Cemiplimab (Libtayo) — PD-1 immunotherapy for cancer treatment

What is cemiplimab (Libtayo) in simple words

Cemiplimab, sold as Libtayo, is an immunotherapy drug. It belongs to the PD-1 inhibitor group.

It is not chemotherapy. It does not attack cancer cells in the usual direct way. Instead, it helps immune cells stop ignoring a tumour that has learned to hide.

That is the simple version. The real decision is more careful: cancer type, stage, PD-L1 testing in lung cancer, previous treatment and the patient’s condition all have to fit.

How cemiplimab works

PD-1 is a checkpoint on T-cells. In normal life it helps prevent the immune system from overreacting. Cancer can misuse that checkpoint.

Some tumours send a “slow down” signal to T-cells. Cemiplimab blocks PD-1, so the immune response may stay active against the tumour.

I never explain this as “the immune system will definitely kill the cancer”. It may respond. It may stabilise. Sometimes it does not work. The biology decides more than the drug name.

What conditions cemiplimab is used for

Cemiplimab is mainly considered in several defined settings:

• metastatic or locally advanced cutaneous squamous cell carcinoma when curative surgery or radiation is not suitable;

• adjuvant treatment for selected high-risk cutaneous squamous cell carcinoma after surgery and radiation;

• locally advanced or metastatic basal cell carcinoma after a hedgehog pathway inhibitor, or when that treatment cannot be tolerated;

• advanced non-small cell lung cancer after PD-L1 and driver mutation testing;

• recurrent or metastatic cervical cancer after progression on platinum-based chemotherapy.

The diagnosis alone is not enough. A patient with a small resectable skin cancer and a patient with an ulcerated tumour invading deeper tissues are not the same clinical problem.

When cemiplimab may be especially relevant

Libtayo usually enters the discussion when a local solution is either impossible, too damaging, or no longer enough.

The most common situations are:

• advanced cutaneous squamous cell carcinoma on the face, scalp, ear or other difficult areas;

• metastatic CSCC, including nodal or distant spread;

• high-risk CSCC after surgery and radiotherapy, where relapse risk remains clinically important;

• basal cell carcinoma that has progressed after hedgehog inhibitor treatment;

• first-line advanced NSCLC with suitable PD-L1 expression and no EGFR, ALK or ROS1 driver alteration;

• recurrent or metastatic cervical cancer after platinum-based treatment.

In skin cancer, the photographs and the physical exam can matter as much as the scan. Pain, bleeding, infection, wound depth, smell, and whether the tumour is still operable all change the discussion.

What needs to be checked before starting treatment

Before starting cemiplimab, an oncologist will usually review:

• biopsy and exact histological diagnosis;

• current stage of the disease;

• CT, MRI or PET-CT results;

• PD-L1 testing in non-small cell lung cancer;

• EGFR, ALK, ROS1 and other driver mutations when lung cancer is involved;

• previous surgery, radiation, chemotherapy, targeted therapy or immunotherapy;

• full blood count and blood chemistry;

• liver, kidney and thyroid function;

• autoimmune disease history;

• organ transplant history;

• performance status and daily function.

This is where a good second opinion often helps. The question is not only whether Libtayo is allowed. The question is whether it is the best next move for this particular case.

How treatment is carried out

Cemiplimab is given as an intravenous infusion. The schedule depends on the approved regimen and the treatment plan; in many protocols it is given once every few weeks.

During treatment, the team watches for both cancer response and immune toxicity. Usual monitoring includes:

• blood counts and chemistry;

• liver enzymes and bilirubin;

• kidney function;

• thyroid tests;

• new cough or breathing changes;

• bowel changes;

• skin reactions;

• CT or PET-CT response assessment.

With visible skin tumours, I also ask patients what has changed at home. Less bleeding, less pain, fewer dressings, or a cleaner wound can be meaningful even before the formal radiology report.

Possible side effects

The side effects are different from classic chemotherapy. Hair loss and low white blood cells are not usually the central problem. Immune inflammation is.

Possible side effects include:

• fatigue;

• itching, rash or dry skin;

• diarrhoea or colitis;

• cough or pneumonitis;

• nausea or appetite loss;

• muscle or joint pain;

• changes in thyroid, adrenal or pituitary function;

• hepatitis, nephritis or other immune-related inflammation;

• infusion reactions, which are less common but possible.

Most problems are manageable when they are caught early. The dangerous ones are often the symptoms a patient tried to “watch for a few more days”.

When to contact a doctor urgently

Call the treating team promptly if any of the following appear:

• new or worsening shortness of breath;

• a cough that is persistent or getting stronger;

• diarrhoea that is frequent, painful or contains blood;

• fever above 38°C;

• yellowing of the skin or eyes;

• severe abdominal pain;

• new confusion, severe headache or vision changes;

• extreme weakness;

• wide rash, blisters or peeling skin;

• a sudden drop in general condition.

With checkpoint inhibitors, early reporting is not “being nervous”. It is part of safe treatment.

Why cemiplimab is not right for everyone

Cemiplimab can be a very good option in the right patient. It can also be the wrong option in the wrong setting.

Reasons to be cautious include:

• an actionable driver mutation where targeted therapy is more appropriate;

• biomarker results that do not support the intended lung cancer regimen;

• active autoimmune disease;

• previous organ transplant;

• poor performance status;

• serious lung, liver, kidney or heart problems;

• rapidly worsening disease that needs a different immediate approach.

Transplant history deserves a separate conversation. PD-1 blockade can activate T-cells against cancer, but it can also increase the risk of organ rejection. That is never a quick yes or no.

Can cemiplimab be combined with other treatments

Yes, but only where evidence supports it. In advanced NSCLC, cemiplimab may be used alone or with platinum-based chemotherapy depending on PD-L1 expression and mutation status.

In skin cancers, cemiplimab is often used alone, while surgery, radiation or wound care may still be part of the wider plan. The order matters. So does the patient’s reserve.

I do not like the idea of adding treatments just to make the plan look stronger. The combination has to answer a real clinical need.

What “no quick response” to treatment means

Immunotherapy is not always dramatic at the start. A patient may have two or three infusions and still feel unsure whether anything is happening.

Sometimes the first useful sign is not shrinkage. It may be slower growth, less bleeding, less pain, or a scan that finally stops getting worse.

At the same time, waiting has limits. If symptoms are clearly worsening or imaging shows true progression, the oncologist should not keep treatment going out of habit.

Oncology consultation for cemiplimab (Libtayo) in Israel

At Tel Aviv Medical Clinic in Israel, patients can discuss whether cemiplimab (Libtayo) fits their diagnosis, stage and biomarker results. This is often useful in advanced skin cancer, lung cancer with several molecular results, cervical cancer after platinum treatment, previous immunotherapy exposure, autoimmune disease, or a difficult surgical decision.

A consultation may help to:

• check whether Libtayo is relevant for the exact cancer type;

• review PD-L1 and mutation testing;

• compare immunotherapy with surgery, radiation, chemotherapy or targeted therapy;

• get a second opinion before starting treatment;

• discuss immune-related risks;

• prepare the right questions for the treating oncologist.

We do not prescribe treatment remotely or replace the treating physician. We help make the reasoning clear.

Frequently Asked Questions — Dr. Stefanskoy

1. Is Libtayo the same as Keytruda or Opdivo?

It is from the same general family. Libtayo, Keytruda and Opdivo all work through the PD-1 pathway. The difference is in the approved indications, the trial data and the clinical situation. I would not swap them casually just because they sound similar.

2. Why is cemiplimab important in cutaneous squamous cell carcinoma?

Because some CSCC tumours are not small skin problems anymore. They can invade, bleed, recur after surgery or spread to lymph nodes. In that setting, cemiplimab may offer systemic control when surgery or radiation alone is not enough.

3. Does every patient need PD-L1 testing?

Not every patient. In lung cancer, PD-L1 is a key part of the decision. In CSCC and BCC, the decision is usually based more on the cancer type, stage, operability and previous treatment. The test that matters depends on the diagnosis.

4. How quickly should Libtayo work?

I do not promise a quick response. Some patients show change after several cycles. Others first show stabilisation. With skin tumours, I look at bleeding, pain, wound condition and daily comfort, not just centimetres on a report.

5. Can a patient with autoimmune disease receive Libtayo?

Sometimes, but the risk is higher. I need to know which autoimmune disease, how active it is, what medication the patient takes and whether there were serious flares before. Often another specialist should be involved.

6. What if cemiplimab stops working?

Then we go back to the whole case: cancer type, sites of progression, previous treatments and current condition. The next step may be chemotherapy, targeted therapy, radiation, surgery for one active area, or another systemic approach.

7. Is Libtayo easier than chemotherapy?

For some patients, yes. But “easier” can be misleading. Immune toxicity can be serious and sometimes delayed. A new cough, diarrhoea, rash or heavy fatigue should be reported early, even if it seems minor.

Important information

The information on this page is for general medical reference only and does not constitute a treatment recommendation. Cemiplimab (Libtayo) may only be prescribed by an oncologist after full assessment of diagnosis, disease stage, biomarker results, test findings and overall patient condition.

Do not start, stop or change treatment without consulting your treating physician.

To arrange an oncology consultation regarding immunotherapy and the potential use of cemiplimab in Israel:

📞 +972-73-374-6844
📧 [email protected]
💬 WhatsApp: +972-52-337-3108