Technology
Products in Development
Xelcis Bio™ is advancing XELCIS XB across a portfolio of oncology programs, with TDOX — our lead XELCIS XB-doxorubicin conjugate — as the primary preclinical asset. Each program leverages the same core platform with modality-specific payload conjugation.
Program Highlights
Each program is built on the same XELCIS XB core platform — with modality-specific conjugation chemistry tailored to the payload class.
TDOX — XELCIS XB-Doxorubicin
TDOX is our lead preclinical program — XELCIS XB surface-conjugated to doxorubicin via Z-Link™ self-immolative disulfide chemistry. It is designed to overcome multidrug resistance (MDR) by improving intracellular doxorubicin concentration at the tumor site while reducing systemic exposure.
Preclinical Data (3D Spheroid MDR Model)
9.5× improved cytotoxic potency vs. Doxil® (3D spheroid MDR model)
90% reduced cardiotoxicity signal vs. Doxil®
14× enhanced cellular uptake vs. Doxil® in MDR cell line
Next milestone: in vivo CDX study (H69AR MDR lung model). IND-enabling studies to follow.
lead
XELCIS XB-OT — Oligonucleotide Therapeutics
Endosomal entrapment remains a major barrier to the effective delivery of siRNA, ASO, and mRNA therapeutics. This challenge has been addressed in prior nanoparticle delivery work advanced at TransCode Therapeutics, including TTX-MC138 (a miR-10b inhibitor), which progressed through early clinical evaluation in oncology patients. These prior programs inform the design and development of XELCIS XB.
Platform Class Validation
Prior nanoparticle delivery program advanced at TransCode Therapeutics progressed through Phase 1 clinical evaluation in oncology patients. These data provide supporting context for the delivery approach informing XELCIS XB, but do not represent clinical data forXELCIS XB.
Seeking Partnership
XELCIS XB-PT — Protein / Peptide Therapeutics
XELCIS XB unlocks cytosolic delivery of protein therapeutics — an enduring challenge in drug delivery. In proof-of-concept studies, BSA and ovalbumin (OVA) conjugates achieved efficient intracellular delivery and cytosolic release, demonstrating robust endosomal escape and validating XELCIS XB as a platform for functional intracellular protein delivery.
Proof-of-Concept Evidence
BSA and OVA protein conjugates demonstrated efficient intracellular delivery and cytosolic release. PCT conversion filed March 2026. Architecture parallels ADC and NDC delivery approaches.
POC Completed
XELCIS XB-TPD Platform
PROTACs and molecular glues require cytosolic access to engage E3 ligases and drive targeted protein degradation. XELCIS XB is designed to deliver these bifunctional molecules beyond the endosomal barrier. The near-term priority beyond TDOX is a PROTAC or molecular glue targeting STAT3 — an oncoprotein with validated biological rationale and no approved degrader to date.
IP Status
Provisional patent application for XELCIS XB-TPD delivery platform scheduled for filing Q2 2026.
Seeking Partnership
XELCIS XB-NDC — Nanobody-Drug Conjugates
XELCIS XB–Nanobody/Drug Conjugates (TNDCs) combine nanobody-based targeting and therapeutic payloads on the XELCIS XB nanoparticle to enable controlled pharmacokinetics and efficient intracellular delivery. Independent conjugation preserves modularity and design flexibility. TNDCs are engineered to overcome size limitations of NDCs and to address endosomal entrapment challenges associated with both NDCs and ADCs.
De-Risking Evidence
Proof-of-concept with protein and protein conjugate delivery completed (BSA/OVA). Nanobody/NDC PCT conversion filed March 2026.
Seeking Partnership
All Programs. One Platform.
Each XELCIS XB program leverages the same core nanoparticle platform — with modality-specific payload conjugation via Z-Link™ surface chemistry. Manufacturing, regulatory, and formulation learnings compound across programs, reducing development risk and timeline for each successive asset.
The XELCIS XB therapeutic delivery platform and all associated therapeutic candidates — including TDOX (XELCIS XB-Doxorubicin), XELCIS XB-PROTAC, XELCIS XB-Nucleic Acid, and XELCIS XB-Nanobody/NDC — are investigational products currently in preclinical development. None of these products have been approved by the U.S. Food and Drug Administration (FDA) or any other regulatory agency for safety, efficacy, or any therapeutic use. Clinical validation data referenced relate to prior nanoparticle delivery work advanced at TransCode Therapeutics and are included to demonstrate the scientific lineage and development experience that informed Xelcis Bio's proprietary XELCIS XB platform. These clinical studies were not conducted by Xelcis Bio™ and do not represent clinical studies of XELCIS XB.