Bacterial 'minicells' deliver cancer drugs straight to the target

"Minicells," nanoparticles built from the membranes of mutant bacteria, have safely delivered cancer drugs in their first clinical trial in people with advanced and untreatable cancer, and have shown the first hints of efficacy.

The bubbles of cell membrane, developed by Australian biotech company EnGeneIC, are designed to deliver cancer drugs directly to the tumor, which could reduce the side effects, cut the dose required, and improve the efficacy of the treatment. The surfaces of the minicells are studded with antibodies that home in on receptors on the tumor. The tumor cell "sees" the bubble of bacterial membrane as an invading bug and engulfs it, and the cancer drug then kills the tumor cell.

In a Phase I trial, minicells were loaded with the cancer drug paclitaxel and coated with cetuximab, antibodies that target epidermal growth factor receptor (EGFR). The treatment, code-named EGFRminicellsPac, was well tolerated, and of the 28 people treated, 10 had stable disease at 6 weeks, and one patient safely received 45 doses over 15 months. The results were presented at the 24th EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics in Dublin by the company's founders.

"This important study shows for the first time that these bacterially derived minicells can be given safely to patients with cancer. It thereby allows further clinical exploration of a completely new paradigm of targeted drug delivery using this platform coupled with different 'payloads' of cell-killing drugs or other treatments such as RNA interference, and with different targeting antibodies," says principal investigator Benjamin Solomon of the Peter MaCallum Cancer Centre in Melbourne, Australia.

Phase II trials are planned, including studies of doxorubicin-loaded minicells for the brain cancer glioblastoma.

- read the press release