Within antibody–drug conjugates, the payload is a compact, highly active small molecule intended to be liberated in targeted intracellular environments after conjugate uptake. Our portfolio is curated for pharmaceutical R&D needs. Catalog items span established research standards as well as specialized warheads for exploratory programs.
What Are Payloads?
Antibody-drug conjugate (ADC) payloads are ultra-potent cytotoxins released after internalization and linker cleavage; it is far too toxic to be given systemically on its own, but when attached to a targeting antibody, it can be released inside cancer cells to kill them effectively while minimizing damage to normal tissues. Optimal payloads show high potency, plasma stability, and linker-compatible handles.
Classification of Payloads
Below are the principal classes, including microtubule inhibitors, DNA-interactive / DNA-alkylating agents, topoisomerase I inhibitors (camptothecin class), and specialized warheads.
Microtubule Inhibitors
Auristatin / Dolastatin family: Dolastatin 10, Auristatin F, isotopic tool compound MMAE-d8.
Maytansinoids & ansamitocins: Maytansinoid B, S-methyl DM1, DM3, DM4-SMe, N-Me-L-Ala-maytansinol, Ansamitocin P-3.
Tubulysin class & related tubulin agents: Tubulysin, Tubulysin A, Taltobulin (HTI-286), Indibulin, TZT-1027; Paclitaxel appears for comparative bench use.
DNA-Interactive / DNA-Alkylating Agents
PBD dimers: SG3199, PBD dimer-2, SJG-136.
Duocarmycin / indolino-benzodiazepine series: Duocarmycin DM (free base), (S)-Seco-duocarmycin SA, Benzyl DC-81, Tomaymycin DM, DC1/DC1SMe/DC0-NH2, TAM470/TAM558 series entries.
Anthracycline-related & others: PNU-159682, Doxorubicin HCl, Daun02, Seco-DUBA (hydrochloride).
Topoisomerase I Inhibitors (Camptothecin class)
Camptothecin cores: SN-38, Camptothecin, Lurtotecan, 7-aminomethyl-10-methyl-11-fluoro camptothecin.
Exatecan-type cores & isotopologues: (4-NH2)-Exatecan, Exatecan-d5 mesylate, Dxd-d5 (useful where analytical tracing is desired).
Specialized Warheads for Exploratory Studies
Amanitin family: β-Amanitin, Dideoxy-amanitin.
Additional potent chemotypes: Aminohexylgeldanamycin, Triptolide.
Roles of Payloads in ADCs
Payloads are integral to cutting-edge therapies across multiple domains:
- Primary Cytotoxic Function: The payload is the main cell-killing component of an ADC, released inside tumor cells to induce death with extremely small amounts after the ADC reaches and enters the target tissue.
- Defines Mechanism of Action: Different payload classes determine how the ADC works—such as damaging DNA, disrupting microtubules, or interfering with essential cellular processes.
- Influences Safety Profile and Therapeutic Window: Payload characteristics also strongly influence the ADC's safety profile and therapeutic window, since an overly potent or easily released payload may cause off-target toxicity, while one that is too weak may limit efficacy.
- Enables Bystander Effect: Certain payloads (such as membrane-permeable payloads) are capable of bystander killing, meaning the released drug can diffuse to nearby tumor cells that may express lower levels of the target antigen, improving treatment of heterogeneous tumors.
- Shapes Overall ADC Design: Factors such as payload hydrophobicity, membrane permeability, and chemical structure influence linker selection, conjugation strategy, and drug–antibody ratio, making the payload central to overall ADC performance.
Frequently Asked Questions
Q1: Are closely related analogs available for structure–property studies?
Yes. Many families include panels of analogs (e.g., maytansinoids, auristatins, duocarmycins, PBD dimers, camptothecins), enabling comparative evaluations under consistent laboratory conditions.
Q2: Do you offer isotopically labeled entries to aid analytical method development?
Select items are available as deuterated variants—for example, MMAE-d8, Exatecan-d5 mesylate, Dxd-d5—which can be useful for tracing and quantitation work during method development.
Q3: How should these materials be handled in the lab?
They are high-activity small molecules; typical practice favors cold, dry, light-protected storage, fresh working solutions in suitable anhydrous solvents.