Now his future is uncertain. “It’s a really bizarre feeling when you discover you might be dead in a couple of years or even in a couple of months,” he said.

Modi is one of the “Elephant Men” who nearly died last March when he and five others took part in a drugs trial at Northwick Park hospital in northwest London.

Modi and his fellow patients were left seriously ill during the trial of the TGN1412 drug. His head swelled up like a balloon and he suffered multiple organ failure.

Ryan Wilson, 21, another guinea pig, suffered gangrene that made his toes and fingers go black. All his toes and three of his fingers will have to be amputated; he had heart failure, kidney failure, pneumonia, septicaemia and liver failure.

Mohamed Abdelhady, 29, a bar manager, suffered severe head and chest swelling. He was so bloated that his girlfriend Myfanwy Marshall said he was unrecognisable.

The patients had volunteered for the trial after being lured with the offer of £2,000 each to test the drug made by TeGenero, a newly formed German drug firm. Parexel, the American firm that administered the tests, told them there would be no serious side effects.

On March 13 this year, Modi and the other five patients were injected with TGN1412 while in the Parexel drug testing suite at Northwick Park.

At first, Modi recalled last week, he did not notice anything. But then a horrifying sequence of events began to unfold: “It started about 40 minutes later with a headache. A couple of minutes later that turned into a severe headache.

“It was like a huge, heavy foot was being pressed down on my head. I started moaning and crying, but the doctor just told me to calm down. He said it would go away. I begged him to do something. I told him the pain was killing me.”

Modi then developed a back pain so severe that he was unable to lie down. “I was in such agony, I was jumping up and down on the bed and screaming.” All around the other patients were going through similar agony.

Modi began retching, fainted, then stopped breathing; he was in and out of consciousness. Nurses tried to put an oxygen mask over his mouth but he kept pulling it off to be sick. The doctor gave him a paracetamol tablet. “I vomited that out in a couple of minutes.” Soon afterwards staff administered pain-killing sedatives.

Modi woke up in the intensive care unit later that day. The next day he was visited by his girlfriend Divya Vegda, 22. Horrified by the sight of his swollen head, she later described him as looking like an “Elephant Man”.

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