The immune system is the body’s first line of defense when
fighting off any illness, attacking foreign organisms or other substances that
may harm or threaten the over health of the body. When the immune system is
compromised, the body is unable to fight infections and becomes weak as the
illness takes over. For those suffering from cancer, especially mesothelioma,
cancerous tumors are able to grow and spread because the immune system is
unable to attack the tumors to stop continued growth. Immunotherapy treatments
for cancer patients focus on improving the immune system using elements created
within the body, to stop the spread of cancer growth without compromising
normal and healthy cells.
Recent results from a Phase I clinical trial have scientists
and researchers hopeful that a combination of chemotherapy and immunotherapy,
known as chemoimmunotherapy may prevent mesothelioma tumor growth within the
body , helping those affected live longer and more comfortable lives while
battling this disease. The clinical trial uses the standard first line
treatment for mesothelioma (pemetrexed and cisplatin) and CRS-207, which is a
Listeria based cancer vaccine that as a bacteria, stimulates immune system
response. By treating patients with a combination of chemotherapy and CRS-207,
scientists hypothesized that the immune system would strengthen, become more
active, and subsequently stall tumor growth.
The study consisted of 35 pleural mesothelioma patients. CRS-207
was administered first – two priming infusions two weeks apart. A combination chemotherapy of pemetrexed and
cisplatin followed CRS-207 two weeks later for six cycles over the course of
three weeks. CRS-207 was then administered again as a booster infusion three
weeks following the last chemotherapy dosage. Patients were then evaluated every
eight weeks until disease progression was detected. Results showed that out of
the 35 patients, 31 showed and overall disease control – almost 90 percent.
Nineteen test subjects saw a partial response, meaning that the mesothelioma
tumor slightly decreased in size. Ten mesothelioma patients saw their tumors
stabilize and one patient had a complete response to the treatment (the tumor
size decreased significantly).
Clinical trials are offered to those who qualify as
alternative treatments and typically administered when traditional treatments
are not having the desired effect. In Phase I trials, typically a small
group (less than 100 participants) are evaluated. The purpose of the Phase I
trial is to test and document safety, and determines any health risks with
associated dosage .The overall positive response from this Phase I trial has
researchers hopeful that Phase II will soon be underway. Phase II testing
involves a larger sample of people (up to 300) along with a placebo to more
accurately define common and uncommon side effects.
Source:
Raffit Hassan, “Live-Attenuated, Listeria monocytogenes
Expressing Mesothelin (CRS-207) with Chemotherapy for Treatment of Malignant
Pleural Mesothelioma,” Clinical Cancer Research (July 1, 2019). [Link]