People suffering from terminal forms of cancer such as leukaemia and lymphoma are often left with few to none treatment options.
However a new trial of a cancer drug that could prolong the lives of such patients is already receiving positive feedback.
Four patients in Plymouth, Devon, have become the first to be treated with the new class of BTK (Bruton's Tyrosine Kinase) inhibiting drugs.
The trial began in the city in 2012 and has since extended worldwide, with more than 30 patients currently receiving the treatment with "positive results".
Professor Simon Rule, a consultant haematologist, called the study "exciting" and a "transformation" in the treatment of patients with the conditions.
Prof Rule, of Plymouth Hospitals NHS Trust and a researcher at Plymouth University Peninsula Schools of Medicine and Dentistry, said his patients had experienced "significant improvements".
"The astonishing thing about these drugs is that they have virtually no side effects, which is unprecedented from my experience," Prof Rule said.
"In some patients the effects are immediate. Patients with lots of symptoms, particularly those with lymphoma, will feel better the next day after taking the medication.
"The UK is at the forefront of this drug development and all of the studies into these drugs are being run from Plymouth. This will completely change the way we manage these diseases. We have access to the next generation of the drug to be part of the next trial phases.
"This is not a cure for cancer but it will mean we are significantly improving our patients' life expectancy and quality of life; similar to managing a chronic condition. I have yet to come across another class of drugs in my career that has been so successful for leukaemia or lymphoma."
The drugs work by inhibiting Bruton's tyrosine kinase (BTK), a protein which plays a role in the signals that cause growth in cancerous cells. Blocking this causes the cancerous cells to die but normal cells are unaffected.
In September 2012, David Hodge, 74, from Plymouth, became the first in the world to be treated with the new medication. He is feeling the benefits more than a year later.
Prior to the trial, Mr Hodge was told he had only several months to live, due to his immune system not functioning. He had also became resistant to all other treatment.
Prof Rule said: "To be brutal, David had no other option. He was resistant to other forms of treatments so I am just pleased to have been able to access this drug and offer it to him.
"I have done a lot of drug trials in my career; this drug and its predecessor, which I was fortunate to be the first person in Europe to use - they are transformational as far as I am concerned.
"Normally what you expect with trials like this is that you treat a patient for a period of time and often what happens is the drug doesn't work; the side effects make you stop the trial or the disease doesn't respond for very long.
"What is very exciting about this drug is the effects are continuing and there are no emerging side effects."
Prof Rule is now planning to run a UK study in Plymouth using the latest BTK drug in a trial against standard chemotherapy.
Mr Hodge, who has had CLL (chronic lymphocytic leukaemia) for the past 17 years, said he had not experienced any side effects from the new drug.
"It's just like, well it's better than taking paracetamol," he said. "I take the medication first thing in the morning at six o'clock and then go back to bed for an hour. Afterwards I get up and get on with my day; I'm fighting fit. I've had no problems, no side effects, nothing."
Mr Hodge plans to continue with the trial.Suggest a correction