This year’s American Association for Cancer Research annual meeting was held in Chicago, from March 31 to April 4, bringing together close to 17,000 scientists from throughout the world. This meeting is always exciting, and offers lots to learn; it includes research into all different kinds of cancers and explores the basic biology of carcinogenesis, metastases, and treatment.
This makes it very distinct from the annual San Antonio Breast Cancer Symposium, which focuses only on breast cancer, and the annual American Society of Clinical Oncology meeting, which focuses primarily on clinical treatment. Like the AACR meeting, this blog will be focused more on the big picture in cancer research and the new approaches that are in the wings rather than particular studies.
I always return from an AACR meeting with my head spinning because the presentations give me so much to think about. The first big observation I made is that the focus of the basic scientists seems to be small. I fully understand that basic research is done by controlling all the factors that you can and then altering just one to see what happens. Nonetheless, for a big picture person such as myself, it often feels like the attention that is given to a very small finding makes it all too easy to forget that this discovery only represents one very, very small piece of the entire cancer puzzle and that while scientists now know what this piece is, we still don’t know what the whole puzzle looks like.
Also, science goes through fads, just like popular culture. A few years ago, all everyone was talking about was targeted therapy: If we could just figure out the one gene, molecule, or pathway that was responsible for the tumor, we could develop more targeted treatments like Herceptin (trastuzumab), which targets HER2-positive breast tumors. To be sure, there is still a lot of interest in targeted therapy, but the triumphs that we had thought were right around the corner have been far fewer than we had hoped. Now, new combinations of targets are being considered, but how this will play out remains to be seen.
The good news, however, is the translation across types of cancers. We used to think that we’d need a breast cancer drug to treat breast cancer, and a lung cancer drug to treat lung cancer. But now, when a new pathway is found to drive a certain type of cancer, researchers first look to see if it is similar to other types of cancers, and if there is an antibody that is being used for another cancer that will work in this one too. As I am fond of saying, it is like infectious diseases where the organ that has the infection is not as important as the type of bacteria causing it. Someday, we may talk about mTor cancers or cKit cancers rather than lung or breast cancers!
Another big topic this year was the microenvironment or, as many of you have heard me call it, the neighborhood the cells, proteins, and tissues that are the background of the tumor. It is becoming more and more clear that this microenvironment is as important as the mutated cells themselves. Again, to use my favorite metaphor, if you clean up a neighborhood by getting rid of graffiti, gangs and drugs and by putting more cops on the streets, you’ll have less crime. In turn, if you clean up the area around mutated cells, you can control the mutated cells and keep the cancer from spreading.
The focus at this year’s meeting was that we need to think of the immune system as part of the neighborhood. Apparently, the tumor causes the immune system to tolerate it, and, in some instances, even help it to grow. Lisa Coussens, PhD, a developmental biologist at Oregon Health & Science University, gave a great talk about how there are good types of immune cells and bad ones and how they can be switched to control cancers. In her mice studies, she showed that by switching these immune cells she was able to prevent metastases. She is now taking this work into the clinic in a multi-center study of women with metastatic breast cancer.
Other research groups explained how they were using vaccines to either block the immune tolerance to tumors or jazz up the immune system. Most of this work is still in animal models, but if this approach pans out we may see future treatments that combine targeted therapies with immune modulators or chemotherapy and surgery and immune approaches. Stay tuned.
Although I found all of this very interesting, it does bother me that all of these approaches will take a long time to come to the clinic. And even then, the pathways and immune approaches will not work for everyone and will be additive at best.
The big prizes are still in the realm of prevention. One of the plenary sessions was on the HPV story. Five percent of all cancers in the world and 25 percent of all cancers that occur in women in developing countries are due to HPV. It is remarkable that we now have a very safe vaccine that not only prevents cancer of the cervix and reduces recurrence in those who have it, but also seems to prevent vulva and vaginal cancers, penis and anal cancers, many head and neck cancers, and genital warts. This is really bang for your buck!
Other preventions include reducing obesity, through changes in diet and increased exercise, as well as avoiding or limiting postmenopausal hormones. While treatment and complicated high-priced drugs may be more interesting to many basic scientists, it is the big public health approaches that will change the world!