Markers to track during metastatic TNBC treatment

TNBC74

Hi

I was diagnosed 12 months ago with a metastatic recurrence of TNBC (3 years after initial Stage II diagnosis of TNBC followed by a double mastectomy and 4 cycles of AC + 4 cycles of T), with mets to the sternum and liver.

I cose Xeloda as a first line treatment vs more aggressive treatments. That lasted about 6 month with a stable disease before progression. Currently on an Eribulin/Pembrolizumab trial.

Given blood work nearly every week, I track various blood markers, chiefly LDH, CA 15-3, CA 27-29, ALP (as well as others). Initially LDH, 15-3, 27-29 all fell. After 2 months, LDH started to rise again (4 readings in a row) while the CA 15-3/27-29 (tracked every 3 weeks) still fell.

What does rising LDH (from a low of 225 to 300) while CA 15-3/27-29 falling mean? (Note: I am not doing anything strenuous that could cause LDH to rise abnormally).

Thank you!