Investors should monitor the initiation and enrollment of the five pivotal phase III trials in 2026, as well as safety and efficacy updates. The high response rates in difficult-to-treat populations suggest Mo-Rez could become a key asset in GSK's oncology portfolio, potentially commanding premium pricing and fast-track regulatory pathways.
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Executive Summary
GSK announced positive phase 1 data for its investigational B7-H4-targeted antibody-drug conjugate mocertatug rezetecan (Mo-Rez), showing confirmed objective response rates of 62% in platinum-resistant ovarian cancer and 67% in recurrent or advanced endometrial cancer. The safety profile was manageable, supporting the initiation of five pivotal phase III trials in 2026.
Key Facts
- Mocertatug rezetecan achieved a 62% confirmed objective response rate (cORR) in platinum-resistant ovarian cancer (PROC) at 5.8 mg/kg (n=21/34; 95% CI: 44, 78)
- Achieved a 67% cORR in recurrent or advanced endometrial cancer (EC) at 4.8 mg/kg (n=8/12; 95% CI: 35, 90)
- Treatment discontinuation due to treatment-related adverse events was low (0% in PROC, 4% in EC)
- Grade ≥3 treatment-related adverse events occurred in 64% (PROC) and 54% (EC), primarily hematologic; interstitial lung disease was low (3%)
- Five pivotal phase III trials planned in 2026: BEHOLD-Ovarian01 (PROC), BEHOLD-Endometrial01 (2L EC), BEHOLD-Ovarian02 (platinum-sensitive), BEHOLD-Ovarian03 (first-line maintenance), and BEHOLD-Endometrial02 (mismatch-repair-proficient EC)
- Mo-Rez is a B7-H4-targeted ADC with a drug-to-antibody ratio of 6, licensed globally from Hansoh Pharma (excluding China, Hong Kong, Macau, Taiwan)
Financial Impact
Potential multibillion-dollar revenue opportunity; ovarian and endometrial cancers represent significant unmet needs with limited current therapies
Risk Factors
- Phase III trials may not replicate phase 1 efficacy results
- Safety profile could worsen in larger, more diverse populations
- Competition from other ADCs and immunotherapies in development for gynecologic cancers
Market Snapshot
Investment Themes
Documents Analyzed
This report is based on 4 SEC documents filed with EDGAR.
| Document | Accession Number |
|---|---|
| 6-K Filing (Primary) | 0001654954-26-003422 |
| Document: 0001654954-26-003422-index-headers.html | 0001654954-26-003422 |
| Document: 0001654954-26-003422-index.html | 0001654954-26-003422 |
| Document: 0001654954-26-003422.txt | 0001654954-26-003422 |
Filters
| Type | Now | ||||
|---|---|---|---|---|---|
Jun 10, 2026 19w ago | 6-K | $25.12 $25.25 | ▲ +0.52% | ▼ −1.62% | $26.12 (+3.98%) |
Jun 9, 2026 20w ago | 6-K | $24.66 $25.50 | ▲ +3.41% | ▲ +1.60% | $26.12 (+5.92%) |
Jun 9, 2026 20w ago | 6-K | $24.66 $25.50 | ▲ +3.41% | ▲ +1.60% | $26.12 (+5.92%) |
Jun 1, 2026 21w ago | 6-K | $24.25 $24.66 | ▲ +1.69% | ▲ +4.44% | $26.12 (+7.71%) |
Jun 1, 2026 21w ago | 6-K | $24.25 $24.66 | ▲ +1.69% | ▲ +4.44% | $26.12 (+7.71%) |
May 28, 2026 21w ago | 6-K | $24.58 $24.66 | ▲ +0.33% | ▲ +0.01% | $26.12 (+6.27%) |
May 27, 2026 21w ago | 6-K | $25.57 $23.94 | ▼ −6.37% | ▼ −7.58% | $26.12 (+2.15%) |
May 26, 2026 22w ago | 6-K | $25.50 $24.25 | ▼ −4.90% | ▼ −5.99% | $26.12 (+2.43%) |
May 26, 2026 22w ago | 6-K | $25.50 $24.25 | ▼ −4.90% | ▼ −5.99% | $26.12 (+2.43%) |
May 22, 2026 22w ago | 6-K | $26.00 $24.25 | ▼ −6.73% | ▼ −8.39% | $26.12 (+0.46%) |
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