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Gene therapy may be much less known in Pakistan, but it is progressing rapidly in the developed world. Owing to the vast potential and promise it holds, Big Pharma and Small Biotech companies are racing to find new therapies. Big Pharma has deep pockets of its own, while Small Biotech are being liberally funded by VCs – Venture Capital firms.
Promises of gene therapy are mainly two: one, the possibility to treat some yet untreatable diseases; two the potential to make unprecedented amounts of money. We shall focus on the innovation for good part only.
“Gene therapy is a technique that modifies a person’s genes to treat or cure diseases. Gene therapy can work by several mechanisms:
- Replacing a disease-causing gene with a healthy copy of the gene
- Inactivating a disease-causing gene that is not functioning properly
- Introducing a new or modified gene into the body to help treat a diseases
Gene therapy products are being studied to treat diseases including cancer, genetic diseases and infectious diseases.”
Gene therapy has three parts. One, identification of the specific gene which needs to be modified or replaced. Two, development of corrected version of gene. Three, transportation of the new/modified gene to the target cells. Various types of ‘Vectors’ are used to carry out the last procedure of this process.
Plasmid DNA, Viruses, Bacteria are among the opted vectors, viruses are preferred due to their ability to reach inside the human cell easily and deliver the genes. The vectors may be used on patient-derived cells in the lab setting or directly in the human body.
Types of Gene Therapy
There are two types of gene therapy:
- Germline Therapy – involves modification of the genes inside germ cells, which include sperm and ova. It is to be used during reproduction, at the time when the sperm and ovum meet, fuse, and start the new offspring. Because the mating sperm or ovum has been loaded with the modified gene, the modified message shall reach all new body cells. In short, this is changing the genome of the future generation. Theoretically, it can prevent hereditary diseases, and it may be used to enhance certain capabilities of the newborn. The intelligence may be altered, physical capability may be altered, threshold for pain etc. may be enhanced; the possibilities are virtually endless. Practically, it has not been tested enough yet. Owing to the potential of exploitation, various countries such as Switzerland, Australia and Germany prohibit the use of this technology. It is not approved by any regulatory agency for human use so far. It is also extremely expensive.
- Somatic Gene Therapy – involves the insertion of therapeutic DNA into body cell through a vector. Obviously, the therapy is intended for the individual on which it is applied and shall not pass on to the next generation. The potential for exploitation, which is still there, will also be limited to the person on whom it is applied. Somatic Cell Gene Therapy – SCGT is being developed for the treatment of various types of cancers.
ZOLGENSMA made headlines couple of years ago. It is adeno-associated virus vector-based gene therapy for the treatment of children less than 2 years old with SMA – Spinal Muscle Atrophy. The reasons for headlines were that it was a first-in-class novel therapy, and it cost 2.12 million US$ for one dose – only one dose is required.
Viruses are the most commonly used vectors for transporting and inserting modified genes into human cells. These are derived from retrovirus, adenovirus, and adeno-associated virus. Others such as herpes simplex virus – HSV-1 are used less extensively.
We shall look at some more details in the next part.
To be continued……
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