New Photodynamic
Therapy Offers Hope As Cancer Treatment
Case research team heading to home
plate with Pc 4
CLEVELAND
Along with Kenney and Oleinick, a team of researchers from the Case School of
Medicine and
Since 1956, Kenney has designed and
synthesized thousands of the bright-blue phthalocyanine
compounds. Pc 4 is among them. In the early 1980s, Oleinick
began assembling a team from the radiology and dermatology departments of Case
and from the Ireland Cancer Center of University Hospitals to investigate the
potential use of PDT as an alternative treatment for cancer patients, who
exhausted their tolerance for radiation therapy.
In looking across campus, Oleinick discovered that Kenney had 30 years of experience
in designing and synthesizing phthalocyanines, and
that some of the compounds which he had made were potential PDT compounds.
Shortly after learning of Kenney’s
work, Oleinick invited Kenney to become the research
group’s primary chemist and to have as his mission the development of new PDT
drugs. Kenney began by selecting 20 of his compounds. Oleinick
then studied how well they worked.
With information from the original
20 compounds, Kenney and his research team returned to the chemistry lab and
synthesized six new compounds (Pc 1- Pc 6). Again Oleinick
studied the new compounds. Of those compounds, Pc 4 consistently performed better
on cancer cell cultures and in mice with tumors in the lab setting, said Oleinick. Shortly after those studies, the research team
developed a project that won funding by the National Cancer Institute.
PDT is not a new science. The
ancient Egyptians rubbed plants containing natural photosensitizers
on diseased areas of their skin. In sunlight, the treated areas sometimes
responded favorably.
During the 1970s, the first
generation of modern PDT drugs was developed. Building on this work, the Case
scientists searched for a second-generation photosensitizing drug through
Kenney’s research.
PDT works through the use of the red
portion of visible light. The red portion penetrates tissue well and is able to
energize a photosensitive drug and cause it to burn away cancer cells. Because
it absorbs red light, Pc 4 is a brilliant blue.
In patients with internal cancers
such as breast cancer or head-and-neck cancer who are being treated with the
first-generation photosensitizer or with Pc 4, the
drug is injected intravenously and reaches cancer cells in tumors. After 24 to
48 hours, the patient—kept away from bright lights to prevent activation of the
photosensitizers which have found their way into the
skin—undergoes a laser treatment targeted to the cancerous area of the body.
Following the treatment with the first-generation photosensitizer,
the patient needs to remain in low-level lights for several weeks to prevent
excessive burning from the photosensitiver remaining
in the skin. Skin photosensitivity is lower with Pc 4.
In a new clinical trial for skin
cancer, Pc 4 is applied directly to skin lesions. After approximately one hour
during which the patient is under normal light, a laser physicist directs the
high-powered laser on the lesion to kill the cancer cells. This new simple
procedure is being directed by Elma Baron, assistant professor of dermatology,
and Kevin Cooper, professor and chair of dermatology.
“It’s normal for a new drug to take
a long time to reach clinical trials,” said Kenney.
The group received FDA approval for
its first clinical trials in 2001 through the
Kenney said that Pc 4, which comes
out of a train of researcher in his laboratories on phthalocyanines
extending over almost 50 years, could be rounding the bases to be that one
chemical hit in 5,000. But he said, as in baseball
###