Interview with Kai Trepka

About Kai

Kai Trepka is a fifth-year MD/PhD student at the University of California, San Francisco (UCSF). He completed his undergraduate studies at Harvard University, where he double-majored in Chemistry and Physics. He then earned a master’s degree in Chemistry at Harvard before beginning the MD/PhD program at UCSF.

In high school, Kai was heavily involved in debate and was convinced he would pursue a career in the humanities. When he got to college, Kai found that he loved his STEM classes and the mathematical thinking they encouraged, especially when applied to biological systems.

Kai decided in his sophomore year of college that he wanted to pursue the MD/PhD path. He loved research and wanted to become a scientist, but it was through volunteering in hospitals that he discovered an appreciation for the collaborative, fast-paced environment of clinical care. For Kai, the MD/PhD path offers a unique sense of freedom: being paid to go to school while also having the flexibility to pursue work and interests outside of academia.

His current research focuses on the gut microbiome and its role in cancer treatment. Kai and his lab collaborate with institutions around the world to collect and analyze a diverse range of human samples, aiming to understand how microbes in our digestive system can interact with oral medications in ways that influence drugs' absorbtivity and toxicity.

One key takeaway for aspiring MD/PhD students is the importance of doing what you love, something that keeps you grounded and balanced alongside the demands of being a pre-med student. For Kai, that’s dancing and running. In fact, his involvement in dance during his undergraduate years at Harvard became a standout aspect of his application and interviews.

My favorite quote from the interview:

I wanted to be a scientist, and then I realized that being a physician is a really incredible way of incorporating humanity into science, and use that to say, I want training in both of these things.

Watch the video or continue reading to learn more about Kai's story.

Transcript

Chelsy Do: Thank you again for taking the time to sit down with me. I know your schedule must be really busy, so I'm really grateful that you're able to get on this call.

Kai Trepka: Yeah, thanks for organizing this and all the other work that you do.

Chelsy Do: Whenever you're ready, we can begin the interview.

Kai Trepka: Sure, that works.

Kai's Educational Background

Chelsy Do: First, I wanted to start talking about you and your educational background. Can you walk me through your journey starting from high school through college?

Kai Trepka: Yeah, I grew up in Iowa, went to public school in Iowa City, and I really loved the social sciences and debate and I was convinced that when I go to college, I'll study something in that domain. Then I went to university and I found that some of the science classes really interested me. I in particular fell in love with chemistry and physics and this idea that you can break down systems into their constituent parts. 

But as I progressed through my coursework and research in college, I began to think a lot of the fundamental problems in chemistry and physics were solved and more of the expanse in science and the more complicated questions are really human questions, like what is the best treatment for someone? How do we balance killing cancer with the side effects of some of these therapies? 

I really decided through a compendium of different experiences during college that I would want to be at the intersection of having very human discussions with people as a physician and then also still thinking about how science can be used to help drive their care. 

And so now starting five years ago, I started a medical scientist training program or the MD PhD program at University of California, San Francisco. and I study biomedical sciences and specifically I work on understanding how the gut microbiome influences cancer treatment.

Chelsy Do: Gotcha. So, going back to your college, I was kind of reading up about you a little bit before we started this interview and I saw that you majored in both chem and physics?

Kai Trepka: Yeah, I studied chemistry and physics in university and took a lot of courses in those areas.

Kai's MD/PhD Journey

Chelsy Do: So, how did you go from that into deciding [to do] biophysics in your MD PhD?

Kai Trepka: I really enjoyed chemistry and physics, but some of my favorite classes in chemistry and in physics were their applications to biological systems. In particular, there was a class taught by a professor Adam Cohen called Fundamentals of Biophysics, which was a graduate chemistry course that I enrolled in. 

And in it, we applied a lot of the mathematical models I'd learned in some upper division physics classes to understanding how do proteins come together and fold over what domain are proteins constrained and when can they move? How do you generate energy as a cell? And if you're a cell, how do you move nutrients from one site to another? And then started thinking even more broadly, how do you design a microscope to look at a neuron? How can you use some of these really complicated quantum techniques to think about really practical problems? And I fell in love with that kind of thinking.

Chelsy Do: Cool, so did you, in your undergrad, was that when you decided that you wanted to pursue an MD/PhD or was it later in your graduate years?

Kai Trepka: It was in undergrad. By the end of my second year, I had decided that I couldn't give up science, but that I really wanted the ability to and the knowledge to be a practicing physician as well. And so starting my junior year–I had always done a lot of research and research related activities during college–but starting my junior year, I started doing the more formal requirements for medical school applications. Things like volunteering in hospitals or taking the MCAT or making sure that I fulfill all of the different specific requirements, class requirements, that medical schools have to apply. 

And then I think as another piece of useful background is for MD PhD programs, often the application is just a culmination of many years and years of preparation. And so it's very normal for someone to decide this is something I'm interested in and then realize there's three years of stuff you have to do before a school would even think about you, which I think ends up excluding a lot of people who would be really great doctors. 

Chelsy Do: Did you take any gap years in between your undergrad into MD PhD?

Kai Trepka: I did not take any gap years. Most of my classmates did. I think attending a very large research university for undergrad gave me the opportunity to conduct a lot of research while I was in undergrad.

A lot of my peers from smaller liberal arts schools or schools with less research funding had to spend some more time in the summers at bigger institutions or the National Institutes of Health or spend a year or two conducting research just to have that component of their application. I think the amount of research experience before applying to an MD PhD is really important for two reasons: 

The first reason is to make sure this is something you want to do for four to six years and then hopefully the rest of your career.

And then the second reason is that the admissions committee the number one thing they look at is like do you know what's involved in getting a PhD? Have you exposed yourself to research and really dived deep in a project? And I had the great fortune of working with an incredible adviser who really helped me design a project to my needs and gave me a lot of independence that I feel very lucky to have. 

But I think if I had not worked with the same person for three years before applying, I certainly would have taken a year or two to dive deeper in between undergrad and med school.

Chelsy Do: And you say that now you're five years into your MD PhD program, right?

Kai Trepka: Just finished my fifth year.

Chelsy Do: Congratulations! I'm sure this is one of the questions that the PhD [admissions] people asked you, but why wasn't just one of the degrees enough? Why did you feel the need to pursue both of them?

Kai Trepka: Thank you. I think from the angle of this question, admissions committees are often asking are you really going to finish the PhD? But for my personal decision, it was never a question of do I want to do science? It was a question of how to get there and how I would feel most valued. So I knew I wanted to be a scientist, and so I wanted to go to some sort of graduate school or work at a company doing research in some capacity. 

And then it was really these classes like biophysics. So when I started thinking about med school, I then volunteered in a hospital and realized I really actually liked the ecosystem of the hospital and the way that diverse teams of doctors and patients and nurse practitioners and physician assistants and volunteers all have to coordinate to get things done.

I really liked that environment and I thought that I could see myself working here forever as well. And so for me I wanted to be a scientist and then I realized that being a physician is a really incredible way of incorporating humanity into science and use that to say, I want training in both of these things, even if I decide to only do one of them in the future. 

One of the fantastic things about the MDPhD program is that it's fully funded. So my tuition is paid for and I am paid to go to school. It's like an incredible privilege to be paid to go to school. And so that gives a lot of flexibility and often makes it feel more like I'm not just stuck in school. I'm a working adult. I work 9 to 5 in the lab and I'm getting married in two weeks and there's time for plenty of other things outside of the course of school.

Chelsy Do: Wow, congratulations.

Kai Trepka: Thank you.

Chelsy Do: Yeah, that's so cool. So, you were talking about working in a hospital, as well as you've known that you wanted to be a scientist. Do you have any idea of what specialty that you're going to work in the future?

Kai Trepka: I'm still deciding. I think I have to see where in the hospital feels like the right fit of the different people I want to work with. The adage I've heard is that every clinical environment has a culture or personality to it and none of them are good or bad per se. It's just about where you feel like you fit in. 

And so at the moment my interests are pulling me towards oncology, cancer care and cancer research just due to some personal experiences and also due to my current research in cancer treatments. But I could see myself being very happy in a variety of environments.

Chelsy Do: Speaking of your current projects, I know you were talking about the microbiome research that you've been doing. Could you talk more about what you've been working on in terms of that?

Kai Trepka: Yeah. When I started medical school, I had only heard about the microbiome from my mom reading health blogs. And I didn't really know what it was or what it did. And during my PhD, I was fortunate to be able to work with Peter Turnbaugh, who's one of the people who's been around since the field of the microbiome started 25 years ago. And I just fell in love with the field immediately after our first conversation, this concept that you have inside of your gut hundreds of different bacterial species; all of them cooperating and competing with each other, eating the same food that we eat, digesting the same drugs that we digest, interacting with human intestinal immune cells, nervous system. It's just this incredible complexity layered onto the already complex being of a human. And so that's why I like the microbiome in general.

My project in particular is just one very small subsection of that field. So I study a specific type of chemotherapies called oral fluoropyrimidines. These are used for cancer treatment. And these therapies are really great in that they can cure cancer in lots of people. But they also can have really devastating side effects and up to 10% of patients need to stop treatment because the side effects are so severe. And one of the big problems is that we can use the human genome and human genetics to predict side effects in a small portion of patients, but for the vast majority of patients, it's not understood why some person takes chemotherapy and feels great, but someone else feels really awful.

And in our lab, we have this hypothesis that the collection of microbes that interact with the drugs that people are putting in their mouths can influence how those drugs are absorbed and dispersed throughout the body and impact toxicity. And so my whole PhD so far has been focused on this concept that the microbes in our gut can change the amount of drug that makes it into our bodies that causes side effects that hits the cancer cells. And beyond that, the gut microbiome can produce things that our body doesn't produce. They produce a vitamin called vitamin K2 that we are incapable of making, and we've done some work showing that this vitamin can also have a role in preventing side effects.

And so I think all of this together suggests that thinking about the microbiome as an additional organ, especially when thinking about cancer treatment, is really the way of the future.

Chelsy Do: That's amazing. Just because I'm curious, can you tell me more about what organisms you're using to research this?

Kai Trepka: Yeah, we use a variety of models to research this.

My favorite model and my starting model is always the human microbiome. We have a variety of clinical trials both at my university and in collaborations with some folks in the Netherlands and in Mexico and other places around the world. And through these trials we obtain human samples and we get a sense of what do bacteria look like in people? How are they changing through cancer treatment? And we do this both through sequencing the DNA from poop and through trying to grow up different bacteria from the poop. 

But we also have really great model systems. So we use mice with complex microbiota and we will deplete the bacteria in these mice using antibiotics. So we'll wipe out their microbiome and sort of see what happens. and then we also will use individual bacteria. Often our model organism is a bug called E.coli. This is a safe variant. I know there are also pathogenic variants. but we'll make genetic modifications to a single gene so that we can understand what is the role of a single gene in a single bacteria on a biological problem.

Chelsy Do: Gotcha. That sounds really cool. That's amazing. So, correct me if I'm wrong. Is your fifth year the year that you finish your PhD?

Kai Trepka: Yeah, that's exactly right. So, in general, an MD PhD program is one or two years of medical school, four or five years of PhD, and then the rest of medical school. And so, for me, I did one and a half years of medical school. I'm almost done with four years of my PhD, and then I'll have two and a half years of medical school remaining. So I graduate this December.

Chelsy Do: Okay. Awesome. And so then after you finish your PhD portion, you're going to start clinical rounds in the hospital?

Kai Trepka: Yeah, the year and a half I did so far is mostly pre-clinical work. So the vast majority of that is learning material for different classes, learning how the different organ systems work, learning about how to diagnose different diseases, and then you get maybe one day a week learning how to do a physical exam or interviewing patients in the hospital and getting tested on that.

Chelsy Do: Now that you're kind of towards the end of your MD/PhD, I guess, do you know what you want in terms of what your work life will look like in the future? Because I know the MDPhD path can offer a lot of career flexibility.

Kai Trepka: Yeah, that's something I've really been exploring throughout the program.

When I entered the program, I thought I wanted to primarily be a scientist and see patients really infrequently. And then through the program and through my PhD in particular, I've been exposed to a lot of physicians who spend about half their time seeing clinics and the other half running clinical trials or overseeing collaborations with basic scientists and writing up research and conducting research in that capacity.

And I'm beginning to think I'm not sure which of those two models I prefer. I think both of them are an incredibly important part of the overall research ecosystem in this country.

And I'm hoping to learn more, especially as I go back into the clinic and see how much time I really want to spend in the hospital interviewing patients, working with people, but then also doing the documentation and having the on call responsibilities that come along with that.

Advice for Aspiring MD/PhDs

Chelsy Do: Okay, awesome. Thank you. We're getting towards the end of the interview. So, we're going to go to the concluding advice–if you have any–portion. Looking back, what do you wish you had known earlier that maybe could have made your journey smoother?

Kai Trepka: I think after I learned that there's all these requirements to go to medical school and that you have to have 15 activities and you write down what you do in all of them, I really took that to heart and tried to check off all the boxes that other people said I should check off. 

But at the same time, something I really loved in college was dance. I was in multiple different dance groups and I choreographed some performances and I had a lot of fun with that and had a lot of my best friends through that. 

And when it came time to interview for medical school and write my application, I found that I could not write nearly as convincingly about any of my so-called medical experiences as I could about this thing that I really liked. And so I wrote my essays about my research and about my involvement in dances and extracurriculars.

And every interview that was all we talked about. It was either my research projects or my involvement in dance. And I think even though I did all of these other things, I could have done much less and focused just on what I was passionate about. Still, make sure to meet our requirements of volunteering in a hospital or seeing patients. but really, if you have a passion or something that makes you unique, focus on that. don't worry about trying to fit in with what every other med student looks like because then every application looks the same and you won't stand out at all.

Chelsy Do: That's amazing. So do you still do dance now? I'm just curious.

Kai Trepka: Yeah, my wife Annie and I, our third date was going to Salsa, and we used to go every week in San Francisco. Now it's become a little bit less frequent with some of the chaos surrounding both of our works as we move towards the end of different projects, but we hope to resume soon.

Chelsy Do: That's awesome. My blog is kind of talking about the intersection between music (and, I love to sing; I'm in chorus) and science. So, I thought it was really cool that you, dance and that was like a passion of yours in undergrad.

Kind of off topic, or not really, but do you think that your passion for dance… help you through your studies or just in life? Did that kind of play well with balancing wanting to get to MD PhD program and then also you have this passion for dance.

Kai Trepka: Yeah. I think it was essential in undergraduate.

Often the premedical cycle of courses, they can feel like pressure cookers. You have 500 students who all want to get into medical school, all of whom are incredibly bright and good at taking tests. And for many of us, this is the first time in our life when we haven't been the best. 

And so having something where I can feel like I'm really enjoying this, I'm learning, I'm growing, outside of that environment was essential to getting me through undergrad. Since I started medical school, I started in the midst of the pandemic. A lot of studios weren't open and so I actually started running instead. And so that's become my new primary passion in San Francisco. But I think no matter whether it's chorus dance or exercise in some capacity, having that third domain outside of your medical life and your research life is really essential for making an entire person.

Chelsy Do: That's really cool that you say that because I've also I'm actually running a half marathon next Saturday. So, have you done any races?

Kai Trepka: This is awesome. Yeah, I did a collection of marathons over the last couple years. I feel like I peaked last year.

This year I'm focusing more on some trail running and mountain climbing and ultramarathons and just enjoying the scenery.

Chelsy Do: Yeah, that's one thing I love about running, just like going outside and seeing. Do you have any advice for completing a race? This is like 180.

Kai Trepka: No, I'm sure you'll do great. I mean, it's just training. The more you train, the faster you go. Don't do anything you haven't done before. My biggest mistake was I wore a new pair of shoes for a race once and I just got the most horrible blisters that really really slowed me down around mile 22.

Chelsy Do: Okay, last question. Do you have any advice for students aspiring to be MD/PhDs, whether they're in high school, college, or just considering this path?

Kai Trepka: Yeah, I think the advice differs depending on stage.

If it's high school, do whatever you want. In high school, my main activity was debate. And that didn't stop me at all from pursuing MD/PhDs. If you're really curious, reach out to a professor whether at a really small university nearby or at a larger university elsewhere and see if they have space for his high school volunteer just to get a sense of what research is like in the lab. But that's definitely not a requirement. That's not something I did. 

For college, make sure that you have something to keep yourself grounded and sane. For me, it was dance. For different people, it's different things. and then at the same time, the most important facet of your application is really research. So make sure that you find something that you like or find out whether or not you like research. And if you like it, I think MD/PhD is a really fantastic career path.

If you're instead near the end of university and you're thinking, I'm really interested in D/PhD, do a culmination of other experiences, probably just see what the differences between what you have now and what the requirements to apply are. 

Usually people who take a couple gap years before applying are naturally, older and more mature and have thought this through a lot. So, I don't have too much advice to give them other than the admissions committees look at your MCAT score and make sure you have all the course requirements and stuff. Yeah.

Chelsy Do: Thank you so much. These are all the questions I have. Thank you again for your time, Kai. It was so nice talking to you. 

Kai Trepka: It's great talking to you and meeting you as well, Chelsy. Thank you for all the fantastic work you do.

Chelsy Do: Thank you so much. Have a great day.

Kai Trepka: Yep. Good luck in your race.