Lagos — HOPE appears to be on the horizon for cancer cure if the potential of harnessing the human immune system's tumour-destroying cells can be properly harnessed. This optimism arises from the case of a 55-year-old man whose own immunity was used to attack the cancer cells in his body.

The man has remained tumour-free more than two years after treatment. The feat was achieved by virtue of the exploits of an American medical team that developed a new way to turn a patient's T-cells against deadly, metastasised skin cancer.

The man had a remarkable response, says Cassian Yee, the immunologist at Fred Hutchinson Cancer Research Center in Seattle, Washington, US, who developed the new treatment.

The team treated eight other melanoma patients, but says it is too early to tell whether their tumours have vanished as well. Cancer experts believe the results could pave way for a cancer vaccine, but more proof with additional patients is needed.

A synthetic chemical based on a compound found in cocoa beans slowed growth and accelerated destruction of human tumours in laboratory studies, and is being tested further for cancer chemoprevention and even treatment, say researchers at Georgetown University Medical Center.

For a tumour to grow and spread, it must trick the immune system into thinking it is normal tissue. Immune cells that keep tumours in check remain oblivious to the malignancy or are too low in number.

But researchers have slowly learned how to unleash this response. The most common strategy is to collect a patient's white blood cells, grow the tumour-killing T-cells in a laboratory incubator and inject them back into the patient. This approach, while sometimes successful, often requires doctors to kill off a patient's other T-cells and give them multiple cell treatments, as well as a toxic cocktail of immune chemicals.

The researchers isolated a handful of these cells from the patient, whose melanoma had spread to his lung and groin. All the cells recognised a protein called NY-ESO-1 - this existed in his tumour, but not most healthy cells.

After the cells had been multiplying in the lab for two months, the team injected about five billion of them into the patient in one dose. The treatment annihilated the tumours within two months, and nearly two years later, there are no signs that the patient's cancer has crept back.

The lab-grown cells remained at high levels for at least three months after treatment. However, it is suspected that the injected CD4-cells also jolted other immune cells into action because tumour cells that didn't make NY-ESO-1 also disappeared.

While encouraging, the new treatment might work for only a fraction of melanoma patients, because many tumours do not contain NY-ESO-1 and not all patients have an immune system that recognises the protein.