Business Times - 09 May 2009
Fresh hope for liver cancer patients
The oral drug sorafenib is now the first-line treatment for liver cancer. By Cheah Ui-Hoon
TREATMENT options for liver cancer are limited but there's a glimmer of hope offered by a new oral drug. Sometimes a drug for a particular disease might work for another as well, as doctors are finding out in the case of sorafenib, a new class of drug that's now being used to treat liver as well as kidney cancer.
Sorafenib, under its brand name Nexavar, was first used as second-line treatment for kidney cancer when it was first developed, says Tan Yew Oo, an oncologist at Gleneagles' Medical Oncology Centre.
But it's now first-line treatment for liver cancer. Good news especially when there're not a lot of targeted drugs out there for many cancers, he notes.
Dr Tan notes that Nexavar was used on a liver cancer patient in Singapore in 2008, the first case where the drug was used as first-line treatment - and the patient had benefited from it, when the traditional TACE (trans-arterial chemoembolisation) treatment didn't show much positive signs.
'At the time when we started, Nexavar wasn't yet accepted as first-line treatment. The established standard then was TACE where a catheter is inserted into the artery and chemotherapy injected into the artery supplying the tumour in the liver,' he notes.
The 61-year-old Chinese patient had gone for screening soon after his brother had died of liver cancer after hepatitis B infection. He found out he was also a hepatitis B carrier and further tests showed he also had liver cancer. 'Hepatitis B infection is commonly transmitted from mother to child,' explains Dr Tan.
Some patients who are hepatitis B carrier develop liver cirrhosis (hardening of liver) which means liver enzymes are high and some of these patients will show up with elevated alpha-fetoprotein (AFP), a liver cancer marker in their blood.
Incidentally, there are a number of new drugs developed in the last five, six years to treat patients who have hepatitis B carriers and many of them were developed as a spin-off of new retroviral drug development used in the treatment of Aids drugs. The human immunodeficiency virus (HIV) and hepatitis B virus are both DNA viruses.
For this 61-year-old man, the use of Nexavar managed to stabilise his liver cancer, as the 'abnormal shadow' of the liver cancer appeared to have shrunk, with no new sites appearing. The patient however can't be described as cancer-free, Dr Tan says, but his condition has stabilised and he's doing well and he has good quality life.
The bad news, however, is that not all liver cancer patients do as well as this 61-year-old man even with Nexavar, says Dr Tan. 'There is no predictive factor to determine who will respond better to the treatment,' he says. 'Overall results of treatment of liver are still quite dismal.'
In a clinical trial done on Asian patients with liver cancer, it showed that liver cancer patients who did not receive Nexavar have a median overall survival of 4.2 month, while those who received the medication improved their overall survival to 6.5 months. 'It does not seem to be very long, but in patients with advanced liver cancer the two months is a big deal,' points out Dr Tan.
It's through small advances like this that doctors and scientists get a breakthrough down the road, he adds.
But, of course, when it comes to health care, it's also a question of how much medication to give and for how long. 'In an ideal situation, the patient should get the full dose of 400mg twice a day (which is four tablets a day), but because he could not tolerate the recommended dose, he has been taking a quarter to half of the amount only,' says Dr Tan.
Nexavar is a molecular targeted therapy drug. Traditionally, cytotoxic chemotherapy drugs kill cancer cells when they are dividing, but molecular targeted or biologic therapy (as it's sometimes called) control cancer cell growth by interfering with the signals that control cancer cell growth or multiplication.
Some of these drugs have the ability to starve the cancer of its blood supply. Nexavar is unique because it has the ability to do all these functions to kill cancer cells, he points out.
Dr Tan says that there are many ongoing clinical trials and new clinical trials being planned to improve the therapy of liver cancer using molecular targeted drugs. Some of the trials combine Nexavar with chemotherapy.
'We will have a better idea in a few years time to offer more effective treatment for many cancers and liver cancer in particular. There are many unmet needs in cancer treatment,' he adds.
A common disorder
LIVER cancer is the sixth most common cancer in the world and the third leading cause of cancer-related deaths globally.
In Singapore, liver cancer is the fourth most common cancer occurring in men, with over 400 new cases each year. The cancer often results from certain liver-related illnesses like hepatitis B and C, alcohol abuse, fatty liver disease and exposure to certain toxins and chemicals. Long-term hepatitis B infection is the most common cause for primary liver cancer in Singapore, says Dr Hsieh Wen-son, consultant medical oncologist and medical director, International Cancer Specialists. 'In many Asian countries, 10 per cent of the population are chronically infected with hepatitis B virus,' he says.
Liver cancer can be cured if discovered early, says Dr Tan, as the tumour can be removed surgically. 'However, most liver cancer patients are diagnosed only when the cancer is in an advanced stage or when their liver function is poor,' he explains.