Immunotherapy for pancreatic cancer
Why immunotherapy is relevant only for selected pancreatic cancers, the dMMR and MSI-H testing behind it, and how suitability and funding are decided.
Patient Resources → Treatment Options → Immunotherapy
Immunotherapy is not a routine treatment for most pancreatic cancers. It may be relevant to a small group of people whose cancer has particular features identified through testing. This guide explains what those findings mean, how treatment is assessed, and questions to ask your care team.
This guide primarily concerns pancreatic ductal adenocarcinoma, the most common type of pancreatic cancer. Treatment for other tumour types can differ.
This guide is general information, not medical advice.
What is immunotherapy?
Some immunotherapy medicines work by blocking signals that stop immune cells from attacking cancer. These medicines are called immune checkpoint inhibitors. Pembrolizumab, also known as Keytruda, is one example that may be considered for selected cancers with dMMR or MSI-H findings, explained below.
Testing: dMMR and MSI-H
| Term | Plain-language meaning |
|---|---|
| Deficient mismatch repair (dMMR) | The cancer’s system for correcting certain DNA-copying errors is not working properly |
| Microsatellite instability-high (MSI-H) | Testing finds a pattern of DNA changes that can result from faulty mismatch repair |
These are related findings, but the tests measure different features. Only a small proportion of pancreatic cancers have them. Understand tumour biomarker testing →
Is this the same as inherited genetic testing?
No. dMMR and MSI-H are findings in the tumour. A tumour finding may lead to a discussion about inherited testing, including assessment for Lynch syndrome — but the tumour result alone does not establish that a person has an inherited condition. See inherited genetic testing for pancreatic cancer.
Could I receive immunotherapy?
Your team considers the tumour findings, the cancer’s extent, previous treatments, other treatment options, and your health. Access also depends on the applicable treatment and funding criteria, which are set by each cancer program.
As one example: BC Cancer’s published protocol for pembrolizumab in dMMR/MSI-H solid tumours covers unresectable or metastatic disease, at least one previous therapy, no satisfactory alternative treatment options, and approval through its Compassionate Access Program. Those are BC-specific criteria — not a national promise of eligibility. A matching test result does not by itself mean you qualify, and criteria differ between provinces and change over time. Ask your treating program about the criteria that apply to you.
What might treatment achieve?
Some people with suitable tumour findings may respond to immunotherapy, but a matching result does not guarantee a response. The pancreatic cancer evidence involves relatively small groups, so results from studies combining many cancer types should not be read as pancreatic-specific outcomes. Your team can explain the evidence and uncertainty for your circumstances.
Side effects and when to contact your team
Immunotherapy side effects differ from chemotherapy’s, and the safety information that matters is specific to the medicine you receive. Before treatment, ask for written information about your medicine, the symptoms requiring urgent attention, and whom to contact at any time of day. Two things are worth knowing in advance: symptoms can also appear after treatment has ended, and you should tell other healthcare providers — including dentists and emergency staff — that you have received immunotherapy.
Immunotherapy in clinical trials
Other immunotherapy approaches and combinations are being studied in clinical trials. A treatment offered in a trial should not be presented as established care simply because it is described as immunotherapy. Explore clinical trials and the other treatment options →
Questions to ask your care team
- Has my tumour been tested for dMMR or MSI-H?
- What does the result mean — and what does it not tell us?
- Do I need inherited genetic testing as well?
- Is immunotherapy clinically appropriate in my situation?
- What access or funding criteria apply?
- What are the alternatives?
- Which side effects require an urgent call?
- Is there an appropriate clinical trial?
Related guides
Sources
- MyPathologyReport (Canadian) — Mismatch repair (MMR) and microsatellite instability (MSI) in gastrointestinal cancers
- BC Cancer — Protocol: pembrolizumab for dMMR/MSI-H solid tumours
- American Cancer Society — Immunotherapy for pancreatic cancer
- Canadian Cancer Society — Treatments for pancreatic cancer
Last reviewed: October 24, 2026