Wednesday, November 23, 2011

Direct Injection of PANVAC Vaccine in Pancreatic Tumor

PANVAC Vaccines

Pancreatic cancer is an extremely aggressive type of cancer, causing most of the affected patients to succumb to the disease in a short period of time, since early diagnostics is not available, and when cancer is identified, it might be too late for the successful recovery for the disease. Current standard cancer treatments such as surgery, chemotherapy and radiotherapy are not effective against this disease as this is a treatment unmanageable disease. The lifetime risk of developing pancreatic cancer is about one in 76 for both men and women and there is a five-year survival rate of only five percent, despite advancements in surgery, chemotherapy and radiation treatment.

Therefore, general vaccination approach as the promising treatment strategy is currently under investigation in multiple research centers. What used to be a relatively esoteric line of research – immunotherapy for cancer -- has become mainstream. In fact, there are so many companies and institutions involved in various aspects of cancer vaccine research that the Albert B. Sabin Vaccine Institute has organized the Cancer Vaccine Consortium to help accelerate the development and licensure of these immunotherapies. Some biotech firms have been investigating cancer vaccines for decades now, and the lessons they've learned over time inform the burgeoning field as it moves forward.

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Beginning 2004, Cambridge, Mass.-based Therion Biologics Corporation submitted its application to the FDA to conduct a Phase III trial under a special protocol assessment, the company prepared published data of 12 different randomized pancreatic cancer trials.

"Median survival of that group was three months, no matter what the agent used was," said Mark Leuchtenberger, president and CEO of Therion. "Unfortunately, I think what we've done is just confirm those data right now."

The Phase III trial, begun in May 2004, enrolled 255 patients with advanced pancreatic cancer and was aiming to show a 50 percent improvement - about a two-month extension - in survival over control chemotherapy. The study was designed from two Phase I studies that showed a median overall survival of more than six months.

Panvac-VF is designed to stimulate the immune system to target anddestroy cancer cells expressing carcinoembryonic antigen and mucin-1, which are found on more than 90 percent of pancreatic tumor cells. The vaccine incorporates Therion's triad of co-stimulatory molecules (B7.1, ICAM-1 and LFA-3) to enhance and sustain a targeted immune response.

However, the trial was NOT successful, and the expected positive outcomes for the patients have not been proven.

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Vaccine Direct Injection in Pancreatic Tumor

In spite of the previous failure of the mainstream clinical trial for pancreatic cancer research, more trials were performed for other types of cancer with this vaccine. And the new boost was given this year with revealing early results of a clinical trial being conducted at The Cancer Institute of New Jersey.

Previous studies by scientists at CINJ have shown that injecting a vaccine and other immunity-producing drugs into a cancer tumor itself — rather than the traditional site of the skin — can result in a reversal of the traditional immune blockade and the development of specific immunity to the tumor. This body-wide tumor-specific immunity has the potential of blocking the growth of the original tumor as well as eliminating small deposits of tumor that can cause the cancer to spread. Stemming from this research is a clinical trial that is the focus of this poster presentation. The study by CINJ investigators further tests this vaccine strategy, designed to harness the body’s own immune system to fight cancer.

Researchers are utilizing two types of PANVAC, containing gene additives that might stimulate a person’s immune system to recognize and develop an immune response to the disease.

PANVAC-V, which uses the same virus as the smallpox vaccine, is a live but weakened vaccinia vaccine (meaning the virus can still multiply) that is given in the arm.

PANVAC-F (a live Fowlpox virus that cannot multiply) is injected into the arm and into the tumor itself. Direct tumor injection takes place through a procedure known as endoscopic ultrasound, in which a scope is inserted through the mouth and into the stomach.

During the first phase of the study, which looked at six participants whose cancer could not be removed through surgery, patients were evaluated for toxicity, tumor progression and the presence of tumor markers for pancreatic cancer. Two patients were removed from the study after two weeks due to rapid disease progression. Of the remaining four patients, three had received gemcitabine – a standard treatment for pancreatic cancer – after receiving vaccination treatment. The other patient was treated with gemcitabine, followed by capecitabine and radiation, prior to the vaccination regimen and received no other treatment after.

Of these four patients, all were shown to have clinically stable disease after 15 months, 13 months, 12 months and nine months respectively. The second part of the trial is accruing additional participants, who are being given a higher dosage of PANVAC-F during direct injection of the tumor.

Elizabeth Poplin, MD, medical oncologist at CINJ and professor of medicine at UMDNJ-Robert Wood Johnson Medical School, is the lead researcher on the study, which is sponsored by the National Cancer Institute (NCI). “By utilizing the body’s own defenses in this way in combination with traditional therapies, we have an opportunity to better identify more effective treatment and management options for this disease, which unfortunately only has a five-year, five-percent survival rate,” said Dr. Poplin.

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