Specificity refers to the ability of any medicine to discriminate between its intended target and its host. Killing a cancer cell in a test tube is not a particularly difficult task: the chemical world is packed with malevolent poisons that, even in infinitesimal quantities, can dispatch a cancer cell within minutes. The trouble lies in finding a selective poison—a drug that will kill cancer without annihilating the patient. Systemic therapy without specificity is an indiscriminate bomb. For an anticancer poison to become a useful drug, Meyer knew, it needed to be a fantastically nimble knife: sharp enough to kill cancer yet selective enough to spare the patient.
typical exchange between myself and a kind friend
friend: so, you’ve started your immunotherapy! how are you feeling?
me: i’m feeling well. i have had two infusions, and so far i haven’t had any of the severe side effects that i feared. i’ve had a few minor ones, but they are manageable.
friend: that is great news. what a relief! i know what chemotherapy is, but what exactly is immunotherapy?
me: well, immunotherapy is a targeted therapy that teaches your immune system to fight any rogue cancer cells that are still in your body. it is very expensive and can potentially be curative. jimmy carter’s melanoma had metastasized to his brain, and after immunotherapy, the tumors disappeared.
friend: right… but what is in the liquid that is actually going into your body?
me: that’s an excellent question. i really have no idea. (while thinking: i really should have some idea!)
this past monday, i had my second immunotherapy infusion. i’ve had the drug (nivolumab) in my body for about three weeks. it is a wild thing, but i actually know very little about the drug that is supposedly going to save my life. i understand it at a conceptual level; but i do not understand the science or the biology behind it. sometimes thinking about things too deeply causes me to feel anxious about it: what are the long term effects of being on immunotherapy? how will we know if i am a responder? what if i’m not one of them? what if my immune system begins to fight against my body itself? to avoid these rabbit holes, i have focused my knowledge around what i can control: knowledge of the side effects and how to manage them.
since i am on the cutting edge of cancer treatment (and while i do theoretically enjoy being on the cutting edge of life, i could have lived without this!), many of my friends and family also know very little about my treatment. so, i will do my best to give you all a sense of what i am going through. much of this is a result of a few hours of research. if any doctors are reading this, the errors are all my own – please comment and correct me!
first let me begin by what immunotherapy is not. immunotherapy is not the same as chemotherapy. chemotherapy is a drug (some people call it a poison, but that is controversial) that attacks rapidly dividing cells. cancer cells grow and divide rapidly, but so do some healthy cells like our hair and our skin. immunotherapy, or biological therapy, is different – it works with our immune systems. at a basic level, our immune system is designed to protect our body from disease. all humans produce potentially cancerous cells on a daily basis, but our immune systems destroy them. germs and cancer cells have molecules on them called antigens. these antigens typically send a signal to the immune system to find them and kill them. obviously, this isn’t fail safe. some cancer cells are excellent at playing hide and seek, and they camouflage by looking like normal cells; or, sometimes the immune system just isn’t strong enough to kill all the cells they find. cancer takes advantage of something called checkpoints, which are present on our immune system cells and essentially act as a regulators. these checkpoints are important because they make sure that our immune system doesn’t kill every cell in our body. immunotherapy “boosts” our immune systems by using checkpoint inhibitors, drugs which block checkpoints present on immune system cells, freeing the immune system to kill the cancer cells.
i’ve simplified a very complicated process:
The immune system normally stops T cells (a type of immune system cell) from attacking normal cells in the body by using proteins called checkpoints. Checkpoints are part of a pathway that the immune system uses to slow down or put the brakes on an immune system response. Some cancer cells can send signals that confuse T cells by turning on a checkpoint pathway and stopping them from attacking cancer cells. This lets the cancer continue to grow because the cancer cells hide from the immune system. Immune checkpoint inhibitors are monoclonal antibodies that work by blocking checkpoint proteins so that immune system cells can attack and kill the cancer cells. There are 2 immune checkpoint pathways that can be blocked to allow the immune system to fight cancer. PD-1 is an immune checkpoint that stops T cells from attacking other cells in the body. It does this by attaching to PD-L1, a protein found on some normal and cancer cells. Some cancer cells have a lot of PD-L1, which helps protect them from being attacked by T cells. Monoclonal antibodies such as atezolizumab (Tecentriq), pembrolizumab (Keytruda) and nivolumab (Opdivo) target PD-1 or PD-L1 to help boost the immune system’s response to attack cancer cells and destroy them.
while many are celebrating immunotherapy as the future of cancer care, this process is not without risks. along with a myriad of serious side effects, the main fear is that the immune system will get confused and begin attacking organs. since i’m billing my new super power to be my new high functioning immune system, i’m hopeful i will not be one of the unlucky twenty percent who get some of the serious side effects. if you want to have nightmares on my behalf, you can google them; they range from colitis to thyroid issues to kidney failure. most of the common non-life threatening side effects of nivolumab (the checkpoint inhibitor that i’m on) are fatigue, skin reactions, digestive issues and flu like symptoms. so far, i have felt a bit tired, i’ve had some slight digestive issues, and i’m more thirsty than normal. i can definitely live with that!
in terms of the logistics, i go to the hospital to receive infusions every two weeks. i will be doing this for 12 months. i sit in a room – not unlike a salon, filled with chairs and beds – where everyone is receiving either chemotherapy or immunotherapy. there is a lot of natural light. so far, i have generally been the youngest in the room. i do my symptom assessment, get weighed, and they check my temperature to ensure i am healthy enough to receive the infusion. then, they begin creating the mixture so that it is suited to my height/weight, and i get put on an IV of saline. the nurses are incredibly friendly. they have explained to me that immunotherapy is usually well tolerated, but i have a card for my wallet in case i have to go to the emergency room. the infusion takes thirty minutes, during which i distract myself by chatting with a friend, working on a project or reading. the room is cold, but they offer me a blanket, and there is always a very kind volunteer who comes by to chat, offering to grab us a water or a coffee.
in terms of standard of care, immunotherapy is still very, very new. it is covered by OHIP (ontario health insurance plan) if a patient has stage 4 melanoma, but it is not yet covered for stage 3. the trial data is very promising, and my oncologist tells me this will change in the next year or two. i’m fortunate that i have private insurance, and they have agreed to cover the cost of immunotherapy. if they had not agreed to pay it, i could have found the money, but it would have decimated my savings. it is frightening to think what people would do if they were not in a fortunate financial position.
i’ve had a slight bit of anxiety in the days leading up to treatment mondays. not the crippling kind. just the feeling of… holy shit i’m putting a crazy new drug into my body and anything could happen. for the first session, i had this sinking feeling that i would feel the drug entering my system, almost like an instantaneous allergic reaction. in reality, it was very anticlimactic. now, three weeks in, i feel like i’m waiting to feel sick, or not to feel sick.
people on chemotherapy often look sick, or feel sick. some people on chemo say that when you feel sick, you know its working. but i don’t. immunotherapy seems magic, so far. i have been SO lucky to have a ton of friends come to ottawa over the past two weeks to support me and “take care” of me. ironically, my energy level has been close to normal. i still don’t know what the liquid is that is going into my body – but this has to be promising.
i’ve always wanted the superpower of being able to snap my fingers and end up in another place. snap – i’m in bangkok. snap – i’m having dinner with my family. snap – i’m at the grocery store. it appeals to my efficiency side, and is way less scary than being able to jump from tall buildings or fly. instead, immunotherapy has given me my cancer superpower: a supercharged immune system that will let me live forever. i can definitely live with that.
1 comment
Thank you Sarah for the education on your cancer treatment. I hope you will continue not to have the severe side effects which, as you say so far are manageable. I look forward to seeing you this week.
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