What happened

Shares of Compugen (NASDAQ:CGEN) are up 20% at 2:24 p.m. EDT Tuesday after the company released encouraging data from an early-stage clinical trial testing its cancer treatment COM701.

So what

Compugen had previously reported that nine of the first 13 patients treated in the clinical trial had stable disease, meaning their tumors weren't growing, but they didn't shrink much, either.

In the newest cohort of patients treated at a higher level, the biotech reported there was one patient with primary peritoneal cancer, a type of ovarian cancer, who had a partial response, meaning their tumor shrunk.

Woman in a head scarf holding hands with another woman

Image source: Getty Images.

Another patient with colorectal cancer treated with COM701 plus Bristol-Myers Squibb's (NYSE:BMY) Opdivo also had a partial response. COM701 is designed to activate T cells, and Opdivo removes a block that tumor cells use to keep T cells from attacking them, so there's rationale for using the drugs in combination.

These are patients who had failed all available standard treatments, so a partial response is an impressive feat.

Now what

Cancer drugs don't typically get approved based on stable disease, so the new results with two partial responses is clearly a step in the right direction.

Of course, drugs also don't get approved based on two responses, so Compugen is going to have to show that COM701 can help more patients, likely in another, larger clinical trial.

Investors should also keep in mind that there's no way to know if the patient treated with COM701 plus Opdivo was helped more by COM701 or Opdivo, or if the combination had a synergistic effect as expected. A clinical trial comparing the combination to Opdivo alone would be the only way to know for sure.