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SDIRSACR Oncology Insights

normal human dermal fibroblasts (NHDF) to mefloquine, a lysosomotropic disruptive agent, in glucose-free medium.
Material and Methods: Cell viability upon treatments was determined by crystal violet and MTT tests, and meflouqine
concentrations with the most pronounced anti-melanoma effects in combined treatment were selected for further
investigation. The type of cell death (apoptosis, necrosis) was determined using Annexin V/PI flow cytometry and
changes in lysosomal acidification were determined by flow cytometry and fluorescent microscopy after staining with
Lysotracker red.
Results: Mefloquine reduced A375 cell viability in a dose-dependent manner and glucose depletion led to proliferation
arrest, with their combination demonstrating higher cytotoxicity. The effect was absent in treated NHDF cells. Apoptosis
was induced by both agents, as demonstrated by Annexin V/PI flow cytometry, and was significantly intensified when
the agents were applied in combination. Furthermore, Lysotracker red staining revealed that lysosomal acidification
decreased following the combined treatment, in contrast to the increase observed with each treatment individually.
Conclusions: Combined treatment with mefloquine and glucose deprivation elicited a potent proapoptotic response in
A375 melanoma cells, while sparing NHDF cells, indicating that this dual-targeting approach may serve as a promising
therapeutic strategy for melanoma.

Acknowledgments and funding: This research was funded by the Ministry of Science, Technological Development and
Innovation of the Republic of Serbia, grant numbers 451-03-137/2025-03/ 200110 and 451-03-136/2025-03/200007.
Dr Ljubica Harhaji-Trajković has received a research donation from the non-profit organization Climbers Against Cancer.

P90

Targeting metabolic vulnerabilities in multiple myeloma: The role of NAD+ depletion and bone marrow
adipose tissue

Drenka Trivanović , Vanja Antonijević , Milica Rajković , Sanja Momčilović , Nikola Bogosavljević , Mila Purić ,
3,4
1
1
2
1
5
Marko Vujačić , Ivana Okić Đorđević , Slavko Mojsilović , Aleksandra Jauković 1
1
3,4
1
1Group for Hematology and Stem Cells, Institute for Medical Research, National Institute of the Republic of Serbia, University of
Belgrade, Belgrade, Serbia
2Group for Neuroendocrinology, Institute for Medical Research, National Institute of the Republic of Serbia, University of
Belgrade, Belgrade, Serbia
3Institute for Orthopedy Banjica, Belgrade, Serbia
4Faculty of Medicine, University of Belgrade, Serbia
5Clinic for Medical Oncology, Institute for Oncology and Radiology of Serbia, Belgrade, Serbia
Keywords: bone marrow adipose tissue, multiple myeloma, NAD+, NAMPT

Background: Multiple myeloma (MM) is a hematological cancer that develops in the bone marrow, where
interactions with bone marrow adipose tissue (BMAT) support tumor growth and therapy resistance. Nicotinamide
phosphoribosyltransferase (NAMPT or visfatin), an enzyme produced by both adipocytes and MM cells, is essential
for NAD+ synthesis, which MM cells need for energy and survival. Thus, targeting NAMPT and NAD+ metabolism
represents a perspective strategy in precision oncology, exploiting cancer cells’ unique metabolic needs to enhance
treatment effectiveness. This study investigates the effects of NAMPT inhibition on MM cell metabolism within the
bone marrow microenvironment.
Materials and Methods: Bone marrow samples were obtained from non-cancer (n=11) and MM patients (n=10) and
used for investigation of BMAT and plasma cells in downstream assays in hypoxic (3% O2) and normoxic (21% O2)
conditions. The FK866 (NAMPT inhibitor) was added to cultures of myeloma cell lines (AMO-1, OPM2 and U266) in
normoxia and hypoxia.
Results: The results indicate that the BM of patients with MM has a significantly lower proportion of BMAT than
that of non-cancer BM, while the distribution of CD138+ plasma cells is increased in cells isolated from the BMAT
compartment. In vitro co-culture assays of bone marrow adipocytes and MM cells show that pre-treatment of MM
cells with FK866 increase their de-lipidation capacity. FK866 at a concentration of 1 nM leads to a significant decrease
in the number of MM cells in hypoxia, but not in normoxia. Moreover, the presence of FK866 increases the clonogenic
potential of myeloma cells in hypoxia, while in normoxia, a decrease in clonogenic potential was determined. Cell cycle
analysis shows that FK866 under hypoxia decreases actively dividing cells (G2-M) and increases cells in the resting
phase (G0). Under normoxia, FK866 reduces cells in the DNA synthesis and mitosis phases (S-M) but increases cells in

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