Q & A
Daniel B. Yarosh, PhD
President and Chairman
AGI Dermatics
1) How have the types of sun protection changed over the past 10, 20 and 30 years?
Attitudes toward sun protection have changed, so that sunburn is viewed not just as a painful experience but is linked in the public's mind with skin cancer. Among older adults and children, this has led to the increasing use of sunscreens. Unfortunately, teens and young adults still worship the sun and their use of sunscreens and sun protection is not as great as it should be. Products are considered more and more for protection than for enhancing a tan; for example consider our substitution of the term "suntan lotion" with "sunscreen." Sunscreens are now found in many cosmetics and makeup, so that the frequency and amount of use of sun protectors among women has gone up dramatically.
2) Are there certain ingredients that we should look for on sun protection labels to make sure we're getting the best protection for our money?
Sun protection products vary greatly in the ingredients and "feel" on the skin. The most important thing is to find one you like and use it often! When choosing a sun protection product, the SPF should be at least 15 and it should have broad-spectrum coverage, that is, absorbance in both the UV-B and UV-A spectrum. Common broad-spectrum sunscreens in the U.S. are titanium or zinc oxide, and with new technology these don't have to give a pasty or ghostly look on the skin.
3) Have you seen or heard of any links between diet and skin cancer or sun protection?
A few small studies in both animals and humans have shown that a diet low in fat reduces the appearance of pre-malignancies and non-melanoma cancer. However, a very large clinical trial of a diet high in beta-carotene failed to show a reduction in the rate of skin cancer.
4) Does sun protection differ depending on how much melanin you have in your skin? Is there a rule for color type I that differs from color group IV?
The type of natural melanin found in your skin has a big impact on sun protection. Black skin has large amounts of eumelanin and has greatly reduced rates of skin cancer. White skin such as that found among Celtics has a red color due to pheomelanin that is much less photoreceptive. The great fallacy is that a tan is protective and that if you are skin type III or IV you should get a tan and not use sunscreens. This is wrong! A tan has an SPF of only about 2, and of course you have to get DNA damage to your skin to get the tan in the first place. When populations which can tan migrate and change their lifestyles, such as when Japanese move from Japan to Hawaii, their skin cancer rates go up. The rule is that the best color for you is the one you were born with.
5) Is there a difference between U.S. sun protectants and those found overseas?
Yes. Several new generations of sunscreen compounds have been introduced in Europe and elsewhere which protect against both UV-A and UV-B and are more stable during sun exposure. Some are more easily formulated so the final product feels quite nice and can be made into a spray, and is therefore more likely to be used, especially by children. These sunscreen ingredients are not included on the U.S. Food and Drug Administration (FDA) list of allowed sunscreens in the U.S. and therefore cannot be included in products sold in the U.S.
6) What is the link between antioxidants and sun protection?
This is an active area of research. Solar UV can form oxygen radicals in skin, and antioxidants do absorb them to prevent damage. Some animal studies have shown that applying antioxidants can reduce skin cancer. However, large-scale clinical studies have not shown a strong connection between the use of antioxidants and skin cancer protection. Certainly, there is nothing wrong with applying antioxidants to skin.
7) I understand that the T4N5 liposome lotion is still not approved by the FDA for marketing, but how is it being tested?
T4N5 liposome lotion, or Dimericine® (Die-MARE-eh-seen), is a DNA repair enzyme that is specific for UV damage. It is being tested first in the most sensitive population, those with genetic diseases or organ transplant patients who are most susceptible to skin cancer.
8) In the studies, how is Dimericine used? Where do the patients use it and how is it packaged?
In the clinical studies of Dimericine, the patients apply the lotion to the face and arms once a day for one year. Three pumps from the bottle is sufficient to cover the area. Since most skin cancers appear on these sun-exposed areas, covering other body sites is not necessary.
9) What is the status of the XP clinical trials?
The XP Trial was registered with the FDA as a Phase III trial because it had a clinical endpoint: reduction of actinic keratoses and skin cancer. Phase I and II trials were completed before this.
10) If there are no further clinical trials planned for XP, does that mean that this application has been shelved?
The application is open. The FDA has undergone reorganization twice in the last three years and our application has been moved. We are discussing the number of XP patients required for market approval.
11) What is the status of the renal transplant clinical trials? When do you expect the results?
This is a Phase IIb study, and patients are being recruited to the study and several are already using the medication/placebo. The results will not be available until mid-to-late 2006.
12) How great is the increase in skin cancer among renal transplant patients, or all organ transplants patients?
The increase is about 100-fold, and even greater in high sun exposure locales. The first publications on this problem were from Australian transplant surgeons in 1972. All organ transplant patients have this problem because of the immunosuppressive drugs, but the largest group is renal transplant.
13) Is the increase known to be due to the immunosuppressive drugs?
Yes. The drugs suppress the immune system so the transplant won't be rejected, but the immune system is needed to identify and destroy cancer cells. When immunosuppressive drugs are withdrawn from transplant patients, their skin cancer rates go down, but the risk of rejection goes up.
14) Do you have plans to use your liposomes to treat any other types of sun-induced DNA damage?
We just published results in the Journal of Investigative Dermatology and presented results at the Society for Investigative Dermatology (May 4-7, 2005) showing that drugs used intransplant immune suppression inhibit DNA repair, and this may contribute to their increased risk of skin cancer. We also presented these findings at the10th World Congress of Cancers of the Skin in Vienna (May 16, 2005). These findings are particularly important because two forms of these drugs, tacrolimus and pimecrolimus, are used topically for treatment of the very common skin condition atopic dermatitis (eczema). Our data would suggest that use of these drugs may increase the risk of skin cancer. The U.S. FDA has just recently required that these drugs carry a special "black box" warning on their labels concerning their potential cancer risk. We now have data that Dimericine can overcome the DNA repair inhibition caused by these drugs.
15) What source are the liposomes coming from? What are some of the main ingredients?
The DNA repair enzyme is made by biotechnology methods from the cloned gene. The liposomes are the delivery vehicle for the DNA repair enzyme. They are mostly made up of the lipid lecithin, from the egg.
16) What are the top five things we can do to best protect our skin from skin cancer?
The top five are:
- Arrange your time in the sun for morning or afternoon, and avoid high noon.
- Use sunscreens often, even if you are not expecting recreational exposure. Every day is best.
- Use the proper amount of sunscreen, and reapply. If you still have the sunscreen bottle from last summer, you are not using it enough.
- Look for personal care products that include sunscreens in them, such as foundation and lip balm.
- Keep an eye on your body and notice changes in pigmented spots. Get your partner involved. Visit your dermatologist regularly for a full body examination. It doesn't take much for a curable skin lesion to change into a nasty problem.
