Oct 28, 2026: a four-minute gap on the Phase 3 result
Genmab traded between $44.64 and $44.91 in premarket trading, flat against the Oct 27 close. It opened at $44.64, the low of the day at $44.35, and drifted to $44.97 by 9:39am. At 9:40am the price jumped to $46.28, then $48.75 a minute later and $50.77 by 9:43am. The high so far is $52.34 and the shares were at $51.83 at 9:49am on 3.8 million shares, already 73% of the 20-day average for a full day of 5.2 million.
What happened:
- The trial. LiGeR-HN1 enrolls about 500 patients with PD-L1 positive recurrent or metastatic head and neck squamous cell carcinoma, CancerNetwork reported, and compares petosemtamab plus pembrolizumab with pembrolizumab alone. Its two primary endpoints are overall survival and objective response rate by blinded independent review.
- The numbers. Genmab reported a 50% lower risk of death, a hazard ratio of 0.50, and an objective response odds ratio of 3.17 (confidence interval 2.06 to 4.89, p<0.0001). The benefit held regardless of HPV status.
- The timing. Selvaraju had expected the readout by the end of 2026, so a result at the first interim look arrived early.
- No sector help. Merck, which makes pembrolizumab, fell 0.2%, and Johnson & Johnson and AbbVie, Genmab's partners on Darzalex and Epkinly, fell 0.3% and 0.4%.
From the Oct 27 close, at about 9:48am:
| Stock or fund | Oct 27 close | Oct 28, 9:48am | Change |
|---|---|---|---|
| Genmab (GMAB) | $44.67 | $51.99 | +16.4% |
| iShares Biotechnology (IBB) | $212.20 | $213.44 | +0.6% |
| AstraZeneca (AZN) | $170.08 | $170.45 | +0.2% |
| SPDR S&P Biotech (XBI) | $154.84 | $154.49 | -0.2% |
| Merck (MRK) | $141.82 | $141.60 | -0.2% |
| Johnson & Johnson (JNJ) | $268.73 | $268.01 | -0.3% |
| AbbVie (ABBV) | $286.39 | $285.23 | -0.4% |
After the jump, RSI(14) stood at 88, the shares sat 44% above their 50-day average and 71% above their 200-day average, volume ran 73% of its 20-day full-day average by 9:49am, and the stock was at a new 52-week high, 119% above the $23.62 low.
What the data mean
Petosemtamab is the asset Genmab got when it bought Merus, a deal BioSpace puts at $8 billion. In an earlier Phase 2 study the combination produced a 63% response rate in first-line patients, against 19% for pembrolizumab in the KEYNOTE-048 trial, and analysts had said a response-rate gain of 40 points or more would support accelerated approval. Today's topline reports the odds ratio, not the response percentages, so we cannot yet say how close it came to that bar. What is clear is the survival result. Hazard ratios in this range are rare in first-line head and neck cancer, and the lower end of the confidence interval, 0.37, rules out a small benefit. For how readouts like this normally move shares, see our explainer on how Phase 3 data move stocks.
Why the stock was already rising
The jump did not start from a quiet base. The shares closed at $34.75 on Oct 2, rose 10.7% on Oct 5 after mid-stage ovarian cancer data, and closed at $40.00 on Oct 22. On Oct 23 they gained 9.5% to $43.79 on 13.0 million shares, after Genmab said its Phase 3 RAINFOL-02 trial of Rina-S in platinum-resistant ovarian cancer met its progression-free and overall survival goals. Genmab's Copenhagen shares then rose as much as 13% on Oct 26 on colorectal data, where petosemtamab with chemotherapy produced a 75% response rate in 45 first-line patients and 67% in 34 second-line patients, Investing.com reported. In early October, Genmab also reported a 51% improvement in progression-free survival for Epkinly in first-line lymphoma, BioSpace noted.
| Date | Event | Close or move |
|---|---|---|
| Oct 5 | Mid-stage Rina-S ovarian data | +10.7% to $38.48 |
| Oct 23 | Phase 3 Rina-S win | +9.5% to $43.79 |
| Oct 27 | Close before the readout | $44.67 |
| Oct 28 | Phase 3 petosemtamab result | +16.0% at 9:49am |
The bull case
- Three Phase 3 wins in about four weeks. Epkinly, Rina-S and now petosemtamab all reported positive late-stage data, which answers the question of what replaces Darzalex.
- A fast regulatory path. The FDA has already granted the combination Breakthrough Therapy designation, and an early positive interim analysis shortens the road to a filing. Our guide to regulatory approvals as catalysts covers the usual steps.
- No squeeze to unwind. Short interest is 1.1% of the float, so the move reflects buying on news, not short covering.
- Room for targets to rise. The consensus target of $44.20 predates the data, and the highest is $58, still above the price.
The risks
- The Darzalex cliff. Darzalex accounts for about 90% of Genmab's sales and its US patents expire in 2029. Selvaraju projects Darzalex revenue of about $3.3 billion in 2028, under $1 billion by 2031, and roughly zero by 2032. The pipeline has to fill that gap on schedule.
- Topline only. Median survival, safety and subgroup data have not been shown in what we could read. Pembrolizumab combinations can add side effects, and the earlier colorectal study reported infusion reactions in 43% to 48% of patients.
- A crowded market. Genmab's chief medical officer said the market is still skeptical of its commercial prospects in a highly competitive field.
- A stretched chart. An RSI of 88 and a 30% four-day gain leave little cushion. See our page on binary event valuation for how to weigh a result that is now known.
What comes next
Genmab is scheduled to publish its interim report for the first nine months of 2026 on Nov 5. The date is in the company's calendar, though sources differ on the time of day. Watch the Darzalex royalty line, any change to petosemtamab filing plans and the pace of the Rina-S and Epkinly launches. Analysts will likely raise targets in the next few days. Our guide to how to value a biotech pipeline shows how those targets are built, and our page on FDA decision dates explains the timetable after a filing. For a comparison with another biotech move, read why Xencor stock rose, or see more of today's biggest stock moves.