The 95% Problem in Colorectal Cancer Finally Has a Trial Aimed at It
In the first week of August 2026, Nanjing-based Leads Biolabs announced that China's National Medical Products Administration (NMPA) cleared an Investigational New Drug (IND) application for Opamtistomig (LBL-024) — a PD-L1 × 4-1BB bispecific antibody — to be studied in combination therapy for metastatic colorectal cancer (mCRC). The company confirmed the clearance in a press release distributed in early August 2026.
The target population is the reason this clearance matters beyond China. Metastatic colorectal cancer carries a 5-year survival rate under 13%. Immune checkpoint inhibitors have transformed a sliver of that disease — the microsatellite instability-high (MSI-H) / mismatch repair deficient (dMMR) subtype — but those patients account for only about 5% of mCRC cases. For the other 95%, the microsatellite stable (MSS) / mismatch repair proficient (pMMR) majority, checkpoint inhibitors alone have offered limited benefit, and the standard of care has stayed at chemotherapy plus targeted therapy. Opamtistomig is designed to attack exactly that 95% — the immunologically "cold" tumors where PD-1/PD-L1 blockade does little on its own.
The numbers that frame the story
What Opamtistomig Does — and Why the Design Matters
Opamtistomig is built on Leads Biolabs' proprietary X-Body bispecific platform. Its mechanism is a two-handed grip on the immune system: one arm blocks PD-L1-mediated immunosuppression (removing the brake), and the other conditionally activates 4-1BB, a co-stimulatory receptor on T cells (pressing the accelerator). The conditional activation is the design detail that separates it from first-generation 4-1BB agonists, which struggled with liver toxicity when stimulated systemically. By linking 4-1BB activation to PD-L1 engagement — meaning the signal fires where the tumor is — the molecule aims to restore exhausted T-cell function, promote T-cell proliferation, and build long-term memory responses with a safety profile comparable to PD-1/PD-L1 inhibitors.
The mechanism has already produced clinical signals in several tumor types, including extrapulmonary neuroendocrine carcinoma (EP-NEC), non-small cell lung cancer, small cell lung cancer and biliary tract cancer. According to the company, Opamtistomig is the first 4-1BB-targeting bispecific antibody globally to advance to a single-arm registration trial as monotherapy — a milestone that has drawn regulatory attention on both sides of the Pacific:
- NMPA Breakthrough Therapy Designation (October 2024) for neuroendocrine carcinoma
- FDA Orphan Drug Designation (November 2024) for neuroendocrine carcinoma
- FDA Fast Track Designation and European Commission Orphan Drug Designation (January 2026) for EP-NEC
To date the molecule has been evaluated across 13 solid tumor indications in China — EP-NEC, NSCLC, SCLC, biliary tract cancer, ovarian cancer, esophageal squamous cell carcinoma, hepatocellular carcinoma, gastric cancer, triple-negative breast cancer and others — with one registration trial and eight proof-of-concept studies in the mix. The new IND extends that franchise into colorectal cancer, where Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, frames the bet in one sentence: MSS/pMMR mCRC is a "cold" tumor, and the PD-L1 × 4-1BB dual mechanism is designed to "restore anti-tumor immune activity in cold tumors" — a differentiated approach with encouraging preliminary signals already seen in earlier studies.
Why This Is Happening in China
The colorectal cancer burden in China is the backdrop. According to the China National Cancer Center, 2022 saw 517,100 new colorectal cancer cases and 240,000 deaths in the country, ranking it second in incidence among all malignancies. Globally, IARC counted 1.926 million new cases and 904,000 deaths in 2022, making CRC the third most common cancer and the second leading cause of cancer-related death worldwide. Roughly 15–30% of CRC patients have distant metastases at initial diagnosis.
China's regulatory environment has made it the proving ground for this generation of bispecific immunotherapy. The NMPA has cleared IND applications for dozens of next-generation immuno-oncology assets built by domestic biotechs — Leads Biolabs, with 14 drug candidates across bispecific, ADC and T-cell-engager platforms, is one of a cohort that includes cell therapy developers now testing in vivo CAR approaches and solid-tumor CAR-T programs. The same ecosystem that produced the world's first approved solid-tumor CAR-T in mid-2026 is now pushing bispecifics into the hardest colorectal subtype. For patients, the practical consequence is simple: the newest immunotherapy trials in the world are enrolling in China, often years before equivalent programs open in other markets.
What the Trial Means for International Patients
For an international patient with MSS/pMMR metastatic colorectal cancer, the IND clearance matters on three levels.
First, it adds a new enrolling program. The Opamtistomig combination is being explored in an ongoing Phase Ib/II study, and Chinese cancer centers accept international patients into trials through their international departments — record review, eligibility screening and treatment planning all happen before travel. MSS/pMMR patients who have exhausted or failed chemotherapy-plus-targeted lines are the population with the fewest options anywhere, and China's trial infrastructure is now among the most active in the world for this subtype.
Second, the cost structure is different. Clinical-trial participation in China typically covers the investigational drug at no charge, with patients bearing hospital and supportive-care costs — a fraction of what equivalent experimental therapy would cost in the United States or Singapore. For patients not eligible for trials, cancer treatment in China remains a fraction of Western pricing, and China's top cancer hospitals run the international departments that coordinate care for Southeast Asian, Central Asian and Middle Eastern patients — the site's core readership.
Third, the supportive-care layer is Chinese medicine. This is the part of cancer care in China that surprises most international patients. At major Chinese cancer centers, integrated Chinese-Western medicine (中西医结合) runs alongside immunotherapy and chemotherapy: acupuncture for chemotherapy-induced nausea and peripheral neuropathy, herbal formulas for fatigue and appetite loss, and tuina or moxibustion for pain and recovery. It is standard practice at the same hospitals running the newest bispecific trials — the newest experimental drug on one floor, traditional Chinese medicine supportive care on the next.
What to Watch in the Next 12–18 Months
Three signals worth tracking. The Phase Ib/II combination readout — how the PD-L1 × 4-1BB mechanism translates into response rates in MSS/pMMR mCRC, the first efficacy signal for this combination in a cold-tumor population. The EP-NEC registration trial — already the first 4-1BB bispecific in a single-arm registration study, its data will determine whether the NMPA grants the first marketing approval for this drug class. The international expansion — with FDA Fast Track and EU orphan designations already granted, a positive China data package would put Opamtistomig on a path toward US and European filings, which would in turn tell international patients whether the therapy will reach their home markets or remain a China-first access story.
The bottom line: China's NMPA has cleared a PD-L1 × 4-1BB bispecific for combination trials in MSS/pMMR metastatic colorectal cancer — the 95% of the disease that standard immunotherapy misses. For the international patient with cold-tumor mCRC, it adds another actively enrolling option at Chinese cancer centers, at trial economics that no Western market can match, with TCM supportive care layered onto the experimental protocol. The first efficacy readout in the next 12–18 months will tell us whether the mechanism delivers in the hardest colorectal population.