ASCO Education Designing Clinical Trials for Patients With Rare Cancers: Connecting the Zebras
Dr. Hope Rugo and Dr. Vivek Subbiah discuss innovative trial designs to enable robust studies for smaller patient populations, as well as the promise of precision medicine, novel therapeutic approaches, and global partnerships to advance rare cancer research and improve patient outcomes.
TRANSCRIPT
Dr. Hope Rugo: Hello and welcome to By the Book, a podcast series from ASCO that features engaging conversations between editors and authors of the ASCO Educational Book. I am your host, Dr. Hope Rugo. I am the director of the Women's Cancers Program and division chief of breast medical oncology at the City of Hope Cancer Center [in Los Angeles].
The field of rare cancer research is rapidly transforming thanks to progress in clinical trials and treatment strategies, as well as improvements in precision medicine and next-generation sequencing that enable biomarker identification. According to the National Cancer Institute, rare cancers occur in fewer than 150 cases per million each year, but collectively, they represent a significant portion of all cancer diagnoses. And we struggle with the appropriate treatment for these rare cancers in clinical practice.
Today, I am delighted to be joined by Dr. Vivek Subbiah, a medical oncologist and the chief of early-phase drug development at the Sarah Cannon Research Institute in Nashville, Tennessee. Dr. Subbiah is the lead author of a paper in the ASCO Educational Book titled "Designing Clinical Trials for Patients with Rare Cancers: Connecting the Zebras," a great title for this topic. He will be telling us about innovative trial designs to enable robust studies for small patient populations, the promise of precision medicine, and novel therapeutic approaches to improve outcomes, and how we can leverage AI now to enroll more patients with rare cancers in clinical trials.
Our full disclosures are available in the transcript of this episode.
Dr. Subbiah, it is great to have you on the podcast today. Thanks so much for being here.
Dr. Vivek Subbiah: Thank you so much, Dr. Rugo, and it is an honor and pleasure being here. And thank you for doing this podcast for rare cancers.
Dr. Hope Rugo: Absolutely. We are excited to talk to you. And congratulations on this fantastic paper. It is such a great resource for our community to better understand what is new in the field of rare cancer research. Of course, rare cancers are complex and multifaceted diseases. And this is a huge challenge for clinical oncologists. You know, our clinics, of course, cannot be designed as we are being very uni-cancer focused to just be for one cancer that is very rare. So, oncologists have to be a jack of all trades in this area.
Your paper notes that there are approximately 200 distinct types of rare and ultra-rare cancers. And, by definition, all pediatric cancers are rare cancers. Of course, clinical trials are essential for developing new treatment strategies and improving patient outcomes, and in your paper, you highlight some unique challenges in conducting trials in this rare cancer space. Can you tell us about the challenges and how really innovative trial designs, I think a key issue, are being tailored to the specific needs of patients with rare cancer and, importantly, for these trials?
Dr. Vivek Subbiah: Rare cancers present a perfect storm of challenges. First, the patient populations are very small, which makes it really hard to recruit enough participants for traditional type trials. Second, these patients are often geographically dispersed across multiple cities, across multiple states, across multiple countries, across multiple zip codes. So, logistics become complicated.
Third, there is often limited awareness among clinicians, which delays referrals and diagnosis. Add to that regulatory hurdles, funding constraints, and you can see why rare cancer trials are so tough to execute. To overcome these barriers, we are seeing some really creative novel trial designs. And there are four different types of trial designs that are helping with enrolling patients with rare cancers.
The first one is the basket trial. So let us talk about what basket studies are. Basket studies group patients based on shared genetic biomarkers or shared genetic mutations rather than tumor type. So instead of running separate 20 to 30 to 40 trials, you can study one therapy across multiple cancers.
The second type of trial is the umbrella trial. The umbrella trials flip that concept of basket studies. They focus on one cancer type but test multiple targeted therapies within it.
The third category of innovative trials are the platform studies. Platform trials are another exciting innovation. They allow new treatment arms to be added or removed as the data matures and as the data evolves, making trials more adaptive and efficient.
The final category are decentralized tools in traditional trials, which are helping patients participate closer to where they are so that they can sleep in their own bed, which is, I think, a game changer for accessibility.
These designs maximize efficiency and feasibility for rare cancer research and rare cancer clinical trials.
Dr. Hope Rugo: I love the idea of the platform trials that are decentralized. And I know that there is a trial being worked on with ARPA-H (Advanced Research Projects Agency for Health) funding in triple-negative breast cancer as well as in lung cancer, I think, and others with this idea of a platform trial. But it is challenged, I think, by precision medicine and next-generation sequencing where some patients do not have targetable markers, or there isn't a drug to target the marker. I think those are almost the same thing.
We have really seen that these precision medicine ideas and NGS have moved the needle in helping to identify genetic alterations. This helps us to be more personalized. It actually helps with platform studies to customize trial enrollment. And we hope that this will result in better outcomes. It also allows us, I think, to study drugs even in the early stage setting more effectively. How can these advances be best applied to the future of rare cancers, as well as the challenges of not finding a marker or not having a drug?
Dr. Vivek Subbiah: Thank you so much for that question. I think precision medicine and next-gen sequencing, or NGS, are truly the backbone of modern precision oncology. They have transformed how we think about cancer treatment. Instead of treating based on where the tumor originated or where the tumor started, we now look at the genetic blueprint of cancer. The NGS or next-gen sequencing allows us to sequence millions of DNA fragments quickly.
Twenty, 30 years ago, they said we cannot sequence a human genome. Then it took almost a decade to sequence the first human genome. Right now, we have academic centers and commercial sequencing companies that are really democratizing NGS across all sites, not just in academic centers, across all the community sites, so that NGS is now accessible. This means that we can identify these actionable alterations like picking needles in haystacks, like NTRK fusions, RET fusions, or BRAF V600E alterations, high tumor mutational burden. This might occur across not one tumor type, across several different tumor types.
So for rare cancers, this is critical because some of these mutations often define the best treatment option. Here is why this matters. Personalized therapy, right? Instead of a one-size-fits-all approach, we can tailor treatment to the patient's unique molecular profile. For trial enrollment, this can definitely help because patients can join biomarker-driven trials even if their cancer type is rare or ultra-rare.
NGS technology has also helped us in designing rational studies. Many times monotherapy does not work in these cancers. So we are thinking about rational combination strategies. So NGS technology is helping us. Looking ahead, I see NGS becoming routine in clinical practice, not just at major niche academic centers, but everywhere. We will see more tumor-agnostic approvals, more molecular tumor boards guiding treatment decisions in real time. And I think we are seeing an expanded biomarker setup.
Previously, we used to have only a few drugs and a handful of mutations. Now with homologous recombination defects, BRCA1/2 mutation, and expanding the HRD and also immunohistochemistry, we are expanding the biomarker portfolio. So again, I personally believe that the future is precision. What I mean by precision is delivering the right drug to the right patient at the right time. And for rare cancers, this isn't just progress. It is survival. And it is maybe the only way that they can have access to these cutting-edge precision medicines.
Dr. Hope Rugo: That is so important. You mentioned an important area we will get to in a moment, the tumor-agnostic therapies. But as part of talking about that, do you think that the trials should also include just standard therapies? You know, who do you give an ADC to and when with these rare cancers? Because some of them do not have biomarkers to target and it is so disappointing for patients and providers where you are trying to screen a patient for a trial or a platform trial where you have one arm with this mutation, one arm with that, and they do not qualify because they only have a p53 loss, you know? They just do not have the marker that helps them. But we see this in breast cancer all the time. And it is tough because we don't have good information on the sequencing. So I wonder, you know, just because for some of these rare cancers it is not even clear what to use when with standard treatments.
And then that kind of gets into this idea of the tumor-agnostic therapies that you mentioned. There are a lot of new treatments that are being evaluated. We have seen approval of some treatments in the last few years that are tumor-agnostic and based on a biomarker. Is that the best approach as we go forward for rare cancers? And what new treatment options are most exciting to you right now?
Dr. Vivek Subbiah: Tumor-agnostic therapies, really close to my heart, are real breakthrough therapies and represent a major paradigm shift in oncology. Traditionally, for the broad listeners here, we are used to thinking about designing clinical trials and therapy like where the cancer originated, breast cancer, kidney cancer, prostate cancer, lung cancer. A tumor-agnostic therapy flips that model. Instead of focusing on the organ, they target the specific genetic alteration or biomarker that drives cancer growth regardless of where the tumor started, regardless of the location of the tumor, regardless of the zip code of the tumor.
So why is this so important for rare cancers? Because many rare cancers share molecular features with more common cancers. For instance, NTRK fusion might occur in pediatric sarcoma, a salivary gland tumor, or a thyroid cancer. Historically, each of these would require separate trials, which is nearly impossible, unfeasible to conduct in these ultra-rare cancers like salivary gland cancer or pediatric sarcomas. Tumor-agnostic therapies allow us to treat all those cancers with the same targeted drug if they share that biomarker.
Again, we are in 2025. The first tissue-agnostic approval, the historic precedent, was in fact an immunotherapy. Pembrolizumab was approved in 2017, May 2017, as the first immunotherapy to be approved in a tumor-agnostic way for a genomic biomarker, for MSI-High and dMMR cancers. Then came the NTRK inhibitors. So today we have not one, not two, but three different NTRK inhibitors: larotrectinib, entrectinib, and repotrectinib, which show response rates of nearly more than 60 to 75% across a handful of dozens and dozens of cancer types. Then, of course, we have RET inhibitors like selpercatinib, which is approved tissue-agnostic, and pralsetinib, which also shows tissue-agnostic activity across multiple cancers.
And more recently, combination therapy with a BRAF and MEK combination, dabrafenib and trametinib, received tumor-agnostic approval for all BRAF V600E tumors with the exception of colorectal cancer. And even recently, you mentioned about antibody drug conjugates. Again, I think we live in an era of antibody drug conjugates. And Enhertu, trastuzumab deruxtecan, which was used first in breast cancer, now it is approved in a histology-agnostic manner for all HER2-positive tumors defined by immunohistochemistry 3+.
So again, beyond NGS, now immunohistochemistry for HER2 is also becoming a biomarker. So again, for the broad listeners here, in addition to comprehensive NGS that may allow patients to find treatment options for these rare cancers for NTRK, RET, and BRAF, immunohistochemistry for HER2 positivity is also emerging as a biomarker given that we have a new FDA approval for this.
So I would say personally that these therapies are game changers because they open doors for patients who previously had no options. Instead of waiting for years for a trial in their specific cancer type, they can access a treatment based on their molecular profile. I think it is precision medicine at its finest and best.
Looking ahead, the third question you asked me is what is exciting going on? I think we will see more of these approvals. My hope is that today, I think we have nine to ten approvals. My hope is that within the next 25 to 50 years, we will have at least 50 to 100 drugs approved in this space based on a biomarker, not based on a location of the tumor type. Drug targeting rare alterations like FGFR2 fusions, FGFR amplifications, ALK fusions, and even complex signatures like high tumor mutational burden. I think we will be seeing hopefully more and more drugs approved. And as sequencing becomes routine, we will identify more patients for these therapies. I think for rare cancers, this is not just innovative approach. This is essential for them to access these novel precision medicines.
Dr. Hope Rugo: Yeah, that is such a good point. I do think it is critical. Interestingly in breast cancer, it hasn't been, you know, there is always like two patients in these tumor-agnostic trials, or if that. You know, I think I have seen one NTRK fusion ever. I think that highlights the importance for rare cancers. And you know, I am hoping that that will translate into some new directions for some of our rarer and impossible-to-treat subtypes of breast cancer. It is this kind of research that is really going to make a difference.
But what about those people who do not have biomarkers? What if you do not fit into that? Do you think there is a possibility of trying to do treatments for rare cancers in some prospective way that would help with that? You know, it is really a huge challenge.
Dr. Vivek Subbiah: Absolutely. I think, you know, you're right, usually many of these rare cancers are driven by specific biomarkers. And again, some of the pediatric salivary gland tumors or pediatric sarcomas like fibrosarcomas, they are pathognomonic with NTRK fusions. And again, given that we have a tumor-agnostic approval, now these patients have access to these therapies. And I do not think that we would have had a trial just for pediatric fibrosarcomas with NTRK fusions. So that is one way.
Another way is SWOG, right? The SWOG DART [1609] had this combination dual checkpoint, it was called the DART study dual combination chemotherapy with ipi/nivo. Now here the rare cancer subtype itself becomes a biomarker and they showed activity across multiple rare cancer subtypes. They didn't require a biomarker. As long as it was a rare or ultra-rare cancer, these patients were enrolled into the SWOG DART trial and multiple arms have read out. Angiosarcoma, Kaposi sarcoma, even gestational trophoblastic disease. Again, they have shown responses in these ultra-rare, rare cancers. Sometimes they might be seeing one or two cases a whole year. And I think this SWOG effort, this cooperative group effort, really highlighted the need for such studies without biomarkers as well.
Dr. Hope Rugo: That is such a fantastic example of how to try and treat patients in a collaborative way. And in the paper, you also emphasize the need for collaborative research efforts, you know, uniting resource expertise across different ways of doing research. So cooperative groups, advocacy organizations that can really help advance rare cancer research, improve access to new therapies, and I think importantly influence policy changes. I think this already happened with the agnostic approvals. Could you tell us more about that? How can we move forward with this most effectively?
Dr. Vivek Subbiah: Personally, I believe that collaboration is absolutely critical and essential for rare cancer research. No single institution, no single individual, or no single state or entity can tackle these challenges alone. The patient populations are small and dispersed. So pooling resources is the only way to run these meaningful trials. Again, it is not like singing, it is like putting a huge, huge, I would say, an opera piece together. It is not a solo, vocal therapy, but rather putting a huge opera piece like Turandot.
You know, you mentioned cooperative groups. Cooperative groups, as I mentioned earlier, the SWOG DART program, the ASCO [TAPUR study]. ASCO is doing a phenomenal work of the TAPUR study. Again, this ASCO TAPUR program has enrolled so many patients with rare cancers who otherwise would not have treatment options. NCI-MATCH, the global effort, right? NCI-MATCH and the ComboMATCH are great examples. They bring together hundreds of sites, thousands of clinicians to run large-scale trials that would be impossible for any individual center or institution. These trials have already changed practice. For instance, the DART demonstrated the power of immunotherapy in rare cancers and influenced NCCN guidelines.
One of the arms of the NCI-MATCH study from the BRAF V600E arm contributed towards the BRAF V600E tissue-agnostic approval. So, the BRAF V600E tissue-agnostic approval was by a pooled analysis of several studies. The ROAR study, the Rare Oncology Agnostic Research study, the NCI-MATCH dataset of tumor-agnostic cohort, and another pediatric trial, and also evidence from literature and evidence of case reports. And all this pooled analysis contributed to the tissue-agnostic approval of BRAF V600E across multiple rare cancers.
There are several patient advocacy organizations which are the real unsung heroes here. Groups like, for instance, we mentioned in the paper, Target Cancer Foundation, don't just raise awareness for rare cancer research, they actively connect patients to trials providing financial, emotional support, and even run their own studies like the TRACK trial. They also influence policy to make access easier.
On a global scale, initiatives like DRUP in the Netherlands, the ROME study in Italy, the PCM4EU in Europe are expanding precision medicine across these borders. These collaborations accelerate research, improve trial enrollment, and ensure patients everywhere can have access to these cutting-edge therapies. Again, it is truly a team effort, right? It is a multi-stakeholder approach. Researchers, clinicians, investigators, industry, regulators, academia, patients, patient advocates, and their caregivers all working together. And it takes a village.
Dr. Hope Rugo: Absolutely. I mean, what a nice response to that. And I think really exciting and it is great to see your passion about this as well. But it helps all of us, I think, getting discouraged in treating these cancers to understand what is happening moving forward. And I think it is also a fabulous opportunity for our junior colleagues as they rise up in academics to be involved in these international collaborative efforts which are further expanding.
One of the things that comes up for clinical trials for patients, and I think it is highlighted with rare cancers because, as you mentioned, people are all over the place, you know, they are so rare. They are all far away. Our patients are always saying to us, "Should I go here for a phase 1 trial?" Can you talk a little bit about how we can overcome these financial and geographic burdens for the patients? You talked about having trials locally, but it is a big financial and just social burden for patients.
Dr. Vivek Subbiah: Great point. Financial cost is a major barrier in rare cancer clinical trials. It is a major barrier not just in rare cancer clinical trials, but in clinical trials in general. The economics of rare cancer research are one of the toughest challenges we face. Developing a new drug is already expensive, often billions of dollars. On an average, it takes 2 billion dollars or 2.8 billion dollars according to some data from drug discovery to approval.
For rare cancers, the market is tiny, which means the pharmaceutical companies have really little financial incentive to invest. That is why initiatives like the Orphan Drug Act were created to provide tax credits, grants, and market exclusivity to encourage development for rare diseases.
Clinical trials themselves are expensive because the small patient populations mean longer recruitment times and higher per-patient costs. Geographic dispersion, as you mentioned, for the patients adds travel, coordination. That is why we need to think out of the box about decentralized trial infrastructure so that we can mitigate some of these expenses. Complex trial designs like basket or platform trials sometimes require sophisticated data systems and regulatory oversight. That is a challenge. And I think some of the pragmatic studies like ASCO TAPUR have overcome those challenges.
Advanced technologies like next-gen sequencing and molecular profiling also add significant upfront cost to this. Funding is also limited because rare cancers receive less attention compared to common cancers. Public funding and cooperative group trials help a lot, but I think they cannot cover everything. Patient advocacy organizations sometimes step in to bridge these gaps, but sustainable financing remains a huge challenge.
So, the bottom line is without financial incentives and collaborating funding models, many promising therapies for rare cancers would never make it to patients. That is why we need system-wide policy changes, global partnerships, and innovative, effective, seamless trial designs which are so critical so that they can help reduce the cost and make research feasible so that we can deliver the right drug to the right patient at the right time.
Dr. Hope Rugo: There is a lot of excitement about the future integration of AI in screening. Just at the San Antonio Breast Cancer meetings, we have a number of different presentations about AI to find markers, even like HER2, and using AI where you would screen and then match patients to clinical trials. Do you have any guidance for the rare cancer community on how to leverage this technology in order to optimize patient enrollment and, I think, identification of the best treatment matches?
Dr. Vivek Subbiah: I think artificial intelligence, AI, is a game-changer in the making. Right now, clinical trial is clunky. Matching patients to trial is often manual, time consuming, laborious. You need a lot of personnel to do that. AI can automate this process by analyzing genomic data, medical records, and trial eligibility criteria to find the best matches quickly, accurately, and effectively.
For the community, the key is to invest in data standardization and interoperability because AI needs clean, structured data to work effectively.
Dr. Hope Rugo: Thank you so much, Dr. Subbiah, for sharing these fantastic insights with us on the podcast today and for your excellent article.
Dr. Vivek Subbiah: Thank you so much.
Dr. Hope Rugo: We thank you, our listeners, for joining us today. You will find a link to Dr. Subbiah's Educational Book article in the transcript of this episode. And please join us again next month on By the Book for more insightful views on key issues and innovations that are shaping modern oncology.
Thank you.
Disclaimer:
The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. Guest statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.
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Disclosures:
Dr. Hope Rugo:
Honoraria: Mylan/Viatris, Chugai Pharma
Consulting/Advisory Role: Napo Pharmaceuticals, Sanofi, Bristol Myer
Research Funding (Inst.): OBI Pharma, Pfizer, Novartis, Lilly, Merck, Daiichi Sankyo, AstraZeneca, Gilead Sciences, Hoffman La-Roche AG/Genentech, In., Stemline Therapeutics, Ambryx
Dr. Vivek Subbiah:
Consulting/Advisory Role: Loxo/Lilly, Illumina, AADI, Foundation Medicine, Relay Therapeutics, Pfizer, Roche, Bayer, Incyte, Novartis, Pheon Therapeutics, Abbvie
Research Funding (Inst.): Novartis, GlaxoSmithKline, NanoCarrier, Northwest Biotherapeutics, Genentech/Roche, Berg Pharma, Bayer, Incyte, Fujifilm, PharmaMar, D3 Oncology Solutions, Pfizer, Amgen, Abbvie, Mutlivir, Blueprint Medicines, Loxo, Vegenics, Takeda, Alfasigma, Agensys, Idera, Boston Biomedical, Inhibrx, Exelixis, Amgen, Turningpoint Therapeutics, Relay Therapeutics
Other Relationship: Medscape, Clinical Care Options