IMMUNE CHECKPOINT INHIBITORS: PD-1,
PD-L1, AND CTLA-4 THERAPY
Prepared by the CancerFax oncology navigation team. Updated regularly based on treatment access and clinical availability.
What Immune Checkpoint Inhibitors Are
Cancer cells often evade the immune system by activating βcheckpointβ proteins that switch off T cells. Checkpoint inhibitors are antibodies that block these signals, allowing T cells to recognise and attack the cancer. Three checkpoint targets are well established: Newer checkpoints such as LAG-3 (relatlimab, used with nivolumab in melanoma) are now part of approved combinations, with TIGIT and other targets under study. These therapies may be used as single agents, in dual checkpoint combinations (such as ipilimumab plus nivolumab), with chemotherapy, with targeted therapy, before or after surgery, or alongside radiation in selected cases.
PD-1 (Programmed Death-1) β found on T cells. Blocked by pem
PD-1 (Programmed Death-1) β found on T cells. Blocked by pembrolizumab (Keytruda), nivolumab (Opdivo), cemiplimab (Libtayo), dostarlimab, and several China-approved agents such as tislelizumab, sintilimab, toripalimab, and camrelizumab.
PD-L1 (PD-1 Ligand) β found on tumour and immune cells. Targ
PD-L1 (PD-1 Ligand) β found on tumour and immune cells. Targeted by atezolizumab (Tecentriq), durvalumab (Imfinzi), and avelumab (Bavencio).
CTLA-4 β an earlier checkpoint controlling T cell activation
CTLA-4 β an earlier checkpoint controlling T cell activation. Ipilimumab (Yervoy) is the main drug; tremelimumab is approved in selected settings.
Cancers Where They May Be Considered
Approved or commonly studied indications include: Indication, line of therapy, and biomarker thresholds differ by country and drug.
Melanoma, including adjuvant after surgery
Melanoma, including adjuvant after surgery
Non-small cell and small cell lung cancer
Non-small cell and small cell lung cancer
Renal cell carcinoma
Renal cell carcinoma
Bladder and urothelial cancers
Bladder and urothelial cancers
Head and neck squamous cell carcinoma
Head and neck squamous cell carcinoma
Hepatocellular carcinoma (liver)
Hepatocellular carcinoma (liver)
Gastric, gastroesophageal junction, and oesophageal cancers
Gastric, gastroesophageal junction, and oesophageal cancers
Hodgkin lymphoma and selected other lymphomas
Hodgkin lymphoma and selected other lymphomas
Triple-negative breast cancer
Triple-negative breast cancer
Cervical and endometrial cancers
Cervical and endometrial cancers
Mesothelioma, Merkel cell carcinoma, and cutaneous squamous
Mesothelioma, Merkel cell carcinoma, and cutaneous squamous cell carcinoma
Any solid tumour with MSI-H, dMMR, or high TMB status
Any solid tumour with MSI-H, dMMR, or high TMB status
Who May Be Suitable
Eligibility depends on multiple clinical factors: Some cancers are treated regardless of PD-L1 expression (such as MSI-H tumours and many melanomas), while others require specific thresholds β for example, first-line PD-1 monotherapy in NSCLC typically requires PD-L1 β₯ 50% under most guidelines.
Confirmed cancer type, stage, and disease status
Confirmed cancer type, stage, and disease status
Biomarker testing β PD-L1 IHC (CPS, TPS, or IC), MSI/dMMR, a
Biomarker testing β PD-L1 IHC (CPS, TPS, or IC), MSI/dMMR, and TMB where relevant
Previous treatment history and response
Previous treatment history and response
Performance status and overall fitness
Performance status and overall fitness
Organ function β liver, kidney, lung, heart
Organ function β liver, kidney, lung, heart
Absence of active autoimmune disease (often a relative contr
Absence of active autoimmune disease (often a relative contraindication)
Stable hepatitis B, C, or HIV status if present
Stable hepatitis B, C, or HIV status if present
Not on high-dose immunosuppressive therapy
Not on high-dose immunosuppressive therapy
Not pregnant or breastfeeding
Not pregnant or breastfeeding
Documents Usually Required for Review
The completeness of these reports often determines how quickly a meaningful treatment plan can be built.
Latest medical summary and oncologistβs opinion
Latest medical summary and oncologistβs opinion
Pathology and IHC reports
Pathology and IHC reports
PD-L1 IHC report (CPS, TPS, or IC, depending on cancer)
PD-L1 IHC report (CPS, TPS, or IC, depending on cancer)
MSI / dMMR testing report
MSI / dMMR testing report
Tumour mutation burden (TMB) and NGS report, if available
Tumour mutation burden (TMB) and NGS report, if available
Hepatitis B, C, and HIV status
Hepatitis B, C, and HIV status
Autoimmune disease history, thyroid function, and cortisol w
Autoimmune disease history, thyroid function, and cortisol where relevant
PET CT, CT, or MRI reports
PET CT, CT, or MRI reports
Recent CBC, liver and kidney function tests
Recent CBC, liver and kidney function tests
Treatment history with dates, drugs, and response
Treatment history with dates, drugs, and response
ECG and echocardiogram if cardiac history
ECG and echocardiogram if cardiac history
Current medication list
Current medication list
How CancerFax Helps
CancerFax supports patients exploring immune checkpoint inhibitor therapy through a structured pathway:
Case review β diagnosis, biomarkers, prior treatments, and c
Case review β diagnosis, biomarkers, prior treatments, and current status are reviewed to assess whether checkpoint inhibitor therapy is realistic.
Drug and protocol mapping β relevant approved options, biosi
Drug and protocol mapping β relevant approved options, biosimilars, and combination protocols are identified across countries such as China, India, Germany, the United States, and others.
Hospital and trial matching β reports are shared with approp
Hospital and trial matching β reports are shared with appropriate oncology teams or trial centres for structured feedback.
Cost and logistics planning β patients receive guidance on d
Cost and logistics planning β patients receive guidance on drug pricing, expected cycles, total duration, accommodation, and stay requirements.
Coordination and follow-up β CancerFax supports admission, i
Coordination and follow-up β CancerFax supports admission, interpreter needs, monitoring schedules, and continuity after returning home.
Important Limitations and Side Effects
Immune checkpoint inhibitors can cause immune-related adverse events (irAEs) because the same immune activation that fights cancer can also affect healthy organs: Most irAEs are manageable with steroids and treatment hold, but some are serious and a few can be life-threatening. Combination CTLA-4 plus PD-1 therapy carries higher rates of significant toxicity than monotherapy. Side effects may also occur weeks or months after stopping treatment. Response rates vary widely by cancer type and biomarker status, and outcomes cannot be guaranteed.
Skin β rash, itching
Skin β rash, itching
Gastrointestinal β colitis, diarrhoea
Gastrointestinal β colitis, diarrhoea
Lung β pneumonitis
Lung β pneumonitis
Liver β hepatitis
Liver β hepatitis
Endocrine β thyroid disorders, hypophysitis, adrenal insuffi
Endocrine β thyroid disorders, hypophysitis, adrenal insufficiency, type 1 diabetes
Kidney β nephritis
Kidney β nephritis
Heart β rare but serious myocarditis
Heart β rare but serious myocarditis
Neurologic β encephalitis and neuropathy in rare cases
Neurologic β encephalitis and neuropathy in rare cases
Where This May Be Available
Checkpoint inhibitor therapy is now available in most major cancer centres across the United States, Europe, Japan, China, India, Singapore, and other regions, although approved indications and biomarker thresholds vary by country. CancerFax is most useful when a specific indication is not approved locally, when a patient is seeking a combination protocol or biomarker-guided regimen unavailable at home, when affordable Chinese-manufactured PD-1 inhibitors may help with long-term cost, or when newer combinations involving LAG-3, TIGIT, or trial-only agents are being considered. The right hospital and protocol matter as much as the country.
Frequently Asked Questions
Answers to common questions from patients and families.
Are immune checkpoint inhibitors a cure?
For some patients with cancers like melanoma, MSI-H tumours, and certain lung cancers, checkpoint inhibitors can produce long-lasting remissions, sometimes lasting many years. However, response cannot be guaranteed, many patients do not respond, and some develop resistance over time. The outcome depends heavily on cancer type, biomarker status, and overall health. These therapies should be viewed as a meaningful option for selected patients, not a universal cure.
How do I know if I am eligible?
Eligibility is based on cancer type, stage, biomarker testing (PD-L1, MSI-H/dMMR, TMB), prior treatments, organ function, and autoimmune history. A complete medical record review is needed before any decision. CancerFax helps patients assemble the necessary reports and obtain structured second opinions from suitable oncologists, but eligibility must always be confirmed by the treating team.
What is the difference between PD-1 and PD-L1 inhibitors?
PD-1 inhibitors block the receptor on T cells, while PD-L1 inhibitors block the partner protein on tumour and immune cells. Both interrupt the same braking signal. Clinically they are often comparable, but specific drugs are approved for specific cancers and lines of therapy. The choice depends on the cancer type, biomarker, country approvals, and the treating oncologistβs protocol.
Why do some cancers need PD-L1 testing and others do not?
PD-L1 expression predicts response in some cancers (such as NSCLC first-line monotherapy and gastric cancer) but not in others (such as melanoma or MSI-H tumours, where benefit is seen regardless of PD-L1). Approval and reimbursement rules also differ by country. The treating team will advise which biomarker tests are clinically relevant for a given case.
How long does treatment continue?
Most patients receive checkpoint inhibitors for up to one or two years, sometimes longer, until disease progression or significant side effects. Some adjuvant protocols (after surgery) have fixed durations, often around one year. Treatment is sometimes stopped earlier if a strong, durable response is seen. Decisions about stopping or continuing are made by the treating oncologist based on response and tolerance.
Can checkpoint inhibitors be combined with other treatments?
Yes. Checkpoint inhibitors are often combined with chemotherapy (in lung, breast, gastric, and other cancers), with targeted therapy (in kidney and liver cancers), with another checkpoint inhibitor (CTLA-4 with PD-1 in melanoma and kidney cancer), and sometimes with radiation. Combinations can improve outcomes but also increase side effect risk. The right combination depends on the cancer type, biomarker, and patient condition.
How CancerFax Helps
CancerFax is a specialist cancer access and patient-navigation platform. We help patients and families understand their options, organise medical records, coordinate hospital communication, and support cross-border treatment planning where appropriate.
We help collect and organise reports, scans, pathology, biomarker results, and treatment history for structured case review.
We communicate with hospitals or trial teams to assess whether a case may be suitable for further screening.
We support appointment coordination, document submission, translation, and direct communication with international departments.
For international patients, we help with practical coordination β travel planning, hospital admission guidance, and local support.
If this option is not suitable, we help explore other relevant treatments, clinical trials, or advanced care pathways.
From inquiry through to follow-up, our coordinators provide a single point of contact for the family.
CancerFax does not guarantee treatment access, eligibility, or clinical outcome. Our role is to help patients access accurate information, structured review, and appropriate specialist pathways.
Need Help Understanding Your Options?
If you or a family member is exploring immune checkpoint inhibitor therapy, CancerFax can help organise the medical records, review biomarker reports, and connect the case with suitable oncologists, hospitals, or clinical trial teams. Share your reports to receive structured guidance before making travel or treatment decisions. CTAs: Share Your Reports | Request a Second Opinion | Explore Clin
This content is for informational purposes only and does not constitute medical advice. Always consult a qualified oncologist before making treatment decisions.