Multiple Myeloma (MM) is the second most common
hematological malignancy and is responsive to a limited number of drugs. Unfortunately, to date, despite the introduction of novel drugs, no relevant increase in survival rates has been obtained.
Proton pump inhibitors (PPIs) have been shown to have significant antitumor action as single agents as well as in combination with
chemotherapy. This study investigates the potential anti-
tumor effectiveness of two PPIs,
Lansoprazole and
Omeprazole, against human MM cells. We found that
Lansoprazole exerts straightforward efficacy against myeloma cells, even at suboptimal concentrations (50 µM), while
Omeprazole has limited cytotoxic action. The
Lansoprazole anti-MM effect was mostly mediated by a
caspase-independent apoptotic-like cytotoxicity, with only a secondary anti-proliferative action. This study provides clear evidence supporting the use of
Lansoprazole in the strive against MM with an efficacy proven much higher than current therapeutical approaches and without reported side effects. It is however conceivable that, consistent with the results obtained in other human
tumors,
Lansoprazole may well be combined with existing anti-myeloma
therapies with the aim to improve the low level of efficacy of the current strategies.