Two Basic Scientists Walk into a Translational Space

Transcription

1 Lasker Awards Conversations Two Basic Scientists Walk into a Translational Space When John Schiller first joined Douglas Lowy s lab at the National Cancer Institute of the NIH, he could have not predicted that their common interest in the molecular biology of oncogenes would set them in path for discoveries that ultimately enabled the development of a vaccine for the human papillomavirus, which causes the majority of cervical cancers worldwide. John and Doug, the recipients of the 2017 Lasker-DeBakey Clinical Award, have joined Cell editor João Monteiro in a Conversation about science, public health, and the joys and challenges of being basic scientists in a translational space. Annotated excerpts from this conversation are presented below. João Monteiro: How long have you two worked together? Was that first encounter at the National Institutes of Health (NIH)? Douglas Lowy: We have worked together for more than 30 years. John Schiller: I came to Doug s lab as a postdoc and basically then just never left; we became colleagues. Eventually I ended up becoming independent and having my own group, but Doug and I continued to collaborate. JM: Were you already working with the human papillomavirus (HPV) by that time, Doug? DL: Actually, I was working on the bovine papillomavirus, an animal papillomavirus, rather than on HPV, because when we started, it was before the discovery of the importance of HPV in cervical cancer and other cancers. JS: When I came to Doug s lab, I wanted to study how bovine papillomavirus, BPV, induces cellular transformation. This virus could make normal fibroblasts become more cancer-like. I was interested in understanding the molecular biology of that phenomenon. I remember very clearly that the second lecture I attended after joining the lab was given by Harald zur Hausen. This was in the beginning of 1983, and Harald came and gave this big lecture here at the NIH, saying, Eureka, we found this papillomavirus in 50% of cervical cancers. All of a sudden we went from studying a basic model of tumor biology to studying a human virus that causes cancer. Things changed a lot when those discoveries came about. JM: Doug, were you first interested in viruses or in cancer? DL: My training after medical school was in a virology lab at NIH in the National Institute of Allergy and Infectious Diseases. That lab studied endogenous mouse retroviruses, so it was viruses plus cancer. When I was a medical student, my first research experience was at New York University with Jan All of a sudden we went from studying a basic model of tumor biology to studying a human virus that causes cancer. Vilcek, who was studying interferon and how interferon inhibited virus infection and replication. So you could argue I first did viruses, but as soon as I went to the NIH, I ended up doing research on cancer viruses. JS: When I applied to Doug s lab, what he was probably best known for was some of his work on the Ras oncogene and endogenous retroviruses. I actually was applying to his lab to work on those sorts of things, not papillomaviruses, but then Doug said, Well, you know we re starting to work on papillomaviruses, and I saw a lot of growth potential in that area, even before HPV was found to be associated with cervical cancer. It seemed like such a good idea to get involved with it, so I really jumped at the chance to do papillomavirus research in this bovine model. It was really an opportune time to get into the field. JM: What do you consider your major discovery? Or perhaps the moment you realized that the work you were doing had the potential to change the way cancer is prevented and have big implications for public health? DL: I think that for us in the lab, our ah-ha moment, if you will, was when we saw that the major structural protein of the papillomavirus would self-assemble and make virus-like particles and that those particles induced high levels of neutralizing antibodies. We thought that we had something potentially very useful as a vaccine. The second moment was when, in collaboration with colleagues at the Pasteur Institute in Paris who were working on the Shope papillomavirus model in rabbits, we saw that the vaccine was highly protective in the rabbit animal model. And the third big moment for me was not our research but actually the research from Merck when they did a study of a monovalent HPV 16 vaccine. In this randomized control trial there were 41 cases of HPV 16 infection between the placebo group and the women who got the vaccine. All 41 cases were in the placebo group. JS: I agree entirely. The only other moment I would add was when we ran the first clinical trial of the VLP (virus-like particles) vaccine in people, in collaboration with our colleagues at Johns Hopkins. This was the first study showing that the vaccine was safe, that there weren t bad reactions, and everybody who got vaccinated generated really high levels of antibodies even if we didn t have any adjuvant in the vaccine. People were always telling us that it s easy to get antibodies in mice and rabbits, but Cell 171, September 21, 2017 ª 2017 Published by Elsevier Inc. 23

2 people aren t the same. Well, it turns out in this case people are like mice, and there was really no difference in the high levels of antibody responses that we saw in people as opposed to the animal models. Then, at least we knew that the vaccine was very immunogenic. Doug is right, though, in the sense that until we actually did the clinical trial, until the efficacy trials came out, we weren t really sure that the vaccine would protect against genital infections. Because the animal models we were using did not involve intravaginal challenges. Later on we developed an assay in which we could test that. But at the time, we weren t really sure that the vaccine would protect against repeated exposure by the infected partner and protect long term. So, it was really important to actually have the clinical data. DL: Let me go back to the beginning because there really were two linked observations. The first was that if you just express this single protein from the virus,... it would make particles, but what made it really interesting was that when you immunize the animal, you raise high titers of neutralizing antibodies. JS: Just as an anecdote, the titers were so high that our postdoc, Reinhard Kirnbaur, who was doing this work at that time, had to repeat the assay three different times because the first time we only diluted the serum 100-fold and we got a complete blocking of infection at 100-fold. Then he did it at 10,000-fold, and we got complete blocking of infection even at 10,000-fold. And it wasn t until we diluted it a million fold in the third assay that we found an endpoint where we got infection. JM: Wow! DL: I should also mention that our previous work with BPV also helped us to develop the assays that we would need in order to test whether antibodies neutralize viral infection. So there really were two critical parts. One was having a ready source of infectious virus, and the second was having a tractable bio-assay so that you could actually measure neutralizing antibodies because the induction of neutralizing antibodies is the cornerstone of most preventive vaccines. JM: After you started getting some of the initial clinical data, how did the vaccine transition then from the lab to the industry to become an actual product? Was it a collaborative effort? I think it is an ongoing struggle to get the vaccine to more womenandmenwhoneedit... You d think that a couple of injections can protect your daughter from cervical cancer. Why aren t you taking it? DL: I think that we need to make a distinction between the early clinical trial that we did which involved a contract laboratory making the virus like particles and what the two commercial companies Merck and GlaxoSmithKline did. They developed their own vaccine. We had a little bit of input into those, but we were not co-authors on the development on either vaccine. They licensed the technology from the NIH, and they made the commercial vaccines. JM: I see. Using the principle you had already developed. JS: Once we had these sky-high neutralizing titers with our model system, we went around and talked to basically almost all the major vaccine manufacturers and all of them were very skeptical. Not of our data but whether a sexually transmitted disease vaccine could work, because they hadn t worked in the past. To this day, HPV is the only one that has worked, in fact. So there was reasonable skepticism. When we went to Merck, we actually first talked to Maurice Hilleman, who was by then Emeritus, but he was like the godfather of Merck vaccines. He was very enthusiastic; he said, You know this is going to work, and Merck s going to do it. As soon as you go, I m going to call the people in the licensing department and we re going to get started working on this. He was the first person we talked to in a major drug company that was enthusiastic about the project. At least I think to my recollection that s the way it was. Then, another company approached us, MedImmune, which was just up the road here in Rockville. They decided that they wanted to do something. After a successful phase one trial, they then sublicensed their vaccine to GSK. We were very happy, because we wanted to have competition in the marketplace and so we wanted the vaccine to be licensed to more than one company. So we had communications with the companies, but I think what Doug said was correct. We weren t active collaborators with the companies during the development of their vaccines. DL: They licensed the technology, and they went ahead and did it. There had been clinical trials in herpes simplex virus vaccines, which had worked in animal models but then did not work in people to give protection. So, from the point of view of most pharmaceutical companies, our data were analogous. They clearly showed that the HPV vaccine worked in an animal model, but how do you know that the animal model is predictive of what will happen in people? Merck and MedImmune, and later GSK, were the companies that were willing to take a chance. JS: It was a leap of faith that this could work. The animal models were imperfect, and there were clear limitations, as the one I mentioned about not having a cervical vaginal challenge model at the time. JM: Now that the vaccines are out there and being used in people, has the impact of the vaccine in public health and cancer prevention matched your expectations? JS: I think it is an ongoing struggle to get the vaccine to more women and men who need it. I must say that personally, I ve been disappointed with the uptake in the United States maybe Doug has a different idea. You d think that a couple of injections can protect your daughter from cervical cancer. Why aren t you taking it? It s now just over 50%, 60%. Some developed countries have done very well, like Australia and England. Scotland also has done very well with uptake of the 24 Cell 171, September 21, 2017

3 John Schiller (left) and Doug Lowry (right), National Cancer Institute, NIH. Photo Credit: National Cancer Institute. vaccines. Other countries, like Japan, have basically abandoned it. So it s a mixed bag. The other big problem is the cost of the vaccine and of delivering three, or now two, intramuscular doses to young women in low-resource settings. There are places where I think there would be demand for the vaccine, and this certainly seems to be playing out in demonstration trials, but they just don t have access to the vaccine and the administration programs. Again, this is something that needs to be addressed. Perhaps, the way to put it is that this vaccine exceeded all expectations in terms of science, immunology, and these sorts of things. But, in terms of uptake, I think it s been underwhelming. What would you say, Doug? The good news is that the vaccine has had a dramatic impact on the incidence of infection and disease that can be monitored short term. DL: The good news is that the vaccine has had a dramatic impact on the incidence of infection and disease that can be monitored short term. In other words, the goal is to try to prevent cancer, but it takes more time from the time of the infection until you get cancer than has elapsed up until now. So it s not realistic to think that you would see a decrease in incidence and mortality from cervical cancer and the other cancers that are caused by HPV. But, when you look at viral immunity, at the reduction in high-grade cervical dysplasia, the reduction in genital warts all of that points to the notion that the vaccine is highly protective. On the other hand, for a variety of reasons, the vaccine has been underutilized. One point has been social or sociologic concerns in some places, such as the United States, another has been safety concerns. As John mentions, the cost of the vaccine has been an important factor as well, especially in low-resource settings, even though companies have done tiered pricing and the cost in the lowest income countries for the vaccine is relatively low. It takes a very long time to prevent cancer. For most vaccines that are preventive, you give the vaccine and you see a benefit from the vaccine in the very few years after vaccination. But that s not the situation with the HPV vaccine, which means that it is important for the cost of the vaccine to be as low as possible while still being safe and effective. Cell 171, September 21,

4 JS: One of the projects we are actively working on is whether we can reduce the number of doses of vaccine that are required to produce long-term protection. We re just starting a clinical trial based upon data that we generated in a previous NCIsponsored trial. It s beginning to look like one dose is going to be enough, which again is unheard for a subunit vaccine. However, we need to demonstrate that this is true in a randomized clinical trial, what we are now beginning to do in a NCI trial co-sponsored by the Gates Foundation. We are actually going to test whether one dose works as well as two doses of both the Merck and the GCK vaccines. We think that this could really be transformative. If you could just give everybody one dose, you wouldn t have to keep track of who got it and things like that. It just would be an enormous cost saver just to give one dose. So we are working on this question. There s still a lot to be done with this vaccine. JM: In those lines, what are other kinds of questions you are currently working on? JS: So right now we think that the most practical thing to move forward with is to reduce the number of doses to one dose. DL: Because we think that the decreased cost and the great simplification of logistics from one dose is key to worldwide uptake. And the reason we re testing the two different vaccines is largely because we want to make sure that both vaccines work well in the one-dose setting. Or, if one of them works well but not the other, we want to be sure that we know that, because there are different adjuvants that are used in the two different vaccines. And, therefore, it s at least theoretically possible that one vaccine might work better in the one-dose setting than the other. But, we certainly look forward to the possibility of both vaccines working well. JS: I think the other thing I might add is we re actually trying on a more basic science level to really understand why this vaccine works so well. We think it has exceptional immunogenicity in terms of inducing antibody responses. This has not been seen for a subunit vaccine where not only everybody responds well but they have plateaued titer where, basically after a year or so, out to 6 or years, the titers don t change. The other point is that in our animal models it looks like very low levels of antibodies are very effective at preventing infection. We re trying to understand from both the immunological and the biological point of view why these vaccines are so exceptional. With the idea that maybe we can translate what we ve learned from the HPV vaccines to other vaccines, sexually transmitted and otherwise. But that s on a more basic science level. Doug and I both sort of came up as basic molecular biologists. You know, where we tried to understand basic virology, basic tumor biology. And it was only after we ve been working together for about 10 years that we really got involved in vaccinology and what I would say really is more translational research. Even to this day, a large component of what we do is more basic research with the idea of trying to understand things. Then we ask if they would have translational implications. We aren t just translational researchers, we really have a very strong we think basic biology component to our studies, and we re continuing that with the vaccines. JM: Do you think the fact that you were at the NIH influenced the way your research evolved and your ability to move through all these different steps? DL: In many ways, the short answer is yes. One of the aspects of being in the intramural program is that you have a level of resources and you can use them for what you think are important problems. Then, you need to defend how you have used them at your lab site visits, which occur every 4 years. We were able to take some of our resources and use them to test, for instance, if expressing viral proteins in insect cells with recombinant baculovirus would produce viral particles. Later, when we were developing the early-phase clinical trials, it was quite helpful to be here because the National Cancer Institute has also a strong clinical research component and we were able to take advantage of that. I will also say that our colleagues of the intramural program in the National Institute of Allergy and Infectious Diseases actually greatly made it easier for us to do this research because they already were working with investigators at Johns Hopkins at the Center for Immunization Research. So we worked with them. More recently, we were involved in another clinical trial with our colleagues medical epidemiologists who specialized in cervical HPV infection. Again that was made easier because these are our intramural colleagues and they basically did an efficacy trial in Costa Rica where historically cervical cancer has been the number one cancer of women. That trial was what told us that you don t need all three doses of the vaccine in order to get protection. And that has led to this second trial that John mentioned, where we are testing the hypothesis: will just one dose of the vaccine be sufficient in young adolescents? JS: I think it is good to point out that when Doug and I started this vaccine work, we had no background whatsoever in vaccinology or immunology. We had been publishing good work on viral oncogenesis and some work on transcriptional regulation of the virus. We really had not done any of this type of translational work. Being at the NIH afforded us the opportunity to take a chance at what we saw as an opportunity to make progress in an area where very little progress had been made in the 10 years since Harald zur Hausen had discovered HPV 16. It allowed us to seize the moment but not have to ask anybody. Because quite frankly, if we would ve made this proposal to a granting agency, or to a study section, they would have laughed at us. They would have said, Well, you guys study how the virus causes cancer, you don t know anything about vaccines or immunology or vaccinology. What are you trying to do here? And so it really was an enormous advantage for us to be in the intramural program, I feel. JM: What an interesting journey! JS: Indeed. It has been an amazing opportunity, for us coming from a virology and cancer backgrounds, to learn about the questions involved with translational research, being involved with the clinical trials and learning what s involved in those types of studies. It has been a very nice way of being involved in the whole spectrum of biomedical research by getting involved in the vaccine project. DL: The way I think about it is that John and I are really basic scientists. But, our research took us in a translational direction, 26 Cell 171, September 21, 2017

5 and because that translational research was successful, it has enabled us to be involved in clinical research and now also in implementation research. It s quite exceptional for scientists who start out as basic researchers to have these kinds of other research experiences. JS: It s not only gratifying to see your basic work leading to what this is into a public health intervention that looks like it s going to save hundreds of thousands of lives. But, it s just interesting to be involved with really good people that do these types of research and learn an awful lot from being able to interact with them. DL: I think the one final point that I would add is that the world should be grateful to the patient volunteers who volunteered to take these vaccines when they were still experimental. Because there was no guarantee that they would be beneficial, and whenever you do something that hasn t been tried in people, there s always a risk. Nonetheless, these people who volunteered in the clinical trials the world needs to be grateful to them because there would not be a vaccine out there without them. JM: Thanks again for talking to us and once more congrats on the Lasker Award! Cell 171, September 21,