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Science behind the New Cancer Cure

  • Category
    Science & Technology
  • Published
    21st Jun, 2022

Overview

  • About the Trial
  • Key terms related to the Trials
  • Cancer and its cure
  • Significance for India

Context

Twelve patients in the United States were completely cured of rectal cancer without requiring any surgery or chemotherapy found in a medical trial.

About

  • The study was done by doctors from the Memorial Sloan Kettering Cancer Centre in New York, and its results have been published in the New England Journal of Medicine.
  • The trial used a monoclonal antibody called dostarlimab every three weeks for six months for the treatment of a particular kind of stage two or three rectal cancer.
  • The participants of the trial had a mismatch repair deficient stage II or III rectal adenocarcinoma.
  • All 12 patients had completed the treatment and were followed for six to 25 months after.
  • No cases of progression or recurrence had been reported during the follow-up, as per the study.
  • The response shown in colon cancer in this study is 100 per cent it needs to be validated involving a larger cohort of patients.
  • Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020, or nearly one in six deaths.

 What is Rectal Cancer?

  • Rectal cancer is cancer that begins in the rectum. The rectum is the last several inches of the large intestine.
  • It starts at the end of the final segment of your colon and ends when it reaches the short, narrow passage leading to the anus.
  • While rectal cancer’s treatments are quite different. This is mainly because the rectum sits in a tight space, barely separated from other organs and structures.
  • The tight space can make surgery to remove rectal cancer complex.
  • Signs and symptoms of rectal cancer include:
    • A change in bowel habits, such as diarrhea, constipation or more-frequent bowel movements
    • Dark maroon or bright red blood in stool
    • Narrow stool
    • A feeling that your bowel doesn't empty completely
    • Abdominal pain
    • Unexplained weight loss
    • Weakness or fatigue

What is PD1 Therapy?

  • PD1 is a type of protein that regulates certain functions of the immune system, including by suppressing T cell activity, and PD1 blockade therapy looks to release the T cells from this suppression.
  • T-cells are the White Blood cells (WBCs). They are critical for developing immunity towards common pathogens or antigens.
  • Although the therapy is usually used for cancers that have metastasised (spread to locations other than where the cancer formed), it is now recommended for all mismatch repair deficient cancers as they result in quicker improvement and lesser toxicity as compared to traditional chemo and radiotherapy.
  • Eliminating other treatments can improve a patient’s quality of life by preserving fertility, sexual health, and bladder and bowel functions.

What are monoclonal antibodies?

Monoclonal antibodies are laboratory-produced molecules engineered to serve as substitute antibodies that can restore, enhance, modify or mimic the immune system's attack on cells that aren't wanted, such as cancer cells.

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Key terms related to the Trial

Mismatch repair deficient cancer

  • It is most common among colorectal, gastrointestinal, and endometrial cancers.
  • Patients suffering from this condition lack the genes to correct typos in the DNA that occur naturally while cells make copies.
  • The anomalies in the DNA result in cancerous growths in patients.

Dostarlimab

  • Dostarlimab belongs to a group of monoclonal antibodies called “checkpoint inhibitors”.
  • These are synthetic antibodies which block the proteins that cancer cells produce to prevent the body’s immune system from attacking them.
  • It is a game of blocking the blocker, so that the native immune system which has recognised the cancer threat is not impeded in launching its attack on the malignant cells.
  • This form of immunotherapy does not attack the cancer cells directly but unshackles the body’s own able defenders.

Checkpoint inhibitors

  • They are named according to the type of protein they block — CTLA-4 inhibitors, PD-1 inhibitors and PD-L1 inhibitors.
  • Dostarlimab is an inhibitor of the Programmed Cell Death Protein (PD-1).
  • PD1 is a type of protein that regulates certain functions of the immune system, including by suppressing T cell activity, and PD1 blockade therapy looks to release the T cells from this suppression.

T cells

  • They are also called T lymphocytes
  • They are a type of white blood cell.
  • T cells are part of the immune system and develop from stem cells in the bone marrow.
  • They help protect the body from infection and may help fight cancer

Analysis

Why is treating Cancer so difficult?

  • The difficulty in treating cancer is that it’s not a single disease, but rather a group of diseases.
  • In total there are more than 100 different types of cancers.
  • Cancers are also caused by different things, so no one strategy can prevent them.
  • Likewise, different cancers respond to different treatments, so no one treatment can cure them all.
  • Treating cancer is further complicated due to the lifestyle and attitude of patients, the different physiology of people and the rate their bodies will metabolise drugs, the blood supply to the tumour affecting the drug getting into the tumour, the tumour physiology and the fact that the tumour can continue to change.

What does the new discovery bring for India?

  • Responsibility for more researches: The trial is a phase II one and conducted in a small set of patients with a short follow-up.
    • Larger phase III studies are required to confirm the results and see whether this is a temporary phenomenon or can the cancer return aggressively.
  • Most cases do not need surgeries: These patients can be well managed with chemotherapy and radiotherapy as well.
    • Around 10 to 15% of cancer patients actually do not need surgeries.
  • High cost: Immunotherapies are expensive and unaffordable for most people in India.
    • An immunotherapy treatment can cost around Rs 4 lakh per month, with patients needing the treatment for six months to a year.
  • Use in initial stages in India: Precision medicine, such as using particular immunotherapy drugs for particular types of cancers, is still at a nascent stage in India

Measures to be taken for early detection of diseases

  • Cancer registry network: A network of cancer registries have to be set up towards this end.
    • To start with hospital based cancer registries can be initiated by the regional cancer centres and they can later on be expanded to population based cancer registries.
  • Strategy matrix: Cancer Control is an area in which we need participation from all sectors of the society.
    • There are areas in which various agencies can put in their contributions. Keeping targets will help to monitor the programme as well as to identify the usefulness of the strategies.
  • Role of international agencies: The World Health Organization has promoted National Cancer Control Programmes and India is one of the few countries that has actively taken up this initiative.

Conclusion

Where resources are limited, diagnosis and treatment services should initially target all patients presenting with curable cancers, such as breast, cervical and oral cancers that can be detected early. They could also include childhood acute lymphatic leukaemia, which has a high potential for cure although it cannot be detected early. Above all, services need to be provided in an equitable and sustainable manner. As and when more resources become available, the programme can be extended to include other curable cancers as well as cancers for which treatment can prolong survival considerably.

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