'New vaccine offers hope for cancer patients'

A newly developed vaccine to treat patients with metastatic HER2-positive cancers has been found to be effective and safe, scientists say.

HER2-positive cancer tests positive for a protein called human epidermal growth factor receptor 2 (HER2), which promotes the growth of cancer cells. Metastasis is the spread of cancer cells to new areas of the body.

Among 11 evaluable patients who received more than the lowest dose of the vaccine, six (54 per cent) had clinical benefit, said researchers from the National Cancer Institute in the US.

One patient with ovarian cancer had a complete response that lasted 89 weeks, one patient with gastroesophageal cancer had a partial response that lasted 16 weeks, and four patients (two with colon cancer, one with prostate cancer, and one with ovarian cancer) had stable disease.

"Immunotherapy marshals the exquisite specificity of the immune system to destroy cancer, and some types may have potentially fewer side effects than traditional chemotherapy," said Jay A Berzofsky from the National Cancer Institute.

"We are using a vaccine approach to generate an immune response to HER2, which is found at high levels on and drives the growth of several types of cancer, including breast, ovarian, lung, colorectal, and gastroesophageal cancers," said Berzofsky.

"Our results suggest that we have a very promising vaccine for HER2-overexpressing cancers. We hope that one day the vaccine will provide a new treatment option for patients with these cancers," Berzofsky said.

The patients' vaccines are individually customised by Berzofsky and colleagues using their own immune cells isolated from their blood.

The blood-derived immune cells are modified in several ways in the laboratory.

The final product, which is administered between the layers of the skin, comprises patient-derived dendritic cells genetically modified with an adenovirus to produce parts of the HER2 protein.

In the phase I clinical trial, patients were injected with the vaccine on weeks 0, 4, 8, 16, and 24 after enrolment in the study.

Among the six patients who received the lowest dose of the vaccine, five million dendritic cells per injection, no clinical benefit was seen, researchers said.

Among the 11 patients who received either 10 million or 20 million dendritic cells per injection, six had clinical benefit, they said.

Adverse reactions were predominantly injection-site reactions that did not require treatment. No toxicity was seen.

"Based on the current safety and clinical benefit data, the dose of the vaccine was increased to 40 million dendritic cells per injection and the trial opened to patients who have previously been treated with a HER2-targeted therapeutic, including patients with breast cancer," said Berzofsky.