Immunotherapy: A breakthrough in cancer research

The fast growing field of immunotherapy was one of the topics extensively discussed during the recently concluded ESMO Asia Congress 2016, held from December 16– 19th December at the Suntec Convention and Exhibition Centre in Singapore. Unlike drug-based chemotherapy, immunotherapy exploits the body’s own immune system to fight cancer and is increasingly touted as the future of cancer treatment. The concept of using the immune system as a disease-fighting tool was introduced by Dr. William Bradley Coley, the ‘Father of Cancer Immunotherapy’, in the 19th century based on his work that sought to stimulate a patient’s own immune system against bacterial infection. However, a persistent question remains since the advent of immunotherapy over a century ago – can the immune system accurately recognize malignant tumor and eliminate it effectively? The answer to this question remains hotly debated owing to the differing opinions and attitudes on the application of immunotherapy. Dr. Coley noticed that in a number of cases, patients with cancer went into spontaneous remission after developing erysipelas. In 1891, Dr. Coley injected streptococcal organisms (which cause erysipelas) into a patient with inoperable cancer and observed remarkable tumor regression. Although he had treated almost 900 patients with bacterial preparations that eventually became known as “Coley’s toxins”, his treatment method was not widely accepted by the medical community possibly owing to the low cure rates and the severe fever caused by the bacteria. Some physicians also feared that the immune system might not have adapted well enough to recognize and eliminate malignant cells exclusively. As a consequence, most oncologists relied on another treatment that was rapidly gaining acceptance at that time, i.e. radiation. It was only after about a century later that the medical community observed a revived interest in immunotherapy. In 1976, a trial was conducted to test the effectiveness of the tuberculosis vaccine Bacille Calmette-Guérin (BCG) in treating superficial bladder cancer. The BCG treatment, in which BCG bacilli are inserted directly into a patient’s bladder via a catheter, proved to be an effective form of immunotherapy and the groundbreaking technique is still used today. In general, studies on immunotherapy have presented researchers with two important conclusions: First and foremost, researchers were finally able to prove that the immune system is indeed capable of recognizing cancer cells as a ‘foreign entity’ although they originate from the body’s own tissues. Secondly, by boosting the immune response, researchers are able to enhance other cancer-killing agents at the same time, thus increasing the chances of a successful treatment via immunotherapy. Based on these conclusions, researchers all over the world now face the challenge of figuring out which therapy works best for a specific type of cancer and why some cancer patients respond better than others to the prescribed treatments.   At the ESMO Asia 2016 congress, lead author Dr. Makoto Tahara presented his paper ‘Asian head and neck cancer patients live longer with immunotherapy than mixed race group’, in which his team of researchers reported the sub-analysis results on the safety and efficacy of pembrolizumab in 26 patients (of Asian Pacific origin) who received a fixed dose of the humanized antibody for 24 months until the detection of disease progression or adverse events. They observed that both the median overall survival and the disease control rate were better in Asians than the overall population, i.e. 11.5 versus 8.4 months and 50.5% versus 37.9%, respectively.   According to Dr. Tahara, “The fixed dose of pembrolizumab was well-tolerated in Asian Pacific patients with recurrent/metastatic head and neck cancer. Although the Asian population was small, our findings suggest that they have better median overall survival with pembrolizumab than a mixed population. The clinical benefit of the fixed dose of pembrolizumab in the first and second line treatment of recurrent/metastatic head and neck cancer is being evaluated head-to-head with standard of care chemotherapy in phase 3 trials around the world, including Asia Pacific.”  Meanwhile, another research paper on immunotherapy presented at the ESMO Asia 2016 was by Dr. Herbert Loong, Clinical Assistant Professor at the Department of Clinical Oncology of the Chinese University of Hong Kong, who discussed about the cost-effectiveness of immunotherapy with pembrolizumab for advanced melanoma patients in Hong Kong. Dr. Loong said, “We have determined that whilst pembrolizumab is expensive, the increase in quality adjusted life years (QALYs) compared with standard cytotoxic chemotherapy, and even so with ipilimumab, qualifies it as a cost-effective approach.” Commenting on the results of the research by Dr. Loong and his colleagues, Dr. Mark Tang – a senior consultant dermatologist said, “Given the high costs of these new treatment options, cost effectiveness studies such as this one are timely and useful as further evidence for the use of pembrolizumab in the treatment of advanced melanoma. This is particularly important in an Asian context where, although rare, acral melanoma has unfortunately been known to present late advanced disease.” Taking all these exciting discoveries into account, a good number of studies have repeatedly shown that progress in cancer immunotherapy has accelerated and resulted in the development of several effective and promising therapies for multiple forms of cancer. At this critical juncture, oncological organizations such as ESMO provide an important knowledge transfer platform for the sharing of expertise and interaction between regional and international experts in the area of onco-immunology. Moving forward, immunotherapy and targeted medicine are expected to remain in the spotlight and will be an indispensable arsenal in the long fight against cancer.