Relatives of two men critically ill after a disastrous medical trial in England are clinging to the news that they may be showing early signs of responding to hospital treatment.
However, the doctor in charge of treating the men, who are in the intensive care unit of the Northwick Park hospital in north-west London, said their condition remains "very serious".
Dr Ganesh Suntharalingam, clinical director of intensive care at the hospital, made the comments as it was revealed that the four other victims of the trial had regained consciousness.
He said: "Some of them have made noticeable progress in response to our treatment and we have been able to reduce the amount of organ support required. "However, it is early days and they will clearly need continued specialist observation for some considerable time.
"There are also some very early signs of response to treatment in the most critically ill patients but I must stress that their condition remains very serious and complex and it would not be sensible to comment on prognosis.
"The families and friends of the patients are obviously distressed and concerned."
He said an advisory panel is meeting regularly and developing a more detailed understanding of what happened to the previously healthy men who fell ill on Monday after taking part in a trial for the drug TGN1412.
The two critically ill patients are 21-year-old Ryan Wilson, of Highbury, north London, and a 28-year-old man reported to be an assistant bar manager. The medical research company responsible for the drug trial has insisted it followed correct procedures during the trial.