US-based Filipino scientist achieves next
generation research in antibodies

By Mary Charlotte Fresco
MediaCore, STII

Dr. Eduardo Padlan, a renowned Filipino scientist and biophysicist now based in Maryland, USA delves into current medical applications of antibodies in treating dreadful diseases such as cancer, asthma, and autoimmune diseases like lupus, and rheumatoid arthritis.

Antibodies demonstrate vigorous potentials to improve advanced medical research in pharmacodynamics and human therapy.  For his expertise in such highly specialized field, Dr. Padlan was appointed consultant by the Department of Science and Technology for its Antibody Biotechnology and Liposome Drug Delivery Technology for Experimental Therapeutics of Breast Cancer or AMOR Program.

Antibodies were long been used as anti-toxins, diagnostic tool for a variety of diseases, and as a means to prevent organ transplant rejection.  It can now be manipulated through genetic engineering to make it compatible to the physiological requirements and features of the human body, Dr. Padlan in an interview said.

Antibodies are normally occurring protein molecules that take important part in human immune system and act primarily as a defense against invasion of foreign substances, among the most common of which is called antigen.

Antigens are proteins found in bacteria and viruses that cause allergies and infections. Antigens normally enter the body through respiratory and digestive tracts, and skin or blood vessels.  These can also be deliberately introduced through vaccination.

Antibodies have molecular arrangement that fits the shape of molecules of antigens.  This clever binding of molecules enables the body to neutralize and eliminate harmful incidence by directly deactivating them.  This enables other blood cells to engulf and destroy antigens, and undermine their surfaces thus rendering them vulnerable to destruction by other blood proteins. 

Conventionally, scientists extract antibodies from nonhuman sources such as mice and horse that are immunized or exposed to disease-causing organisms.  The animal-based antibodies are purified through a rigid process known as chromatography.

But animal-based antibodies' protein structure is different from those in humans, and the human body acts to repel them, Padlan added.

Dr. Padlan's current important research involves “humanization” of antibodies, considered one of the fastest growing drug development programs today.  Humanization, he said, is the technique of modifying the protein composition of antibodies molecules to produce desirable characteristics and to make them compatible to human molecules with less antigenic activity.

Production of large amounts of pure antibodies is a leading concern in pharmacodynamics.  But current technologies are not efficient enough, resulting to an acute supply shortage, he added.

Statistics in online sources show that in 1999, sales of humanized antibodies reached approximately US$0.9 billion.  By 2001, annual sales went up to a feverish US$ 3.5 billion. 

Dr. Padlan, who since 1985 has devoted time in the study of antibodies humanization achieved favorable results in his attempt to reduce immunogenicity of nonhuman antibody so the human body will not try to eliminate them.  This is made possible by incorporating mainly antibody residues that are only involved in interaction with antigens.

He added that many humanized antibodies are in clinical trials while several were approved for medicinal and human use.

In the Philippines, the future is bright for antibody engineering.  The AMOR program conceived in February 1998 with funds from DOST's Philippine Council for Health Research and Development gathered Filipino scientists currently exploring the possibility of using immunoliposomes to deliver anti-tumor drugs against cancer cells.

Dr. Padlan, who chairs the program, spends several months in the Philippines to work with the researchers and provide consultancy.  He also conducts scientific lectures and seminars among fellow scientists as well as college students.

He is recipient of numerous awards here and abroad including DOST's Balik Scientist Award, and the DOST—Philippine Science Heritage Center Outstanding Scientist Award, both conferred in 1998.