Immatics Phase I Data Update: Promising Data, But Still Very Early

Summary

• Immatics released top-line results from a combination of clinical trials across their three clinical-stage programs (IMA201-203).
• The data is very early, with the longest followup being 12 weeks.
• No overt safety issues and signals of efficacy. Questions remain over durability/deepening of response.

Last week I published an article on Immatics (IMTX) exploring their platform, oncology products, and outlook. I was pretty bullish on the stock given their platform and partnerships with big pharma. They are a very early stage company with few assets in clinical trials. Today they released top-line results from their only assets in clinical trials (IMA201-203). These are TCR-engineered T cells that target cancer-testis antigens across multiple cancers.

The data released is from their Phase 1a dose-escalation and only contains data from dose levels 1/2.

The patient population actually is heavily pre-treated. Most clinical trials at this stage include patients that have had several lines of therapy, but these patients are very sick. Old, multiple failed lines, and with metastatic disease make this a very hard patient population to treat. Keep this in mind when we look at efficacy.

When we look at the toxicity, there is nothing that jumps out at me as bad. These T cell treatments require lymphodepletion ahead of time and all the adverse events seem to in line with these regime. TCR-engineered T cells have had fatal toxicity in the past, so its a great sign to see no severe reactions.

T cell persistence also seems good, with the caveat that even longest patient was only tracked out to 24 weeks. There appears to be a 10-fold reduction by 24 weeks. What this means for efficacy remains to be determined though.

Now for the part that most people want to see, the efficacy! Now this is what I consider a bit a mixed bag. A home-run result in my mind would include at least a complete-response whereas a strikeout would be multiple (3-5) progressive disease. Immatics results fall right in the middle. Only one progressive disease, but the rest is just stable disease and 1 partial response. However this comes with four big asterisks:

-This is a mixture of only a few patients from each therapy (IMA201-203), so trying to extrapolation if one therapy is more efficacious is meaningless at this point.

-These results are very early. Most patients are less than 12 weeks after treatment.

-This is only from the lowest two doses.

-The two examples shown in the presentation indicate that responses do appear to deepen over time.

Now what does this mean moving forward? First safety looks great at the two lowest doses. Anything super severe (aka fatality-causing) would likely come up at this stage so I don't expect the highest dose to be much different. 

In regards to the efficacy, it wasn't a knock out of the park. The data wasn't bad, but it wasn't great either. The deepening responses over time give me hope that more of the stable diseases will turn into partial responses. More importantly, the upcoming higher doses might (key word MIGHT) lead to better efficacy.

My overall thesis remains intact and I am looking forward to what is released later this year. I'll be looking to see if the higher dose is more efficacious and if responses deepen over time.