Published: 6 September 2018


Spotlight on Pembrolizumab (Keytruda)

Prescriber Update 39(3): 34–35
September 2018

Key Messages

  • Pembrolizumab (Keytruda) is an immune checkpoint inhibitor used in the treatment of some advanced or metastatic cancers.
  • Modify the dose for patients experiencing immune-mediated adverse reactions or infusion-related reactions.
  • Seek specialist advice before administering any vaccine to patients receiving immune checkpoint inhibitors, as well as those who have stopped treatment within the past six months.


The spotlight series continues with this article on pembrolizumab. Key information on pembrolizumab, including recent developments and adverse reaction reporting in New Zealand, is described.

Please refer to the medicine data sheet for full prescribing information (

What is pembrolizumab and what is it used for?

Pembrolizumab (Keytruda) is a monoclonal antibody used in the treatment of some advanced or metastatic cancers. These currently include:

  • melanoma
  • non-small cell lung carcinoma (NSCLC)
  • classical Hodgkin Lymphoma (cHL)
  • urothelial carcinoma.

Pembrolizumab is commonly known as an immune checkpoint inhibitor because it blocks the PD-1 pathway on immune dampening cells. This action helps the immune system to boost its response against cancer cells1.

Recent developments

Immune-mediated adverse reactions are known to occur with immune checkpoint inhibitors, including pembrolizumab1.

The pembrolizumab data sheet was recently updated to include dose modifications in the presence of immune-mediated adverse reactions or infusion-related reactions, including new recommendations for myocarditis. These dose modifications are stratified according to the severity of the adverse reaction. In general, the advice is to withhold treatment until adverse reactions improve, or to permanently discontinue treatment.

The following side effects have also been recently identified:

  • thyroiditis
  • myasthenic syndrome
  • encephalitis
  • sarcoidosis
  • graft-versus-host-disease (GVHD) in patients with a history of allogeneic haematopoietic stem cell transplant (HSCT).

In March 2018, chapter four of the Immunisation Handbook 2017 was updated to include information for vaccinators about oncology patients treated with immune checkpoint inhibitors2.

Vaccinators are advised to seek specialist advice before administering any vaccine to patients who are currently being treated with immune checkpoint inhibitors, as well as those who have discontinued treatment within the past six months2. There are currently no international consensus statements on the use of vaccines in patients being treated with immune checkpoint inhibitors as this is a rapidly evolving therapeutic area. Caution is advised, particularly with live vaccines2.

Adverse reactions reported in New Zealand

As at 30 June 2018, the Centre for Adverse Reactions Monitoring (CARM) has received 21 adverse reaction reports where pembrolizumab was considered to be the suspect medicine.

The following is a list of some interesting cases reported within the last two years:

  • four reports of reactions relating to changes in renal function and/or nephritis (CARM ID numbers: 123300, 124915, 125854, 126553). Three of these patients were also taking omeprazole, which has been associated with acute interstitial nephritis3
  • two reports describing reactions relating to diabetes (123772, 123983)
  • one report describing symptoms likely to be hypophysitis (124301)
  • one fatal case of pneumonitis (123805).

The reported reactions listed above, including monitoring requirements, are all listed in the pembrolizumab data sheet.

Please report any adverse reactions to pembrolizumab to CARM (

  1. Medsafe. 2017. New anti-cancer therapy – immune checkpoint inhibitors. Prescriber Update 38(4): 50. URL: (accessed 2 July 2018).
  2. Ministry of Health. 2018. Immunisation Handbook 2017 (2nd edn). Wellington: Ministry of Health. URL: (accessed 9 July 2018).
  3. Medsafe. 2015. Keeping it renal: drug-induced acute interstitial nephritis. Prescriber Update 36(2): 26–7. URL: (accessed 9 July 2018).
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