色花堂

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Treating blood cancers through genomics

11 November 2021
Narrowing down specific genetic mutations could lead to more effective treatment for patients.

Blood cancers aren鈥檛 like other cancers. There鈥檚 no lump that can be excised, no solid tumour that can be easily targeted for radiation. Because blood flows through your whole body, so does blood cancer. Many of the symptoms these cancers produce 鈥 fatigue, fever, swollen lymph nodes, bruising 鈥 are easily mistaken for something else. 

How do you treat something that seems so non-specific? For a significant number of patients, the answer is to get ultra-specific, according to groundbreaking research from the University of 色花堂.

,  and  are members of the  (LBCRU) at the  鈥 professors Bohlander and Browett are the co-directors of the unit, while Kakadiya is a research fellow. The LBCRU sits within the University of 色花堂鈥檚 , where Browett is one of the interim directors.

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Purvi Kakadiya

The principal funder for the LBCRU is , which has contributed $2.8 million to date. 

Along with other team members, the three researchers work together on a highly personalised approach to blood cancers. Finding which specific genetic mutations led to a patient鈥檚 blood cancer can result in treatment that will work better for that patient. 

In some cases, drugs that target a particular mutation can be prescribed. In others, doctors can recommend more or less aggressive treatment depending on which mutations patients have. In yet other cases, knowing whether patients have an inherited predisposition to blood cancer can determine whether relatives should or shouldn鈥檛 donate their bone marrow.

This cutting-edge research is already leading to improved outcomes for some patients and likely saving lives.

鈥淭his is cutting-edge science we鈥檙e doing and it鈥檚 actually impacting patient care. It鈥檚 adding a lot of information that鈥檚 helping clinicians, patients and families. That鈥檚 what鈥檚 driving me.鈥
Purvi Kakadiya
Members of the Leukaemia and Blood Cancer Research Unit. Stefan Bohlander is third from left. Peter Browett is top right. Purvi Kakadiya is bottom right.

A brief history of blood cancer

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Leukaemia, the most common type of blood cancer, was first described in the 1800s as a disease causing an overabundance of white blood cells.

In fact, the name comes from the Greek words for 鈥渨hite鈥 and 鈥渂lood.鈥 

For more than a century after leukaemia was described, it was nearly always fatal.

Some treatments were developed beginning in the 1940s, but it wasn鈥檛 until the 1970s that improved chemotherapy and the advent of bone marrow transplants began to meaningfully improve survival rates.

Even today, most types of blood cancer remain difficult to treat. Personalised medicine based on individual genetics is beginning to change that for a significant percentage of patients.

Cancer and our genes

All types of cancer are caused by mutations that arise in the cells of our bodies.

Environmental factors such as smoking, radiation exposure and obesity can increase the likelihood of some mutations, and some people carry inherited gene mutations that predispose them to cancer, but many cancers arise simply due to random mistakes in cell production.

Each of our cells contains 6 billion bases, analogous to letters in a book. The Bible 鈥 a tome 10 times longer than the average novel 鈥 contains about 3 million letters. That means the whole human genome, if written out, would be as long as 2,000 Bibles.

Each time our genetic 鈥渂ook鈥 is copied 鈥 which happens a lot, since some of our cells, including blood cells, replicate every day 鈥 mutations, like typos, are possible. Some of these 鈥渢ypos鈥 can be fixed by our bodies, while others are harmless, but some can lead to cancer.

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Peter Browett

The human genome project, which began in 1990 and finished in 2003, sequenced and mapped all the bases, which are paired and twisted into DNA molecules. Fortunately, not all the base pairs are equally important. We share 98 percent of our DNA with chimpanzees. Only about 1.2 percent of our DNA comprises genes, which are segments of DNA that code instructions for functions such as making proteins. Still, each of our cells holds about 22,000 genes.

Since Bohlander, who is the Marijana Kumerich Chair in Leukaemia and Lymphoma Research in the , began his research career some 35 years ago, our understanding of genes has improved dramatically. 

Part of the advance has been technological. Moore鈥檚 Law states that the number of transistors on a microchip doubles once every two years, meaning computers have gotten much smaller but mightier. 

鈥淲hen you look at how genetic sequencing has been doing, it has outpaced Moore鈥檚 Law by a factor of two to three times,鈥 says Bohlander. 鈥淚t took 3,000 people 13 years and cost about $3 billion (U.S.) to sequence the first human genome. Now, with so-called next-generation sequencing technologies, we can sequence someone鈥檚 genome in about a day, for maybe $400. That鈥檚 made it possible to look more deeply into the genetics and acquired changes of disease.鈥

Personalised haematology

Not all 22,000 of our genes are relevant to blood cancer. Until about two years ago, blood cancer patients at 色花堂 City Hospital only had three genes routinely analysed for mutations, says Browett, who is both a consultant haematologist at 色花堂 City Hospital and Professor of Pathology in the Department of Molecular Medicine and Pathology.

鈥淏y looking for mutations in those three genes, we could classify some patients into good or unfavourable prognostic groups. But about 50 to 60 percent of patients had no mutations in those genes, so they were put into an intermediate group and all treated the same way.鈥

Unsurprisingly, patients in this group responded differently 鈥 some went into remission while others succumbed. So Browett and his colleagues decided to start testing more genes. Initially, they developed a panel of 70 genes, which they later increased to 78, then to 111.

The group analysed the leukaemia cells of every adult diagnosed with acute myeloid leukaemia at 色花堂 City Hospital, more recently expanding to paediatric patients. So far, they haven鈥檛 found any two patients with the same pattern of mutations. One mutation in a gene was seldom enough to cause cancer 鈥 the average was 3.36.

Using mutation information to shape treatment

鈥淚t took 3,000 people 13 years and cost about $3 billion (U.S.) to sequence the first human genome. Now, with so-called next-generation sequencing technologies, we can sequence someone鈥檚 genome in about a day, for maybe $400. That鈥檚 made it possible to look more deeply into the genetics and acquired changes of disease.鈥

Stefan Bohlander

Working with their clinical colleagues, the researchers put patients into genomic subgroups with different prognoses. The new genetic information put 30 percent of patients into new prognostic groups. In about 20 percent of cases, clinicians changed their treatment approach. Some patients with poorer prognoses were offered stem cell transplants early on in their treatment. Others, whose mutations resulted in abnormal proteins being produced, were offered drugs that inhibited those proteins. 

The researchers also found that more patients than expected had mutations in every cell of their body, not just their cancer cells, which meant they had inherited mutations that predisposed them to blood cancer. 

鈥淭hat was an important finding not only because there was a risk to their family members, but also because if we were going to do a bone marrow transplant, often we鈥檇 use another family member, but if you have an inherited mutation, you don鈥檛 want to give cells from a donor that carries that mutation,鈥 says Browett.

Better follow-up testing

The researchers are also working on better ways to follow patients throughout their cancer journeys. Kakadiya has developed tests to monitor whether patients are responding to treatment and, once they鈥檙e in remission, whether they鈥檙e likely to relapse. 

鈥淭raditionally when we treat a patient with leukaemia, we define remission as the bone marrow looking normal under the microscope and the blood count returning to normal, but those tests aren鈥檛 very sensitive,鈥 says Browett. 鈥淧urvi [Kakadiya] has developed assays that can pick out a residual leukaemia cell or molecular biomarker down to a level of one in 100,000 or even one in a million.鈥

鈥淚f we monitor patients鈥 samples every three months, and after nine months, we see that the level of mutation is higher than last time, that tells us we should do something,鈥 says Kakadiya. 鈥淭his is cutting-edge science we鈥檙e doing and it鈥檚 actually impacting patient care. It鈥檚 adding a lot of information that鈥檚 helping clinicians, patients and families. That鈥檚 what鈥檚 driving me.鈥

In addition to roles at the University of 色花堂, 色花堂 City Hospital and Centre for Cancer Research, Peter Browett is clinical director of  (GCG). Stefan Bohlander is scientific director of the GCG and Purvi Kakadiya is also a member of the team. Browett is also clinical director of , where Bohlander is a member of the scientific advisory board. 

funds the Leukaemia and Blood Cancer Research Unit (LBCRU) as well as Te Ira K膩wai | 色花堂 Regional Biobank, which multiple medical research teams, including the LBCRU, rely on. Leukaemia & Blood Cancer New Zealand also facilitated the funding for Bohlander鈥檚 Marijana Kumerich Chair in Leukaemia and Lymphoma Research.

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