Tumours disappear in all participants of small cancer drug trial

Dr Khan looks at ground-breaking results from a drug trial with a dozen rectal cancer patients in the US.

A drawing of doctors in a lab
[Muaz Kory/Al Jazeera]

Colorectal cancer, or bowel cancer, is the third most common cancer worldwide; the third most common in men and the second most common in women.

Now a small rectal cancer drug trial, carried out in the United States, has shown extremely promising results: tumours were found to have disappeared in 100 percent of participants.

What is colorectal cancer?

Colorectal cancer (CRC) is a disease in which cells in the colon or rectum grow out of control. Sometimes it is called colon cancer, for short. The colon is the large intestine or large bowel. The rectum is the passageway that connects the colon to the anus.

The symptoms of CRC include:

  • A persistent change in bowel habit
  • Bleeding from the back passage, or blood in stools
  • Unexplained weight loss or tiredness
  • Unexplained abdominal pain
  • Any new lumps, swelling or masses in the abdomen

Anyone experiencing any of these symptoms should speak with a healthcare professional. It may not be anything serious, but if it is cancer, finding it early dramatically improves the chances of getting better.

There were more than 1.9 million new cases of CRC in 2020. The global burden of CRC is expected to increase by 60 percent to more than 2.2 million new cases and 1.1 million deaths by 2030.

The treatment for those diagnosed with colorectal cancer usually involves:

  • Surgery: the cancerous segment of the bowel is cut out; this is the most effective way of curing bowel cancer
  • Chemotherapy: medicines to kill cancer cells
  • Radiotherapy: using radiation to kill cancer cells

Due to the sheer numbers being diagnosed with this disease globally, and the burden it puts on patients and healthcare systems, we urgently need new effective and safe treatments to be made available.

What does the new research show?

Scientists and healthcare professionals are excited by the new research published in the New England Journal of Medicine in June. The study, carried out at the Memorial Sloan Kettering Cancer Center in New York, followed 12 patients who had a specific form of rectal cancer and were given the new drug, dostarlimab, developed by pharmaceutical company GlaxoSmithKline.

The drug was given to the patients every three to six months at a cost of $11,000 for each dose. Some of the participants also had standard chemo/radiotherapy and surgery, but for those who responded well to the drug, this step could be skipped.

At the end of their treatment, all 12 participants were found to be in remission and no trace of cancer was found on physical examination or scans.

The type of cancer being treated was a specific mismatch repair deficient (MMRd) locally advanced rectal cancer. Mismatch repair genes are involved in correcting mistakes made when DNA is copied in a cell. When they are deficient, as is the case with these tumours, DNA mutations can take place and lead to cancer.

Dostarlimab is from a group of drugs called anti-programmed death-1 (anti-PD1) monoclonal antibodies. These specific rectal tumour cells being treated have special immunosuppressive properties known as programmed death-1 (PD-1), which down-regulate immune cells known as T-cells which are needed to destroy them. Dostarlimab, an anti-PD1, interferes with this process so the cancer cells can no longer protect themselves against the T-cells and the immune system is then able to attack and kill them.

The new study takes us a step closer to the ultimate goal of cancer treatment, to provide individual personalised care to each patient specific to their tumour. Every person’s cancer will have subtle differences in the type of mutations the cancer cells have, by giving drugs that are targeted to that individual’s specific cancer type and, more importantly, the very specific mutations that patients have will improve positive outcome rates.

Side effects of the drug were reported as minimal, but it is not yet known how long the participants will remain cancer-free, so scientists are unable to call this treatment a cure yet.

One of the hopes for this kind of immunotherapy is that it will reduce the need for surgery and chemo/radiotherapy for cancer sufferers in the future, especially for younger people. Both chemotherapy and radiotherapy can affect fertility in particular, for both men and women, meaning eggs and sperm have to be frozen where possible and then artificially fertilised and implanted at a later date. Bowel surgery for cancer itself carries risks, with many patients left with stoma bags and/or difficulty going to the toilet to open their bowels afterwards. If dostarlimab reduces the need for all of these other treatments, we may well see an improvement in the quality of life of those being treated for bowel cancer.

How can we reduce our risk of colorectal cancer?

Being diagnosed with any type of cancer is never the fault of the individual, and people should never be made to feel this way. Often, unavoidable things like genetics play a big part and if you have a strong family history of colorectal cancer you should be under regular surveillance from a healthcare team. People may be at higher risk of CRC if they have other bowel problems such as inflammatory bowel disease and should be especially vigilant to any new and unexplained symptoms.

There are, however, things we can all do to reduce our risk of CRC. There is evidence that eating red and processed meat – including beef, lamb, pork and goat – can increase the risk of bowel cancer, so we should try to limit our intake to one-two portions per week. Eating more fibre – such as whole grains, oats, chickpeas, lentils and beans – has been shown to reduce our risk of bowel cancer, and we should be eating approximately 30gm per day.

Obesity has been linked with bowel cancer, so maintaining a healthy weight will reduce our risk of developing the disease. People who are physically active have a lower risk of developing bowel cancer. Alcohol is linked to seven types of cancer, including bowel cancer, so ensure you are drinking alcohol to safe levels only and make sure you have at least two alcohol-free days per week. Smoking has also been linked to bowel cancer, so stopping smoking will not only reduce the risk of this cancer but of several other health conditions also.

Many countries now have screening programmes in place to help detect bowel cancer in its early stages before symptoms develop. If you are offered a test as part of a screening programme, which may include giving in a stool sample, please do it. The earlier these things are detected, the better your chances of survival.

And lastly, never be embarrassed to talk about your bowel habits with a healthcare professional; we are used to it and need to know if you have had any changes in yours. Remember, it might not be anything serious, but it is better to know early than to wait until it is too late.

Source: Al Jazeera