Causality assessment · Expected pharmacological effect

Temozolomide and Thrombocytopenia: is the FAERS signal real?

n=1,572 co-reports · PRR 14.3 · ROR 15.4

Temozolomide side-effect profile All assessments See in the full list

A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.

Expected pharmacological effect

Temozolomide ↔ Thrombocytopenia

n=1,572 co-reports · PRR 14.3 · ROR 15.4

Temozolomide is an oral alkylating agent for glioblastoma; myelosuppression, especially thrombocytopenia and neutropenia, is its dose-limiting toxicity and carries 1,572 thrombocytopenia co-reports here (PRR 14.3). The effect is cumulative, which is why the label requires frequent blood counts throughout each cycle and dose adjustment by haematological nadir.

Regulatory basis: temozolomide (Temodar) prescribing information — myelosuppression/thrombocytopenia; frequent monitoring.

Bradford Hill viewpoint	Status	Note
Temporality (necessary)	met	Platelet fall during cycles
Strength	met	PRR 14.3, large
Consistency	met	Consistent across trials
Specificity	met	Fairly specific to alkylating agents
Biological gradient	met	Cumulative dose-related
Plausibility	met	Bone-marrow stem-cell damage
Coherence	met	Fits the mechanism
Experiment	met	Trials recorded thrombocytopenia
Analogy	met	Analogous to other alkylating-agent myelosuppression

This table is this page's own qualitative read of the literature cited above, not an automated or citation-gated assessment — see the note at the bottom of this page.

✓ Trial evidence found — A Phase III Trial of With Marizomib in Patients With Newly Diagnosed Glioblastoma (NCT03345095)

Adverse event	Experimental Arm (n=305) · Standard Arm (n=297)
Pancytopenia	1/305	0/297
Thrombocytopenia	7/305	1/297

Post-marketing signal terms appear in this trial's posted adverse-event tables; per-arm counts shown as affected/at-risk. View on ClinicalTrials.gov →