FDA Grants Fast Track Designation to Phanes' Spevatamig for Biliary Tract Cancer

FDA has granted fast track designation to Phanes Therapeutics' (Phanes) spevatamig for the treatment of advanced and metastatic biliary tract carcinoma (BTC), the company announced August 14, 2026.¹ Spevatamig is a bispecific antibody targeting claudin 18.2 (CLDN18.2) and CD47 that Phanes classifies as an innate immunity enhancer (I2E), an emerging class of immuno-oncology agents, and is currently being studied in phase 2 trials across multiple gastrointestinal cancers.¹

"Spevatamig has the potential to be a transformational treatment option for patients with BTC," said Ming Wang, PhD, president and CEO of Phanes, in a company press release.¹ "Following the successful completion of enrollment in our phase 2 clinical trial of spevatamig in combination with chemotherapy for the frontline treatment of metastatic pancreatic ductal adenocarcinoma [PDAC], we are making significant progress in the phase 2 study of the molecule in BTC."

Why is a new treatment approach needed for biliary tract cancer?

This fast track designation highlights the unmet need for novel treatments in BTC, according to Phanes.¹ The 5-year survival rate for BTC patients in the United States and Europe is less than 20%, and the disease is frequently diagnosed at advanced stages when treatment options are limited.²

How does spevatamig work?

Spevatamig is designed as an I2E, a category of agents intended to activate macrophages and dendritic cells to recognize and destroy cancer cells, offering a mechanism the company says is complementary to immune checkpoint inhibitors (ICIs), particularly for "cold tumors" less likely to respond to ICIs alone.¹ It has the potential to become the first I2E approved for a solid tumor indication, according to the company.¹

Spevatamig is being evaluated in the ongoing TWINPEAK study (NCT05482893), a phase 1/2 trial in patients with advanced gastric, gastroesophageal junction, pancreatic ductal, and biliary tract adenocarcinomas. As of December 2025, 107 patients had been treated with spevatamig in the US across monotherapy and combination cohorts.³

What other regulatory and collaboration milestones has spevatamig achieved?

Spevatamig previously received FDA orphan drug designation for metastatic pancreatic cancer in 2022 and fast track designation for metastatic CLDN18.2-positive pancreatic adenocarcinoma in 2024.¹ In July 2026, Phanes expanded its existing clinical trial collaboration and supply agreement with Merck, originally signed in 2023, to study spevatamig in combination with Merck's pembrolizumab (Keytruda) and chemotherapy as a frontline treatment for BTC.⁴

What are the limitations?

While fast track designation facilitates more frequent FDA interactions, it does not necessarily guarantee eventual approval. The phase 2 BTC and PDAC data referenced by Phanes remain unpublished beyond conference presentations and have not been peer-reviewed in a journal.

References

1. Phanes Therapeutics. Phanes Therapeutics receives FDA fast track designation for spevatamig in advanced and metastatic biliary tract carcinoma. News release. Published August 14, 2026. Accessed August 14, 2026. https://www.prnewswire.com/news-releases/phanes-therapeutics-receives-fda-fast-track-designation-for-spevatamig-in-advanced-and-metastatic-biliary-tract-carcinoma-302851460.html
2. Baria K, De Toni EN, Yu B, Jiang Z, Kabadi SM, Malvezzi M. Worldwide incidence and mortality of biliary tract cancer. Gastro Hep Adv. 2022;1(4):618-626. doi:10.1016/j.gastha.2022.04.007
3. Phanes Therapeutics. Phanes Therapeutics announces positive phase 2 results of spevatamig (PT886) in combination with chemotherapy in frontline (1L) treatment of metastatic PDAC at ASCO GI 2026. News release. Published January 9, 2026. Accessed August 14, 2026. https://www.prnewswire.com/news-releases/phanes-therapeutics-announces-positive-phase-2-results-of-spevatamig-pt886-in-combination-with-chemotherapy-in-frontline-1l-treatment-of-metastatic-pdac-at-asco-gi-2026-302656945.html
4. Phanes Therapeutics. Phanes Therapeutics announces expansion of clinical trial collaboration and supply agreement with Merck to evaluate spevatamig in combination with KEYTRUDA (pembrolizumab) and chemotherapy for treatment of biliary tract cancer. News release. Published July 21, 2026. Accessed August 14, 2026. https://www.prnewswire.com/news-releases/phanes-therapeutics-announces-expansion-of-clinical-trial-collaboration-and-supply-agreement-with-merck-to-evaluate-spevatamig-in-combination-with-keytruda-pembrolizumab-and-chemotherapy-for-treatment-of-biliary-tract-cancer-302830097.html