Solbec claims cancer success with plant extract

Western Australian biotech company Solbec Pharmaceuticals (ASX:SBP) may have struck therapeutic gold in a thorny wayside weed called devil's apple (Solanum linnaeanum) .

Dr Bruce Robinson's research group at the University of Western Australia has shown that two glycoalkaloids extracted from the plant's fruits kill 160 different tumour cell lines in vitro.

Seriously ill volunteers with advanced, metastatic cancers have experienced a range of benefits after treated with the experimental therapy, called SBP002.

The volunteers were enrolled in a trial under the provisions of the Therapeutic Goods Administration's special access scheme.

They included a number of patients with mesothelioma and metastatic melanoma. The therapy variously caused tumour growth to slow, stabilise, shrink or, several cases, disappear completely, prolonging their lives.

Robinson's team has shown the alkaloids have novel tumour-killing activity: they enter cells via an as-yet undisclosed receptor that is over-expressed in a very broad range of tumours. Once inside, the compounds trigger necrosis by activating the cell's lysis system.

Solbec MD Stephen Carter said SBP002's potential as a broad spectrum cancer therapeutic derived from a combination of activities. Apart from inducing cell death by necrosis, it also appears to induce the immune system to attack tumours, and suppresses production of the potent cytokine interleukin-6 (IL-6).

IL-6 causes patients with advanced cancers to feel unwell, experience severe pain, and lose weight rapidly -- a phenomenon called cachexia.

Carter said palliative care nurses had reported that terminal cancer patients treated with SBP003 became sufficiently pain-free to stop taking morphine and other narcotics, had begun eating again and stopped losing weight, and reported that they felt well.

The ability of SBP002 to reduce IL-6 levels indicates it could be also help treat other IL-6 related diseases, including inflammatory diseases like rheumatoid arthritis, microbial diseases like HIV/AIDS, chronic fatigue syndrome and malaria, as well as cardiomyopathy, Alzheimer's disease, atherosclerosis, thyroiditis and Castleman's disease.

Carter said the two glycoalkaloids were shown to be the most active ingredients in an original extract of alkaloids from devil's apple.

By manipulating the ratio of the two molecules, their cell-killing efficacy can be improved by a factor of 300 per cent. They have also been found to enhance the efficacy of conventional chemotherapeutics like taxol, and cis-platin.

Solbec is focusing on SBP002's application to mesothelioma and malignant melanoma, so it can qualify for fast-tracking under the US Food and Drug Administration's orphan drug program.