Over the years, the diagnosis of blood cancers have improved so much that in some cases, a bone marrow examination may not be needed. And with new treatments such as monoclonal antibodies, cures are now possible for some types of leukaemia, said Dr Freddy Teo, a haematologist and Senior Consultant at Parkway Cancer Centre.
Dr Teo was speaking to some 45 doctors attending a Continuing Medical Education seminar on 7 July organised by Parkway Cancer Centre.
In his talk, he explained how some cancers such as chronic myeloid leukaemia (CML) could be diagnosed with just a blood sample these days because CML is characterised by a chromosomal abnormality which can be detected by cytogenetic analysis, a chromosomal analysis of blood.
“If you see this (abnormality), it is leukaemia, even if the total white blood cell count is low,” he said. Leukaemia is typically diagnosed when total white blood cell counts are very high.
As a result, in cases where patients are elderly, they might be spared a bone marrow examination if the cytogenetic analysis uncovers the abnormality. Thirty years ago, confirming leukaemia required a bone marrow examination.
The discovery of molecular markers for cancer, the availability of cytogenetic analysis and other new tests, and a class of drugs known as tyrosine kinase inhibitors, meant that some people can be cured of CML with drugs. Previously, only stem cell transplants could provide a cure for this form of leukaemia.
Cytogenetic analysis has also made a difference in the diagnosis and treatment of chronic lymphocytic leukaemia (CLL).
Oncologists can now look for chromosomal abnormalities that are characteristic of an aggressive form of CLL, which has to be treated differently from the ‘indolent’ variant, he noted.
Another seminar speaker, Dr Colin Phipps Diong, a Parkway Cancer Centre Consultant specialising in lymphoma, blood cancers and haematopoietic stem cell transplantation, spoke about the use of immunotherapy for blood cancers, focusing on monoclonal antibodies and introducing newer immunotherapeutic modalities like bispecific T-cell engagers and checkpoint inhibitors.
Monoclonal antibodies are antibodies that are made in the laboratory which target blood cancer cells by recognising specific proteins that are found on the surface of the cancer cells.
A number of monoclonal antibodies have been developed to target different proteins and thus different types of lymphoma and leukaemia, and there are many new monoclonal antibodies undergoing trials now, he said.
“This is an evolving field, with many new agents in clinical testing. Cure rates have improved and are continuing to improve.”
The seminar also featured Dr Anselm Lee, a paediatric haematologist-oncologist, who spoke about thalassaemia, an inherited blood disorder, and Dr Lucas Chan, a scientist who talked about CAR T-cell therapy, a new form of cancer treatment.
CAR T-cell therapy: Possibilities and challenges
A new form of cancer treatment known as chimeric antigen receptor (CAR) T-cell therapy has plenty of promise but is not a silver bullet, according to Dr Lucas Chan, the Chief Scientific Officer at Stem Med, a company related to Parkway Cancer Centre.
Dr Chan, who was involved in the treatment of the first person in the world to receive CAR T-cell therapy, was speaking at a Continuing Medical Education talk organised by PCC in July.
He noted that the therapy had been shown to be effective on certain kinds of blood cancers such as B-cell acute lymphoblastic leukaemia, high grade B-cell lymphoma and multiple myeloma. However, even here, it sometimes comes with serious side effects.
One of the most serious is cytokine release syndrome, which is caused by a large, rapid release of cytokines (an immune substance) into the blood from immune cells affected by immunotherapy. In some patients, the reaction is life-threatening.
Another side effect is neurotoxicity, and scientists are still trying to understand the mechanism by which the brain is affected, he said. “This is a rapidly evolving field and there are lots of things that scientists and clinicians don’t know.”
CAR T-cell therapy uses T-cells (a kind of white blood cell) that have been modified in the laboratory to recognise cancer cells. Specific proteins that can recognise and engage the cancer cells are attached to the T-cells which are then given to the patient. These modified T-cells can then identify and kill their intended target.
The process involves using the re-engineered form of HIV, because, as Dr Chan explained, “HIV is very good at what it does, it infects immune cells very well.” In a clean room laboratory, the pathogenic genes are removed from the virus so that it does not cause disease. As a result, the re-engineered vectors can be used safely to deliver only the therapeutic genes, he said.
While CAR T-cell therapy has been hailed in the media as a major step in curing cancer, Dr Chan warned against believing the hype wholesale. “In certain cases, it is very, very effective, whilst in other types of non-haematological “solid” tumours, efficacy is rather limited and there are still lots of observations where scientists and clinicians do not understand. We are learning along the way as clinical trials are conducted and they continue to educate and sometimes surprise us. So, we need to take the encouraging news (about a cure for cancer) with a balanced perspective in this rapidly evolving and exciting field.”
Dr Chan’s talk was well-received by those who attended, with Dr Ng, a haematologist, describing the talk as “high powered”.
Diagnosing thalassaemia ‘not straightforward’
Diagnosing the blood disorder thalassaemia is not as straightforward as many doctors think and relying on a simple blood test might miss people with thalassaemia traits.
This was the warning delivered by Dr Anselm Lee, a paediatric haematologist-oncologist at Parkway Cancer Centre (PCC). He was speaking at a Continuing Medical Education seminar organised by PCC in July.
In his talk, he noted that diagnosing thalassaemia usually begins with a blood test, with follow-up tests ordered for patients whose tests showed a low mean cell volume (MCV) in their blood. However, among other things, not all thalassaemia traits show up with low MCVs, said Dr Lee.
He warned that doctors should be careful about issuing a clean bill of health to patients. “Never tell patients ‘you don’t have thalassaemia’ until you have all the proof,” he said.
The disorder exists as two variants: thalassaemia minor and thalassaemia major. With thalassaemia minor, the day-to-day impact is small and most people with the disorder are unlikely to notice they have it. An Italian study has even suggested that people with thalassaemia minor might be less prone to heart attacks.
However, the concern is that if two people with thalassaemia minor marry, they might have children with thalassaemia major, a major medical disorder.
Dr Ong, a family physician who attended the event, said Dr Lee’s talk would be very useful in his clinical practice. Another member of the audience, Dr Ching, said he had discovered late in life, that he had thalassaemia minor. The possibility that he might be less prone to heart attacks was cheering news, said the general practitioner.
Written by Jimmy Yap
Tags: blood cancer, bone marrow, cancer latest breakthrough, continuing medical education (CME), new ways to treat cancer, stem cell therapy, thalassaemia