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Plain-English Medicine Reference

What is Pembrolizumab?
Cancer Drug & Side-Effect Explainer

Concise, easy-to-understand explanations of how your cancer drug works, what side effects to expect, and which warning signs require immediate medical attention. Not medical advice — designed for patient empowerment.

Educational summary only: This reference is prepared to help you understand medical discussions with your oncologist. It is not a substitute for clinical advice. Always consult your oncology team regarding your personal treatment plan and symptoms.

PD-1 Immunotherapy

Pembrolizumab (Brand: Keytruda)

How It Works

An immunotherapy that turns off the 'brakes' on your immune cells (T-cells), empowering them to identify and destroy cancer cells across melanoma, lung, breast, and bladder cancers.

Ask Your Oncologist:

What baseline blood tests (thyroid, liver, kidney) are required before each infusion?

Common Expected Effects
  • Feeling more tired than usual (fatigue)
  • Mild skin itching or rash
  • Slight loss of appetite or mild nausea
  • Aching joints or muscles
Red Flags (Call Doctor)
  • New or worsening dry cough / shortness of breath (pneumonitis)
  • Severe or persistent watery diarrhea with abdominal cramping (colitis)
  • Yellowing of skin or whites of eyes (hepatitis)
  • Severe headache or unusual extreme hormone exhaustion (hypophysitis)
PD-1 Immunotherapy

Nivolumab (Brand: Opdivo)

How It Works

A humanized monoclonal antibody designed to block the PD-1 immune checkpoint, restoring the body's natural anti-tumor immunity in lung, renal, and gastrointestinal cancers.

Ask Your Oncologist:

Should I keep oral corticosteroids at home in case of an immune-related flare-up?

Common Expected Effects
  • Mild tiredness or sleepiness
  • Musculoskeletal aches
  • Minor rash or dry skin patches
  • Mild nausea or constipation
Red Flags (Call Doctor)
  • Unexplained fever or chills
  • Persistent loose stools (>4-6 times per day)
  • Sudden vision changes or severe eye irritation
  • Severe numbness or tingling in hands and feet
HER2 Targeted Antibody

Trastuzumab (Brand: Herceptin)

How It Works

A targeted therapy that locks onto HER2 receptors overexpressed on certain breast and stomach cancer cells, halting rapid cell division and alerting immune cells to target the tumor.

Ask Your Oncologist:

When is my next echocardiogram (ECHO/MUGA) scheduled to monitor my heart function?

Common Expected Effects
  • Mild headache or muscle aches after infusion
  • Nosebleeds or runny nose
  • Mild gastrointestinal upset or diarrhea
  • Sleep difficulty or mild fatigue
Red Flags (Call Doctor)
  • Swelling in ankles, legs, or feet (fluid retention/cardiac stress)
  • Sudden shortness of breath while lying flat in bed
  • Irregular, fluttering, or unusually rapid heartbeat
  • Severe fever or chest pain during or immediately post-infusion
VEGF Angiogenesis Inhibitor

Bevacizumab (Brand: Avastin)

How It Works

A targeted protein that blocks VEGF, starving tumors of the microscopic new blood vessels they need to receive oxygen, nutrients, and grow.

Ask Your Oncologist:

How frequently should I log my blood pressure readings at home between visits?

Common Expected Effects
  • Mild elevation in routine blood pressure
  • Frequent minor nosebleeds or dry nasal passages
  • Minor protein found in routine urine tests
  • Taste alterations or dry mouth
Red Flags (Call Doctor)
  • Severe, throbbing headache with blurry vision (severe blood pressure spike)
  • Coughing up blood or heavy gastrointestinal bleeding
  • Sudden severe abdominal pain (risk of gastrointestinal perforation)
  • Poor wound healing after surgical procedures or dental extractions
EGFR Tyrosine Kinase Inhibitor

Osimertinib (Brand: Tagrisso)

How It Works

A third-generation oral targeted tablet for non-small cell lung cancer with specific EGFR gene mutations (including T790M), stopping cancer growth signals inside the cell.

Ask Your Oncologist:

What moisturizing creams or antibiotics do you recommend for EGFR skin and nail rash?

Common Expected Effects
  • Dry skin, acne-like skin rash on face/back
  • Nail changes, tenderness around nail beds (paronychia)
  • Mild intermittent diarrhea
  • Minor mouth sores or dry eyes
Red Flags (Call Doctor)
  • Sudden worsening difficulty breathing or dry persistent cough (interstitial lung disease)
  • Dizziness, lightheadedness, or feeling like your heart is racing (QT prolongation)
  • Rapid eye pain, severe redness, or light sensitivity (corneal ulcer)
Immunomodulatory Agent

Lenalidomide (Brand: Revlimid)

How It Works

An oral targeted therapy used primarily for multiple myeloma and myelodysplastic syndromes, helping the immune system attack abnormal plasma cells and blocking blood vessel growth in the bone marrow.

Ask Your Oncologist:

Do I need to take a daily aspirin or blood thinner to prevent blood clots while taking Revlimid?

Common Expected Effects
  • Mild constipation or diarrhea
  • Tiredness or weakness
  • Muscle cramps, especially in legs at night
  • Mild skin itching
Red Flags (Call Doctor)
  • Sudden swelling, pain, or warmth in one leg/calf (deep vein thrombosis / blood clot)
  • Sudden chest pain or shortness of breath (pulmonary embolism)
  • High fever, shaking chills, or signs of severe infection (low white blood cell count)
  • Strict caution: Never handle if pregnant or without contraception due to severe birth defects
CDK4/6 Inhibitor

Palbociclib (Brand: Ibrance)

How It Works

An oral targeted capsule that blocks CDK4 and CDK6 enzymes, stopping hormone receptor-positive (HR+) breast cancer cells from replicating and dividing.

Ask Your Oncologist:

When should I get my blood count (CBC) checked during the first 2 cycles?

Common Expected Effects
  • Low white blood cell counts (neutropenia - usually asymptomatic)
  • General tiredness
  • Mild nausea or hair thinning
  • Mild mouth irritation
Red Flags (Call Doctor)
  • Any fever of 38°C (100.4°F) or above with chills (neutropenic infection emergency)
  • Persistent chest congestion or dry cough
  • Unusual bruising or bleeding gums
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Frequently Asked Questions

Chemotherapy directly attacks rapidly multiplying cells (both cancer cells and healthy cells like hair follicles and stomach lining). Immunotherapy (like Pembrolizumab or Nivolumab) does not directly kill cells; it re-trains your immune system to detect and destroy cancer naturally, which creates different types of side effects.