Heat Biologics’ Phase 2 drug HS-410 is safe


On November 30th, Heat Biologics ($HTBX) plans to present the top-line Phase 2 data of their new drug HS-410. I read the data, and so far it looks good! HS-410 appears to be safe and the treatment makes sense. However, HTBX still hasn’t shown that HS-410 is actually an effective treatment — a Phase 3 pass might be difficult. For now, though, HTBX is a company worth watching.

The Drug

HS-410 is a drug designed to help the immune system fight cancer naturally. Normally I am very pessimistic about immune-oriented cancer therapies, but in this case it makes sense. HS-410 treats non-muscle invasive bladder cancer (NMIBC), and the current standard of care for NMIBC relies on the immune system as well.

Basically, the treatment for non-muscle invasive bladder cancer is to scrape the cancer cells out of the bladder, then put a bacteria that’s a lot like tuberculosis into the bladder so that the immune system comes in and fights any cancer that might be left over. This bacteria — called BCG — is supposed to activate a specific type of T-Cell (immune system cell) called CD8+. HS-410 is targeted to activate the same type of T-Cell, and the researchers seem to be hoping that the two treatments will stack.

The Research

Since HS-410 is activating the same type of T-cell as BCG, the researchers designed a multi-arm study, which is smart. Basically, it works like this: If a patient is going to get BCG, they get slotted into one of three groups. Group 1 tests a low dose of HS-410. Group 2 tests a high-dose of HS-410. Group 3 tests BCG by itself as a control group. Group 4 is for patients who won’t get BCG, to test HS-410 by itself.


Study Design
Study Design


There are a few ways that HS-410 could work. If 410 amplifies the response of BCG, that would be great! If 410 works by itself, that would almost be better, as patients would prefer to get an injection (HS-410) than get a drug pushed up through the urethra into the bladder (BCG). I don’t know about you, but that doesn’t sound like much fun at all.

The Results

Everything looks good, so far. The drug is looks like it’s quite safe. The researchers are reporting that recurrence-free survival (no cancer) was about 85% after a year, but didn’t mention which arm (or arms) that was. I took a look at some of the historical research behind BCG to see how that stacks up, and it appears to be about the same. We’ll have to wait for the complete data to see the differences between arms, but right now it looks like this is going to be a Phase 2 pass. The Phase 3 trial is where they will really need to demonstrate that the drug has an effect.

Potential Market

Bladder cancer is the 5th most common cancer in the United States. There are two paths to success for this drug: boosting the efficacy of BCG or being able to replace BCG. The FDA has granted HS-410 fast track status, which is also a good thing.

We will need to see the full set of Phase 2 data in order to make a prediction about Phase 3, but for now, a Phase 2 pass seems almost guaranteed.

Prediction: Phase 2 Pass