Petosemtamab Receives FDA Breakthrough Therapy Designation: Head / Neck Cancers

Between September and January, however, the tumors in my neck shrank by about 20%, which is a startingly good response by R / M HNSCC standards.

Perhaps the most interesting question will ultimately be whether oncologists prescribe petosemtamab for patients who get early clean surgical margins, in an effort to prevent recurrence. Oncologists are reluctant to impose chemo-radiation because of chemo's deleterious side effects, but petosemtamab, though it causes rashes, paronychia, and other skin problems.

Also the treatment targets two cancer genes at the same time. The first is EGFR, which is a very well known therapeutic target. The second is LGR5, and I’m not as familiar with that one, but I think it might be a novel target for cancer. So that's important in that more drugs might target this gene or combinations of LGR5 and others and they might be more effective than this first effort.

That is indeed what it means. The other metric you'll see is Overall Survival, which also is what it sounds like it is.

>> “We look forward to continued constructive conversations with the FDA as we move forward in our plan to initiate a phase 3 trial in previously treated HNSCC mid-2024 and prepare for a potential phase 3 trial evaluating the combination of petosemtamab and pembrolizumab [Keytruda] in previously untreated patients."

I understand the caution, but I firmly believe oncologists need to get more aggressive with multi-line treatments.

The overall response rate is a combination of complete response (tumor not measurable radiologically) and partial response (>20% reduction in size). That is a common trial endpoint.

As someone else said the Breakthrough designation is common and does not necessarily lead to efficacious drug approvals.

This is a population who has already been treated with a PD-1 (or PDL-1) therapy and platinum chemotherapy, which is pretty much the best treatment available, and their cancer has come back.

ESMO (European) guidelines suggest "Taxane or methotrexate or cetuximab or BSC (best supportive care)" for these patients.

Median OS for this drug was 11.5 months while the KEYNOTE-048 trial had the current standard of care at 10.7 months. So this drug is at least as good as current therapy which is very promising in such a small trial and difficult to treat population.