Leads Biolabs Wins Second FDA Fast Track for Opamtistomig

The U.S. Food and Drug Administration has granted Fast Track designation to opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody developed by Leads Biolabs, for first-line treatment of advanced or metastatic biliary tract cancer (BTC). The Nanjing, China-based, Hong Kong-listed biotech announced the designation on 12 October 2026 — the second Fast Track designation the FDA has granted opamtistomig in nine months, after a January 2026 designation for an unrelated cancer, extrapulmonary neuroendocrine carcinoma (EP-NEC). The company says the FDA cleared this request in nine days.

Opamtistomig’s October in four numbers

2ndFDA Fast Track designation for opamtistomig, after January 2026’s EP-NEC nod

9 daysfrom Leads Biolabs’ submission to FDA’s decision, per the company

70patients enrolled in the Phase II first-line BTC trial, NCT07111546

2:2X-body format — two PD-L1-binding arms, two 4-1BB-binding arms

Figures from Leads Biolabs’ 12 October 2026 announcement and its Phase II trial record.

Two approved regimens, one open seat

Biliary tract cancer remains a thin field of approved first-line options for a disease usually caught too late for surgery. AstraZeneca’s durvalumab (Imfinzi), paired with gemcitabine and cisplatin, became the first checkpoint inhibitor approved for first-line advanced BTC in September 2022, after the Phase III TOPAZ-1 trial showed a median overall survival of 12.8 months against 11.5 months for chemotherapy alone. Merck’s pembrolizumab (Keytruda) followed the same chemotherapy backbone into a first-line approval in October 2023, backed by KEYNOTE-966’s 12.7-versus-10.9-month survival edge. Jazz Pharmaceuticals’ zanidatamab (Ziihera) cleared accelerated approval in November 2024, but only for patients already treated once, and only for the HER2-positive minority of BTC tumors; its first-line trial, HERIZON-BTC-302, is still running. None of the three is a bispecific built to co-stimulate T cells inside the tumor, and none is aimed at the broader, biomarker-unselected population that opamtistomig’s two chemotherapy-combination cohorts target.

BTC’s market, two ways of counting it

$3.65B → $7.03B

Global biliary tract cancer therapeutics market, 2025 to 2032, per 360iResearch (August 2026); Coherent Market Insights’ narrower-scope estimate for the same years is shown for comparison.

2025$3.65B

2032$7.03B

2025 (Coherent MI)$0.87B

2032 (Coherent MI)$1.28B

Sources: 360iResearch, Biliary Tract Cancers Market, August 2026 · Coherent Market Insights, Biliary Tract Cancers (BTCs) Market

Regulatory News outlook

We estimate a third first-line immunotherapy option in BTC could add $700 million to $1.4 billion a year in global peak sales by the early 2030s — a minority share behind the two combinations already approved first-line.

How we got here: 10%–20% of 360iResearch’s $7.03 billion 2032 global BTC market forecast = $703 million to $1.406 billion, rounded to $700 million–$1.4 billion.

Opamtistomig against BTC’s two approved combos

Product	Mechanism	Line of therapy	U.S. regulatory status	Reported efficacy
Opamtistomig (Leads Biolabs)	PD-L1/4-1BB bispecific antibody + chemo or bevacizumab	First-line	FDA Fast Track, Oct 2026 (Phase II, NCT07111546); not approved	20-patient safety run-in well tolerated; full data due at ESMO 2026
Durvalumab + gemcitabine/cisplatin	PD-L1 monoclonal antibody + chemo	First-line	FDA approved, Sept 2022 (TOPAZ-1)	Median OS 12.8 vs. 11.5 months; ORR 27% vs. 19%
Pembrolizumab + gemcitabine/cisplatin	PD-1 monoclonal antibody + chemo	First-line	FDA approved, Oct 2023 (KEYNOTE-966)	Median OS 12.7 vs. 10.9 months
Zanidatamab	HER2-targeted bispecific antibody, monotherapy	Previously treated, HER2-positive only; first-line trial ongoing	FDA accelerated approval, Nov 2024	ORR 52%; median duration of response 14.9 months
Gemcitabine + cisplatin alone	Cytotoxic chemotherapy doublet	First-line, pre-immunotherapy backbone	Standard of care since 2010 (ABC-02 trial)	Median OS 11.7 vs. 8.1 months for gemcitabine alone

From each company’s labelling and FDA approval announcements, and the ABC-02, TOPAZ-1 and KEYNOTE-966 trial publications; not a head-to-head clinical comparison.

Two arms for PD-L1, two for 4-1BB

Opamtistomig is built on Leads Biolabs’ X-body platform as a 2:2 bispecific — two binding domains for PD-L1, two for the co-stimulatory receptor 4-1BB (CD137) — rather than the simpler 1:1 pairing used in some earlier bispecific designs. The company’s stated design logic, repeated across its regulatory announcements, is that anchoring the molecule to PD-L1 on tumor and tumor-infiltrating immune cells restricts 4-1BB activation to the tumor microenvironment, instead of triggering it throughout the body. That distinction matters because standalone 4-1BB agonist antibodies developed a decade ago, including Bristol Myers Squibb’s urelumab, were shelved or had their dosing narrowed after causing severe, sometimes fatal, liver toxicity when 4-1BB was engaged systemically. Leads Biolabs reports no cumulative hepatotoxicity signal with long-term treatment to date across its pipeline — a company claim, not yet an independently published finding.

Three design choices behind the safety profile

01

PD-L1-anchored 4-1BB

4-1BB co-stimulation is designed to fire only where PD-L1 is present, aiming to spare the liver toxicity that limited earlier systemic 4-1BB agonists.

02

2:2 binding, not 1:1

Two PD-L1 arms and two 4-1BB arms per molecule, a bivalent-bivalent design the company says strengthens the conditional activation.

03

One molecule, two FDA nods

The same antibody now carries Fast Track status in two unrelated cancers, EP-NEC and BTC, nine months apart.

Nine days, and a second nod

Leads Biolabs says the FDA granted the Fast Track designation nine days after it filed the request. Charles Cai, the company’s chief medical officer, also said the company welcomed the FDA’s recommendation that it begin early discussions on a U.S. registration strategy for opamtistomig combined with chemotherapy in BTC — a step that precedes, but does not guarantee, an eventual filing.

“The FDA’s decision is an encouraging milestone for opamtistomig and our first-line BTC program.” Charles Cai, MD, Chief Medical Officer, Leads Biolabs — 12 October 2026 announcement

The designation rests on Leads Biolabs’ Phase II study (NCT07111546), which pairs opamtistomig with cisplatin and gemcitabine in one cohort and with bevacizumab in a second, each structured as a safety run-in followed by an expansion cohort, with objective response rate under RECIST 1.1 as the primary endpoint. An April 2026 update on the 20-patient safety run-in described the combination as generally well tolerated, with no new safety signals; the trial, led by Jian Zhou of Zhongshan Hospital, Fudan University, finished enrolling all 70 patients on 30 July 2026. Fast Track designation speeds FDA’s review process and allows a rolling submission; it is not a marketing approval, and the October announcement itself did not include survival or response-rate figures for the BTC cohorts.

Six years, two Fast Track nods

Six years, two Fast Track nods

1. 2012

   Leads Biolabs founded

   Founded in Nanjing, China, to develop bispecific antibodies, T-cell engagers and antibody-drug conjugates for oncology and autoimmune disease.

2. 25 July 2025

   HKEX listing

   Listed on the Main Board of the Hong Kong Stock Exchange under stock code 9887.HK, raising roughly USD 189 million including the over-allotment option.

3. October 2025

   First patient dosed in BTC trial

   Jian Zhou of Zhongshan Hospital, Fudan University, dosed the first patient in the Phase II first-line biliary tract cancer study.

4. 14–15 January 2026

   First Fast Track designation

   FDA granted opamtistomig Fast Track designation for extrapulmonary neuroendocrine carcinoma (EP-NEC), a different indication from the one in this story.

5. April 2026

   BTC trial advances to expansion

   The 20-patient safety run-in was generally well tolerated with no new safety signals; the study moved into its expansion cohort.

6. 30 July 2026

   BTC enrollment completes

   All 70 patients enrolled across the trial’s two chemotherapy-combination cohorts.

7. 12 October 2026

   Second Fast Track designation

   FDA granted Fast Track designation for opamtistomig in first-line advanced or metastatic biliary tract cancer, nine days after submission.

8. 23–27 October 2026

   ESMO 2026, Madrid

   Leads Biolabs is scheduled to present detailed BTC clinical data, among six company studies selected for the congress.

• ESMO 2026 (23–27 October, Madrid): the first detailed look at response and survival data from the BTC cohorts, not disclosed in the Fast Track announcement.
• FDA registration discussions: the agency recommended Leads Biolabs begin talks on a U.S. registration strategy for opamtistomig plus chemotherapy in BTC; no filing date has been set.
• A confirmatory study: the company has said it plans a confirmatory BTC study once more efficacy data mature — a step short of any accelerated-approval pathway being agreed.
• The EP-NEC track in parallel: opamtistomig’s first Fast Track indication already has an NMPA-accepted filing and a CDE-cleared Phase III trial under way in China, running alongside the BTC program.

The gaps ESMO still has to fill

Fast Track designation is a process tool, not a verdict on the drug: it commits FDA to more frequent communication and the option of a rolling filing, not to a faster or more favorable review outcome. Opamtistomig is not approved anywhere for biliary tract cancer, and the October announcement reported no objective response rate, survival figure or comparison with the durvalumab- or pembrolizumab-based regimens already on the market. FDA does not maintain a public, searchable database of Fast Track designations the way it does for approvals and 510(k) clearances, so this designation’s primary record is Leads Biolabs’ own announcement, corroborated here by independent trade coverage; there is no separate FDA database entry to check it against.

Frequently asked questions

What did the FDA grant Leads Biolabs on 12 October 2026?

Fast Track designation for opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody, for first-line treatment of advanced or metastatic biliary tract cancer (BTC). The company says FDA granted it nine days after submission.

Is this the same Fast Track designation opamtistomig received in January 2026?

No. The January 2026 designation covered a different cancer, extrapulmonary neuroendocrine carcinoma (EP-NEC). The October 2026 designation is a separate, second Fast Track grant specific to first-line biliary tract cancer.

Has opamtistomig been approved to treat biliary tract cancer?

No. Fast Track designation speeds up FDA’s review process and permits a rolling submission; it is not a marketing approval and does not guarantee one. Opamtistomig remains in a Phase II trial (NCT07111546) for BTC, with no U.S. or other approval in this indication.

When will detailed clinical data for the BTC trial be available?

Leads Biolabs has said detailed results from the trial’s two chemotherapy-combination cohorts are planned for the ESMO Annual Meeting in Madrid, 23–27 October 2026. The October Fast Track announcement itself did not include response-rate or survival figures.