Daniel Leffler, MD, MS, AGAF, has some advice for young physicians starting out in their careers: Don’t be afraid of change.
“Just because you’re a doctor doesn’t mean you have to spend the rest of your career doing patient care. We don’t teach that in medical school as well as we should,” said Dr. Leffler. “If you’re interested in a skill set and move in a different direction, that’s totally okay. Many people have major career shifts, whether it’s early, mid- or late career.”
Dr. Leffler followed his own advice in 2016 when he left his longtime job as an associate professor at Harvard Medical School and accepted a position with Takeda Pharmaceuticals. As its medical director, he had a specific goal: To find more therapeutic options for patients with celiac disease.
“Gastroenterology is a fantastic field of medicine, and it somehow continues to get more and more exciting,” said Dr. Leffler, who continues to see patients at Beth Israel Deaconess Medical Center in Boston. “There are just so many careers you can have within gastroenterology, whether you are a full-time endoscopist, in a teaching career, or doing lab work.”
He discussed the events that led to this career change in an interview with GI & Hepatology News.
Q: Why did you choose GI?
Dr. Leffler: I think for a lot of people GI is just an incredibly diverse field where you can see all types of patients and you have an unusually wide armamentarium of diagnostic and therapeutic options. Our ability to see inside in the GI tract relatively easily and obtain tissue and do functional studies is unique. It makes it a very dynamic field.
Q: What gives you the most joy in your day-to-day practice?
Dr. Leffler: I think it’s taking a fresh look at somebody whose symptoms have been incorrectly diagnosed or diagnosed preliminarily as one thing and opening different options and working with the patient to hopefully find a more targeted therapy based on a more definitive diagnosis.
Q: Describe your biggest practice-related challenge and what you are doing to address it.
Dr. Leffler: There are two challenges. For celiac disease, all I have is a gluten-free diet. It would be nice to have other options, the same way we do with almost every other GI disease, whether it’s acid-related disorders or chronic constipation or inflammatory bowel disease. We have a range of therapies we can pick and choose from, tailoring those to the individual. We are not there yet, unfortunately, in celiac disease, so that’s a huge challenge.
Another challenge is awareness of celiac disease. It’s not what it should be. We see a lot of patients who either were misdiagnosed or went many years without getting a proper diagnosis or got diagnosed and did not have proper education or follow up.
Q: How has your job changed since you first began your career? Perhaps we could discuss your switch from Harvard/Beth Israel Deaconess to Takeda Pharmaceuticals.
Dr. Leffler: I became convinced some years ago that the next big thing for celiac disease was an effective therapy beyond the gluten-free diet. Takeda had acquired rights to two of the therapies that I was most interested in, even though they were very early. There was a new glutenase, TAK-062, and a new immune-tolerizing molecule that became TAK-101. Takeda had moved its research center to Boston, and they were looking for someone to work on their celiac program. Moving from an academic position, which I loved, was a really difficult decision.
I didn’t leave without a conversation with the division chief at the time, Tom Lamont, MD. I basically said, “If this doesn’t work out, will you take me back?” I wasn’t sure how much I’d like working in industry. The other thing, on both sides, was that I was allowed to keep a clinic. I still see patients on Fridays and really, to me, I have the best of both worlds.
Q: What teacher or mentor had the greatest impact on you?
Dr. Leffler: I really think of Ciaran Kelly, MD at Beth Israel Deaconess, Detlef Schuppan, MD, who also was at Beth Israel Deaconess, but is now at the University of Mainz in Germany. And Peter Green, MD at Columbia University. These three are the physicians I’ve interacted with the most and learned the most from.
Q: What habits have you established that have benefited your career most?
Dr. Leffler: I do try to focus on being a good collaborator. Playing that long game of working for the good of the project and not necessarily what is next for you, has served me very well over the years.
Lightening round
Superpower?
Optimism
Favorite movie to quote?
The Big Lebowski
What is your favorite form of exercise?
Elliptical
Name one thing on your bucket list.
Ethiopia travel
How many cups of coffee do you drink per day?
Two-ish
Dr. Leffler is on LinkedIn.
Summary content
7 Key Takeaways
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Developed a paper-based colorimetric sensor array for chemical threat detection.
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Can detect 12 chemical agents, including industrial toxins.
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Production cost is under 20 cents per chip.
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Utilizes dye-loaded silica particles on self-adhesive paper.
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Provides rapid, simultaneous identification through image analysis.
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Inspired by the mammalian olfactory system for pattern recognition.
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Future developments include a machine learning-enabled reader device.
The guidelines emphasize four-hour gastric emptying studies over two-hour testing. How do you see this affecting diagnostic workflows in practice?
Dr. Staller: Moving to a four-hour solid-meal scintigraphy will actually simplify decision-making. The two-hour reads miss a meaningful proportion of delayed emptying; standardizing on four hours reduces false negatives and the “maybe gastroparesis” purgatory that leads to repeat testing. Practically, it means closer coordination with nuclear medicine (longer slots, consistent standardized meal), updating order sets to default to a four-hour protocol, and educating front-line teams so patients arrive appropriately prepped. The payoff is fewer equivocal studies and more confident treatment plans.
Metoclopramide and erythromycin are the only agents conditionally recommended for initial therapy. How does this align with what is being currently prescribed?
Dr. Staller: This largely mirrors real-world practice. Metoclopramide remains the only FDA-approved prokinetic for gastroparesis, and short “pulsed” erythromycin courses are familiar to many of us—recognizing tachyphylaxis limits durability. Our recommendation is “conditional” because the underlying evidence is modest and patient responses are heterogeneous, but it formalizes what many clinicians already do: start with metoclopramide (lowest effective dose, limited duration, counsel on neurologic adverse effects) and reserve erythromycin for targeted use (exacerbations, bridging).
Several agents, including domperidone and prucalopride, received recommendations against first-line use. How will that influence discussions with patients who ask about these therapies?
Dr. Staller: Two points I share with patients: evidence and access/safety. For domperidone, the data quality is mixed, and US access is through an FDA IND mechanism; you’re committing patients to EKG monitoring and a non-trivial administrative lift. For prucalopride, the gastroparesis-specific evidence isn’t strong enough yet to justify first-line use. So, our stance is not “never,” it’s just “not first.” If someone fails or cannot tolerate initial therapy, we can revisit these options through shared decision-making, setting expectations about benefit, monitoring, and off-label use. The guideline language helps clinicians have a transparent, evidence-based conversation at the first visit.
The guidelines suggest reserving procedures like G-POEM and gastric electrical stimulation for refractory cases. In your practice, how do you decide when a patient is “refractory” to medical therapy?
Dr. Staller: I define “refractory” with three anchors.
1. Adequate trials of foundational care: dietary optimization and glycemic control; an antiemetic; and at least one prokinetic at appropriate dose/duration (with intolerance documented if stopped early).
2. Persistent, function-limiting symptoms: ongoing nausea/vomiting, weight loss, dehydration, ER visits/hospitalizations, or malnutrition despite the above—ideally tracked with a validated instrument (e.g., GCSI) plus nutritional metrics.
3. Objective correlation: delayed emptying on a standardized 4-hour solid-meal study that aligns with the clinical picture (and medications that slow emptying addressed).
At that point, referral to a center with procedural expertise for G-POEM or consideration of gastric electrical stimulation becomes appropriate, with multidisciplinary evaluation (GI, nutrition, psychology, and, when needed, surgery).
What role do you see dietary modification and glycemic control playing alongside pharmacologic therapy in light of these recommendations?
Dr. Staller: They’re the bedrock. A small-particle, lower-fat, calorie-dense diet—often leaning on nutrient-rich liquids—can meaningfully reduce symptom burden. Partnering with dietitians early pays dividends. For diabetes, tighter glycemic control can improve gastric emptying and symptoms; I explicitly review medications that can slow emptying (e.g., opioids; consider timing/necessity of GLP-1 receptor agonists) and encourage continuous glucose monitor-informed adjustments. Pharmacotherapy sits on top of those pillars; without them, medications will likely underperform.
The guideline notes “considerable unmet need” in gastroparesis treatment. Where do you think future therapies or research are most urgently needed?
Dr. Staller: I see three major areas.
1. Truly durable prokinetics: agents that improve emptying and symptoms over months, with better safety than legacy options (e.g., next-gen motilin/ghrelin agonists, better-studied 5-HT4 strategies).
2. Endotyping and biomarkers: we need to stop treating all gastroparesis as one disease. Clinical, physiologic, and microbiome/omic signatures that predict who benefits from which therapy (drug vs G-POEM vs GES) would transform care.
3. Patient-centered trials: larger, longer RCTs that prioritize validated symptom and quality-of-life outcomes, include nutritional endpoints, and reflect real-world medication confounders.
Our guideline intentionally highlights these gaps to hopefully catalyze better trials and smarter referral pathways.
Dr. Staller is with the Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston.