the inaugural episode of Humaneva Insights, host Patrick McManus speaks with Dr. Brandon Fletcher, Head of Medical Affairs and Cell & Gene Therapy at Kapadi, about when a single adequate and well-controlled clinical trial may be sufficient to support an FDA regulatory decision in oncology.

A one-trial pathway is not a shortcut to a lower evidentiary standard. In immuno-oncology, the study still needs to produce evidence that is interpretable, attributable, internally credible, and clinically meaningful. Patrick and Brandon discuss when an exceptional response signal may speak for itself, why uncertainty around causality and contribution of components can still require randomization, and how early design choices determine whether a promising program reaches the application stage with evidence regulators can confidently assess.

Key Takeaways

• One pivotal trial may be sufficient, but it should not be interpreted as less evidence.
• When one study carries the weight of an entire development program, the control arm, population definition, response assessment, missing-data strategy, and endpoint attribution must be defensible from the outset.
• Regulatory strategy, estimand definition, biomarker strategy, imaging methodology, and confirmatory planning should be integrated early rather than treated as downstream activities.
• A very large and durable response may sometimes support accelerated approval in a refractory population with a well-characterized natural history and limited treatment options.
• Combination regimens, heterogeneous post-immunotherapy populations, delayed immune effects, retreatment, and investigator interpretation can make clinically impressive results difficult to attribute.
• Randomized expansion cohorts can establish the contribution of treatment components, reduce dependence on historical controls, and close evidentiary gaps before a traditional phase 3 program.

Featured Expert

Dr. Brandon Fletcher is Head of Medical Affairs and Cell & Gene Therapy at Kapadi. She brings more than three decades of drug development experience, with a deep focus on immuno-oncology and cell and gene therapies. Her work spans clinical development strategy, protocol design, scientific and medical oversight, investigator engagement, and translating complex biology into executable clinical programs. She was an original collaborator with the NCI’s origination of cancer cell and gene therapeutics and has continued in the field of immuno-oncology and genetically modified cell therapeutics since. She co-founded a global philanthropic organization that supports and trains investigators in underserved countries.

What is Humaneva Insights?

Humaneva Insights is a podcast for the business and operational leaders shaping the future of clinical research. Brought to you by Humaneva Group, a leading clinical research organization with a network of research sites, the podcast explores how to make clinical trials more efficient, overcome operational challenges, and accelerate clinical development. Hear from industry experts and thought leaders on the strategies, trends and innovations shaping the way trials are designed and delivered — and how we can ultimately get treatments to patients faster.

[00:16] PATRICK MCMANUS
Hello and welcome to the very first episode of Humaneva Insights, the podcast where we explore the science, strategy, and operational realities shaping the future of drug development.
My name is Patrick McManus, and I'll be the host for today's show. For our inaugural episode, we are tackling a question that has become particularly timely: When can one clinical trial truly be enough to support a regulatory decision?
Recent discussions around the FDA's willingness to accept a single adequate and well-controlled study have generated considerable attention across the industry. For some, this may sound like lowering the evidentiary bar, but the reality is much more nuanced. The critical question is not simply whether a development program includes one pivotal trial or two. It is whether the evidence generated by the trial is interpretable, attributable, internally credible, and clinically meaningful.
And nowhere is that distinction more important than in immuno-oncology, where combination therapies, prior treatments, response kinetics, patient heterogeneity, and assessment methodology can make seemingly compelling results much more difficult to interpret.
So, for our first episode, we have chosen a title that gets directly to the heart of the issue: One trial may be enough. One uninterpretable trial is not.
To explore what this means for oncology drug developers, I'm delighted to introduce Dr. Brandon Fletcher, Head of Medical Affairs and Cell & Gene Therapy at Kapadi.
Brandon brings more than three decades of drug development experience, with a deep focus on immuno-oncology and cell and gene therapies. As a biochemist, drug development specialist, and cancer immunologist by training, she has worked across academic, hospital, biotech, sponsor, and CRO environments and was an early collaborator in the National Cancer Institute's development of cancer cell and gene therapeutics.
Throughout her career, Brandon has helped shape clinical development strategy, protocol design, scientific and medical oversight, investigator engagement, and the translation of complex biology into executable clinical programs.
In this episode, she will examine why statistically and clinically impressive results are not necessarily the same thing as regulatory-grade evidence, and why, when a single study carries the weight of an entire development program, trial design and interpretability matter more than ever.
Welcome, Brandon.
[02:51] DR. BRANDON FLETCHER
Thanks, Patrick, for having me. I'm really excited about this podcast series.
[02:55] PATRICK MCMANUS
Great to have you here, Brandon. So, if FDA is increasingly willing to accept a single adequate study for approval, does that actually make oncology development easier, or does it simply place more pressure on getting the design right the first time?
[03:12] DR. BRANDON FLETCHER
Well, it's more likely the latter. One study should not be interpreted as less evidence. It means that a single study may be sufficient when it is adequately controlled, statistically persuasive, internally consistent, and capable of answering the relevant regulatory question without substantial residual uncertainty.
In some aspects, this raises the stakes. When a program is built around one pivotal study, there is much less tolerance for an inappropriate control arm, poorly defined populations, inconsistent response assessment, missing data, or an endpoint that cannot be clearly attributed to the investigational treatment.
The opportunity may be greater, but so are the consequences of design ambiguity. If you really think about it, it makes sense.
For oncology sponsors and CROs like ourselves, the practical lesson is that regulatory strategy, estimand definition, biomarker strategy, imaging methodology, and confirmatory planning simply cannot be treated as downstream activities.
We really have to think about this. This is something that we spend every day trying to get our heads around at Kapadi because it really matters. This is what we do, and we do it well.
The study must be designed from the outset to withstand the question the FDA - or the EMA or another regulatory authority - will ultimately ask. Particularly here, it is the FDA: Does this trial provide a reliable and interpretable estimate of treatment effect? That's really what we're talking about here.
[05:22] PATRICK MCMANUS
That focus on a reliable and interpretable estimate of treatment effect brings us to one of the most difficult questions in oncology development. Brandon, in a refractory population, when a therapy produces both high response rates and unusually durable responses, why should the FDA still insist on a randomized control group? At some point, shouldn't the magnitude of benefit speak for itself?
[05:48] DR. BRANDON FLETCHER
That's a really great question. It is a question that I think a lot of us are asking ourselves. I think the answer is: sometimes it can, particularly in a disease with a well-characterized natural history or limited treatment options, and an effect so large that conventional explanations are simply implausible. That has been the basis of several accelerated approvals.
The difficulty arises when the study involves a combination regimen, a heterogeneous post-immunotherapy population, or response criteria that may be affected by treatment beyond progression, delayed immune effects, retreatment, or investigator interpretation.
A response rate may be clinically impressive while still leaving uncertainty regarding causality. The central issue is not whether the responses are real. It is whether the study can determine how much of the observed benefit was produced by the investigational agent, whether the result is reproducible, and whether the same effect would be expected in the intended commercial population.
Can we say these results are real and extrapolatable? That is why randomized expansion cohorts can be so valuable even before a traditional phase 3 program. They do not necessarily need to answer the entire approval question, but they can establish the contribution of components, reduce dependence on historical controls, and prevent a really promising program from reaching the application stage with a fundamental evidentiary gap.
We never want that to happen. That's so important. We need to think ahead and plan for these things. This really matters. It's such an interesting topic. Thanks for that question.
[08:18] PATRICK MCMANUS
Thank you so much, Brandon, for your insights. I think the central takeaway from our conversation is clear. As the title already said, one pivotal trial may be enough, but one uninterpretable trial is not.
An exceptional response signal can sometimes speak for itself, particularly in a refractory population with a well-understood natural history. But when questions remain about causality, reproducibility, the contribution of individual treatment components, or whether the results can be applied to the intended patient population, the magnitude of benefit alone may not close the evidentiary gap.
These questions must be anticipated and addressed from the very beginning of the development program.
Thank you, Brandon, for sharing your expertise and perspective in this podcast. And thank you to everyone listening.
If you found today's discussion valuable, please subscribe to the Humaneva Insights podcast so you do not miss future episodes.
If you would like to explore this topic further or discuss how these considerations could affect your oncology development program, please feel free to reach out to us. You will find the contact information in the show notes.
Until next time, have a good day, everyone.