Anticancer mRNA Vaccine

• 20 Dec 2022

For Prelims: mRNA vaccine, mRNA-4157/V940, cancer, Covid-19, Programmed Death-1, types of vaccines.

For Mains: Types of Vaccine and Significance

Why in News?

Recently, the results of a trial of messenger Ribonucleic Acid (mRNA-4157/V940) vaccine made by Moderna and MSD (Merck & Co.) when taken along with an immunotherapy drug Keytruda has shown promising results against advanced melanoma, a kind of skin cancer.

What is mRNA Vaccine Therapy for Advanced Melanoma?

• About:
  • It is a personalised cancer vaccine i.e., tailor-made for every patient.
  • To build the vaccine, researchers took samples of patients’ tumors and healthy tissue.
    • After analysing the samples to decode their genetic sequence and isolate mutant proteins associated only with the cancer, that information was used to design the vaccine.
  • The personalised cancer vaccine uses the same m-RNA technology that was used to produce the Covid-19 vaccine.
    • mRNA vaccines use mRNA to teach our cells how to make a protein that triggers an immune response inside our bodies.
• Mechanism:
  • It allows the body’s immune system to seek and destroy cancerous cells.
  • The personalised cancer vaccine works in concert with Keytruda, to disable a protein called Programmed Death 1 (PD-1), that helps tumors to evade the immune system.
  • When injected into a patient, the patient’s cells act as a manufacturing plant, producing perfect copies of the mutations for the immune system to recognise and destroy.
  • Having been exposed to the mutations without the virus, the body learns to fight off the infection.
• Efficacy:
  • The vaccine showed a 44% reduction in the risk of dying of cancer or having the cancer progress.
  • The combination of mRNA-4157/V940 and Keytruda was generally safe and demonstrated the benefit compared with Keytruda alone after a year of treatment.

What are Different Types of Vaccines?

• Inactivated Vaccines:
  • Inactivated vaccines use the killed version of the germ that causes a disease.
  • Vaccines of this type are created by inactivating a pathogen, typically using heat or chemicals such as formaldehyde or formalin. This destroys the pathogen’s ability to replicate, but keeps it “intact” so that the immune system can still recognize it. (“Inactivated” is generally used rather than “killed” to refer to viral vaccines of this type, as viruses are generally not considered to be alive.)
  • They usually don’t provide immunity (protection) that’s as strong as live vaccines. So, you may need several doses over time (booster shots) in order to get ongoing immunity against diseases.
    • They are Used to protect: Hepatitis A, Flu (shot only), Polio (shot only), Rabies.
• Live-attenuated Vaccines:
  • Live vaccines use a weakened (or attenuated) form of the germ that causes a disease.
  • Because these vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response.
  • The limitation of this approach is that these vaccines usually cannot be given to people with weakened immune systems.
  • Live vaccines are used against: Measles, Mumps, Rubella (MMR combined vaccine), Rotavirus, Smallpox among others.
• Messenger (m) RNA Vaccines:
  • mRNA vaccines make proteins in order to trigger an immune response. mRNA vaccines have several benefits compared to other types of vaccines, including shorter manufacturing times and, because they do not contain a live virus, no risk of causing disease in the person getting vaccinated.
  • The vaccines are used to protect against: Covid-19.
• Subunit, Recombinant, Polysaccharide, and Conjugate Vaccines:
  • They use specific pieces of the germ - like its protein, sugar, or capsid (a casing around the germ). They give a very strong immune response.
  • They can also be used on people with weakened immune systems and long-term health problems.
  • These vaccines are used to protect against: Hib (Haemophilus influenzae type b) disease, Hepatitis B, HPV (Human papillomavirus), Pneumococcal disease among others.
• Toxoid Vaccines:
  • They use a toxin (harmful product) made by the germ that causes a disease. They create immunity to the parts of the germ that cause a disease instead of the germ itself. That means the immune response is targeted to the toxin instead of the whole germ.
  • Toxoid vaccines are used to protect against: Diphtheria, Tetanus.
• Viral Vector Vaccines:
  • Viral vector vaccines use a modified version of a different virus as a vector to deliver protection.
  • Several different viruses have been used as vectors, including influenza, vesicular stomatitis virus (VSV), measles virus, and adenovirus, which causes the common cold.
    • Adenovirus is one of the viral vectors used in some Covid-19 vaccines being studied in clinical trials.
  • The vaccines are used to protect against: Covid-19

UPSC Civil Services Examination, Previous Year Questions (PYQs)

Prelims

Q1. With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements:

1. Genetic engineering is applied in the development of these vaccines.
2. Bacteria and viruses are used as vectors.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Ans: (c)

Q2. In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements: (2022)

1. The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform.
2. Sputnik V vaccine is manufactured using vector based platform.
3. COVAXIN is an inactivated pathogen based vaccine.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Ans: (b)

Exp:

• COVISHIELD vaccine is based on the platform which uses a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 Spike (S) glycoprotein. Following administration, the genetic material of part of coronavirus is expressed which stimulates an immune response. Hence, statement 1 is not correct.
• Sputnik V is the world's first registered vaccine based on a well-studied human adenovirus vector platform. It has been approved for use in 71 countries with a total population of 4 billion people. The vaccine is named after the first Soviet space satellite. The vaccine’s efficacy is 97.6%, based on the analysis of data on the incidence of coronavirus among Russians vaccinated with both vaccine components between December 5, 2020 and March 31, 2021. Hence, statement 2 is correct.
• Covaxin is an inactivated viral vaccine. This vaccine is developed with Whole-Virion Inactivated Vero Cell-derived technology. They contain inactivated viruses, which cannot infect a person but still can teach the immune system to prepare a defence mechanism against the active virus. Hence, statement 3 is correct.
• Hence, option (b) is correct.

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Mains

Q. What is the basic principle behind vaccine development? How do vaccines work? What approaches were adopted by the Indian vaccine manufacturers to produce COVID-19 vaccines? (2022)

Source: TH