Pembrolizumab (checkpoint inhibitors) and Hypothyroidism: is the FAERS signal real?
Pembrolizumab (checkpoint inhibitors) ↔ Hypothyroidism
Immune-checkpoint inhibitors such as pembrolizumab work by unleashing the immune system against cancer, and a predictable consequence is that the same immune activation can attack healthy organs — so-called immune-related adverse events. Thyroid dysfunction is the single most common endocrine irAE: patients frequently develop an early, transient hyperthyroid phase (thyroiditis) followed by hypothyroidism requiring lifelong replacement. In the clinical trials this is usually called thyroid disorders. Because these events are frequent, mechanistically understood, and manageable with hormone replacement, the labeling and oncology guidelines require baseline and periodic thyroid-function testing during therapy; unlike many signals on this page, this one is routinely captured in trial data precisely because it is so common.
Regulatory basis: pembrolizumab prescribing information (immune-mediated thyroid disorders; monitoring guidance). Randomized trial results (e.g. KEYNOTE-010).
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Thyroid changes appear during therapy, often an early hyperthyroid phase then hypothyroidism |
| Strength | met | PRR 20 with a large co-report count and high event rates in trials |
| Consistency | met | Reproduced across the whole checkpoint-inhibitor class and across trials |
| Specificity | met | A distinctive class effect of immune-checkpoint blockade, rare with most non-immunotherapy drugs |
| Biological gradient | partial | Broadly related to immune activation rather than to a simple dose gradient |
| Plausibility | met | Release of T-cell checkpoint restraint leads directly to organ-directed autoimmunity |
| Coherence | met | Coheres with the broader immune-related AE spectrum (colitis, pneumonitis, hypophysitis) |
| Experiment | met | Randomized trials (e.g. KEYNOTE-010) directly measure thyroid-event rates by arm |
| Analogy | met | Analogous across all PD-1/PD-L1 inhibitors |
This page's own qualitative read, not an automated/citation-gated assessment.
✓ Trial evidence found — pembrolizumab (2 vs 10 mg/kg) vs docetaxel in NSCLC (KEYNOTE-010, NCT01905657), N=1,030
| Term (as recorded) | Pembrolizumab 2 mg/kg (n=339) | Pembrolizumab 10 mg/kg (n=343) | Docetaxel (n=309) |
|---|---|---|---|
| Hypothyroidism (non-serious) | 29 | 29 | 1 |
| Hyperthyroidism (non-serious) | 12 | 19 | 3 |
Thyroid events are roughly 30-fold more frequent on pembrolizumab than on chemotherapy in a randomized trial — one of the strongest trial-level confirmations on this page, reflecting how common and measurable immune-checkpoint thyroid toxicity is. The hyperthyroid-then-hypothyroid sequence typical of thyroiditis is visible in the combined counts. View on ClinicalTrials.gov →