Mismatch repair deficient (MSI-high) pancreatic ductal adenocarcinoma: the decisions you may face
4 treatment settings, 2 with more than one named option. Each section lays out the options the standard of care names, what each is for, the trials behind them with their recorded results, the side effects and cautions on record, and questions to ask. Built from the cancer page's standard-of-care rows; nothing here is advice for your case.
Testing
Mismatch repair immunohistochemistry or microsatellite instability testing for every pancreatic adenocarcinoma at diagnosis, with germline testing for Lynch syndrome when deficient.
A test of the DNA you were born with, to find inherited risk genes such as BRCA or Lynch syndrome.
- Actionable for patient and relatives
- Cheap
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
- VUS burden
- Uptake and counselling capacity
- Is Germline (hereditary) testing the only reasonable path for me, or is there a trial, a different sequence or a wait-and-see option?Why: A single standard does not mean a single choice; timing and trials are decisions too.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Pancreatic Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (testing), which of the standard options do you recommend and why?Why: Guideline options include: Mismatch repair immunohistochemistry or microsatellite instability testing for every pancreatic adenocarcinoma at diagnosis, with germline testing for Lynch syndrome when deficient.
Add these to your appointment list, or take the full question set for this cancer.
Advanced, first line
Chemotherapy as for other pancreatic adenocarcinoma; pembrolizumab first line for patients unfit for chemotherapy or in trials.
FOLFIRINOX is a four-drug chemotherapy combination that, in 2011, became the first treatment to meaningfully extend life in metastatic pancreatic cancer; it is now the standard before and after surgery.
Gemcitabine plus nab-paclitaxel is the gentler of the two standard chemotherapy backbones for pancreatic cancer, and the base on which most new drugs are being tested.
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients | 8% | - |
| Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 3.4% | - |
| Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 1.7% | - |
| Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 0.7% | - |
- No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Between FOLFIRINOX / mFOLFIRINOX, Gemcitabine + nab-paclitaxel and Pembrolizumab, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- Which side effects of Pembrolizumab are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Pancreatic Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (advanced, first line), which of the standard options do you recommend and why?Why: Guideline options include: Chemotherapy as for other pancreatic adenocarcinoma; pembrolizumab first line for patients unfit for chemotherapy or in trials.
- Am I a candidate for FOLFIRINOX / mFOLFIRINOX, Gemcitabine + nab-paclitaxel, Pembrolizumab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Add these to your appointment list, or take the full question set for this cancer.
Advanced, after chemotherapy
Pembrolizumab (tumour-agnostic approval, KEYNOTE-158 pancreatic cohort) or dostarlimab (tumour-agnostic approval for mismatch repair deficient solid tumours).
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
Dostarlimab is a PD-1 blocker famous for making rectal cancer disappear without surgery in every patient with a mismatch-repair-deficient tumour.
Immune checkpoint inhibitors are antibodies against CTLA-4, PD-1 or PD-L1 that release the brakes on T cells so they attack the cancer. They are approved in more than 20 tumour types and produce lasting, sometimes curative responses that chemotherapy rarely does, but most patients do not respond and autoimmune side effects are the cost.
- Durable, sometimes curative responses
- Broad applicability
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients | 8% | - |
| Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 3.4% | - |
| Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 1.7% | - |
| Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 0.7% | - |
- No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Most patients do not respond
- Autoimmune toxicity
- Biomarkers are imperfect
- Between Pembrolizumab, Dostarlimab and Immune checkpoint inhibitors, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- Which side effects of Pembrolizumab are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Pancreatic Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (advanced, after chemotherapy), which of the standard options do you recommend and why?Why: Guideline options include: Pembrolizumab (tumour-agnostic approval, KEYNOTE-158 pancreatic cohort) or dostarlimab (tumour-agnostic approval for mismatch repair deficient solid tumours).
- Am I a candidate for Pembrolizumab, Dostarlimab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Add these to your appointment list, or take the full question set for this cancer.
Resectable
Surgery and adjuvant chemotherapy as for other pancreatic adenocarcinoma; neoadjuvant immunotherapy only in trials.
FOLFIRINOX is a four-drug chemotherapy combination that, in 2011, became the first treatment to meaningfully extend life in metastatic pancreatic cancer; it is now the standard before and after surgery.
- Tests FOLFIRINOX / mFOLFIRINOXAdjuvant therapy after resection of PDAC: mFOLFIRINOX vs gemcitabine
OS 54.4 vs 35.0 months, HR 0.64.
Disease-free survival (months): Adjuvant mFOLFIRINOX 21.6 (n=247) vs Adjuvant gemcitabine 12.8 (n=246) · HR 0.58 · source
No side-effect rates or interaction flags are recorded for these options yet. The side-effect lookup and interaction checker cover the products that have them.
- Is FOLFIRINOX / mFOLFIRINOX the only reasonable path for me, or is there a trial, a different sequence or a wait-and-see option?Why: A single standard does not mean a single choice; timing and trials are decisions too.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in PRODIGE 24 / CCTG PA6, and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Pancreatic Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (resectable), which of the standard options do you recommend and why?Why: Guideline options include: Surgery and adjuvant chemotherapy as for other pancreatic adenocarcinoma; neoadjuvant immunotherapy only in trials.
- Am I a candidate for FOLFIRINOX / mFOLFIRINOX, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of PRODIGE 24 / CCTG PA6 apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Add these to your appointment list, or take the full question set for this cancer.