Targeted Therapies: What does it all mean?
When my kids were little, I loved reading to them Arnold Lobel’s Frog and Toad books including “The Corner” in Frog and Toad All Year. In it, Frog assures Toad on a cold, rainy day that spring is just around the corner. Frog says that when he was younger, on a similar cold, rainy day, he searched for spring around many corners until he eventually found it-sunshine and flowers-around the corner of his house.
And so it is with us cancer patients, constantly peering around every corner for the still elusive cure. Researchers at ASCO 2015 offered the most encouraging, hopeful news yet that we won’t have to look around the corner much longer.
Or will we?
Cancer is a tricky disease, in fact many tricky diseases, constantly morphing and exploiting loopholes to outwit us. The buzzwords at this year’s annual meeting in Chicago included “immunotherapy,” combination therapy and “biomarkers.” Immunotherapy has become the fourth arm to battle cancer, after surgery, chemotherapy and radiation. On the upside, scientists are making great strides to develop ways for the body’s immune system to fight the cancer. These are called checkpoint inhibitors. Inhibitors basically release the brakes in cells to allow our immune systems to charge and attack the bad guys, e.g. cancer cells. And since the cancer is being attacked at a molecular level, this should work for everyone. But it doesn’t. And that has proved vexing to researchers. Every specialist with whom PEN spoke at ASCO – from melanoma to lung and prostate cancer to colorectal disease – acknowledges that they don’t yet know why the inhibitors aren’t working for all of us.
That’s where the biomarkers come in. Researchers are working to identify specific markers on an individual’s cell to determine if a specific anti-PD1 or
PD-L1 inhibitor will work on a patient. Or why it won’t work.
For my cancer Chronic Lymphocytic Leukemia, CLL, combination therapy made headline news at ASCO. Through clinical trials, scientists have found that combining a checkpoint inhibitor, Ibrutinib, with a standard chemotherapy called bendamustine along with the monoclonal antibody Rituxan yielded an 80% response rate. That’s a “wow,” but it still isn’t 100%. What is it about the 20% that their bodies resisted the combo therapy?
Maybe the key to unlock the mystery lies with genetics. On the last day of the conference, ASCO announced a joint effort with the NCI, National Cancer Institute, to conduct basket trials. These trials group patients together with specific genetic mutations in a patient’s tumor rather than the location of the tumor. So a prostate cancer patient may achieve complete remission or, dare we say, cure by being treated with a drug developed for breast cancer because of the same genetic mutation found in both.
Will that be the magic bullet that cures cancer? I am optimistic that the answer is just around the corner.