Qualifying for immunotherapy depends on a combination of factors: your cancer type, specific biomarkers found in your tumor, your overall physical fitness, and in many cases, whether previous treatments have already been tried. There is no single checklist that applies to everyone. Instead, oncologists evaluate several overlapping criteria to determine whether immunotherapy is likely to work for you and whether your body can safely handle it.
Biomarkers That Determine Eligibility
The most important factor in qualifying for immunotherapy is what’s happening at the molecular level inside your tumor. Doctors test for specific biomarkers, biological signals that predict whether your immune system can be effectively activated against cancer cells. Three biomarkers matter most.
PD-L1 expression measures how much of a specific protein appears on the surface of your tumor cells. Cancer cells use this protein to hide from your immune system, and checkpoint inhibitor drugs work by blocking that hiding mechanism. The threshold you need to meet varies by cancer type and situation. In non-small cell lung cancer, for example, a PD-L1 level of 50% or higher can qualify you for immunotherapy as a first-line treatment on its own. A level of 1% or higher may qualify you for immunotherapy combined with chemotherapy, or as a second-line option after chemotherapy has failed. Other cancers measure PD-L1 differently: triple-negative breast cancer looks at immune cells surrounding the tumor rather than the tumor cells themselves, and cervical cancer uses a composite score combining both.
Microsatellite instability (MSI-H) or mismatch repair deficiency (dMMR) refers to a problem in your cells’ ability to fix DNA copying errors. When this repair system is broken, tumors accumulate many mutations, which actually makes them more visible to the immune system and more responsive to immunotherapy. This biomarker is notable because it qualifies patients regardless of where the cancer originated. If your solid tumor tests positive for MSI-H or dMMR and is metastatic or can’t be surgically removed, you may qualify for pembrolizumab no matter the cancer type.
Tumor mutational burden (TMB) counts the total number of mutations in your tumor’s DNA. A score of 10 or more mutations per megabase of DNA sequenced is considered “TMB-high,” and roughly 15% of patients with solid tumors meet this threshold. Like MSI-H, high TMB can qualify you for immunotherapy across cancer types, because more mutations generally mean more targets for your immune system to recognize.
Cancer Types and Stages
Immunotherapy was initially approved only for advanced or metastatic cancers that had stopped responding to other treatments. That landscape has shifted significantly. Checkpoint inhibitors are now approved for dozens of cancer types, including lung, bladder, kidney, melanoma, head and neck, liver, and certain breast and colorectal cancers.
The trend is moving toward earlier-stage disease. The FDA approved nivolumab with chemotherapy before surgery for patients with resectable early-stage non-small cell lung cancer. In late 2024, durvalumab was approved for limited-stage small cell lung cancer in patients whose disease hadn’t progressed after initial chemotherapy and radiation. These approvals mean you no longer need to have advanced cancer to qualify for immunotherapy in certain situations.
Your cancer’s specific molecular profile often matters more than the stage. Two people with the same type and stage of cancer may have completely different eligibility based on their biomarker results.
First-Line Versus Later Treatment
Whether you qualify for immunotherapy as your first treatment or only after other options have failed depends largely on your biomarker levels and cancer type. In non-small cell lung cancer, PD-L1 expression of 50% or higher can qualify you for immunotherapy right away, without trying chemotherapy first. When PD-L1 is between 1% and 49%, immunotherapy is typically combined with chemotherapy as a first-line approach.
For patients whose PD-L1 levels don’t meet first-line thresholds, immunotherapy remains an option after chemotherapy stops working. Multiple checkpoint inhibitors have been shown to improve survival as second-line treatment in advanced lung cancer regardless of PD-L1 status. The same pattern applies across many cancer types: higher biomarker expression opens the door to immunotherapy sooner, while lower expression may mean trying standard chemotherapy first.
Physical Fitness Requirements
Biomarkers alone don’t guarantee eligibility. Your overall physical condition plays a major role. Oncologists use a scale called the ECOG performance status, which rates your daily functioning from 0 (fully active) to 4 (completely bedridden). Most clinical trials that led to immunotherapy approvals enrolled only patients scoring 0 or 1, meaning they were either fully active or restricted in strenuous activity but still able to carry out light work and daily tasks.
A score of 2 or higher, meaning you spend more than half your waking hours out of bed but need help with some self-care, often disqualifies you from standard immunotherapy protocols. This is a significant barrier in practice, because many patients with advanced cancer fall into this category by the time immunotherapy is considered. Some oncologists will still prescribe immunotherapy to patients with a score of 2 on a case-by-case basis, but formal treatment programs and insurance coverage frequently require a score of 1 or better.
You also need adequate organ function. Your liver, kidneys, heart, and lungs need to be working well enough to handle potential side effects, which can include inflammation in virtually any organ system.
Autoimmune Conditions and Immunosuppression
Pre-existing autoimmune diseases complicate immunotherapy eligibility because these drugs work by removing the brakes on your immune system. If your immune system is already attacking your own tissues, amplifying that response carries real risks. Patients with autoimmune conditions have been routinely excluded from the major clinical trials that established immunotherapy’s safety profile.
That said, having an autoimmune condition doesn’t automatically disqualify you. Patients with well-controlled, non-life-threatening autoimmune diseases may still be considered. The key distinctions are severity and type. Conditions like mild psoriasis or well-managed thyroid disease are viewed differently than neurological autoimmune diseases like myasthenia gravis, where a flare could be life-threatening. In studies of patients with pre-existing autoimmune conditions who received immunotherapy, about 62% needed treatment for immune-related side effects, including flares of their underlying condition.
Patients already taking high doses of immunosuppressive medications face a double problem. The immunosuppression may reduce the effectiveness of immunotherapy, and managing new immune-related side effects on top of existing autoimmune treatment becomes significantly more complex.
Age Is Not a Barrier
There is no upper age limit for immunotherapy. In fact, immunotherapy’s side effect profile is generally more tolerable than traditional chemotherapy, making it an attractive option for older patients who struggle with the toxicity of conventional drugs. Elderly patients who respond poorly to chemotherapy or can’t tolerate its side effects may be better candidates for immunotherapy than for standard treatment.
The caveat is that older patients are more likely to have other health conditions that affect eligibility, including reduced organ function, autoimmune diseases, or lower performance status scores. For this reason, many oncologists recommend a comprehensive geriatric assessment before starting immunotherapy in older adults, evaluating not just the cancer but overall health, cognitive function, and daily independence. Combination immunotherapy regimens, which pair two checkpoint inhibitors together, tend to cause more side effects and are less commonly used in older patients even when they show strong results in younger populations.
CAR-T Cell Therapy Has Stricter Criteria
CAR-T cell therapy, a form of immunotherapy where your own immune cells are genetically reprogrammed to attack cancer, has notably stricter eligibility requirements than checkpoint inhibitors. This treatment is currently approved for certain blood cancers, including specific types of lymphoma and multiple myeloma, and you generally must have tried and failed multiple prior treatments before qualifying.
For large B-cell lymphoma, you typically need to have cancer that either didn’t respond to or came back within 12 months of initial chemotherapy. For multiple myeloma, at least three prior treatment regimens are usually required, including specific drug classes. In all cases, you need an ECOG performance score of 0 or 1 and adequate organ function. Because CAR-T involves collecting your immune cells, manufacturing the modified cells over several weeks, and then infusing them back after a preparatory chemotherapy regimen, the physical demands on your body are substantial.
How Testing and Qualification Works
Qualification typically starts with a biopsy or surgical sample of your tumor being sent for biomarker testing. PD-L1 testing uses a staining method on tumor tissue and returns a percentage score. MSI and MMR testing can be done through genetic sequencing or protein staining. TMB requires broader genomic sequencing, often through commercial panels that analyze hundreds of genes at once.
Results usually take one to three weeks. If your biomarkers meet the relevant thresholds for your cancer type, your oncologist will then evaluate your physical fitness, organ function, medication use, and autoimmune history to complete the eligibility picture. In some cases where standard biomarker criteria aren’t met, clinical trials may offer access to immunotherapy under expanded eligibility rules, particularly for less common cancer types or unusual molecular profiles.