Avenzo Therapeutics, Inc., the San Diego-based clinical-stage oncology developer pursuing a merger with Nasdaq-listed Rallybio Corporation (Nasdaq: RLYB), announced on October 13, 2026, that its Chinese development partner VelaVigo will present preliminary Phase 1 results for VBC103, also known as AVZO-103, at the European Society for Medical Oncology Asia Congress in Singapore. The December 4 presentation will examine early safety, tolerability and antitumor activity for an investigational bispecific antibody-drug conjugate targeting Nectin-4 and TROP2 in patients with advanced solid tumors.
The announcement confirms acceptance of an oral presentation but does not disclose the number of treated patients, objective response rates, dose-limiting toxicities or other numerical clinical findings. Those results will be important in determining whether the dual-target design produces sufficiently encouraging human evidence to justify continued dose optimization and larger studies. The candidate is intended to recognize two tumor-associated proteins while delivering a topoisomerase I inhibitor payload, a strategy that Avenzo believes could address tumor heterogeneity and resistance to existing treatments.
The development is particularly relevant to urothelial cancer, where Nectin-4-directed treatment has already become part of established oncology practice. AVZO-103 received United States Food and Drug Administration Fast Track designation in November 2025 for adults with locally advanced or metastatic urothelial cancer previously treated with enfortumab vedotin. Avenzo is separately evaluating the therapy in its ongoing BEACON-1 Phase 1/2 study outside Greater China, while VelaVigo retains development responsibility for mainland China, Hong Kong, Macau and Taiwan.
The presentation could become an important scientific milestone for Avenzo as it prepares for a proposed public-market transition. However, neither the presentation acceptance nor the existing regulatory designation establishes that AVZO-103 is effective in patients resistant to enfortumab vedotin. Its clinical and commercial prospects will depend on demonstrated response durability, acceptable toxicity and whether simultaneous targeting of Nectin-4 and TROP2 provides a meaningful advantage over existing antibody-drug conjugates.
What will VelaVigo’s December 4 Phase 1 presentation reveal about VBC103?
VelaVigo’s presentation is scheduled for December 4, 2026, from 10:45 a.m. to 10:55 a.m. Singapore time during the developmental therapeutics and precision medicine session at ESMO Asia. Professor Jian Zhang of Fudan University Shanghai Cancer Center will present abstract 2370, covering the first-in-human investigation of VBC103 as monotherapy in patients with advanced solid tumors. The congress runs from December 4 through December 6, making the presentation an early opportunity for researchers to evaluate the molecule’s emerging clinical profile.
The Chinese clinical programme is registered as NCT07299747, a multicenter, open-label Phase 1/2a study involving dose escalation and subsequent expansion. The registry lists an estimated total enrollment of 255 participants across the planned development programme, but that figure is not the number of patients included in the forthcoming presentation. The actual treated population, dose levels and evaluable patient numbers have not been disclosed in the October announcement.
The initial investigation is designed to establish safety, tolerability, pharmacokinetics and an appropriate dose for subsequent development. Its primary assessments include dose-limiting toxicities during an approximately 21-day evaluation period and serious adverse events over the defined observation period. Secondary measures include objective response rate, duration of response, disease control and exposure to the antibody-drug conjugate and its components.
These endpoints will help establish whether VBC103 can deliver its cytotoxic payload at doses that produce measurable antitumor effects without unacceptable toxicity. However, the early-stage, uncontrolled design means that observed tumor responses cannot establish superiority over existing treatments. Any favorable findings will need to be interpreted alongside the number of evaluable patients, prior therapies, follow-up maturity and dose-related adverse events.
How could dual Nectin-4 and TROP2 targeting improve antibody-drug conjugate activity?
AVZO-103 is designed to recognize two cell-surface proteins, Nectin-4 and TROP2, that are expressed in several solid tumor types. Nectin-4 is involved in cellular adhesion and is particularly relevant to urothelial cancer, where it has already been validated as a therapeutic target. TROP2 is another tumor-associated protein expressed across multiple epithelial cancers and has become an established target for antibody-drug conjugate development.
The central premise of a bispecific ADC is that recognizing two antigens could provide additional opportunities to engage tumor cells with heterogeneous protein expression. Within an individual tumor, some malignant cells may express relatively high levels of Nectin-4, others may express more TROP2, and some may express both. A therapy capable of engaging these different populations could theoretically extend drug delivery to cells that might be less effectively targeted through a single antigen.
That possibility is particularly relevant in advanced cancer because tumors can contain biologically distinct cell populations. Target expression may also change during treatment, potentially contributing to resistance when therapy depends heavily on a particular molecular feature. Avenzo believes the dual-target strategy could help address this heterogeneity, although the clinical importance of simultaneously recognizing Nectin-4 and TROP2 has not yet been demonstrated for AVZO-103.
There are also important unanswered questions about the mechanics of targeting. A bispecific antibody may interact with cells expressing one or both target proteins, but the relationship between antigen density, cellular uptake and payload delivery must be established experimentally for the specific molecule. Dual binding alone does not guarantee stronger internalization, greater tumor selectivity or better clinical outcomes.
Normal tissues can also express proteins targeted by ADCs, creating the possibility of adverse effects outside malignant tissue. Consequently, broader antigen recognition could influence both therapeutic activity and toxicity. The Phase 1 findings will be important for understanding whether the molecular design provides an acceptable biological and clinical balance.
Why is AVZO-103’s topoisomerase I inhibitor payload important after enfortumab vedotin treatment?
AVZO-103 combines its bispecific targeting structure with a topoisomerase I inhibitor payload. Topoisomerase I is an enzyme involved in managing DNA structure during processes such as replication and transcription. Inhibiting its activity can produce DNA damage and interfere with cancer-cell survival, providing a mechanism of cytotoxic activity distinct from the action of certain established ADC payloads.
This difference matters because enfortumab vedotin, marketed as Padcev, delivers monomethyl auristatin E, a microtubule-disrupting agent. Its payload interferes with the cellular machinery required for cell division rather than directly inhibiting topoisomerase I. AVZO-103 therefore differs from enfortumab vedotin in both its targeting architecture and the class of cytotoxic drug delivered.
Avenzo’s development hypothesis is that these differences may provide antitumor activity after patients have received enfortumab vedotin. However, progression during or after an ADC can result from multiple mechanisms, including reduced target expression, altered intracellular trafficking, drug efflux and changes in cellular sensitivity. A different payload does not automatically overcome all resistance mechanisms, particularly when several biological processes contribute to treatment failure.
The clinical significance of the topoisomerase I payload will also depend on its delivery and release characteristics. Researchers will need to understand how much active drug reaches tumor tissue, whether exposure produces meaningful responses and how much systemic toxicity occurs. The drug-to-antibody ratio, linker characteristics and payload stability may influence these outcomes, but the October announcement does not provide sufficient comparative manufacturing or pharmacological data to establish superiority.
For AVZO-103, the most persuasive evidence of differentiation would come from responses in patients whose cancers have progressed after prior ADC treatment. Such findings would need appropriate information on previous therapy, the timing of progression, target expression and response durability. Early activity in patients without prior exposure to enfortumab vedotin would support antitumor potential but would not independently validate the proposed resistance-overcoming strategy.
Why does the established Padcev and Keytruda regimen create a demanding competitive benchmark?
The commercial context for AVZO-103 has changed substantially as Nectin-4-targeted treatment has become established in advanced urothelial cancer. Enfortumab vedotin, developed by Astellas Pharma and Pfizer, is approved in combination with Merck & Co.’s pembrolizumab, marketed as Keytruda, for locally advanced or metastatic urothelial cancer. The United States Food and Drug Administration granted traditional approval to the combination in December 2023 based on randomized Phase 3 evidence.
In the EV-302 trial, the combination achieved median overall survival of 31.5 months compared with 16.1 months for platinum-based chemotherapy. Median progression-free survival reached 12.5 months versus 6.3 months, respectively, supporting a substantial improvement over the chemotherapy comparator in the previously untreated advanced disease population. These findings helped establish Nectin-4-directed ADC treatment as an important component of modern urothelial cancer management.
However, patients can still experience disease progression after receiving enfortumab vedotin and pembrolizumab. The availability of effective initial treatment has therefore increased interest in subsequent therapies capable of producing meaningful activity after exposure to an ADC and an immune checkpoint inhibitor. Avenzo is positioning AVZO-103 within that evolving treatment landscape.
The challenge is that favorable early responses cannot be directly compared with the results of EV-302. The populations would differ in treatment history, prognosis, disease burden and study design, making isolated comparisons of response rates or survival unreliable. AVZO-103 must establish its own clinical value in the specific treatment setting being investigated.
An important distinction also concerns its Fast Track designation. The designation applies to adult patients with locally advanced or metastatic urothelial cancer previously treated with enfortumab vedotin, not to every solid tumor expressing Nectin-4 or TROP2. It recognizes the potential relevance of the investigational programme to a serious condition with unmet medical need, but it does not establish effectiveness or predict approval.
How will Avenzo’s BEACON-1 trial complement VelaVigo’s Chinese clinical findings?
Avenzo initiated its BEACON-1 Phase 1/2 clinical study in September 2025 after receiving United States FDA clearance for its Investigational New Drug application. Registered as NCT07193511, the open-label study is recruiting adults with locally advanced or metastatic urothelial cancer and other selected advanced solid tumors. Its current registry information lists an estimated enrollment of 355 participants across the planned programme.
The study begins with dose escalation to characterize safety, tolerability, pharmacokinetics and the maximum tolerated or recommended Phase 2 dose of AVZO-103. Subsequent expansion is intended to evaluate antitumor activity, including as monotherapy and in combination with other agents. Objective response rate is an important efficacy assessment for the expansion phase, while duration of response, disease control and survival-related outcomes can provide additional evidence as follow-up matures.
BEACON-1 has defined clinical eligibility requirements. Participants must generally have an Eastern Cooperative Oncology Group performance status of zero or one, measurable disease and sufficient expected survival to participate in the study. The protocol also excludes certain patients with active central nervous system metastases, previous drug-induced interstitial lung disease and selected serious medical conditions.
These restrictions are important for interpreting the eventual results. Early-stage oncology studies often enroll patients with relatively preserved functional status and exclude individuals with conditions that could complicate treatment safety. Their findings may therefore not reflect outcomes among all patients with advanced urothelial cancer, particularly those with substantial comorbidities or poor performance status.
The VelaVigo and Avenzo programmes are separate investigations conducted under different regional development responsibilities. The Chinese trial is currently generating the data scheduled for presentation in December, while BEACON-1 is independently evaluating AVZO-103 outside Greater China. Findings from the two programmes may eventually provide complementary information, but differences in dose, population and study conduct must be considered before their results are compared or combined.
Which safety signals will be most important for VBC103’s dual-target ADC development?
Safety will be central to the interpretation of the first-in-human presentation because ADC toxicity can arise from both the targeting component and the cytotoxic payload. The extent of systemic drug exposure, stability of the linker and distribution of the target proteins can influence adverse events. Avenzo has not disclosed VBC103-specific rates of treatment-related adverse events in its October announcement, so no definitive conclusion about tolerability is currently supported.
Topoisomerase I inhibitor-based ADCs require attention to gastrointestinal and hematological adverse effects, among other potential toxicities. Clinically important events associated with some drugs in this broader class have included neutropenia, anemia, diarrhea and interstitial lung disease. However, these are class-level considerations and should not be presented as adverse events already demonstrated with VBC103.
The Chinese study’s eligibility criteria exclude patients with certain existing pulmonary conditions, including a history of interstitial lung disease. Patients with active keratitis or corneal ulceration are also excluded, reflecting the importance of carefully monitoring ocular and other tissue-related risks during early development. These exclusions support safer trial conduct but also limit conclusions about patients with those underlying conditions.
The upcoming results will need to distinguish treatment-emergent adverse events from events assessed as related to the investigational drug. Information on grade 3 or higher toxicity, dose reductions, interruptions, discontinuations and serious adverse events will help clarify whether the treatment can be administered repeatedly at biologically active doses. Dose-limiting toxicity findings will be particularly important for defining the recommended development dose.
A favorable early safety profile would support continued investigation, but it would not establish that uncommon complications have been excluded. Small dose-escalation cohorts often cannot reliably characterize rare events or toxicities requiring prolonged exposure. Larger patient populations and longer follow-up would therefore remain necessary even if the initial presentation reports encouraging tolerability.
What does Avenzo’s VelaVigo licensing agreement mean for global development rights?
The relationship between Avenzo and VelaVigo originated in November 2024, when the companies established an exclusive option arrangement covering the Nectin-4/TROP2 bispecific ADC programme. Under that agreement, VelaVigo retained rights in Greater China while Avenzo could obtain development, manufacturing and commercialization rights elsewhere. Avenzo exercised its option in September 2025, securing the agreed territorial rights for AVZO-103.
The original transaction contemplated an upfront payment and potential near-term payments totaling up to $50 million, including the option exercise component. It also included future development, regulatory and commercial milestones totaling approximately $750 million, alongside tiered royalties on sales in Avenzo’s territories. The maximum potential transaction economics therefore approached $800 million before accounting for royalties.
Those figures do not represent money already received by VelaVigo or a guaranteed payment obligation of the full headline amount. Much of the potential consideration depends on achieving future clinical, regulatory or commercial milestones. The companies have not disclosed a revised transaction valuation associated with the October ESMO announcement.
The arrangement allows development to proceed in parallel across major geographic markets. VelaVigo can generate clinical evidence through its Chinese programme, while Avenzo advances BEACON-1 and prepares potential regulatory strategies elsewhere. This structure may expand the evidence available for the asset, although the companies must maintain appropriate manufacturing consistency and interpret clinical findings according to their respective protocols.
The commercial value of the agreement will depend on successful product development rather than territorial rights alone. If AVZO-103 demonstrates promising efficacy and safety, the partnership could become increasingly important to both companies. Until then, licensing milestone potential should be distinguished from realized revenue or an established market opportunity.
How does Avenzo’s proposed $215 million financing and Rallybio merger affect its oncology strategy?
Avenzo’s clinical development programme is progressing alongside a significant proposed corporate transaction. On June 1, 2026, Rallybio Corporation and Avenzo announced a definitive merger agreement under which the combined company would operate as Avenzo Therapeutics. The transaction is accompanied by a planned $215 million private placement involving institutional healthcare investors, including accounts associated with T. Rowe Price Investment Management and other life sciences investment firms.
The companies stated that the financing, together with the anticipated financial position at closing, was expected to support operations into late 2028 and fund multiple clinical milestones. However, the financing is linked to completion of the merger and should not be described as fully available operating cash until the relevant transactions close. The latest reviewed transaction documentation continued to describe the merger as proposed, with completion targeted for the fourth quarter of 2026.
The transaction would also affect Avenzo’s relationship with public equity markets. Under the announced terms, the combined company is expected to trade on Nasdaq under the ticker AVZO after completion. Until that transition is confirmed, Avenzo’s investigational pipeline should not be treated as an existing separately listed company with its own verified trading history.
For Avenzo, the strategic significance lies in securing resources for four clinical-stage programmes rather than relying on a single oncology candidate. Alongside AVZO-103, the portfolio includes AVZO-1418, an investigational EGFR/HER3 bispecific ADC, AVZO-021, a selective CDK2 inhibitor, and AVZO-023, a selective CDK4 inhibitor. These assets target different biological pathways and tumor populations, providing diversification while creating competing demands for development capital.
The December VBC103 presentation could influence how investors evaluate the scientific breadth of that portfolio. Strong initial data might support confidence in Avenzo’s ADC strategy, while inconclusive findings could reinforce the importance of its other programmes. However, the value of the proposed public-market transaction cannot be attributed to AVZO-103 alone, and no direct stock-price reaction to the December data can yet be assessed.
What must the December ESMO Asia results show to justify further AVZO-103 development?
The first major question will be the number of patients treated and evaluable for response across the investigated dose levels. A small population can provide useful early evidence, but headline response percentages become difficult to interpret when individual patients account for a substantial proportion of the analysis. Reporting both the numerator and denominator for responses will therefore be essential.
The second issue will be whether antitumor activity is accompanied by acceptable safety. A dose that produces substantial tumor shrinkage may still be unsuitable for further development if clinically important toxicity prevents sustained treatment. Conversely, a well-tolerated dose with limited antitumor activity may not support a compelling later-stage programme.
Response durability will provide another important distinction. Early tumor shrinkage can be encouraging, particularly in heavily pretreated populations, but its clinical value depends partly on how long disease control persists. The presentation should clarify whether responses were confirmed under RECIST criteria, how long patients remained on therapy and whether sufficient follow-up was available to characterize progression.
The relationship between prior ADC treatment and observed activity could be especially informative. Patients previously treated with enfortumab vedotin represent a clinically relevant population for Avenzo’s United States development strategy. However, the announcement does not establish how many such patients are included in VelaVigo’s forthcoming analysis, making any conclusion about resistance following Padcev premature.
The results may also provide information about tumor types responding to treatment. Because Nectin-4 and TROP2 expression differs across malignancies, evidence of activity in several solid tumor populations could strengthen the rationale for broader development. Nevertheless, responses in a mixed population would need disease-specific interpretation, particularly if later trials focus on urothelial cancer.
For Avenzo and VelaVigo, ESMO Asia 2026 represents the first major opportunity to present a detailed human clinical profile for their Nectin-4/TROP2 bispecific ADC programme. The dual-target architecture and topoisomerase I payload provide a scientifically plausible approach to expanding ADC activity, while the ongoing regional trials and FDA Fast Track designation establish a framework for continued development.
The decisive question is whether that rationale translates into reproducible clinical activity with manageable toxicity in patients who have limited remaining treatment options. A favorable Phase 1 presentation could support further dose optimization and expansion into better-defined populations, but it would not establish superiority over existing ADCs or guarantee regulatory success. The December 4 results will determine whether AVZO-103’s dual-target design begins to demonstrate the clinical differentiation that Avenzo and VelaVigo are seeking.
