IDWeek 2026: John Rex Discusses Antifungal Innovation and Career Connections

Developing a new antifungal requires persistence, particularly when the goal is to treat life-threatening infections in patients with limited therapeutic options. For John Rex, MD, chief medical officer at F2G, that work builds on about 40 years in infectious diseases and an early fascination with medicine’s ability to identify infections, treat them, and make them go away.

At IDWeek 2026, held in Washington, DC, from October 21 to 24, 2026, Rex spoke with Infection Control Today^® in a quiet room about the development of olorofim, the challenges of selectively targeting fungi, and the potential value of an oral treatment for invasive aspergillosis. He also reflected on how professional meetings helped shape his career and why returning year after year can be valuable for clinicians and researchers.

Editor’s note: Responses have been lightly edited for clarity and length, and questions have been added to organize the interview. Olorofim remains investigational. The reported phase 3 finding was noninferiority, rather than identical efficacy; the study also reported fewer drug-related renal adverse events with olorofim, rather than an absence of such events. These clarifications are provided separately to preserve the speaker’s wording.

ICT: What drew you to infectious diseases and drug development?

John Rex, MD: I’m John Rex. I am the chief medical officer at F2G, and deeper than that, I’m an internist who specializes in infectious diseases [IDs]. I have been an ID doc for about 40 years at this point. I got interested in infectious diseases because I liked the way that it involved problem-solving and actually curing things.

A lot of other parts of medicine, you don’t cure stuff. You take care of hypertension for the rest of your life, take care of cardiovascular disease for the rest of your life. But [with] infectious diseases, we make things go away, and I always thought that was fun. I got interested in the question of how you make those diagnoses and how you create the drugs that do the work.

Antiinfectives have been a magic act since they were first discovered about 100 years ago. Sir Alexander Fleming, the first discovery of penicillin, just absolutely transformative. So I’ve always liked that about infectious diseases.

I was an academic doc for about 20 years, and I’ve been in industry for about 20 years. Those overlap a little bit, so I’m not really 1000 years old. In the last 20 years, I’ve gotten involved in developing new antibacterials and new antifungals, and what I do at F2G is we’ve been developing a new antifungal drug.

ICT: How long has the development process taken?

JR: At IDWeek this year, we had the opportunity to share the results of our recently completed phase 3 study of our new antifungal drug.

Technically, it’s year 28 of the bus ride that created this drug. The company that discovered the drug was founded in 1998. I got on the bus 14 years ago. This is how long it takes to discover a new drug. That’s an interesting thing about the whole anti-infective space. It takes a long time to find an interesting starting point and then to get it developed.

ICT: Why is finding a new antifungal particularly difficult?

JR: Finding new antifungals is actually quite hard. In one sense, it’s easy to find things that kill fungi: steam, fire, bleach. Fantastic antifungals. They’re just also antihuman.

The question of how you find a new antifungal gets into the fact that fungi and human beings are closely related. Almost everything about our biology is shared with fungi. A few things aren’t, but most things are. So, it makes it hard to find things that selectively kill fungi and not human beings.

The company I work for discovered a completely new mechanism drug. To date, there are only 4 or 5, depending on how you count them, mechanisms that are used to treat invasive fungal infections.

We’re not talking here about toenail infections. Not talking about stuff between your toes. Not talking about vulvovaginal candidiasis, all of which are important. Here, I’m talking about the kinds of fungi that kill you when you’re getting chemotherapy, kill you when you’re getting a stem cell transplant, and we’ve only got a few drugs that do that. So, the idea of having a completely new kind of drug is a huge moment.

ICT: What treatment need did the phase 3 study address?

JR: What we have done with this drug over the past decade is bring it through phase 1 and through phase 2, and now we’ve completed a big phase 3 study in a particular infection, invasive aspergillosis. People with leukemia who have undergone stem cell transplants, as well as lung transplant patients, can get into trouble with this fungus.

What we did was study it as an alternative to the current standards of therapy. For the past 20 years, we’ve been using a class of drugs called the mold-active azoles for invasive aspergillosis, and those are very, very good drugs.

But there’s a percentage of folks for whom a mold-active azole is not the right therapy. There’s resistance that’s developed. There can be drug-drug interactions. There are several reasons why you might say, “I wish I had an alternative,” and the only alternative you currently have is an IV drug that’s also hard on the kidneys.

ICT: What did you share about the findings and the potential value of an oral option?

JR: What we did was take our new drug and compare it with the alternative in people who couldn’t use a mold-active azole. We showed that the 2 were identical in terms of their efficacy.

The cool thing is, here we’ve got a therapy that’s a third way. If you can use a mold-active azole, you should. When you can’t, your choice up until now has been an amphotericin-based regimen. Now we’re giving you a third choice that is comparable to the amphotericin-based regimen.

The last thing about it is it’s a pill, and the fact that it’s a pill has an obvious pragmatic advantage: You get to go home taking a pill. We saw people leaving the hospital sooner on Olorofim.

That’s the data we shared this week. It’s been a massive project that has involved hundreds of people, and we’ve all enjoyed being able to share the results of that study this week at IDWeek.

ICT: What advice would you give someone attending IDWeek for the first time?

JR: IDWeek is an enormous conference for the ID community. I’ve been coming to it for years and years. Everything is here, and it is like drinking from a fire hose.

If you’ve never been, my advice is inhale, exhale, pick a track, and just go to as many sessions as you can stand. But you can’t go to everything. These days, stuff is video, and you can actually see it later if you want to. But the real value is to turn up at a meeting like this and network. This is where, over time, you’ll build relationships with people.

As a young academic, this is where I developed ideas for what I was going to do for the next year. You’d meet with colleagues, you’d think of research projects, you’d hear a talk about something, and you’d say, “Ooh, could I do something with that idea?” That’s why you come to meetings like this.

You just sort of pick a track and follow it through. But turn up year on year, and the connections you will make will actually drive your entire career.