Cannabis for Peripheral Neuropathy

This podcast episode is made possible, in part, by a grant from Lilly.

Jamie DePolo: Hello, thanks for listening. I’m podcasting from the 2023 American Society of Clinical Oncology Annual Meeting. My guest is someone that many of you know, Dr. Marisa Weiss, who is founder and chief medical officer of Breastcancer.org. At this meeting she presented results from her study looking at cannabis to ease peripheral neuropathy; that’s tingling and numbness in the hands and the feet caused by chemotherapy. She’s joining us to discuss the results.

Dr. Weiss, welcome to the podcast.

Dr. Marisa Weiss: Thank you so much for letting me share our results and to work with you, Jamie. You’re amazing. We all love you at Breastcancer.org.

Jamie DePolo: Oh, well, thank you. So, to start, just in case anyone’s unfamiliar, could you explain to us how chemotherapy causes peripheral neuropathy and how you know when it’s a problem?

Dr. Marisa Weiss: Okay. So, in the clinic, you know, taking care of people who are dealing with breast cancer and I noticed that so many of them were dealing with what we call peripheral neuropathy, which can be described as numbness and tingling or pain in the hands and the feet, and it can also make it harder to perform special things like buttoning a shirt or opening a jar. Basically it gets in the way of everyone’s daily quality of life and your ability to perform the things that you need to do for living each day at home, at work, in the community, wherever you are.

And there are certain chemotherapies that are more likely to produce peripheral neuropathy. They are the taxanes…the biggest culprit is Taxol, also known as paclitaxel. Taxotere, or docetaxel, can also do it but at a lower rate. And then there are medicines like carboplatin and cisplatin and the platin-based chemotherapies that are also guilty to cause this problem. 

And then women, people of color -- we don’t know why -- are more likely to develop it. The risk of developing peripheral neuropathy from those types of chemotherapies can range anywhere from like, 25% up to 50%, depending on the study. And so, as a doctor in a hospital, I noticed that so many people were suffering from this side effect and we know from research that this is a dose-limiting side effect of chemotherapy, which means that if you’re going through chemo and you have this side effect, your doctor might have to reduce the dose or even stop the chemotherapy early because you can’t tolerate or the symptom is so bad that it’s in the way of your finishing…it gets in the way of your finishing the treatment. 

And so, it’s actually a reason for, part of the reasons for, health disparities because women of color are more likely to have this side effect and they’re more likely to stop their chemotherapy early and not get the full benefit of it. And so, it’s a significant problem, and at Breastcancer.org in our discussion forums and in various places, we’ve been, you know, have our finger on the pulse and noticed that many of you are suffering from this side effect. So, we know this was an important problem that needed to be studied further, and we know that there are some medicines already out there like gabapentin or Lyrica or Cymbalta. These are medicines that your doctor might give you to reduce chemotherapy-induced peripheral neuropathy. 

But it wasn’t doing enough and so, we looked around and we saw that in studies of mice that cannabidiol or CBD that can be derived from hemp or marijuana, those are both cannabis plants, has a nerve protective property to it.

Jamie DePolo: Okay. Before you go into all that I wanted to just ask you, could you explain a little bit how does chemotherapy cause peripheral neuropathy? Like, why is it so much associated with that treatment as opposed to others?

Dr. Marisa Weiss: Yeah. Yeah. So, for example, Taxol, which is one of the chemos that is associated with a higher risk of peripheral neuropathy, the medicine affects the microtubules. Those are like, little parts of the nerve structure, and basically it prevents the nerves from healing themselves. So, the chemo affects the nerves and the nerves can’t really heal themselves so well because the chemo limits the nerves’ ability to do that. So, that’s probably one reason why.

And by the way, there’s a lot of different kinds of neuropathy. People could have diabetic neuropathy because of other reasons like, the little blood vessels that feed the nerve tissues have withered and they’re just not working very well, and that’s a cause for another kind of peripheral neuropathy. And if you add one type of neuropathy to another like, if you’ve got diabetic peripheral neuropathy and then you get Taxol, it’s a double whammy.

So, you definitely want to think about ways to reduce the incidence of peripheral neuropathy, and there was actually a study at ASCO that looked at the use of cold mittens basically that you use during the chemotherapy to reduce the incidence, and it was helpful. Some people can’t tolerate that cold feeling but it is useful for a lot of people.

Jamie DePolo: Okay. So, now tell us, why did you think cannabis could help? You were mentioning the mouse studies. 

Dr. Marisa Weiss: Right. So, why do we think that cannabis would actually help for peripheral neuropathy? Well, we saw that there were some studies in mice that showed that if you give mice cannabidiol, which is CBD, during their chemotherapy that it reduced the incidents, the number of mice that had that symptom. And then so, we thought, oh, well, let’s try to give CBD together with chemo but the FDA wouldn’t let us do that. 

So, then we looked at studies that used CBD for mice that already had peripheral neuropathy to see if it helped them reduce the severity of the peripheral neuropathy or how long it lasted, the duration. And that was also impressive. So, it was on the basis of those insights from mouse studies that we thought wow, maybe we should try to use this in people to see if it helps them because what good is it if it just helps mice? We want to know if it’s going to help people.

So, our study was launched at the beginning of the pandemic and it was open to people who had breast cancer, ovarian, endometrial cancer, colorectal cancer who had grade 2 or grade 3 peripheral neuropathy, which is basically numbness, tingling, pain, or difficulty doing fine motor things that bothers you in your everyday life. And half the people in this study were assigned to the CBD arm and half the people were given the placebo. And for the CBD arm it was 135 milligrams of whole plant, and this was hemp derived, CBD extract from the Ananda Health Company, who sponsored the study.

Jamie DePolo: And these were capsules, right?

Dr. Marisa Weiss: And these were gel caps. Exactly. So, they took three 15-milligram gel caps morning, middle of the day, and the evening. First, we found that it was well tolerated, that people weren’t bumping into walls, no one was high, no one was stumbling, whatever, that basically people tolerated it pretty well and they were able to perform their jobs and sleep like they needed to and do other things like they needed to. 

And what we found at the end of the study, and there were about 45 people on the study. We had hoped for 100 people on the study but because of the pandemic it was hard to get those people in the door. But what we found was that at the end of our study and with relatively early data that the CBD was able to reduce the amount of numbness and tingling that people experience who have peripheral neuropathy compared to the people who got the placebo. Okay? 

So, that’s a very meaningful finding because in the clinic so often it’s the numbness and tingling that really gets in people’s way and interferes with quality of life. The CBD did not seem to impact on the amount of pain you had or your ability to perform like, certain things like, buttoning a shirt or opening a jar, but it’s also true that although it looked like it might be helpful, our data weren’t strong enough to show that. 

Jamie DePolo: So, if you had a larger…

Dr. Marisa Weiss: Exactly.

Jamie DePolo: …group you might see that.

Dr. Marisa Weiss: If we had had more time and more funding to get to 100 people in the study, then it’s very possible that we could have learned more than we were able to learn, and it’s important to know that a number of people who are on the study were also taking gabapentin or Lyrica or Cymbalta, those other medicines that doctors more regularly use to manage peripheral neuropathy symptoms. And the reason why they joined the study is because those medicines helped a little bit but not enough. So, they still had leftover peripheral neuropathy that they wanted to get help with, and they wanted to participate in a clinical trial.

Jamie DePolo: Let me ask you this before you go on, sorry. Does everyone who has peripheral neuropathy have the pain? Or can it be just tingling and numbness?

Dr. Marisa Weiss: Yeah. Well, it’s so interesting because one of the fascinating things at Breastcancer.org and where I take care of patients in a hospital is that everyone is unique, right? And everyone uses different words and terms to describe what’s happening in their life, and I’d say a lot of times people will say, you know, I don’t feel something which means numbness, or it’s I’ve got this tingling, pins and needles kind of feeling, which is tingling, and some people might say, I don’t have pain but I have soreness or I have tenderness, or they might use different words to describe pain. 

It's also very cultural like, you know, some cultures you don’t use the word pain because it’s sort of like complaining and that’s like, negative. But they use other words like, it’s really bothering me or it’s aching me. So, a lot of people have numbness and tingling despite efforts that they’ve made, or it may be that they had numbness, tingling, and pain but they were able to get relief from some of the pain but they have leftover numbness and tingling that’s still bothering them.

And so, this study is important because the product that we used which was a whole-plant extract of the hemp plant which was, you know, contained mostly CBD, a teeny-weeny bit of THC in there. It was made by a company, Ecofibre or Ananda Hemp, which is available online, that it did show that it improved numbness and tingling compared to placebo. You don’t need a medical marijuana card to get it, but because it’s a whole-plant extract from hemp, there is a teeny-weeny bit, a trace amount of THC that’s in there and that’s the psychoactive part of marijuana or cannabis that makes you feel high.

Jamie DePolo: Right.

Dr. Marisa Weiss: But if you are at a job with zero tolerance. That is, you could lose your job if a random urine test were to show that you had THC in it…like, let’s say you are a school bus driver or you work in the military or you’re a corrections officer or you’ve got a job like that, then you can’t use a whole-plant extract CBD product because it will have a trace of THC and you might lose your job because of it.

Now, if you hear about this study and you have one of those jobs, or you have a job like, you’re in nursing, whatever it is, where you’re not allowed to use cannabis while you’re working, you may go to your HR director and go to the head of your department and say, “Hey, look. I had breast cancer and I am suffering from this side effect that’s left over from my chemotherapy and I need to do something about it, and the medicines I’ve been using aren’t doing the trick. So, I’d like to participate in this clinical study, or I’d like to just buy it online, and I don’t want to lose my job.”

So, in that situation you can get the head of nursing or the head of whatever where you’re working to give you a note that says, or tell you if you get a note from your doctor, or if you get certified, get medical certification clearance to do it, then your job will be secure. What I’m saying is to try for them. It can’t guarantee that it’s going to happen for you but it’s definitely worth looking into.

Jamie DePolo: Right. Now, you said it was well tolerated. Were there any side effects at all?

Dr. Marisa Weiss: Well, if you think about for anyone who’s just finished their chemotherapy and the people in the study, they were finished their chemotherapy within a year or two, they were still feeling side effects from their chemotherapy. So, when we asked them how they’re doing they were saying, the people said, you know, I have fatigue, you know, I’m a little bit foggy from my chemo. You know, I can’t walk as well as I used to or I can’t run so much anymore, you know, I fell down. You know, that they were knocked out from the treatment that they’ve been in, but there didn’t seem to be significant additional side effects that could be attributed to the CBD product that we were offering on our clinical trial.

Jamie DePolo: Okay. And then finally, you’ve kind of done this but just to summarize, could you put the results in context for us? So, if I’m a person, I’m receiving chemotherapy or I’ve just completed chemotherapy…

Dr. Marisa Weiss: Yes.

Jamie DePolo: …and I’ve got peripheral neuropathy due to the chemotherapy. So, how would you advise me?

Dr. Marisa Weiss: So, I would say…so, if you just finished your chemotherapy and you’ve got this side effect and it’s bothering you, it’s getting in your way, it’s affecting your quality of life. Then it’s important to know that you’re not alone, that anywhere from 25% to 50% of people who receive either Taxol or Taxotere or carboplatin chemotherapy will develop that side effect. It could go away on its own, you know, if you give it some time. But while you’re suffering from side effects like numbness, tingling, or pain, or inability to perform like, different functions with your hands and maybe with your feet, there are things that you can do to reduce the amount of symptoms that you have.

So, you could ask your doctor about medicines that they’re using regularly already like, gabapentin, Neurontin, or Lyrica, or duloxetine, or Cymbalta, those kind of medicines to see if it helps you. Okay. But if you still have these side effects or if you’re someone who doesn’t want to use, you know, pharmaceutical medicines and you’d rather go with something more natural, then you could try CBD. And the product we used was pharmaceutical grade which means it was nice and clean. It didn’t have heavy metals in it, it didn’t have pesticides in it, it didn’t have any mold in it. It was a medical-quality product and that’s why we worked with the Ecofibre and Ananda Hemp Company because they would provide it for people on the study.

Then that medicine taken 135 milligrams a day so, that was 45 milligrams in the morning, 45 in the middle of the day, 45 milligrams at night. You work your way up to that dose. That could help you reduce the numbness and tingling from chemotherapy. The patients on our study used it for three months and during the time that they used it we were, you know, they visited with us every two weeks and they filled out questionnaires and they had neurologic exams, and we did all kinds of things to evaluate how they were doing.

But there are definitely options for you, and if you’re listening to this and you haven’t started chemotherapy, or maybe you had a dose or a cycle or so already and you feel like this side effect, ask your doctor about the cold mitts or the cryo mitts. There are different words, the terms that are used to describe it, but basically cold mitts that you put your hands in and feet in during the infusion and just afterwards to try to reduce the amount of chemo that goes to your fingertips or goes to your feet to try to reduce the risk that you’d even get that side effect. 

Jamie DePolo: I just have to ask one final question. Could somebody start the CBD while they were receiving chemo or is it better to wait until you’ve completed all the chemotherapy?

Dr. Marisa Weiss: Yeah. Well, it’s an excellent question because, you know, of course, we would always like to prevent a side effect rather than to get it and have to treat it and make you suffer from it.

Jamie DePolo: Right.

Dr. Marisa Weiss: And for my particular study we tried to do it up front together with chemotherapy but the FDA wouldn’t let us do that. 

Jamie DePolo: Right.

Dr. Marisa Weiss: And the reason why is because both CBD, as well as THC, and some of these chemotherapies are both broken down by the liver and we couldn’t be sure that it was safe to use them together. So, we would love to do that study. The fact that giving this medicine had no significant side effects and liver function was perfectly fine because we check that in our patients, gives us more ability to go back to the FDA and say we want to do this study in people who are in the process of getting their chemotherapy to try to prevent this side effect. And we also know that a lot of people are using cannabis these days, more and more and more during their chemo to manage side effects like nausea, vomiting…

Jamie DePolo: Right.

Dr. Marisa Weiss: …insomnia, pain, and they’re getting certified…like, in the state of Pennsylvania I certified people. I participate in the Pennsylvania medical marijuana program and I’ll certify people, and they’ll take it during their chemotherapy to manage side effects because they still have nausea [and] vomiting despite medicines, or they don’t want to use pharmaceutical medicines, they’d rather use something natural. So, the people are taking it and people are tolerating it fine.

Jamie DePolo: Okay. 

Dr. Marisa Weiss: But we just don’t have any data to…

Jamie DePolo: You need to have data.

Dr. Marisa Weiss: …show that. But I would say that if you’re interested in using something during chemotherapy, I wouldn’t be using inhalational products unless you need to, because you’re exposing the lung to a chemical and if you’re getting chemo on top of that and we’re still in the midst of the tail winds of the pandemic, it’s probably a good idea to use other types of products like, the gel caps that we use in our study or a tincture that you put under your tongue or a pill, or some people use a lotion.

Jamie DePolo: Right. Okay. Okay. Well, thank you very much, Dr. Weiss. This has been super helpful. 

Dr. Marisa Weiss: Thank you for having me. I appreciate it.