Phanes Advances Dual-Action Cancer Drug for Lethal Biliary Tract Cancers

SAN DIEGO, CA – April 07, 2026 – Clinical-stage biotech firm Phanes Therapeutics has initiated a significant expansion of its clinical study for spevatamig, a novel cancer therapy, in combination with chemotherapy for patients with biliary tract cancer (BTC). The move follows the successful clearance of safety hurdles at two different dose levels, signaling a promising step forward for a drug aimed at one of the most aggressive and hard-to-treat malignancies.

The announcement marks a critical milestone for spevatamig, a first-in-class bispecific antibody, and offers a potential new avenue of hope for patients with a disease that has long seen limited therapeutic progress. The dose expansion phase will allow researchers to treat a larger group of patients to further evaluate the drug's safety and preliminary efficacy.

A New Strategy for a Lethal Cancer

Biliary tract cancer, a group of rare cancers that form in the bile ducts, gallbladder, or liver, is notoriously difficult to treat and carries a grim prognosis. In the United States, an estimated 12,610 new cases of gallbladder and other biliary cancers are expected in 2025. For patients diagnosed after the cancer has spread to distant parts of the body, the five-year survival rate can be as low as 3%.

For decades, the standard of care has been limited primarily to chemotherapy. While the recent FDA approval of Merck's immunotherapy drug pembrolizumab in combination with chemotherapy has provided a new option, significant unmet needs persist. The high recurrence rates and molecular complexity of BTC mean that novel, targeted approaches are desperately needed.

Spevatamig enters this challenging landscape with an innovative design. Its advancement into dose expansion suggests a manageable safety profile when combined with standard chemotherapy, a crucial factor in developing new treatments for this fragile patient population. As one oncology expert noted, the field is in dire need of therapies that can offer meaningful benefits without adding prohibitive toxicity to existing regimens.

The Power of a Dual-Targeting Approach

What sets spevatamig apart is its unique dual-action mechanism. As a bispecific antibody, it is engineered to bind to two different targets simultaneously. One arm of the antibody targets claudin 18.2 (CLDN18.2), a protein that is typically hidden within tissues but becomes exposed on the surface of certain cancer cells, including those in gastric, pancreatic, and biliary tract tumors. This makes it a highly specific beacon for the therapy.

The other arm targets CD47, a protein often called the “don’t eat me” signal. Cancer cells use CD47 to protect themselves from being engulfed and destroyed by the body's innate immune cells, particularly macrophages. By blocking this signal, spevatamig essentially removes the cancer's camouflage, marking it for destruction.

This dual-targeting strategy is designed to create a powerful one-two punch. The targeting of CLDN18.2 ensures the drug is directed to the tumor, while the blockade of CD47 unleashes the immune system to attack it. Critically, Phanes has engineered the CD47-binding portion of spevatamig to preferentially bind to cancer cells over red blood cells. This is a key innovation aimed at mitigating the risk of anemia, a common and sometimes severe side effect that has plagued the development of other CD47-targeting drugs.

Building a Case with Clinical Momentum

The confidence to expand the BTC trial is not based on safety data alone. Spevatamig, also known as PT886, is building a compelling record across multiple cancer types within its ongoing Phase 1/2 TWINPEAK study. The drug has already received both Orphan Drug and Fast Track designations from the FDA for its development in pancreatic cancer, another notoriously lethal malignancy.

Earlier this year, Phanes presented encouraging data from a cohort of first-line metastatic pancreatic cancer patients at the American Society of Clinical Oncology Gastrointestinal Cancers Symposium (ASCO GI). In that group, spevatamig combined with standard chemotherapy demonstrated a median progression-free survival of 7.3 months and a disease control rate of 93%. Importantly, the combination was well-tolerated and did not appear to add significant toxicity to the chemotherapy backbone, with the maximum tolerated dose yet to be reached.

With more than 160 patients having been dosed with spevatamig globally in various settings as of March 2026, the company is accumulating a substantial body of evidence. Phanes is slated to present further findings in three separate posters at the upcoming American Association for Cancer Research (AACR) Annual Meeting, indicating a commitment to transparently sharing its progress with the scientific community.

Strategic Alliances in a Competitive Field

Phanes Therapeutics is navigating a competitive but highly validated area of oncology. The CLDN18.2 target was recently legitimized with the landmark approval of Astellas' zolbetuximab for gastric cancer. This approval has ignited the field, but spevatamig's bispecific approach may offer a next-generation advantage.

Similarly, the CD47 pathway is a bustling area of research, with over 80 drugs in development. However, spevatamig’s unique combination of targets and its safety-engineered design help it stand out. The company is not going it alone. In 2023, Phanes entered into a clinical collaboration with pharmaceutical giant Merck to evaluate spevatamig in combination with its blockbuster anti-PD-1 therapy, pembrolizumab. This partnership provides powerful validation for spevatamig's potential and aligns with the broader oncology trend of combining different immunotherapies to achieve deeper and more durable responses.

The progression of spevatamig in biliary tract cancer, supported by its promising data in pancreatic cancer and a major strategic partnership, underscores the potential of Phanes' proprietary drug development platforms. For patients with few good options, the advancement of such innovative, multi-pronged therapies represents a significant and welcome step forward in the fight against cancer.