Immunotherapy drugs may improve cancer survival
  

  

 Dr Ben Janaway II  NOV 14 2016

  
New research has further cemented the potential for ‘immunotherapy’ in the successful treatment in a variety of cancers expressing certain proteins. ‘Keytruda’, known also as penbroluzimab,  is a drug that interacts with bodily chemical signaling, increasing the work done by our immune system. These new findings, although not curative, show definite increased survival time.  So far ‘Immunotherapy’ is liscenced for a few cancers, including ‘melanoma’  (an aggressive skin cancer) and ‘non small cell lung cancer’. 

The excitement lies not just in Keytrudas use in these cases, but its potential as representative of new treatment directions.

How Keytruda and immunotherapy works

Immunotherapy is the process of interacting with the body’s own protective processes to tackle disease. Our white cells are one of the first lines of defense against cancer, sniffing out abnormal cell growth and stopping it in its tracks.  Our white cells work together to label and terminate rogue cells, but in some cancers the messenger is switched off. The presence of a surface receptor on some cancers known as PDL1 can bind to a surface protein on T cells, causing them to ‘self-destruct’.  This kills the T cell, leaving the cancer to grow.  These ‘lock and key’ reactions are common in activating body pathways.
Keytruda inhibits this process, allowing the body’s defenses to work more effectively for longer.

Although the process is not curative or permanent, it has been shown to buy extra time for patients with resistant or advanced disease, with a 16% increase in 1-year survival in those with PDL1 expressing tumors and a 4-month greater median survival.

Immunotherapy, potential and downsides

Treatment for cancer may include chemotherapy, radiotherapy and surgery. There is strong evidence for the use of immunotherapy for the treatment of melanoma, and growing evidence for its use in gastro-esophageal (food pipe) and ‘non-small cell’ lung cancer. Up to 24% of gastro-esophageal cancers may be susceptible, with screening useful in detecting possible cases.

Side effects of these drugs are known to include rashes, stomach upset, lung inflammation, liver problems, nerve and sensory issues and in some cases swelling of the brain. There are a growing number of cases where use of drugs has worsened pre-existing ‘autoimmune disease’ such as diabetes and psoriasis, where stimulation of immune cells adds to their destructive potential. Treatment is with steroids.

Summary

Although research is promising and outcomes good, it must be remembered that immunotherapy is often targeted and relies on the presence of key proteins to work. Much like the exhaust port on the death star, unless you have the plans the fleet will be powerless, which limits the variety of cancers treated.  Side effects can be treated using steroids, but this obviously limits the effect of therapy by either cutting it short or modulating immune response. 
Immunotherapy has proven benefits, and with more research may lead the way in the treatment of many cancers in future.


  
Dr Ben Janaway MBChB  //   @drjanaway
Any opinions above are the author's alone and may not represent those of the NHS. Guidance is based on the best available evidence at the time of writing.  All data is based on externally validated studies unless expressed otherwise. Novel data is representative of sample surveyed. Online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice.
 
Dr Ben Janaway is a medical doctor and Editor for the online healthcare and education  source ‘Mind and Medicine’.  He writes regularly for patient.co.uk and other national news sources. Contact Dr Janaway at www.twitter.com/drjanaway with stories or for discussion

Sources

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Friedman CF (2016) Treatment of the Immune-Related Adverse effects of Immune checkpoint inhibitors: A review’

Hottinger AF (2016) Neurologic complications of immune checkpoint inhibitors ‘Curr Opin Neurol 806-812

Jazirehi AR et a (2016) PD-1 inhibition and treatment of advanced melanoma- role of pemobroliumab.’ Am J Cancer Res  1:6 (10) p 2117-2128

Jin Z, Yoon HH (2016) The promise of PD-1 inhibitors in gastro-esophaeal cancers: microsatellite instability vs PD-L.   J. Gasto-intest oncol 7(5)P 771-788

Phadke SD (2016) Pembroluzimab therapy triggering an exacerbation of Pre-existing Autoimmune disease: a report of 2 patient cases’ J Investig Med High Impact Case Rep. 25;4

Vachhani P, Chen (2016)  Spotlight on pembrolizumab in non-small cell lung cancer: the evidence to date Onco Targets Ther 23;9 p5855-5866

https://www.washingtonpost.com/national/health-science/immunotherapy-moves-to-the-front-lines-in-fight-against-lung-cancer/2016/11/10/1bdb725a-a27a-11e6-8832-23a007c77bb4_story.html