ASCO Spotlight: New mRNA Therapy Shows Promise in Ovarian and Other Solid Tumors

A new kind of cancer treatment is emerging—one that turns the patient’s own body into a drug factory.

In a pioneering first-in-human trial presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, Dr. Timothy Yap of MD Anderson Cancer Center shared promising early data on BNT142, a cutting-edge mRNA-based therapy. Developed by BioNTech—the company behind one of the most effective COVID-19 vaccines—BNT142 is being studied as a treatment for advanced, treatment-resistant solid tumors that express Claudin 6 (CLDN6).

For patients, this represents a breakthrough. Many in the study had run out of standard treatment options. Yet with BNT142, some are seeing tumor shrinkage and disease stabilization, without the harsh side effects of chemotherapy. Importantly, the therapy was well tolerated, with a manageable safety profile.

“This is not a vaccine—it’s a therapeutic,” Dr. Yap tells BlackDoctor.org. “What’s remarkable is that we’re giving patients a piece of mRNA that gets taken up by the liver, translated into a bispecific antibody, and then that antibody targets the tumor and recruits immune cells to kill it. It’s a completely new way to treat cancer.”

What Is BNT142?

BNT142 is a first-in-class investigational drug that uses mRNA to instruct the liver to produce a bispecific antibody. This antibody, known as RiboMab02.1, simultaneously targets CLDN6 on tumor cells and CD3 on T cells. The result: immune cells are guided directly to the tumor to destroy it.

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This approach is part of BioNTech’s RiboMab® platform, which builds on the company’s expertise in mRNA science. Unlike traditional antibody therapies manufactured outside the body, BNT142’s mRNA is delivered using lipid nanoparticles, enabling the patient’s liver to produce the therapeutic agent in vivo.

The Phase I Trial: Design and Patients

The Phase I trial enrolled 65 patients with advanced CLDN6-positive solid tumors—including ovarian cancer, germ cell tumors, and non-small cell lung cancer (NSCLC)—all of whom had previously failed standard therapies.

• 67.7% of patients had ovarian cancer
  
• 77.3% of these had platinum-resistant disease
  
• CLDN6 positivity was confirmed in all patients (≥10% membrane staining)
  
• Doses ranged from 50 ng/kg to 100 µg/kg, administered weekly
  
  

Safety Profile and Tolerability

The treatment was generally well tolerated:

• Most adverse events were Grade 1 or 2, including mild cytokine release syndrome (CRS) and transient liver enzyme elevations
  
• Higher doses were associated with more Grade ≥3 events, but these remained manageable
  
• A transient dose-dependent increase in cytokines like IFN-γ and IL-6 was most notable during the first cycle
  
  

Only a few patients required dose reductions or treatment discontinuation due to side effects.

Encouraging Signs of Efficacy

The study showed promising clinical activity, particularly in ovarian cancer patients:

• 7 patients achieved partial responses (PR), including 3 confirmed responses
  
• 28 patients experienced stable disease
  
• The overall disease control rate (DCR) was 57%
  
• No strong correlation was observed between CLDN6 expression levels and treatment response
  
  

What This Means for Patients

This research could open the door to a new class of targeted cancer therapies. For patients with CLDN6-positive tumors—including ovarian, testicular, and NSCLC—BNT142 offers a potential treatment strategy after conventional therapies fail.

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The implications are especially significant for women with platinum-resistant ovarian cancer, a notoriously difficult-to-treat subtype with high recurrence rates. With manageable side effects and early signs of efficacy, BNT142 may become an important addition to the oncologist’s toolkit.

“In the future, we won’t just treat cancer based on where it starts in the body,” Dr. Yap says. “We’ll personalize treatment based on what the tumor expresses—like CLDN6. That’s where this approach is heading.”

Next Steps and Future Outlook

Enrollment for the current trial has been completed, and additional data from treated patients are being analyzed. Findings will be shared in future scientific forums.

While more research is needed, BNT142’s early success suggests it could pave the way for further mRNA-based bispecific antibody treatments targeting other tumor markers.

For now, it represents hope—a chance at renewed options—for patients who need them most.