“I consider the approach is remarkable and more than intriguing,” said Dr. Friend, who is now at Sage Bionetworks in Seattle. But he warned that cancer cells are very versatile and can “evolve around any pressure you put on them,” so that no single approach is likely to afford a cure.

The EnGeneIC method uses minicells to deliver a variety of agents to tumor cells, including both anticancer toxins and mechanisms for suppressing the genes that make tumors resistant to toxins.

The minicells are generated from mutant bacteria which, each time they divide, pinch off small bubbles of cell membrane. The minicells can be loaded with chemicals and coated with antibodies that direct them toward tumor cells.

No tumor cell, so far as is known, produces a specific surface molecule for toxins to act on. But 80 percent of solid tumors have their cell surfaces studded with extra-large amounts of the receptor for a particular hormone, known as epidermal growth factor.

The minicells can be coated with an antibody that recognizes this receptor, so they are more likely to attach themselves to tumors than to the normal cells of the body. The tumor cells engulf and destroy the minicells, a standard defense against bacteria, and in doing so are exposed to whatever cargo the minicells carry.

What also helps direct the minicells toward tumors, the EnGeneIC researchers say, is that the blood vessels around tumors tend to be leaky, and the minicells are small enough to leave the circulation at the leak sites.

The minicells do not seem to be highly provocative to the immune system, even though they are made of bacterial cell membrane. The reason may be that the provocative parts of the membrane are masked by antibodies with which the minicells are coated, Dr. Brahmbhatt said.