Hope in fight against one of the deadliest cancers
Even after surgery or chemotherapy, the disease may
never go away completely.
By some estimates, malignant tumors in the pancreas can
recur in up
to 80 percent of patients.
Those with certain gene mutations
appear particularly at risk of the disease returning.
A new clinical trial, led by a researcher at the Mayo
Clinic, has put a potential vaccine to the test.
In a randomized phase 2 trial, nearly every patient who
received this vaccine developed an immune response against a mutated gene
called KRAS.
Mutations in KRAS are found in about 90 percent of
pancreatic ductal adenocarcinomas, which is the most common type of pancreatic
cancer.
If a medicine can target cells that express these mutations,
it could theoretically keep the cancer at bay.
This does not prove that this vaccine can stop pancreatic
cancer from coming back, but these are hopeful signs, especially since other
cancer vaccines have shown similar immune
responses are linked to improved survival.
The findings are published in Nature Medicine.
"Historically, pancreatic cancer has been very difficult to treat with immunotherapy," explains first author and medical oncologist Ben George.
"What is encouraging is that we were able to generate a
strong immune response against KRAS mutations in nearly every patient we
evaluated. In an exploratory analysis, patients with greater immune responses
to the vaccine appeared protected with longer disease-free survival
times."
The novel vaccine is called camupepimut, and it is designed
to teach the body's immune cells to recognize and attack cancer cells that
express seven common mutations in the KRAS gene.
These mutations can help pancreatic cancer survive and
thrive.
The phase 2 trial included 144 patients who had been treated
for KRAS-mutated pancreatic cancer with surgery and chemotherapy.
When they started the trial, none of these patients showed
visible signs of cancer in imaging tests.
George and colleagues randomly assigned 96 of these patients
to receive the vaccine, while another 48 served as controls.
Importantly, there was no statistically significant
difference in disease-free survival between the two groups.
But those who received the vaccine showed a stronger immune
response compared with before vaccination.
Of the 90 patients who received this medicine and could be
assessed, 98.9 percent developed increased T-cell responses against mutated
KRAS.
In more than 80 percent of patients, the T-cell response was
more than nine times greater than before vaccination.
"We've shown that we can teach the immune system to
recognize these KRAS mutations," George says.
"The next step is finding out whether doing that can
change the course of the disease for patients."
The results from the phase 2 trial provide a
proof-of-concept for the potential clinical benefit of the vaccine, the authors
argue.
The novel medicine targets the body's lymph nodes, and so
far it seems to reach these sites and alter immune responses with success.
Beyond that, however, its benefits are unclear.
A planned phase 3 trial will add additional boosters of the
vaccine to the roster, and possibly test how this medicine works in combination
with other cancer treatments.
Recently, for instance, the first
personalized mRNA cancer vaccine succeeded in a phase 3 clinical trial when
combined with standard immunotherapy, according to results presented at a major
cancer conference.
The two drugs in combination reduced the risk of melanoma
returning or causing death by 42 percent compared with standard treatment
alone.
This melanoma vaccine also triggers an immune response,
similar to the pancreatic vaccine. But the difference is that the melanoma one
has shown clear clinical benefits.
Even if this pancreatic vaccine doesn't extend survival,
there is another in the pipeline.
This drug, however, is a personalized mRNA vaccine, like the
melanoma one.
The vaccine is still in clinical trials, but as of this
year, researchers said
seven patients with pancreatic cancer whose immune systems mounted a response
to the mRNA vaccine are alive and well.
One of the patients was diagnosed with the deadly cancer at
age 66 and received nine doses of the vaccine.
She is now 72 years old.
The future for cancer vaccines is looking brighter than
ever.
The research has been published in Nature Medicine.
This article was fact-checked by Rebecca Dyer and edited by
Rebecca Dyer. While we
pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
