The information on this website is not intended for diagnosis or treatment. Please consult your physician for health concerns.

+90 850 321 50 00

Pembrolizumab Immunotherapy: PD-1 Checkpoint Inhibitor

Mechanism, indications and management of immune-related adverse events

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Onkoloji department. Book Appointment →

What is Pembrolizumab Immunotherapy: PD-1 Checkpoint Inhibitor?

Pembrolizumab is an IgG4 humanized monoclonal antibody targeting the PD-1 receptor on T lymphocytes.

By blocking PD-1 it prevents PD-L1/PD-L2 ligands from suppressing the immune response, allowing T cells to recognize and kill tumor cells.

It is administered intravenously every 3 or 6 weeks at fixed doses (200 mg q3w or 400 mg q6w).

Approved indications include melanoma, NSCLC, classical Hodgkin lymphoma, urothelial carcinoma, MSI-H/dMMR cancers, gastric cancer, cervical and triple-negative breast cancer.

Tumor PD-L1 expression, MSI/dMMR status and tumor mutational burden are key biomarkers guiding patient selection.

Symptoms

Common side effects include fatigue, pruritus, rash, diarrhea, decreased appetite and arthralgia.
Immune-related adverse events may affect any organ: pneumonitis, colitis, hepatitis, endocrinopathies (thyroiditis, hypophysitis, type 1 diabetes), nephritis, dermatitis.
Rare but severe events include myocarditis, encephalitis, Guillain-Barre-like neuropathy and severe cutaneous reactions.
Symptoms can occur during treatment, between cycles or even months after stopping therapy and require prompt evaluation.
Infusion reactions are uncommon but should be monitored during the first administrations.

Risk Factors

Pre-existing autoimmune disease increases the risk of severe immune-related toxicity.
Prior thoracic radiotherapy or interstitial lung disease raises the risk of pneumonitis.
Concomitant use of high-dose corticosteroids or strong immunosuppressants may reduce efficacy.
Active hepatitis B/C infection should be evaluated and managed before starting.
Older age, performance status and organ comorbidities may influence tolerability and outcomes.

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • New onset shortness of breath, persistent dry cough or chest pain may indicate immune pneumonitis.
  • Diarrhea more than 4 stools above baseline, abdominal pain, blood in stool or mucus may signal immune colitis.
  • Yellowing of skin or eyes, dark urine or right upper quadrant pain suggests hepatitis.
  • Severe fatigue, hypotension, hyponatremia, polyuria and polydipsia raise concern for endocrine toxicity.
  • Skin blistering, mucosal involvement, neurological symptoms or chest pain warrant immediate emergency evaluation.

Treatment Methods

01
Mild (Grade 1) immune-related events are managed with symptomatic care while continuing pembrolizumab under close monitoring.
02
Moderate (Grade 2) events typically require treatment interruption and oral prednisone 0.5-1 mg/kg/day with slow taper.
03
Severe (Grade 3-4) toxicities need permanent discontinuation, high-dose corticosteroids 1-2 mg/kg/day and possible second-line immunosuppression (infliximab, mycophenolate, vedolizumab).
04
Endocrinopathies often require lifelong hormone replacement (levothyroxine, hydrocortisone, insulin) without need to permanently stop pembrolizumab.
05
Multidisciplinary management with oncology, organ-specialty teams and intensive monitoring of biomarkers and imaging is essential to balance efficacy and safety.

Which Department to Visit?

You can visit our Onkoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Onkoloji Department

Let us help you

You can make an appointment with our specialists or contact us for your concerns.

Book AppointmentContact Us

Related Health Topics

Other articles from the same department you may want to explore.

Anaemia

Dahiliye (İç Hastalıkları)

Anaemia is a low haemoglobin level that reduces oxygen delivery, causing fatigue, pallor, and shortness of breath. It is not a disease itself but a sign of many underlying conditions. Most cases are correctable with appropriate diagnosis and treatment.

Iron Deficiency Anaemia

Dahiliye (İç Hastalıkları)

Iron deficiency anaemia develops when dietary intake, absorption, or losses create an iron shortfall, most often affecting women and children. Identifying the underlying cause is the core of management, alongside iron replacement.

Vitamin B12 Deficiency

Dahiliye (İç Hastalıkları)

Vitamin B12 deficiency can cause megaloblastic anaemia, neurological symptoms, and cognitive impairment. Early treatment with intramuscular or oral B12 largely prevents irreversible complications.

Hypertension (High Blood Pressure) Management

Dahiliye (İç Hastalıkları)

Hypertension is often called the silent killer because it progresses symptom-free for years and can damage the heart, brain, kidneys, and eyes. Regular monitoring, lifestyle change, and evidence-based drug therapy dramatically reduce cardiovascular risk.

Chronic Kidney Disease

Dahiliye (İç Hastalıkları)

Chronic kidney disease is one of the most common complications of chronic conditions such as diabetes and hypertension, and can be silent in its early stages.

Hepatitis B (HBV)

Dahiliye (İç Hastalıkları)

Hepatitis B is a DNA virus infection causing acute and chronic hepatitis with risk of cirrhosis and hepatocellular carcinoma; diagnosis integrates HBsAg, HBeAg, anti-HBc, and HBV DNA with management based on disease phase using nucleos(t)ide analogues (entecavir, tenofovir) and universal infant vaccination.

Hepatitis C (HCV)

Dahiliye (İç Hastalıkları)

Hepatitis C is an RNA virus causing chronic hepatitis that may progress to cirrhosis and hepatocellular carcinoma; modern direct-acting antiviral (DAA) pangenotypic regimens (sofosbuvir/velpatasvir, glecaprevir/pibrentasvir) achieve sustained virologic response over 95% in 8–12 weeks with universal adult screening and cure for nearly all patients.

Fatty Liver Disease

Dahiliye (İç Hastalıkları)

Non-alcoholic fatty liver disease (NAFLD) is closely related to obesity and metabolic syndrome and is largely reversible with early treatment.

Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.