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Genitope CLL Vaccine Trial Update

Date: October 16, 2024

In earlier articles we brought to your attention the kick-off of the Genitope “MyVax” custom made vaccine clinical trial. If you are not familiar with this clinical trial or the technology that drives it, I suggest you might want to read our earlier articles, links below for your convenience.

Idiotype Vaccines
Vaccine Trials

“MyVax” Interim Update

Please be aware this is not the last word on the subject, just a quick peek for those of us who are not exactly the patient variety. First, a quick overview of the trial design:

• Study 2024-11 is a multi center, open label, single arm Phase-2 study to see if MyVax vaccine is safe, and if it can get any kind of response in previously untreated CLL patients.
• The vaccine is custom made for each patient, a long drawn-out and expensive process. But hey, we would not complain if it actually proved to be the holy grail of all cancer research, a non-toxic therapy capable of really curing CLL, right?
• The vaccine is administered along with GM-CSF (granulocyte macrophage colony stimulating factor, a growth factor, trade name: “Leukine”) and KLH (Keyhole limpet hemocyanine). KLH is a protein obtained from a giant sea slug found off of the coast of California, I am told. Human bodies find this foreign protein so bizarre that all kinds of alarm bells go off and they mount immediate and strong reaction against it. Both the GM-CSF and KLH are therefore given to “goose” the immune system to a state of high alert, the equivalent of homeland security declaring RED security alert, as it were.

The plan is to recruit 87 early stage and previously untreated CLL patients and give them a series of 16 vaccination shots over the course of a year. This interim report is based on 22 patients. Roughly twice as many men as women volunteered, and the vast majority of them were very early Rai Stage 0-1. Only 13% were even Rai Stage – 2, none higher than that. It makes sense to recruit an “easy” crowd when testing vaccines, patients who are new to the cancer scene and whose immune systems may still be reasonably intact. As the cancer grows and patients are exposed to various drugs, there is inevitable damage to their immune systems and they are no longer able to respond effectively to vaccinations.

Most of us are familiar with childhood vaccinations. After getting the shot, we wait to see if it “took”, i.e., if it got any kind of a response from the body. Often, the site of the injection becomes redder, warm and tender to the touch for a couple of days. This is the outward signal of the body’s immune system responding to the antigen presented in the vaccine. In plain English, it is an indication that the body has acknowledged it has been shown the mug-shot of a dangerous enemy, and will be on the watch out for him in future. The first step in certifying any vaccine is that it is capable of getting this kind of a ‘humoral’ immune response from the body.

Results

As we described above, KLH is sure to get just about anyone’s immune system in a state of high alert. And sure enough, every one our 22 guys participating in this clinical trial mounted an immune response against it, same as the much larger cohort of non-Hodgkin’s lymphoma patients in an earlier trial. This confirms that in these early stage and previously untreated CLL patients, the immune system is still uncorrupted and able to respond to vaccinations (something to remember, as you consider the usefulness of flu shots and pneumonia vaccinations).

Responding to KLH is all very nice, but how did the patients respond to the business end of the vaccination, the MyVax component that targets CLL? This million dollar question is addressed in a single sentence in the summary that I almost over-looked. Out of the 22 CLL patients tested, only 4 showed the tell-tale immune response to the CLL antigen. In a mere 18% of the patients tested thus far, there was indication that the vaccine may have had an impact. This does not guarantee that even in these patients the CLL cells will be robustly attacked and rooted out. It just means that in these 4 patients the mug-shot of the criminal was duly received and put up on the “Wanted” bulletin board of the police station. It is yet to be seen if the officers will be able to apprehend the criminal, now that they have been given the information on what to look for.

Frankly, I am disappointed. I know, this is an early stage clinical trial, and these are very early stage preliminary results. Compared to the 100% immune response to the KLH, the 18% response to MyVax suggests the antigen used to describe the cancer cells was not sufficiently attention-grabbing. Most of the officers yawned politely and went off to get their second donut. Perhaps Genitope will consider reformulating the vaccine, make the CLL mug-shot look a lot more dangerous and attention grabbing some how. The fact that the same bunch of patients responded strongly to the KLH component suggests there is reason to hope, these early stage patients seem capable of responding to a well-designed vaccine. I will be the first to agree, this is easier said than done.

This information was presented by the company as a poster at the last International CLL conference (IWCLL) in London, September 2024. I have it as a PDF. Please do write if you wish to read all the details.

Be well,

Chaya
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