ADC TOXICITY ATLAS
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Lorvotuzumab mertansine

Discontinued
IMGN901; IMGN-901; BB-10901; huN901-DM1; huN901-SPP-DM1; N901-DM1; IMGN901-TAP
Sponsor
ImmunoGen
Indication
CD56+ solid tumors (small-cell lung cancer, Merkel cell carcinoma, ovarian); also CD56+ multiple myeloma (combo)
Target family
Nectin / Ig-CAM
RP2D dose
60 mg/m2/day (D1-3)
Days 1-3 Q3WRP2D
01
Multi-organ toxicity

Fingerprint & organ drill-down

Also reported
0%severity100%
0
Assessed · clear
true 0%
No data
never assessed
2 adverse-event terms

Ocular

Any-grade
4.7%
G3+
0%
RP2D
sagittal schematic · Reversible

Tissues shaded by reported adverse-event rate.

Cornea
AE
-
Express.
-
Limbus
AE
-
Express.
-
Conjunctiva
AE
-
Express.
-
Lens
AE
-
Express.
-
Retina / RPE
AE
-
Express.
-
Dominant tissue
Ocular surface
Surface subtype
Mixed
Reversibility
Reversible
Reported ocular events
Eye redness4.7%
Reversible posterior leukoencephalopathy syndrome (RPLS) with cortical blindness-
G3+ 1%
02
Construct

Molecular anatomy

Antibody
IgG1
Humanized
Linker
Cleavable
3.5
DAR
Payload
Tubulin inhibitor
Linker structureC14H16N2O4S2
[H]c1nc(SSC([H])(C([H])([H])[H])C([H])([H])C([H])([H])C(=O)ON2C(=O)C([H])([H])C([H])([H])C2=O)c([H])c([H])c1[H]
Payload structureC35H48ClN3O10S
C[C@@H]1[C@@H]2C[C@]([C@@H](/C=C/C=C(/CC3=CC(=C(C(=C3)OC)Cl)N(C(=O)C[C@@H]([C@]4([C@H]1O4)C)OC(=O)[C@H](C)N(C)C(=O)CCS)C)\C)OC)(NC(=O)O2)O
03
Antibody

Antibody & Fc engineering

Antibody
Lorvotuzumab (huN901)
Isotype
IgG1
Origin
Humanized
Fc modifications
None
Glycoengineering
Standard
Effector silencing
-
FcγR binding
Retained
C1q binding
Retained
04
Linker & conjugation

Linker chemistry

Linker profile
Linker
SPP (N-succinimidyl 4-(2-pyridyldithio)pentanoate)
Class
Cleavable
Cleavage
Cleavable
Attachment
Lysine
Conjugation
Conventional Lys (SPP NHS ester)
Symmetry
Symmetric
DAR (mean)
3.5
DAR homogeneity
Heterogeneous
Plasma t½
-
Cleavage trigger
Non-enzymatic; reductive disulfide cleavage by intracellular glutathione/thiols. Hindered (alpha-methyl) disulfide confers greater plasma stability than an unhindered disulfide.
Release control
Conditional
Hydrophilicity mask
None
Formula
C14H16N2O4S2
Linker MW
340.426 Da
Linker TPSA
76.57 Ų
Linker xLogP
2.5978
ADCdb linker
LIN0QDUUQ
In-vitro stability
-
05
Payload

Payload & physicochemistry

Payload profile
Payload
DM1 (mertansine, free)
Class
Maytansinoid
Mechanism
Tubulin inhibitor
Released catabolite
Free DM1 (thiol-bearing maytansinoid); can be S-methylated to lipophilic S-methyl-DM1, conferring partial membrane permeability/bystander activity (cleavable disulfide).
Mechanistic subtype
Tubulin-maytansinoid
Stereochem / salt
-
Bystander
Partial
PAMPA rank
-
MW
738.3 Da
XLogP3
2.2
logD₇.₄
2.5
TPSA
157 Ų
pKa
4.8 pKa
Charge pH 7.4
0
H-bond donors
3
H-bond acceptors
11
IC50 (HCEC)
-
Formula
C35H48ClN3O10S
PubChem CID
11343137
ADCdb payload
PAY0JCIBW
Hydrophobicity · logD₇.₄
hydrophilic −2+2.5+4 lipophilic
Bioactivity note
No payload IC50 reported on the ADCdb page. ADCdb clinical efficacy datum: Objective Response Rate (ORR) 28.30% in relapsed/refractory CD56-positive multiple myeloma. (DM1 is a tubulin/microtubule-polymerization inhibitor maytansinoid; sub-nanomolar antiproliferative potency typi
06
Dosing & regimen

Dosing

RP2D dose
60 mg/m2/day (D1-3)
Schedule
Days 1-3 Q3W
Route
IV
Fractionated
Yes
n at RP2D
38
Dose basis
BSA
Trial phase
Phase 1
Dose-OAE available
No
Tox summary basis
RP2D
07
Ocular & expression

Ocular profile & eye-tissue target expression

Target profile
OAE any-grade
4.7 %
OAE grade 3+
0 %
OAE data status
reported
Severity (weighted)
1.41
Keratopathy
-
Conjunctival
-
Dry eye
-
Blurred vision
-
Dominant tissue
Ocular surface
Surface subtype
Mixed
Grading scale
CTCAE v4
Reversibility
Reversible
Target expression in eye tissues (HCA detection · HPA bulk)
Cornea (central)
-
Cornea (limbal)
-
Conjunctiva
-
RPE
-
Retina (HPA)
-
Cross-trial comparability · source-verified
Ascertainment: Symptom-driven reportingScale: CTCAE v4Denominator: RP2D⚠ OAE rate not directly comparable across trials
08
Identity & registry

Identifiers, registry & notes

ADC id
lorvotuzumab-mertansine
Approval status
Discontinued
Approval year
-
UniProt
P13591
ADCdb ADC
DRG0SDZSF
ADCdb antibody
ANI0VELIR
ADCdb target
TAR0YOEAI
Primary source
Shah et al. Invest New Drugs 2016;34(3):290-9 (IMGN901 Ph1, CD56+ solid tumors; PMID 26961907); ocular per Eaton et al. ADC ocular-AE review (PMC4677113)
Aliases & development codes
IMGN901; IMGN-901; BB-10901; huN901-DM1; huN901-SPP-DM1; N901-DM1; IMGN901-TAP
Notes
Composition/linker/payload IDs from ADCdb DRG0SDZSF and linker LIN0QDUUQ. IMPORTANT: ADCdb lists conjugation as "Random Cysteines," but SPP (N-succinimidyl 4-(2-pyridyldithio)pentanoate) is an NHS-ester linker that conjugates to antibody LYSINE residues (the 2-pyridyldithio group then forms the cleavable disulfide to DM1's thiol); the alias "IMGN901-TAP" confirms ImmunoGen's lysine-linked maytansinoid (TAP) platform. Recorded here as Conventional Lys conjugation (chemically correct and consistent with the DB's other maytansinoid rows); the ADCdb "Random Cysteines" annotation appears to be an error. Linker is a hindered (alpha-methyl) disulfide -> cleavable/reductive (GSH). Because it is cleavable, the released species is free DM1 / S-methyl-DM1 (partial bystander), so FREE-DM1 physchem is used (MW 738.3), NOT the charged Lys-SMCC-DM1 catabolite values (MW 1103.7) used for the non-cleavable T-DM1. Clinical data: Phase I CD56+ solid-tumor study, Shah MH et al., Invest New Drugs 2016;34(3):290-9 (PMID 26961907; PMC4859861; DOI 10.1007/s10637-016-0336-9). IV days 1-3 every 21 days (fractionated); dose 4-94 mg/m2/day; MTD 75 mg/m2; RP2D 60 mg/m2 (n=38 in expansion); safety population N=97 (52 escalation + 45 expansion); CTCAE v4.0. Reported rates are pooled over n=97 (the publication does not break out AE rates by dose), so the "RP2D" line_context flags the primary/headline cohort while the n column carries the n=97 denominator. OCULAR (reason for inclusion): (1) Eye redness <=G1-2 in 3/64 (4.7%) at three dose levels, per the Eaton ADC ocular-AE review (PMC4677113) citing the IMGN901 solid-tumor dose-escalation (n=64). This denominator differs from the n=97 full publication, which did not separately tabulate eye redness. (2) One RPLS-associated reversible cortical blindness at the 60 mg/m2 RP2D (1/97; bilateral parieto-occipital MRI lesions; CNS-mediated; causality to IMGN901 unverifiable per authors; residual visual field deficit). No keratopathy/conjunctivitis/dry eye/blurred vision reported - unlike classic DM4 maytansinoid corneal toxicity, this DM1 ADC shows only low-grade nonspecific surface eye redness plus a single neuro-ocular event. oae_g3plus_pct=0 refers to the ophthalmic-surface OAE (eye redness, all G1-2); the RPLS cortical blindness (G3+ visual) is captured as a separate toxicity row. ocular_surface_subtype="Mixed" reflects the surface (eye redness) + visual (cortical blindness) signals; neither is a classic corneal keratopathy. HEMATOLOGIC: the verified primary publication did NOT quantify anemia/neutropenia/thrombocytopenia (those PT words are absent; no patient met the grade-4 neutropenia DLT). Only a 7.2% "Blood and lymphatic system disorders" SOC aggregate is reported. A secondary web summary quoting anemia 55%/thrombocytopenia 48%/PN 52% directly contradicted the verified PN 17.5% and was excluded as unreliable. OTHER: Headache 26.8% and "meningitis-like symptoms" were prominent (likely CD56/NCAM-related meningismus; managed with prophylactic steroids; among the DLTs) - noted here but not forced into the fixed organ-system rows. Most common Grade 3/4 TEAEs overall: hyponatraemia 8.2%, dyspnoea 8.2%, GGT 7.2%; 80.4% had any Grade 3/4 TEAE (37.1% treatment-related). No infusion-related anaphylaxis reported; no quantified infusion-reaction PT, so the Infusion organ system is left blank. CAVEATS: payload_pka ~4.8 is taken from the DB's canonical free-DM1 value but appears low versus the structurally analogous DM4 thiol (~10.3) - possible DB reference typo; flagged. Antibody isotype IgG1 and origin Humanized are from established huN901/lorvotuzumab nomenclature (the "-zumab" stem; humanized murine N901), not explicitly stated in the fetched sources -> tier C for those two fields. Program discontinued (ADCdb: "Phase 2 (Terminated)").