Mylotarg
gemtuzumab ozogamicin
Species
MonkeyRat
Longest study
12 wk
Genotox
Conducted Conducted
Carcinogenicity
Not conducted Not conducted
Repro
Conducted Conducted
First dose
Not conducted Not stated publicly
Speciesopen answer page →
Species
Rat and cynomolgus monkey (neither pharmacologically relevant; no CD33 cross-reactivity)
“In view of the absence of cross-reactivity of gemtuzumab ozogamicin with CD33 from laboratory species, studies of kinetics in animals can only be of limited value, as there will be no binding, specific intracellular uptake, and metabolism of the conjugate that underlies its therapeutic action in humans.”
Why that species
No relevant species: antibody does not bind monkey CD33 or stain rat/monkey tissues; species used for off-target payload toxicity
“hP67.6 bound strongly to human CD33-transfected CHO cells but did not bind to the monkey CD33-transfected CHO cells (study 084032).”
Surrogate molecule
No surrogate; clinical ADC tested in non-binding rat and monkey (plus old vs new cell line bridging)
“Repeat-dose studies included six cycle intravenous toxicity studies in rats and monkeys and a six cycle comparative study in monkeys for the old and new antibody cell lines.”
Species: general tox
Rat and monkey (six-cycle weekly IV studies, plus monkey cell-line comparability study)
“Repeat-dose studies included six cycle intravenous toxicity studies in rats and monkeys and a six cycle comparative study in monkeys for the old and new antibody cell lines.”
Species: DART
Rat only (fertility and EFD); FDA agreed one species sufficient after positive pilot study
“Based on the unequivocally positive results obtained from a pilot study, the Agency previously agreed with the Applicant that one species would be sufficient to support an NDA application for CMA-676 in a leukemia indication.”
Species: carcinogenicity
Not conducted
“Formal carcinogenicity studies have not been conducted with gemtuzumab ozogamicin.”
Surrogate used in
No surrogate used; antibody shows no specific binding in rat or monkey tissues
“A tissue cross-reactivity study using rat or cynomolgus monkey cryosections determined that specific staining by hP67.6 was absent in all tissues of both animal species.”
Study lengthopen answer page →
Longest pivotal study
12 weeks
“A GLP-compliant general toxicity study in monkeys was also completed in which 12 doses of gemtuzumab ozogamicin were given once weekly by intravenous bolus injection to groups of 3 male and 3 female cynomolgus monkeys at doses of 0 (sterile water), 2.2, 6.6, or 11 mg/m2 /week.”
Pivotal GLP studies
6-week (weekly IV) rat and monkey with 4-week recovery; 6-cycle monkey cell-line bridging study; 12-week weekly IV monkey
“Rats were administered 6 weekly doses at 0 (PBS control), 7.2 (hP67.6 antibody control), or CL 555,201 (GO) at doses of 0.6, 2.4, or 7.2 mg/m2 /week and observed for an additional 4 weeks.”
Route in tox
IV (weekly bolus/infusion)
“Monkeys were administered 6 weekly IV doses at 0 (PBS control), 22 (hP67.6 antibody control), or CL 555,201 at doses of 2.4, 7.2, or 22 mg/m2 /week (5, 15 or 45 mcg/kg/week calicheamicin equivalents) and observed for an additional 4 weeks.”
Skipped studiesopen answer page →
Genotoxicity
Conducted: ADC clastogenic in mouse micronucleus; free calicheamicin DMH mutagenic and clastogenic in vitro
“Gemtuzumab ozogamicin was found to be clastogenic. This is consistent with the known induction of DNA breaks by calicheamicin and other enediyne antitumour antibiotics.”
Carcinogenicity
Not conducted; rat liver preneoplastic oval cell hyperplasia noted in tox studies
“No carcinogenicity studies have been conducted with gemtuzumab ozogamicin (see discussion on non-clinical aspects).”
Reproductive & developmental
Rat male/female fertility and rat EFD (one species agreed); embryolethal, teratogenic, male fertility impaired; no PPND
“Based on the unequivocally positive results obtained from a pilot study, the Agency previously agreed with the Applicant that one species would be sufficient to support an NDA application for CMA-676 in a leukemia indication.”
Safety pharmacology
Standalone non-GLP studies (mouse, rat, dog CV) plus payload hERG; dog BP decrease and HR increase at >=13 mg/m2
“Gemtuzumab ozogamicin was evaluated for potential effects on nervous, cardiovascular, gastrointestinal, hepatic, and renal systems in vivo and/or in vitro.”
Genotox: Ames
Calicheamicin DMH payload: positive (mutagenic in bacterial reverse mutation assay)
“N-acetyl gamma calicheamicin dimethyl hydrazide (the released cytotoxic agent) was mutagenic in the bacterial reverse mutation assay and clastogenic in the in vitro micronucleus assay in human TK6 cells.”
Genotox: in vitro mammalian
Calicheamicin DMH payload: positive (clastogenic) in human TK6 micronucleus assay
“N-acetyl gamma calicheamicin dimethyl hydrazide (the released cytotoxic agent) was mutagenic in the bacterial reverse mutation assay and clastogenic in the in vitro micronucleus assay in human TK6 cells.”
Genotox: in vivo
ADC: positive (clastogenic) in mouse bone marrow at single doses ≥22.1 mg/m2
“Gemtuzumab ozogamicin was clastogenic in vivo in the bone marrow of mice that received single doses greater than or equal to 22.1 mg/m”
Carcinogenicity model
Not conducted (formal studies); preneoplastic liver oval cell hyperplasia seen in rat toxicity studies
“Formal carcinogenicity studies have not been conducted with gemtuzumab ozogamicin. In toxicity studies, rats developed preneoplastic lesions (minimal to slight oval cell hyperplasia) in the liver”
Carcinogenicity timing
Not conducted
“No carcinogenicity studies have been conducted with gemtuzumab ozogamicin”
hERG / QT
Calicheamicin DMH: <1% hERG inhibition; IC50 >6.77 µM
“Less than 1% inhibition of mean hERG current amplitude was observed relative to vehicle control. The IC50 for the inhibitory effect of N-Ac-ɤ-calicheamicin DMH on hERG potassium channels was >6.77 mcM (10,000 ng/mL).”
First doseopen answer page →
First-in-human starting dose
Not stated in public reviews
Why it's blank
The public FDA and EMA reviews of Mylotarg don't say how the first human dose was chosen. That rationale is in the IND, which is confidential, so it is missing for most approved products.
How it's usually set for ADCs
ADCs with cytotoxic payloads follow the S9 rules (1/10 STD10 or 1/6 HNSTD of the ADC, scaled by body surface area). For immune agonists, a MABEL-based start dose should be considered instead.
“For example, for cytotoxic payloads, the starting clinical dose can be determined using either 1/10th the Severely Toxic Dose (STD) in 10% of animals (STD10) in rodents or 1/6th the Highest Non- Severely Toxic Dose (HNSTD) in non-rodents, for the ADC based on body surface area, depending on which is the most appropriate and/or sensitive species.”
This product's starting point
NOAEL / key findings: 6-week NOAEL 2.4 mg/m2/wk monkey, 0.6 rat; 12-week monkey no NOAEL; liver, kidney, marrow, lymphoid, reproductive organs (FDA pharmacology/toxicology review, p. 18)
NOAEL / key findings
6-week NOAEL 2.4 mg/m2/wk monkey, 0.6 rat; 12-week monkey no NOAEL; liver, kidney, marrow, lymphoid, reproductive organs
“The NOAEL was defined at 2.4 mg/m2 /week based on target organ toxicity in the kidney, liver, and lympho-hematopoietic organs at ≥7.2 mg/m2 /week.”
Risksopen answer page →
Immune & cytokine safety
ADA in rats (reduced exposure) and some monkeys; marked eosinophilia and hypersensitivity reactions in monkeys
“Marked eosinophilia occurred at all dose levels and was associated with hypersensitivity reactions in few monkeys dosed with the old cell line.”
Biodistribution & persistence
Rat [3H]-ADC tissue distribution limited (tissue/plasma <=0.54; liver, kidney, spleen highest); little in vivo payload release
“In rats, distribution of [3H]gemtuzumab ozogamicin radioequivalents into red blood cells and tissues was limited, with tissue-to-plasma AUC ratios ≤ 0.54 for all tissues evaluated.”
Modality-specific risk
Target-independent calicheamicin toxicity: hepatotoxicity/VOD via sinusoidal endothelium, myelosuppression, nephrotoxicity, genotoxicity
“Toxicity is suspected to arise from uptake by liver sinusoidal cells and breakdown of gemtuzumab ozogamicin leading to local cellular toxicity where this occurs.”
Anti-drug antibodies: animals
ADA in 95% of rats and 8.3–33% of monkeys; rat time-dependent exposure changes not assessable
“After repeat-dose administration of gemtuzumab ozogamicin, the total incidence of ADA-positive animals was 95% in rats and 8.3% to 33% in monkeys. Due to the high incidence of ADA in the 6-week repeat-dose rat toxicity study, time-dependent changes in exposure could not be assessed in these species.”
Anti-drug antibodies: patients
<1% across 4 clinical studies with ADA data
“Overall, the incidence rate of ADA development after MYLOTARG treatment was < 1% across the 4 clinical studies with ADA data.”
Label warnings
Boxed warning: Hepatotoxicity
- Hepatotoxicity, Including Veno-occlusive Liver Disease (VOD)
- Infusion-Related Reactions (Including Anaphylaxis)
- Hemorrhage
- QT Interval Prolongation
- Use in AML with Adverse-Risk Cytogenetics
- Embryo-Fetal Toxicity
HepatotoxicityHypersensitivity & infusion reactionsBleedingCardiovascularEmbryo-fetal toxicity
US prescribing information, Boxed Warning and Warnings and PrecautionsDailyMed ↗
Tox packageopen answer page →
Before first-in-human
First-in-human: where
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
Repeat-dose tox before first-in-human
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
First-in-human starting dose
Not stated in public reviews
Why it's blank
The public FDA and EMA reviews of Mylotarg don't say how the first human dose was chosen. That rationale is in the IND, which is confidential, so it is missing for most approved products.
How it's usually set for ADCs
ADCs with cytotoxic payloads follow the S9 rules (1/10 STD10 or 1/6 HNSTD of the ADC, scaled by body surface area). For immune agonists, a MABEL-based start dose should be considered instead.
“For example, for cytotoxic payloads, the starting clinical dose can be determined using either 1/10th the Severely Toxic Dose (STD) in 10% of animals (STD10) in rodents or 1/6th the Highest Non- Severely Toxic Dose (HNSTD) in non-rodents, for the ADC based on body surface area, depending on which is the most appropriate and/or sensitive species.”
This product's starting point
NOAEL / key findings: 6-week NOAEL 2.4 mg/m2/wk monkey, 0.6 rat; 12-week monkey no NOAEL; liver, kidney, marrow, lymphoid, reproductive organs (FDA pharmacology/toxicology review, p. 18)
Longest repeat-dose systemic studies
Longest repeat-dose study and recovery
12-week GLP cynomolgus monkey study (12 weekly IV bolus doses)
“A GLP-compliant general toxicity study in monkeys was also completed in which 12 doses of gemtuzumab ozogamicin were given once weekly by intravenous bolus injection to groups of 3 male and 3 female cynomolgus monkeys at doses of 0 (sterile water), 2.2, 6.6, or 11 mg/m2 /week.”
Pivotal GLP studies
6-week (weekly IV) rat and monkey with 4-week recovery; 6-cycle monkey cell-line bridging study; 12-week weekly IV monkey
“Rats were administered 6 weekly doses at 0 (PBS control), 7.2 (hP67.6 antibody control), or CL 555,201 (GO) at doses of 0.6, 2.4, or 7.2 mg/m2 /week and observed for an additional 4 weeks.”
DART package
Species: DART
Rat only (fertility and EFD); FDA agreed one species sufficient after positive pilot study
“Based on the unequivocally positive results obtained from a pilot study, the Agency previously agreed with the Applicant that one species would be sufficient to support an NDA application for CMA-676 in a leukemia indication.”
Reproductive & developmental
Rat male/female fertility and rat EFD (one species agreed); embryolethal, teratogenic, male fertility impaired; no PPND
“Based on the unequivocally positive results obtained from a pilot study, the Agency previously agreed with the Applicant that one species would be sufficient to support an NDA application for CMA-676 in a leukemia indication.”
PPND / ePPND: when
Peri- and postnatal studies not conducted
“Since peri- and postnatal studies were not conducted, no information is available on the effect of CMA-676 on parturition, lactation, functional development, locomotion or learning ability.”
Carcinogenicity
Species: carcinogenicity
Not conducted
“Formal carcinogenicity studies have not been conducted with gemtuzumab ozogamicin.”
Carcinogenicity model
Not conducted (formal studies); preneoplastic liver oval cell hyperplasia seen in rat toxicity studies
“Formal carcinogenicity studies have not been conducted with gemtuzumab ozogamicin. In toxicity studies, rats developed preneoplastic lesions (minimal to slight oval cell hyperplasia) in the liver”
Carcinogenicity timing
Not conducted
“No carcinogenicity studies have been conducted with gemtuzumab ozogamicin”
Safety marginopen answer page →
Safety margin at NOAEL
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
NOAEL / key findings
6-week NOAEL 2.4 mg/m2/wk monkey, 0.6 rat; 12-week monkey no NOAEL; liver, kidney, marrow, lymphoid, reproductive organs
“The NOAEL was defined at 2.4 mg/m2 /week based on target organ toxicity in the kidney, liver, and lympho-hematopoietic organs at ≥7.2 mg/m2 /week.”
Efficacy evidenceopen answer page →
Efficacy evidence
CD33+ HL-60 leukemia xenograft in mice: >80% tumor growth inhibition
“In vivo antitumor effects of CMA-676 were studied in an HL-60 xenograft tumor model. CMA-676 showed a dose-response effect with >80% inhibition of tumor growth at doses between 0.8 and 2.4 mg/m2 NAc-gamma calicheamicin DMH equivalents”
Why that model
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
Reviewer's view of the efficacy data
Xenograft doses far exceeded clinical doses, partly because subcutaneous HL-60 grows as a solid tumor
“were much higher than the doses used in clinical trials (0.25 to 9 mg protein/m2 ) at least in part because the subcutaneously implanted HL-60 leukemia grows as a solid tumor.”
Flexibilityopen answer page →
Flexibility accepted
SpeciesVerdict not stated
No pharmacologically relevant species: antibody does not bind monkey CD33 or rat and monkey tissues; toxicity studies address off-target effects only
“hP67.6 bound strongly to human CD33-transfected CHO cells but did not bind to the monkey CD33-transfected CHO cells (study 084032).”
DARTAcceptedBeyond the letter
Embryo-fetal development studied in one species (rat) only
Why: Unequivocally positive pilot study results; leukemia indication · Weight of evidence · Serious disease
“Based on the unequivocally positive results obtained from a pilot study, the Agency previously agreed with the Applicant that one species would be sufficient to support an NDA application for CMA-676 in a leukemia indication.”
GLPVerdict not stated
Safety pharmacology studies not GLP compliant
“Safety pharmacology studies were not GLP compliant.”
Impurity or metaboliteVerdict not stated
In vivo metabolism not studied with gemtuzumab ozogamicin; inotuzumab ozogamicin data in rats used instead
Why: Inotuzumab ozogamicin shares the same linker-payload and IgG subclass · Class precedent
“In vivo metabolism of gemtuzumab ozogamicin was not evaluated in nonclinical species; however, in vivo metabolism was evaluated in rats after IV administration of [3H]inotuzumab ozogamicin, which shares the same linker-payload and mAb IgG subclass as gemtuzumab ozogamicin”
Similar precedents
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