Engineering the Immune Response: How a Dual-Targeting Antibody is Rewiring Cancer Defense

SAN DIEGO – October 14, 2026 – In the ongoing effort to dismantle the complex defense mechanisms of solid tumors, the biotechnology sector is increasingly turning to architectural solutions. Rather than simply flooding the body with systemic blockers, researchers are engineering molecules that act as localized biological logic gates. Today, Phanes Therapeutics, a clinical-stage biotech company based in San Diego, announced a significant milestone in this systemic approach: the first patient with colorectal cancer has been dosed in the ongoing Phase I/II TWINPEAK clinical study of spevatamig.

Spevatamig represents an emerging class of immuno-oncology agents known as innate immunity enhancers. Specifically, it is a first-in-class native IgG-like bispecific antibody designed to simultaneously target claudin 18.2 and CD47. By expanding its clinical evaluation to include colorectal adenocarcinomas, the company is testing whether this dual-targeting mechanism can crack a notoriously resistant biological environment, potentially reshaping the therapeutic landscape for advanced gastrointestinal oncology.

The CD47 Dilemma and the Bispecific Bypass

To understand the significance of this clinical milestone, one must look at the historical mechanical failures of CD47 inhibitors. CD47 is a membrane protein that functions as a "don't eat me" signal to the body's macrophages, effectively cloaking cancer cells from the innate immune system. For years, the pharmaceutical industry viewed CD47 as a holy grail of immuno-oncology. However, the systemic application of CD47 blockers encountered a severe biological roadblock: the protein is also widely expressed on healthy red blood cells and platelets.

Previous generations of therapies acted as blunt instruments, binding to CD47 universally. This created a massive "antigen sink," where the drug was absorbed by healthy blood cells before it could reach the tumor, leading to severe, often dose-limiting hematologic toxicities like anemia and thrombocytopenia.

Spevatamig attempts to bypass this systemic flaw through its bispecific architecture. By requiring a secondary anchor—the tumor-associated antigen claudin 18.2—the antibody is designed to localize its CD47 blockade exclusively to the tumor microenvironment. Preclinical models and early clinical data presented at major oncology conferences suggest this localized targeting significantly reduces binding to red blood cells. In early cohorts of the TWINPEAK study, the severe hematologic toxicities that plagued earlier CD47 agents were notably minimized, with patients primarily experiencing manageable, lower-grade adverse events such as nausea and fatigue.

Charting New Territory in Colorectal Cancer

The decision to expand the TWINPEAK study (NCT05482893) into colorectal cancer represents a calculated risk in tumor targeting. Claudin 18.2, a tight junction protein, has recently been validated as a highly effective therapeutic target, most notably by Astellas' zolbetuximab in gastric and gastroesophageal junction cancers. In those indications, claudin 18.2 expression is remarkably high, present in up to 80% of patients.

In contrast, the competitive landscape for claudin 18.2 in colorectal cancer is relatively sparse. While pharmaceutical giants and emerging biotechs alike are aggressively pursuing claudin 18.2 through monoclonal antibodies, antibody-drug conjugates, and even CAR-T cell therapies, the vast majority of these programs—including advanced assets from Legend Biotech and BioNTech—remain heavily concentrated on gastric and pancreatic indications.

Colorectal cancer presents a vastly different systemic challenge. The prevalence of claudin 18.2 expression in these tumors is significantly lower and highly heterogeneous, typically ranging from 10% to 30%. Furthermore, advanced colorectal tumors are notoriously "cold"—meaning they possess an immunosuppressive microenvironment that actively repels immune cell infiltration, rendering standard immunotherapies largely ineffective for the vast majority of patients with microsatellite stable disease.

By requiring patients in the expansion cohort to demonstrate claudin 18.2 expression in at least 10% of their tumor cells, the trial is employing strict biological gating. Oncology experts note that if the dual-targeting molecule can successfully tether to this sparse antigen and locally strip away the CD47 cloak, it could force macrophage-mediated phagocytosis. This process not only destroys the immediate cancer cells but also facilitates antigen presentation, theoretically converting a cold colorectal tumor into an immunologically active one.

A Two-Pronged Systemic Assault

The mechanical potential of spevatamig is further amplified by a strategic clinical collaboration agreement established in 2023 with Merck. The partnership evaluates the bispecific antibody in combination with pembrolizumab, a blockbuster anti-PD-1 therapy.

From a systems biology perspective, this combination represents a comprehensive assault on tumor defense mechanisms. Spevatamig acts on the innate immune system, mobilizing macrophages to consume tumor cells and present their antigens. Pembrolizumab acts on the adaptive immune system, blocking the PD-1 pathway to overcome T-cell exhaustion and unleash a targeted attack.

This synergistic hypothesis suggests that enhancing innate immunity at the tumor site can prime the environment for a more robust and durable adaptive immune response. For patients with advanced gastrointestinal cancers who have exhausted standard chemotherapy regimens, this dual-pathway disruption could offer a critical new lifeline.

Scaling the Pipeline Across Gastrointestinal Oncology

The dosing of the first colorectal cancer patient is part of a much broader, methodical expansion strategy by the San Diego-based biotech. The TWINPEAK study aims to enroll up to 200 participants across its Phase II cohorts, casting a wide net that includes gastric, pancreatic ductal, and biliary tract adenocarcinomas.

This multi-tumor approach is supported by a string of regulatory validations. The FDA previously granted the therapy Orphan Drug Designation for pancreatic cancer in 2022. This was followed by Fast Track designations for claudin 18.2-positive pancreatic adenocarcinoma in 2024, and more recently, for advanced and metastatic biliary tract carcinoma. Simultaneously, the company is recruiting gastrointestinal cancer patients across parallel Phase I and Phase II clinical trials in China, ensuring a global footprint for its data collection and reflecting the high global incidence of these specific malignancies.

As the biotechnology industry continues to move away from systemic sledgehammers in favor of precision-engineered biologics, the progress of this innate immunity enhancer offers a compelling case study. It highlights a fundamental shift in how we approach the mechanics of disease: not by simply attacking the tumor, but by strategically rewiring the body's own complex systems to recognize and eliminate the threat. The coming years of clinical data will ultimately determine if this sophisticated molecular architecture can translate into durable survival for patients facing some of the most intractable forms of cancer.