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An Auckland biotech company has suspended a human trial of an experiment Parkinson's disease treatment following the retraction of previous animal research.
Living Cell Technologies (LCT) had been running the trial at Auckland Hospital, which involved injecting specially encapsulated pig-derived cells (NTCELL) into human brains.
One New Zealand woman had already been treated before the company halted the trial after it was found that data from an original study was incomplete.
The study, published in the journal Regenerative Medicine, had stated that implanted cells were effective in treating animal models of Parkinson's disease in rats.
"The publication is being withdrawn following an internal quality assurance audit which showed that the source data for the study held on file at LCT are incomplete and therefore the efficacy conclusions in the publication cannot be confirmed," LCT said in a statement.
In the light of the retraction LCT, which is a listed company on the Australian stock exchange, announced its early stage human trial taking place at Auckland hospital would not be recruiting further patients.
But the company said none of the pre-clinical studies supporting the potential safety of NTCELL in humans had been withdrawn and the patient already taking part in the trial would continue treatment as planned.
The patient had not experienced any adverse effects, the company said.
The company said this was a "precautionary measure"to "allow the company to work with the New Zealand medicines regulator (Medsafe) and the data safety monitoring board (DSMB) to fully understand the impact of the withdrawal of the rat efficacy data on the Phase I clinical trial".
Professor Gareth Jones, of Otago University's Bioethics Centre, said the transplantation of neural grafts into patients with Parkinson's Disease has had a long and unsatisfactory history, even though it was originally based on well conducted and encouraging studies in animals.
"In light of this it behoves any new procedures to be exceedingly careful and rigorous about the pre-clinical work undertaken on animal models," he said.
"This is essential since the transplantation is into patients with a debilitating neurological disease, and who expect to benefit from these procedures, and are not simply treated as experimental subjects."
In the case of the LCT study, he said the procedures were particularly complex, involving xenotransplantation (from pigs), and therefore if the procedures were to be ethical there had to be no doubt that the porcine tissue transplants worked in the first place in animal models.
"The slightest doubt about this should automatically exclude any use of the porcine tissue in human subjects.
"If additional caution is not exercised in a case like this one, its ethical character has to be questioned."
But Dr George Slim, chief executive of biotech industry group NZBio, said the most important issue this particular case highlighted is the complete response of LCT.
"As soon as the issue was raised in an internal audit the company has taken a precautionary approach; suspending the clinical trial, having the paper retracted and more importantly taking care of the patient already enrolled in the trial," Dr Slim said.
"They have been prepared to communicate with investors and the media.
"I think this professional response to something that did not in fact raise safety issues is a lesson to companies world-wide, not just in New Zealand."