So, Dr. Scholz, we have a lot of new things coming out in the kind of landscape of prostate
cancer and it seems like a lot of new things are coming out all at once and compared to maybe even
10 years ago. So, can you explain why we're seeing so much new development in the data?
I think we're reaping the, you know, the investment in what the scientists call basic
science. In other words, instead of looking to jump right to a cure what they've done
is invested a tremendous amount of money and time and energy in learning how cancer works
how the biochemistry of the cell works, and in the process of doing that they've discovered
how cancer is different than a normal cell. If you think of it an analogy like a computer it's like
a glitch in the cell, and once they find those glitches they've also developed ways to create
patches—they call them for computers—but for the treatment of cancer it's usually a medication and
that medication acts as a bridge where the glitch is and helps restore the cancer cell to a more
normal state which is, you know, not growing furiously out of control the way cancer does.
So some of the new treatments that are coming out or we're
looking you know hoping will come out soon is really in the immunotherapy section. So
how do you see Keytruda playing out in the trials? Is it going well?
So, Keytruda is a medicine that they talk about it taking the brakes off the immune system. Our
immune systems are so powerful they have to be heavily controlled. When they get out of control
you get multiple sclerosis, rheumatoid arthritis, lupus, a lot of sometimes even deadly conditions
where the immune system is running unchecked. In fact, some of the concerns about the Covid
virus is that it the virus is turning the immune system on so vigorously that it makes the patient
ill or you could even kill someone. So, there's a balance that's happening in our immune systems all
the time and Keytruda and other medicines like Opdivo and Yervoy work by taking the brakes off
the immune system which is certainly a worthy risk in someone that might be dying of cancer,
and Keytruda itself is in phase III trials for prostate cancer right now
and we don't know the answer yet. We've used it in phase II trials; it has activity;
it's well tolerated. It's particularly famous because president Carter had a advanced melanoma
in his brain several years ago and now he's still alive. He got an amazing response to Keytruda.
It's infused every three weeks and I would say that these medicines like Keytruda, Opdivo, and
Yervoy are being used — they're very much in their infancy. We don't know how to optimize them; we
give the medicine and hope for the best. In the future we're going to
be able to select patients who are going to more who are going to be more likely
to benefit and i'm sure we'll figure out ways to enhance the immune effect.
What percentage of men would you say are responding to Keytruda?
Well, it depends on the type of people you treat. If people have less advanced cancer, their immune
systems are more intact and the immune resistance of the cancer is not as profound—the roots aren't
as deep—so when you talk about people with very advanced cancers their immune systems are weak
and have cancer all over their body. The response rates are not that great 10%, 15%, 20% perhaps
of people will get some benefit. When you look at earlier stage men maybe as many as
50 percent are getting a benefit as signaled by a decline in PSA after starting the treatment.
You mentioned side effects, what type of side effect profile does
it have and is there any concerns with it interacting with other medications?
Not so much interactions with other medicines, but the immune system is, you know, operates in all
areas of our bodies. So, over immune activity for your skin is a rash problem, over immune activity
in your lung is an asthma problem, over immune activity in your intestine is a diarrhea problem,
the overactive immune system can create problems in any organ system
and it is unpredictable. So, it really challenges the skill
of the doctors that are giving these medicines to be very vigilant — to check thyroid levels,
check adrenal function because if the immune system knocks out the adrenal glands and people
become deficient in cortisol which is dangerous, or if it knocks out the pituitary gland or the
thyroid gland, so intense monitoring is always a component when we're using these medicines.
So that's a lot of different side effects that could happen.
Do you know based on the trial data how many patients this would happen to?
Out of the percentage of patients on the trial, probably about 20 percent of patients that take
these medicines will run into something that will need either a dose reduction or discontinuation or
some sort of maybe some cortisone to kind of calm the immune system down. As we mentioned before,
Joanne Weidhaas, MD at UCLA and others are working on ways to test our immune systems and
through through looking at genetics and determine who's likely to get side effects,
and some of the preliminary work that we've seen in our office indicates that this is effective.
They can identify people who are unlikely to get immune side effects and in the limited number of
patients that we've treated with Keytruda who were predicted to have a low incidence
of side effects indeed have really not had any side effects. So, we've been testing people in
advance of these medicines and withholding Keytruda in those that are likely to have
side effects and administering it and those that are at low risk for side effects.
That type of testing is obviously really incredible for a patient
who's looking to take Keytruda and would be able to know ahead of time.
When can we see this testing be more widespread across the U.S.?
Well, like any research process it takes anywhere from six to twenty four, sometimes even two three
years, before things — the trials are completed, the FDA approval is happening, and I think that's
why we're having this talk today is that there are ways for savvy patients to access medicines that
are not approved. For example, we're all excited about the recent approval of PSMA pet scans, but
people have been getting PSMA PET scans for two or three years on clinical trials and and benefiting
greatly, so this is why I think in our modern era being sensitive and having an understanding of
what's going on behind the scenes can really make a big difference for some patients.
So you mentioned Opdivo and Yervoy.
How do you see those different from Keytruda, or do you use them in combination?
Opdivo is more similar to katruda. Yervoy is a little different although
they all work by taking the brakes off the immune system,
and Bristol Myers makes Opdivo and Yervoy and they've been used in combination a lot with
a notable benefit in prostate cancer and at least in preliminary trials. My
sense is that the combination of Opdivo-Yervoy is more likely to be associated with side effects and
perhaps more likely to be associated with a good response, but that's limited exposure and these
things are early. Ongoing research is in process and we'll know more as time goes on, but it's nice
to know that there is activity associated with these medicines for prostate cancer patients.
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