CRISPR-Cas9 is a customisable tool that lets scientists cut and insert small pieces of DNA at precise areas along a DNA strand. This lets scientists study our genes in a specific, targeted way.
Credit: Ernesto del Aguila III, National Human Genome Research Institute, NIH
Researchers from the Karolinska Institutet in Sweden have identified potential pitfalls in the use of the gene editing technique CRISPR-Cas9, a gene scissors that is used for cancer treatments. Their findings are published in Life Science Alliance.
The study has identified that a cancer cell line, derived from leukaemia, removes a region that encodes a tumour-suppressing gene and genes that control cell growth.
“We found that this elimination often occurs when cancer cells are exposed to stress, such as when using CRISPR, gene scissors, or other treatments such as antibiotics. The elimination changes gene regulation in a unique way, which in turn affects basic biological processes such as DNA replication, cell cycle regulation, and DNA repair,” says Claudia Kutter, research group leader at the Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet.
This knowledge is important for researchers, clinicians, and biotechnologists to correctly interpret and apply gene editing results. The study also has clinical relevance, as the observed eliminations are in genes associated with cancer, which has implications for cancer research and treatment.
“Shockingly, this elimination has been unintentionally overlooked by many researchers who modify genes in cancer cells by CRISPR screenings. The elimination also occurred more frequently in patients who have undergone cancer treatment. The treated cancer cells had, due to the elimination, a selective advantage, which is bad for the patient’s long-term survival as these cells remained after the treatment,” says Claudia.
“The study mainly serves as a warning signal, but also opens doors for further research aimed at harnessing the potential of gene editing while minimising unintended consequences,” Claudia concludes.
A multinational study of almost one million individuals confirms a strong and clear association between radiation exposure from CT scans in young people and an increased risk of blood cancers. These results, published in Nature Medicine, highlight the importance of continuing to apply strict radiological protection measures, particularly in paediatric populations.
The benefits of computed tomography (CT) for imaging in patient management (including diagnostic efficacy, treatment planning and disease follow-up) are undisputed. But in recent decades the extensive use of this procedure has raised concerns about the potential cancer risks associated with exposure to ionising radiation, particularly in young patients.
“The exposure associated with CT scans is considered low (less than 100mGy), but it is still higher than for other diagnostic procedures,” says Elisabeth Cardis, Head of the Radiation Group at ISGlobal and senior author of the study. Previous studies have suggested an increased risk of cancer in in children exposed to CT scans, but they had several methodological limitations.
To address these limitations, clinicians, epidemiologists and dosimetrists from nine European countries (Belgium, Denmark, France, Germany, Netherlands, Norway, Spain, Sweden, and UK) came together to conduct a multinational, European-funded study, EPI-CT, coordinated by the International Agency for Research on Cancer (IARC).
“Implementing this large, multinational study was challenging – it involved extracting data from radiology records of 276 hospitals and linking them to population-based registries in nine countries, all while maintaining the confidentiality of the individuals’ data,” says Cardis.
A dose-dependent association
The study analysed data from almost one million people, who underwent at least one CT scan before the age of 22. The dose of radiation delivered to the bone marrow, where blood cells are produced, was estimated for each person. By linking this information to national cancer registries, EPI-CT researchers were able to identify those who developed a blood cancer over time. Individuals were followed for an average of 7.8 years, although for those who had CT scans in the early years of the technology, researchers were able to monitor cancer incidence for more than 20 years after the first scan.
The results show a clear association between the total radiation doses to the bone marrow from CT scans and the risk of developing both myeloid and lymphoid malignancies. A dose of 100mGy approximately tripled the risk of developing a blood cancer. These results suggest that a typical scan today (with an average dose of about 8mGy) increases the risk of developing these malignancies by about 16%. “In terms of absolute risk, this means that, for every 10 000 children who have a CT scan, we can expect to see about 1–2 cases of cancer in the 12 years following the examination,” says first author Magda Bosch de Basea, ISGlobal researcher at the time of the study.
The authors point out that more work is needed to ensure that doses and technical parameters are systematically and adequately collected in the clinics in real time to further improve risk estimates in the future.
Public health implications
Today, more than one million children in Europe undergo CT scans every year. Although radiation doses from CT scans have decreased substantially in recent years, the findings of this study underline the need to raise awareness among the medical community and to continue to apply strict radiation protection measures, especially in the youngest patients. “The procedure must be properly justified – taking into account possible alternatives – and optimised to ensure that doses are kept as low as possible while maintaining good image quality for the diagnosis,” Cardis explains.
A new targeted drug, may offer a new treatment option for patients with blood cancers, including chronic lymphocytic leukaemia (CLL) and Non-Hodgkin lymphoma (NHL) whose disease has stopped responding to standard treatments.
In the first clinical trial of this drug in humans, nemtabrutinib was effective in three-fourths of cancer patients tested, without severe side effects. The results of the trial were published in the journal Cancer Discovery.
“Blood cancers that have relapsed after initial treatments can be difficult to treat, and even with our effective medications, some patients run out of standard treatment options. In this trial, nemtabrutinib looks very promising for patients whose cancer has progressive after other treatments.” said Woyach, who is co-leader of the Leukemia Research Program at the OSUCCC – James.
How this drug therapy works
When an antigen, such as a virus or bacteria, enters the bloodstream, it triggers a set of signals in B-cells to produce antibodies. In some people, said Woyach, this process goes haywire. Instead of fighting infections, the B-cells begin to divide uncontrollably, resulting in cancer. Drugs against B-cell cancers work by binding to a key enzyme, called Bruton’s tyrosine kinase (BTK). This enzyme is involved in the signaling process. The drugs block the action of the enzyme, and as a result, the abnormal B-cells die.
In many patients, this effect is temporary with available drugs. Over time, the BTK enzyme to which the drugs bind mutates so they can no longer stop its action. Soon, the cancer returns. Nemtabrutinib was designed to bind to BTK even in the presence of common mutations that make other BTK inhibitors stop working. It also binds to a number of proteins besides BTK that are important in B cell cancers. These two properties made this drug very appealing to study in this patient population.
Study methods and results
The researchers tested the new drug on 47 patients who have had at least two prior therapies for their blood cancer. Over half of these patients had relapsed CLL, while the others had NHL. The researchers gave these patients one pill of nemtabrutinib every day, with different doses along the trial. They observed the patients’ response to the drug over time and monitored them for side effects.
The study found more than 75% of the patients with relapsed CLL responded to the drug, at an optimal dose of 65mg. These included patients who had mutations in BTK. Most patients remained cancer free for at least 16 months during the trial. While all patients experienced some side effects – which is common with chemotherapeutic drugs – many of these were minor and manageable, proving that the drug was also very safe.
“The drug is being moved to larger and more definitive trials, where it will be compared against other standard-of-care drugs, and in combination with other active medications,” said Woyach.
The blood cancers investigated in this trial affect B lymphocytes, which is a cell that is responsible for producing antibodies and fighting infections. CLL is the most common leukaemia making up a quarter of leukaemia cases among adults, and NHL accounts for 4% of all cancers in the United States.
Leukaemia has been identified as the most prevalent cancer among the country’s youth, according to the latest report from the National Cancer Registry (NCR) of South Africa (2021). However, approximately half of children with cancer remain undiagnosed, with the majority of cases only being detected during the advanced stages of the illness. This is partly attributed to a lack of awareness of the early warning signs of childhood cancer.
As the world observes Bone Marrow & Leukaemia Awareness Month until the 15th of October, Dr Candice Hendricks, Paediatric Haematologist and Medical Spokesperson for DKMS Africa shares that leukaemia can be categorised as acute leukaemias or chronic leukaemias, each with varying symptoms. “Acute leukaemias are far more common in children and can further be divided into acute lymphoblastic- (ALL) and acute myeloid leukaemia (AML). Among children, especially those aged between two and 10, Acute Lymphoblastic Leukaemia (ALL) is the most common blood cancer in this age group.
“This disease arises from genetic mutations in immature lymphocytes called lymphoblasts which are located in the bone marrow. The mutations lead to uncontrolled growth of these lymphoblasts,” she explains. “Lymphoblasts are abnormal blood stem cells that lose the ability to make mature blood cells. The uncontrolled growth of these cells in the bone marrow displaces normal blood cell development and leads to a decrease in properly functioning red blood cells, white blood cells, and platelets. Patients may potentially present with an elevated white blood cell count on blood results, however, their impaired function leaves the body vulnerable to infections.”
Aligned with the NCR, Dr Hendricks emphasises that early symptoms often go unnoticed, as they mimic common, mild conditions, causing many patients and those who care for them to overlook them. “However, the severity of these symptoms escalates rapidly with acute leukaemias and persist even after standard treatment for infections. A high index of suspicion is required in diagnosing patients, and if any symptom persists, an immediate full blood count test is necessary, followed by additional tests if irregularities are detected.”
Prominent symptoms indicating the disease include:
Blood clotting disorders or blood diathesis characterised by easy bruising from minor impacts and the appearance of small reddish spots on the skin. Other signs encompass blood in urine, as well as uncontrollable gum and nose bleeding.
Muscle and joint pain, particularly in the limbs, along with frequent limb numbness.
Fever and night sweats.
Anaemia caused by a deficiency of red blood cells, leading to constant fatigue, reduced exercise capacity, lethargy, sleepiness, and pale skin.
Recurrent infections that persist despite antibiotic treatment due to cancer cells impairing the immune system. Pathological cancer cells displace healthy leukocytes, rendering the body susceptible to various viral, bacterial, and fungal infections.
Loss of appetite and weight loss.
Enlarged lymph nodes.
Stomach pain resulting from spleen and/or liver enlargement.
In support of Bone Marrow & Leukaemia Awareness Month, DKMS Africa continues to raise awareness and funds to cover the registration costs for as many potential stem cell donors as possible. Stem cell donations offer the best chance of survival for children afflicted by high-risk leukaemia which does not respond to or recurs after standard treatment. Answer the call! If you’re aged between 17 and 55 and in good general health, please register at https://www.dkms-africa.org/register-now. Registration is entirely free and takes less than five minutes.
For further information, get in touch with DKMS Africa at 0800 12 10 82.
About DKMS DKMS is an international non-profit organisation dedicated to saving the lives of patients with blood cancer and blood disorders. Founded in Germany in 1991 by Dr. Peter Harf, DKMS and organisations of over 1,000 employees have since relentlessly pursued the aim of giving as many patients as possible a second chance at life. With over 11 million registered donors, DKMS has succeeded in doing this 100,000 times to date by providing blood stem cell donations to those in need. This accomplishment has led to DKMS becoming the global leader in the facilitation of unrelated blood stem cell transplants. The organisation has offices in Germany, the US, Poland, the UK, Chile and South Africa. In India, DKMS has founded the joint venture DKMS-BMST together with the Bangalore Medical Services Trust. International expansion and collaboration are key to helping patients worldwide because, like the organisation itself, blood cancer knows no borders.
DKMS is also heavily involved in the fields of medicine and science, with its own research unit focused on continually improving the survival and recovery rate of patients. In its high-performance laboratory, the DKMS Life Science Lab, the organisation sets worldwide standards in the typing of potential blood stem cell donors.
Giving three years of chemotherapy to children with acute lymphoblastic leukaemia (ALL) instead of two years lowers the risk of their disease coming back after treatment by three times. The survival rate of all children with ALL, the most common form of childhood cancer, together has further increased to 94%. Less intensive therapy proved safe for three groups of children, resulting in a better quality of life. These findings on a large Dutch study into ALL were reported at the annual conference of the American Society of Hematology (ASH).
Many children with ALL have good outcomes. After two years of chemotherapy treatment, nine out of ten children are cured. But some children have a more aggressive disease, such as having the Ikaros mutation in their leukaemia cells, have a greater risk of recurrence after treatment. In order to improve the chances of survival and quality of life of all children with leukaemia, the treatment protocol has been continuously adapted over the years, based on the latest scientific insights.
Prof Rob Pieters, medical director and paediatric oncologist at the Princess Máxima Center for paediatric oncology in the Netherlands, presented the outcomes of the ALL-11 treatment protocol. The Dutch researchers tested the benefit of an adapted treatment in specific groups of children with leukaemia, including children with the Ikaros mutation. More than 800 children in the Netherlands were treated with this protocol between April 2012 and July 2020.
Threefold lower risk of recurrence
Children with Ikaros leukaemia received an extra year of chemotherapy in the ‘maintenance phase’ on top of the first two years of treatment. This change lowered the risk of their cancer coming back by threefold: this happened in only 9% of them, compared to 26% of the children in the previous treatment protocol.
87% of children with Ikaros leukaemia survived their disease for five years without their cancer coming back, an improvement on the 72% in the previous protocol. Because of the extra year of chemotherapy, this group of children had a slightly higher risk of infection, but these were treatable. The extended therapy did not lead to any additional side effects.
Analysis of data from all children with ALL, regardless of subtype, showed that the five-year survival rate has improved stepwise over the past 30 years from 80% to 94% under the ALL-11 protocol.
Safe reduction of treatment
In the ALL-11 protocol, doctors and researchers also looked at the benefit of a less intensive treatment plan for three groups of children. This included children with a leukaemia mutation linked to a very high chance of recovery, and children with Down syndrome who experience more severe side effects. These children received treatment without or with a lower dose of anthracyclines, a type of leukaemia drug that increases the risk of heart damage and infections. The reduced treatment proved successful: children had the same or even a better chance of survival, while their quality of life improved due to a lower risk of infections and damage to the heart.
Global interest
Globally, there is much interest in the Dutch research as it has been unclear how to improve therapy for children with Ikaros leukaemia. The results have now been presented for the first time at the largest blood cancer conference, and could lead to changes in treatment protocols for these children worldwide.
In the Netherlands, there are about 15 children with ALL each year for whom existing treatments stop working. Since 2019, they have been eligible for treatment with CAR T-cell therapy, a promising form of immunotherapy that now leads to a cure in 40% of these children.
Making a difference
Prof Monique den Boer, medical biologist and group leader at the Princess Máxima Center, played an important role in the adapted therapy for children with the Ikaros gene change. She says: ‘The Ikaros mutation was first discovered about 15 years ago in children with leukaemia who had a poor prognosis, partly thanks to the emergence of new DNA technologies. We saw that the cancer came back in many of these children shortly after the end of the two-year treatment plan. I am very proud that our lab findings have now found their way into the clinic and can make such a big difference for children with leukaemia.”
More cure with fewer side effects
Prof Pieters concludes: The five-year survival rate for children with acute lymphoblastic leukaemia has increased enormously since the 1960s, from zero to 94%, but the last steps are the most difficult. We are now one step closer to curing all children with ALL. We have also largely been able to remove a drug that poses a risk of heart damage from the treatment of children with a less aggressive form of the disease. The latest results for children with leukaemia therefore fit in perfectly with our mission: curing more children with cancer, with fewer side effects.”
Children living near unconventional oil and gas (UOG) or ‘fracking’ developments at birth had a 2–3 times greater risk of leukaemia diagnoses between 2 and 7 years old, researchers have found.
Their study, published in the journal Environmental Health Perspectives, included nearly 2500 Pennsylvania children, 405 of whom were diagnosed with acute lymphoblastic leukaemia (ALL).
ALL arises from mutations to lymphoid immune cells. Although long-term survival rates are high, survivors may have long-term health risks and psychological issues. Unconventional oil and gas development, more commonly referred to as fracking (short for hydraulic fracturing), is a method for extracting gas and oil from shale rock. The process involves high-pressure injection of water, sand, and chemicals into bedrock to release oil or gas for extraction.
For communities living nearby, UOG development can pose a number of potential threats. As well as air pollution from vehicles and construction, there is also water pollution from hydraulic fracturing or spills of wastewater. Hundreds of chemicals have been reportedly used in UOG injection water or detected in wastewater, some of which are known or suspected carcinogens. The lack of data about this has given rise to concerns over the proximity of UOG to residential areas.
“Unconventional oil and gas development can both use and release chemicals that have been linked to cancer, so the potential for children living near UOG to be exposed to these chemical carcinogens is a major public health concern,” said the study’s senior author, Nicole Deziel, associate professor of epidemiology at the Yale School of Public Health.
“Studies of UOG exposure and cancer are extremely few in number. We set out to conduct a high-quality study to further investigate this potential relationship,” added Cassandra Clark, the study’s first author and a postdoctoral associate at the Yale Cancer Center. “Our results indicate that exposure to UOG may be an important risk factor for ALL, particularly for children exposed in utero.”
Oil and gas-related chemicals exposure could be through drinking water, the researchers found. The watershed, the zone from which a drinking water well serving their home would likely draw water, were compared with the distance from the home to the nearest of those UOG wells. UOG wells falling within the watershed area are expected to be more likely to impact the home’s drinking water supply, they said.
This work adds to a growing body of literature on UOG exposure and children’s health used to inform policy, such as setback distances (the required minimum distance between a private residence or other sensitive location and a UOG well). Current setback distances are the subject of much debate in the United States, with some calling for setback distances to be lengthened to more than 305m and as far as 1000m. The allowable setback in Pennsylvania, where the study was conducted, is 152m.
“Our findings of increased risk of ALL at distances of two kilometres or more from UOG operations, in conjunction with evidence from numerous other studies, suggest that existing setback distances, which may be as little as 150 feet (50m), are insufficiently protective of children’s health,” Clark said. “We hope that studies like ours are taken into account in the ongoing policy discussion around UOG setback distances.”
Patients with blood cancers have an impaired immune system due to their disease and its treatment, putting them at risk of severe COVID infection and a reduced COVID vaccination response. In a recent study published in CANCER, less than half of patients with haematologic malignancies including leukaemia, lymphoma, and multiple myeloma mounted detectable antibodies after initial COVID vaccination, but 56% of ‘nonresponders’ produced antibodies after receiving a booster dose.
For the study, Thomas Ollila, MD, and colleagues retrospectively analysed antibody responses to initial and booster COVID vaccination in 378 patients with hematologic malignancies.
Anti-SARS-CoV-2 antibodies were detected in the blood of 181 patients (48%) after initial vaccination with one of three FDA-authorised or approved COVID vaccines, and patients with active cancer or those recently treated with an immune cell–depleting therapy were least likely to produce these antibodies. Among patients who did not mount an antibody response following initial vaccination, responses were observed after a booster dose in 48 of 85 (56%) patients who were assessed.
By the end of February 2022, 33 patients (8.8%) developed a COVID infection, with three COVID-related deaths (0.8%). Although there was no significant link between post-vaccination antibody response and incidence of COVID infection, no patient with antibody responses died from COVID
Also, no patient who received tixagevimab plus cilgavimab was diagnosed with a COVID infection. Tixagevimab and cilgavimab are antibody therapies that bind to non-overlapping portions of the SARS-CoV-2 spike protein, preventing the virus from binding to and infecting cells. The FDA authorised the combination therapy for emergency use during the COVID pandemic as a way to help prevent COVID infection in certain individuals.
“Our findings build on the wealth of literature showing that patients with hematologic malignancies have an impaired response to COVID vaccination. Importantly, we show that many of these patients who did not respond initially will in fact have a response to booster vaccination,” said Dr Ollila. “Moreover, when we looked at outcomes, we found that deaths from COVID in the patient population we reviewed only occurred in those with undetectable antibodies, and nobody who received prophylactic antibody therapy was diagnosed with COVID. This suggests to us the importance of checking antibody levels in these patients and arranging prophylactic antibody therapy.”
Dr. Ollila encourages providing booster vaccines for patients and prioritising prophylactic antibody therapy when indicated. “This is real world evidence that these actions can save lives,” he said.
A drug screen on various cancer cell lines revealed hundreds of compounds with inhibitory effects on cancer, and one in particular, the leukaemia drug clofarabine, showed effectiveness in two specific types of bladder cancer. The study was published in the journal European Urology.
A joint study group conducted a drug screen which investigated the effects of over 1700 chemical compounds on 23 cell lines representing different stages and subtypes of bladder cancer. From this, the researchers identified more than 470 substances with inhibitory effects. These included a large number of drugs already used for cancers, but also medications for other diseases, such as malaria, parasitic diseases and various mental disorders.
One of these compounds, clofarabine, an antimetabolite drug currently used to treat childhood leukaemia, was studied in more detail. For this purpose, the researchers developed models from patient material representing different types of bladder cancer. Besides ‘conventional’ urothelial carcinoma, they were also able to establish an animal model for sarcomatoid carcinoma – a rare subtype of bladder cancer, for which there is currently no effective chemotherapy.
Describing the results, first author Iris Ertl said: “We found that clofarabine induced complete remission in mice with conventional urothelial carcinoma and massive, sustained tumour shrinkage in animals with sarcomatoid carcinoma, while not causing any apparent side effects.”
Next steps will be clinical trials in which patients with metastatic bladder cancer who cannot receive cisplatin-based therapy, will be treated with clofarabine prior to radical cystectomy. Shahrokh Shariat explains: “Our discovery was made possible by the close interdisciplinary collaboration with CeMM and the Center of Cancer Research. We very much look forward to continuing to work with our partners to incorporate our findings into clinical practice.”
Dasatinib, a drug that often is used to treat certain types of leukaemia, may have significant potential as an antidiabetic drug, according to new research published in Mayo Clinic Proceedings.
Dasatinib is a tyrosine kinase inhibitor used to treat tumours and malignant tissue, as well as chronic myelogenous leukaemia. Dasatinib is a senolytic drug, which target senescent cells that accumulate in many ageing tissues and at sites of pathology in chronic diseases. Senolytic drugs appear to delay, prevent or alleviate age-related changes, chronic diseases and geriatric syndromes in animal studies.
“Our findings suggest that dasatinib or related senolytic drugs may become diabetic therapies,” said senior author Robert Pignolo, MD, PhD. “More study is needed to determine whether these findings also are observed in patients with type 2 diabetes mellitus but without underlying malignant disease.”
Researchers used records for a total of 9.3 million individuals from 1994 to 2019 who were screened for use of either dasatinib or imatinib, another tyrosine kinase inhibitor that was approved for treatment of a type of leukemia in 2001 but with weak senolytic activity. Of those patients, 279 were treated with imatinib and 118 with dasatinib, and after further screening, a total of 48 patients were included in the study. The findings show that dasatinib lowers serum glucose in patients with pre-existing type 2 diabetes to a greater extent than imatinib and comparable to first-line diabetic medications such as metformin and sulfonylureas.
More work is needed to determine whether the antidiabetic effect of dasatinib is due largely to its senolytic properties, explained Dr Pignolo. If it is, the effectiveness of combining dasatinib with another senolytic drug such as quercetin may be greater than with dasatinib alone.
“This study was really the first proof-of-concept that a senolytic drug may have substantial long-term beneficial effects in humans,” Dr Pignolo says. “According to research in animal models, it is not necessary to give senolytic drugs continuously, and so patients may need only take a drug such as dasatinib every few weeks, reducing possible side effects.”
Cold Spring Harbor Laboratory Professor Christopher Vakoc and his lab have found that acute myeloid leukaemia(AML), an aggressive cancer that originates in the bone marrow, depends on a transporter to bring in the nutrient inositol, and the researchers believe they can find a way to cut off the cells’ food supply and kill them.
Cancers may streamline certain cell processes and rely on just one method to survive; for example, some remove backup pathways for DNA repair, “putting all their eggs in one basket” and depending only on a single pathway for survival. Prof Vakoc’s lab could then develop treatments to knock out that remaining pathway, killing the cancer cells.
In a study published in Cancer Discovery, Prof Vakoc and his lab reported that AML depends on inositol, an abundant sugar that is made in many human body tissues. It is also found in a wide variety of foods like fruits, beans, grains, and nuts, so cells can obtain it from outside the body, via the bloodstream.
Prof Vakoc discovered that the AML cells had streamlined and boosted their growth by disabling their own inositol production, instead relying on external inositol, bringing it in with a transporter on the cell surface. If a simple treatment could turn off or block this transporter, the cancer cells would starve. As Prof Vakoc explained, “An antibody approach would be very attractive. You could make an antibody that just sticks to this transporter. It doesn’t need to get into the cell, and it could shut off the transport function. The other possibility, from a drug development point of view, is inositol. You could build a molecular medicine that sort of looks like inositol, but maybe it has a few chemical differences that can clog the transport function.”
Not only could this method kill the cancer cells, but it would also leave normal cells unharmed since they can make their own inositol.
