Table 2.
CT‐L Activity and Proteasome Subunit Levels in Baseline Primary Myeloma Cells and Multiple Myeloma Cell Lines
| Baseline CD138+ bone marrow proteasome activity and subunit composition | |||||
|---|---|---|---|---|---|
| Trialsa | Average number of prior regimens (range) | CT‐L (AMC/protein [μM/μg]) | β5 (ng/μg protein) | LMP7 (ng/μg protein) | LMP7 (%) |
| PX‐171‐003, PX‐171‐004, PX‐171‐005 | 5 (1–13) | 11∙3 ± 2∙8 | 0∙9 ± 0∙1 | 2∙6 ± 0∙4 | 74∙3 |
| Number of samples | 29 | 18 | 22 | ||
AMC, 7‐amino‐4‐methylcoumarin; CT‐L, chymotrypsin‐like; LMP, low‐molecular mass protein.
a
Bone marrow aspirates were collected from patients in trials PX‐171‐003, PX‐171‐004 and PX‐171‐005 prior to carfilzomib dosing and sorted into CD138+ and CD138− populations. CD138+ samples were analysed for proteasome activity and subunit occupancy as described in Fig. 1.