Drugs › CD33-directed immunoconjugate
Brand name · Gemtuzumab ozogamicin
Mylotarg: adverse event reports filed with FDA
1,818 reports list it as a suspect or interacting product, 2004–2026. Class: CD33-directed immunoconjugate. Also reported as Mylotarg /01278901/.
- 1,818
- reports as suspect product
- 0% of all reports · about 81 a year
- 33
- reports, 12 months to June 2026
- 62 in the 12 months before
- 95.2%
- marked serious by the reporter
- 97.3% across the class
- 31.4%
- record death among outcomes, as reported
- 571 reports · not verified by FDA
1,818 adverse event reports received by FDA list the brand name Mylotarg (gemtuzumab ozogamicin) as a suspect or interacting product, from January 2004 to June 2026. A further 104 reports list it only as a concomitant medication, and those are not counted in the figures on this page.
In the 12 months to June 2026, 33 reports listed it, down 47% from 62 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 81 reports a year and 0% of the 20,646,523 reports in the database, and 53.8% of the reports for the CD33-directed immunoconjugate class. How many people take it is not in the data, so a count is not a rate of occurrence.
Reporters most often recorded febrile neutropenia (18.4%), pyrexia (11.6%) and platelet count decreased (10%). A report can list several reactions, so shares add to more than 100%; 501 different terms appear across these reports. Febrile neutropenia is recorded in 18.4% of these reports, about the same share as in the median CD33-directed immunoconjugate drug (19.5%).
95.2% of the reports are marked serious by the reporter (97.3% across the class); 31.4% record death among the outcomes and 50.3% record hospitalisation, as reported. 42.1% of the reports came from physicians, and the largest patient age group is 45 to 64 (27%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Mylotarg reports recording the termmedian drug in cd33-directed immunoconjugate
- Febrile neutropeniafever with low white blood cells18.4%334
- Pyrexiafever11.6%211
- Platelet count decreasedlow platelet count10%181
- Sepsisa severe body-wide response to infection8.6%157
- White blood cell count decreasedlow white cell count8.4%152
- Aspartate aminotransferase increasedraised liver enzyme (AST)7.6%138
- Venoocclusive liver disease7%127
- Chillschills or shivering6.6%120
- Thrombocytopenialow platelets6.3%115
- Infusion related reactiona reaction during or soon after an infusion6.2%112
- Alanine aminotransferase increasedraised liver enzyme (ALT)5.9%107
- Neutropenialow neutrophils, a type of white blood cell5.2%95
- Pneumonialung infection5.2%94
- Weight increasedweight gain5.1%92
- Disease progressionthe disease advanced5%90
- Acute myeloid leukaemia4.9%89
- Haemoglobin decreasedlow haemoglobin4.8%88
- Anaemialow red blood cells4.6%84
- Hypotensionlow blood pressure4.6%83
- Pancytopenialow counts of all blood cells4.2%77
- Nauseafeeling sick4%72
- Pleural effusionfluid around the lung3.7%67
- Condition aggravatedthe condition being treated got worse3.5%64
- Bone marrow failure3.4%62
- Ascitesfluid in the abdomen3.3%60
- Diarrhoealoose or frequent stools3.2%58
Top 30 of 501 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 2 drugs in the cd33-directed immunoconjugate class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 3,378 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 41.1% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Acute myeloid leukaemia | 1,100 | 60.5% |
| Acute myeloid leukaemia recurrent | 161 | 8.9% |
| Acute leukaemia | 40 | 2.2% |
| Myelodysplastic syndrome | 20 | 1.1% |
| Acute promyelocytic leukaemia | 16 | 0.9% |
| Acute myeloid leukaemia refractory | 8 | 0.4% |
The indication field is filled in by the reporter and is often blank; shares are of all 1,818 reports.
Drugs most often listed in the same reports
| Drug (any role in the report) | Reports | Share of Mylotarg reports |
|---|---|---|
| Cytarabine | 636 | 35% |
| Daunorubicin | 222 | 12.2% |
| Daunorubicin hydrochloride | 154 | 8.5% |
| Allopurinol | 129 | 7.1% |
| Acyclovir | 115 | 6.3% |
| Vancomycin | 100 | 5.5% |
| Diflucan | 91 | 5% |
| Acetaminophen | 90 | 5% |
| Etoposide | 90 | 5% |
| Fluconazole | 59 | 3.2% |
Other products listed in reports where Mylotarg is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.
In context
| Measure | Mylotarg | CD33-directed immunoconjugate | All reports |
|---|---|---|---|
| Reports as suspect product | 1,818 | 3,378 | 20,646,523 |
| Share of that pool | — | 53.8% | 0% |
| Reports, latest 12 months | 33 | — | 1,332,454 |
| Marked serious | 95.2% | 97.3% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 314 | 319 | 91 |
| Hospitalisation recorded, per 1,000 reports | 503 | 483 | 213 |
| Consumer-filed share | 4.9% | 3.8% | 45.8% |
| Top term, share of reports | Febrile neutropenia 18.4% | median 19.5% | 0.3% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the cd33-directed immunoconjugate class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Gemtuzumab ozogamicin | generic | 1,560 | 43 | 99.7% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Mylotarg reports
How many adverse event reports has FDA received for Mylotarg?
1,818 reports list Mylotarg as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 33 of them arrived in the latest 12 months. Another 104 list it only as a concomitant medication.
What reactions are recorded in Mylotarg reports?
febrile neutropenia (18.4%), pyrexia (11.6%), platelet count decreased (10%), sepsis (8.6%) and white blood cell count decreased (8.4%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Mylotarg was responsible.
How serious are the reports?
95.2% are marked serious by the reporter. Among the outcomes recorded, 31.4% of reports include death and 50.3% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
physician (42.1%), not given (27%) and other health professional (19.7%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Mylotarg rising?
33 reports in the 12 months to June 2026, down 47% from 62 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Mylotarg was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Mylotarg?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Mylotarg as a suspect or interacting product; reports listing it only as a concomitant medication (104) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.