Contrary to simply stopping tumor growth, the biomedical engineers at Duke University have successfully demonstrated a new treatment for pancreatic cancer in a mouse model that may make a real difference for patients.
SciTech Daily’s recent article reported that combined chemotherapy and internal radiation can dissolve tumors in eighty percent of mice in multiple models including tumors that are usually resistant to treatment.
Dr. Jeff Schaal, who conducted the research while preparing for his Ph.D. in Ashutosh Chilkoti’s laboratory, said that the researchers analyzed over 1100 treatments and did not locate any other incidents where tumors completely disappeared.
A New Approach
In the new treatment, radioactive iodine-131 is implanted in the tumor in a gel-like depot which the body then absorbs after the radiation is diminished. The new approach is combined with standard chemotherapy. This is in contrast to current procedures that send radiation via an exterior beam that travels through normal tissue.
The journal Nature Biomedical recently published the study.
About Pancreatic Cancer
Pancreatic cancer has one of the highest mortality rates of any major cancer. The five-year rate of survival for combined stages is eleven percent. Its tumors are resistant to a variety of drugs due to aggressive mutations that are usually identified late when they have spread to various areas in the body.
One of the most widely used treatments is a combination of chemotherapy that keeps a radiation beam focused on the tumors for a protracted length of time and prevents them from reproducing. Yet, in order to be effective, a specific amount of radiation must have reached the tumor. There is also the challenge of avoiding severe damage.
Researchers also use a sophisticated method involving a radioactive unit covered in titanium and implanted into the tumor. The challenge here is that all radiation, except gamma rays, is blocked by the titanium, which travels outside of the tumor. The titanium cannot remain within the body for any length of time without damaging the surrounding tissues.
Elastin-Like Polypeptides (ELPS)
Dr. Schaal and the team attempted to circumvent these issues by implanting a substance composed of ELPS.
- The polypeptides are synthetic amino acid chains that when bonded together form a gel.
- When stored at room temperature, the ELPs are in a state of liquidity.
- However, when ELPs are in the human body, the warmer temperature creates a stable gel substance.
- When the ELPs together with a radioactive substance are injected into the tumor, a depot is formed that encases radioactive atoms.
Iodine-131, a radioactive isotope of iodine, has been used by doctors for years and was combined with ELPs. By encasing the iodine-131, the ELP depot prevents it from entering the body.
- Beta radiation is emitted by the iodine-131 which penetrates the bio gel.
- Its energy is deposited in the tumor but does not affect the tissue surrounding the tumor.
- The ELP degrades into amino acids and is absorbed by the body.
- Iodine-131 then decays and harmlessly disappears into xenon.
Dr. Schaal and the team then used the chemotherapy drug paclitaxel to treat pancreatic cancer in mouse models. It is well known that pancreatic cancer is highly resistant to treatment.
The researchers accepted this challenge by showing that the radioactive implant is more effective than short-lived radiation beam therapy.
The newly created therapy was tested on mice who had cancer beneath the skin. The cancers were created by mutations from pancreatic cancer. More difficult tests were also conducted on tumors in the pancreas.
The Overall Response Rate
Test results showed a one hundred percent response rate across all models. Tumors were eliminated in seventy-five percent of mice models about eighty percent of the time.
About Side Effects
Other than side effects ordinarily resulting from chemotherapy, no other side effects were found.
The next step for the researchers is to conduct trials on large animals so that they can determine whether the technique will work using endoscopy techniques along with the clinical tools the doctors have used in their training.
Dr. Chilkoti added that for twenty years he has worked on developing cancer treatments but found this study to be one of the most exciting.