Summary of Key Points
CDH17 has emerged as one of the hottest targets in the field of innovative drugs for gastrointestinal tumors in recent years,被视为 the next “star” after CLDN18.2. The first CDH17 ADC (antibody-drug conjugate) drug, AMT-676, has released phase I clinical data: it shows better efficacy than traditional chemotherapy, but no significant advantage compared to other ADCs targeting similar targets. However, safety concerns (such as colitis and hematotoxicity) are more concerning. Nevertheless, this is just the debut of this target, and dozens of CDH17-related drugs are in development worldwide, including through various technological approaches like ADCs and CAR-T therapies, indicating that the field still holds significant potential.
Why Is CDH17 Such a Target of Interest?
CDH17 acts as a “cell adhesive” that normally binds intestinal cells together, maintaining the intestinal barrier. In tumors such as colorectal cancer and gastric cancer, it becomes exposed on the cell surface, making it an excellent target for anticancer drugs:
1. High Expression in Tumors: The expression of CDH17 is nearly 100% in patients with colorectal cancer, meaning almost all patients could potentially benefit from this target.
2. Suitable for ADCs: CDH17 is hidden within normal cells but exposed on tumor cells, allowing ADC drugs (which act like toxic missiles) to target the tumors precisely without harming normal cells.
3. High Clinical Need: Current treatments for colorectal cancer are limited in effectiveness for patients in advanced stages or with low CDH17 expression, so there is a clear need for new therapies.
As a result, in just two years, more than 30 CDH17 ADC projects have been initiated globally, with giants like GSK and Roche joining the competition, making it one of the most crowded areas in ADC research.
Phase I Results: Better Than Chemotherapy, but Not Outperforming Other Competitors
The phase I data from AMT-676 involved 125 patients with advanced colorectal cancer:
- Compared to Chemotherapy: AMT-676 showed a higher overall response rate (ORR) of 18% in all dose groups and 21% in the highest-dose group, compared to only 3% for standard chemotherapy and 6% when combined with bevacizumab, indicating antitumor activity.
- Compared to Other ADCs: AMT-676 did not outperform other ADCs targeting targets like cMet or EpCAM. For example, the highest response rate for EpCAM ADCs was 32%, and that for CEACAM5 ADCs was 31%.
While these data cannot be directly compared head-to-head due to differences in patient populations and dosage regimens, they do suggest that AMT-676 does not have a distinct competitive advantage.
Safety Concerns: Colitis and Hematotoxicity Are Major Issues
The side effects are more concerning than the efficacy:
1. Colitis Risk: One case of grade 3 colitis was observed in the 8mg/kg dose group. This is significant because CDH17 plays a role in maintaining the intestinal barrier; ADC drugs may inadvertently damage normal intestinal cells, leading to inflammation. This side effect has not been seen with other ADCs, raising concerns for the entire CDH17 field.
2. Hematotoxicity: One case of grade 5 neutropenic sepsis (severe infection due to low white blood cell counts) occurred in the 10mg/kg dose group. Although neutropenia is a common side effect with ADCs, the high payload of AMT-676 may have led to this severe reaction, possibly indicating “off-target” effects on healthy hematopoietic cells.
These issues mean that the “therapeutic window” for AMT-676 (the dose range that is both effective and safe) is narrow: higher doses improve efficacy but increase risk, while lower doses are less effective.
The Field Is Not Yet Over
The performance of AMT-676 does not mean the entire CDH17 field is dead. Many companies are exploring different strategies:
1. ADC Technology Improvements:
- YinEn Biotech’s DB-1324 uses a high payload (DAR=8) to enhance toxicity.
- Maiwei Bio’s 7MW4911 uses a new toxin to improve plasma stability and reduce off-target effects.
- Innovent Biologics’ ICP-B208 uses a hydrophilic linker, making it effective even in tumors with low CDH17 expression.
2. Dual-Target Approaches: Orange Sail Medicine’s VBC108 is a dual-ADC targeting both CDH17 and CLDN18.2, potentially offering broader efficacy.
3. Other Technologies:
- TCE (bispecific antibodies) like ARB202 can directly recruit T cells to attack tumors, bypassing the toxicity limitations of ADCs.
- CAR-T therapies like CHM2101 show preclinical evidence of targeting only tumor cells without harming normal cells.
These drugs are all in early clinical stages, but they demonstrate that the story of CDH17 is far from over.
In Conclusion: Don’t Discount This Target Yet
Although AMT-676’s initial results were modest, the high expression of CDH17 in colorectal cancer and the unmet therapeutic needs make it a promising target. The significant investment from giants (such as Roche and Hansoh) indicate that the market remains optimistic. As long as future drugs can address safety issues and improve efficacy, CDH17 has the potential to become the next major target for gastrointestinal tumors. After all, the development of innovative drugs is never a straightforward process, and these initial results are just the beginning.