Hear Ye, Hear Ye--serum her2 test validated & may even ID those who need higher doses

[Lani]

of herceptin

8 years ago a paper from the Charite Hospital in Berlin whose authors included Dr Slamon demonstrated that a 20% drop in serum her2 value between pre and
post first dose of herceptin predicted efficacy of herceptin and better response/survival.

For what may have been political reasons--I certainly can't fathom why-- serum her2 testing has never caught on, even though it is apparently both accurate and reproducible.

Now a Danish group have published a paper showing how serum HER-2 (also known as serum Her2 ECD) predicts response and resistance to trastuzumab treatment in her2+ breast cancer.

Before herceptin began widespread use for Stage IVs (long before it became FDA approved for early breast cancer) a paper by authors at Genentech reported that herceptin was utilized/used up/"metabolized" at very different rates of speed in different patients and that the difference between those who
"used up" the herceptin fastest vs those who "used up" the herceptin slowest was as much as 40%!!!! It seems here too serum her2 ECD testing might be useful to identify who might need higher or more frequent doses of herceptin
Unfortunately this study is based on results in 48 patients---this study will need to be repeated with much larger numbers of patients before consideration can be made to modifying clinical guidelines for testing.

I certainly hope larger studies are carried out and soon. This test has been available for so long that it is going "off patent"--let's see if that makes it cheaper (from what I understand it is not a particularly expensive test to start with)




Clin Chem Lab Med. 2013 Feb 18:1-10. doi: 10.1515/cclm-2012-0558. [Epub ahead of print]
Serum HER-2 predicts response and resistance to trastuzumab treatment in breast cancer.
Petersen ER, Sørensen PD, Jakobsen EH, Madsen JS, Brandslund I.
Abstract
Abstract Background: Serum HER2 (S-HER2) was approved in 2003 by the US Food and Drug Administration (FDA) for monitoring trastuzumab treatment in tissue HER2 positive breast cancer patients. Information of the value of S-HER2 is scarce. We hypothesised that S-HER2 would reflect the clinical effect of trastuzumab. Methods: We followed 48 patients eligible for trastuzumab treatment for up to 6 years or until death. S-HER2 was measured on an ADVIA Centaur System and S-Trastuzumab was measured by an in-house developed fluorescent enzyme immunoassay system on the ImmunoCap 100. Results: A decrease in S-HER2 of ≥20% was correlated to no progression in the disease in 20 out of 21 clinical courses (p<0.0001). An increase in S-HER2 of ≥20% was correlated to progression in the disease in 40 out of 44 clinical courses (p<0.0001). Patients with no recurrence after trastuzumab treatment (n=18) had a median S-HER2 concentration of 10.5 μg/L, whereas patients alive with recurrence (n=13) had a median S-HER2 of 20.1 μg/L (p=0.002). Patients who died prompted by recurrence (n=17) had a median S-HER2 of 232.4 μg/L at latest measurement before death (p=<0.0001) compared to patients without recurrence. In two patients with S-HER2 values above 1000 μg/L the concentrations of S-trastuzumab were measured below the target trough concentration in serum of 10 mg/L. Conclusions: Decreasing values of S-HER2 predicts response to treatment whereas increasing levels predict resistance. S-HER2 above 1000 μg/L warns that standard doses of trastuzumab may be insufficient as reflected by low concentrations of S-trastuzumab.
PMID: 23420288

[Kim in CA]

Thank you for posting this Lani.

My current oncologist only uses the Her2 Serum test because I have hounded him to do so, and told him that I believe in it, at least for me. That along with the CA15-3 was all we were using to monitor me while I took my almost 1 year Herceptin break.

The Serum Her2 was actually the first marker to rise back in April of 2012, at 15.5. The CA15-3 didn't go above the normal range until July. By the time I got authorized to get back on Herceptin it was August.

I really believe that had I started back on the Herceptin when the Her2 Serum started to rise, I may not have needed the Taxotere. Just my gut feeling though of course.

In any case, I will print this out, because the new oncologist I will be seeing at Kaiser has already told me they don't use the Serum Her2 test. That's gonna have to change!

Thanks again, Kim