A Cancer Vaccine Just Cracked One of Oncology's Toughest Codes

Think of it like a wanted poster. Tedopi shows the immune system exactly what the bad guys look like, then sends out a search party. When combined with pembrolizumab (Merck's blockbuster checkpoint inhibitor Keytruda), you get both the search party and the removal of obstacles that would slow it down.

There's one important catch: Tedopi only works in patients with a specific genetic marker called HLA-A2, which roughly 25 to 35% of Western populations carry. It's not for everyone, but for those who qualify, the early data are striking.

The Numbers That Turned Heads

The TEDOVA trial enrolled 185 patients with platinum-sensitive recurrent ovarian cancer. These were women who had already been through the wringer: platinum-based chemo, PARP inhibitors, bevacizumab. They'd used the standard playbook and needed something new.

The trial split patients into three groups: best supportive care (essentially monitoring), Tedopi alone, and Tedopi plus pembrolizumab. The primary goal was straightforward: does the combination keep cancer from progressing longer than supportive care alone?

It did. The combo arm achieved a median progression-free survival of 4.1 months versus 2.8 months for supportive care. The hazard ratio was 0.53, with a p-value below 0.001. In plain English, patients on the combination were about half as likely to see their cancer worsen at any given time.

Now, 4.1 months might not sound revolutionary on its own. But context matters enormously here. This is a maintenance setting, meaning patients had already responded to prior therapy. The comparison is against best supportive care, not a competing drug. And in an indication where checkpoint inhibitors alone have repeatedly failed to show any benefit, a statistically robust signal is noteworthy.

Perhaps more intriguing: the comparison between the two Tedopi arms (with and without pembrolizumab) showed a 28% reduction in risk when the checkpoint inhibitor was added (hazard ratio 0.72, p = 0.074). That p-value didn't quite hit traditional significance thresholds, but it suggests Tedopi has some activity on its own and gets meaningfully better with Keytruda on board.

Why Wall Street Should Pay Attention

OSE Immunotherapeutics is not a household name. The company trades on Euronext Paris in the mid-single-digit euro range, with a market cap that makes it a rounding error compared to the pharma giants. Analysts covering the stock have a consensus "Buy" rating with price targets ranging from €12.50 to €21, implying 100 to 200% upside from current levels.

That gap between price and targets tells you something important: the market acknowledges the scientific potential but is heavily discounting execution and financing risk. OSE has cash runway into 2027 and a history of partnerships with companies like Boehringer Ingelheim, Servier, and AbbVie, which provides some credibility. But it's still a small company with big ambitions.

The ovarian cancer data lands at a particularly interesting time. Tedopi is also in a Phase 3 trial for lung cancer and recently posted positive Phase 2 results in pancreatic cancer. Three mid-to-late-stage readouts across different tumor types starts to look less like a lucky break and more like a platform with legs.

Full data from TEDOVA are scheduled for oral presentation at ASCO 2026 on May 30, which will give oncologists and analysts a much deeper look at subgroup analyses, duration of response, and safety details.

The Bigger Picture for Ovarian Cancer

The ovarian cancer treatment landscape is shifting fast, though not primarily because of immunotherapy. Antibody-drug conjugates (ADCs), which are essentially guided missiles that deliver chemo directly to tumor cells, are dominating the competitive pipeline. Programs targeting proteins like folate receptor alpha and B7-H4 are racing through Phase 2 and 3 trials.

Tedopi occupies a different niche. As a vaccine, it's trying to solve the fundamental problem of ovarian cancer immunotherapy: the absence of tumor-targeting immune cells. If it can reliably "heat up" cold tumors, it could become a foundation that other therapies build on, not a competitor to ADCs but a complement.

The safety profile will matter a lot as the data mature. The combination arm predictably showed more adverse events, including immune-related side effects consistent with pembrolizumab. For a maintenance therapy that patients might take for months, tolerability is not a footnote; it's a dealbreaker.

What Comes Next

OSE now faces the classic biotech inflection point. Phase 2 success in a tough indication is exactly the kind of catalyst that attracts partnership interest from larger pharma companies. The question is whether the ASCO presentation will be compelling enough to trigger serious deal discussions, or whether partners will want to see Phase 3 data before writing a check.

For the thousands of women with recurrent ovarian cancer who've exhausted standard options, the calculus is simpler. A vaccine that trains their immune system to fight back, in a disease where the immune system has historically been a bystander, represents genuine hope. It's early. The numbers are modest. But in a graveyard of failed trials, any sign of life is worth watching closely.

$290M Says Your Migraine Drugs Aren't Good Enough

A Paragon Biosciences spinout just raised $290 million to go after migraine prevention with a totally different approach. The bet: current drugs leave half of patients undertreated, and a protein called PACAP could be the missing piece.