Loncastuximab tesirine

FDA-approved

Zynlonta; ADCT-402

Target

CD19 · CD19

Sponsor

ADC Therapeutics

Indication

CD19+ DLBCL

Target family

Immunoglobulin superfamily

RP2D dose

0.15 mg/kg x2 then 0.075 mg/kg

Q3WRP2D

Multi-organ toxicity

Fingerprint & organ drill-down

Also reported

0%severity100%

Assessed · clear

true 0%

No data

never assessed

0 adverse-event terms

Ocular

Any-grade

G3+

RP2D

sagittal schematic · Unknown

↳

Tissues shaded by reported adverse-event rate.

Cornea

Express.

Limbus

Express.

Conjunctiva

Express.

Lens

Express.

Retina / RPE

Express.

0.05%

0 nTPM

Dominant tissue

Surface subtype

None

Reversibility

Unknown

Reported ocular events

No granular adverse-event rows recorded for this system.

Construct

Molecular anatomy

Antibody

IgG1

Humanized

Linker

Cleavable

2.3

DAR

Payload

SG3199 (PBD dimer)

DNA cross-linker

Linker structureC41H65N5O15

[H]OC([H])([H])c1c([H])c([H])c(N([H])C(=O)[C@@]([H])(N([H])C(=O)[C@@]([H])(N([H])C(=O)C([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])OC([H])([H])C([H])([H])N([H])C(=O)C([H])([H])C([H])([H])N2C(=O)C([H])=C([H])C2=O)C([H])(C([H])([H])[H])C([H])([H])[H])C([H])([H])[H])c([H])c1[H]

Payload structureC33H36N4O6

CC1=CN2[C@@H](C1)C=NC3=CC(=C(C=C3C2=O)OC)OCCCCCOC4=C(C=C5C(=C4)N=C[C@@H]6CC(=CN6C5=O)C)OC

Antibody

Antibody & Fc engineering

Antibody

hRB4v1.2 (loncastuximab)

Isotype

IgG1

Origin

Humanized

Fc modifications

None

Glycoengineering

Standard

Effector silencing

None

FcγR binding

Retained

C1q binding

Retained

Linker & conjugation

Linker chemistry

Linker profile

Linker

VA dipeptide (tesirine)

Class

Cleavable

Cleavage

Cleavable

Attachment

Cysteine (interchain)

Conjugation

Conventional interchain Cys

Symmetry

Symmetric

DAR (mean)

2.3

DAR homogeneity

Heterogeneous

Plasma t½

17.0 d

Cleavage trigger

Cathepsin B (Val-Ala)

Release control

Conditional

Hydrophilicity mask

Discrete-PEG-spacer

Formula

C41H65N5O15

Linker MW

867.991 Da

Linker TPSA

247.85 Å²

Linker xLogP

-0.2829

ADCdb linker

LIN0YRUBS

In-vitro stability

Stability note

Conjugated antibody steady-state t½ 20.6 d after ~15 weeks (Hamadani Blood 2021 LOTIS-2 popPK); 2-compartment linear model with time-dependent CL → t½ at C1 ≈ 13 d, increases on multiple dosing. PBD released as stable DNA-guanine adduct, not free drug; warhead toxicity not driven by free-drug circulating

Payload

Payload & physicochemistry

Payload profile

Payload

SG3199 (PBD dimer)

Class

PBD dimer

Mechanism

DNA cross-linker

Released catabolite

SG3199 (pyrrolobenzodiazepine [PBD] dimer)

Mechanistic subtype

DNA-crosslinker-PBD

Stereochem / salt

(11aS,11a'S)-configured PBD dimer (single defined stereoisomer); free base (no salt)

Bystander

Partial

PAMPA rank

584.7 Da

XLogP3

2.8

logD₇.₄

2.5

TPSA

102 Å²

pKa

5 pKa

Charge pH 7.4

H-bond donors

H-bond acceptors

IC50 (HCEC)

Formula

C33H36N4O6

PubChem CID

90132565

ADCdb payload

PAY0LZRXU

Hydrophobicity · logD₇.₄

hydrophilic −2+2.5+4 lipophilic

Bioactivity note

SG3199 is a sequence-selective DNA minor-groove interstrand crosslinking PBD dimer; ADCdb lists its molecular target as human DNA (hDNA). No numeric IC50 reported on the ADCdb ADC page or the PubChem record.

Dosing & regimen

Dosing

RP2D dose

0.15 mg/kg x2 then 0.075 mg/kg

Schedule

Q3W

Route

Fractionated

n at RP2D

145

Dose basis

TBW

Trial phase

Approved

Dose-OAE available

Tox summary basis

RP2D

Ocular & expression

Ocular profile & eye-tissue target expression

Target profile

OAE any-grade

0 %

OAE grade 3+

0 %

OAE data status

documented-absent

Severity (weighted)

Keratopathy

Conjunctival

Dry eye

Blurred vision

Dominant tissue

Surface subtype

None

Grading scale

CTCAE v4

Reversibility

Unknown

Target expression in eye tissues (HCA detection · HPA bulk)

Cornea (central)

0 %

Cornea (limbal)

0 %

Conjunctiva

0 %

RPE

0.05 %

Retina (HPA)

0 nTPM

Cross-trial comparability · source-verified

Ascertainment: Symptom-driven reportingScale: CTCAE v4Denominator: RP2D⚠ OAE rate not directly comparable across trials

Identity & registry

Identifiers, registry & notes

ADC id

loncastuximab-tesirine

Approval status

FDA-approved

Approval year

2021

UniProt

P15391

ADCdb ADC

DRG0TKVCB

ADCdb antibody

ANI0AWZRF

ADCdb target

TAR0EBTXG

Primary source

FDA Zynlonta label; Caimi LOTIS-2 Lancet Oncol 2021

Aliases & development codes

Zynlonta; ADCT-402

Notes

PBD warhead released as DNA-guanine adduct, not free drug