Background: Renal impairment is seen in up to 50% or more of patients with multiple myeloma and has been linked to inferior short- and long-term treatment outcomes, in part because patients with renal failure tend to have higher levels of disease burden. However, renal failure is associated with a wide range of metabolic derangements that can impact both the tumor and its microenvironment, and their individual contributions have not been fully dissected. One example is hyperuricemia, which is found in up to 50% of myeloma patients with renal failure, and also in about 25% of myeloma patients even in the absence of renal insufficiency, where it can be due to factors such as diet, increased cell turnover, and tumor lysis syndrome. We therefore sought to examine the impact of hyperuricemia on myeloma biology and drug sensitivity in both in vitro and in vivo models.

Methods: Multiple myeloma cell lines representing a variety of molecular subtypes were propagated in media with vehicle or with supplemental uric acid over a range of physiologically relevant concentrations up to 10 mg/dL. The impact of anti-myeloma therapeutics under these conditions was studied using tetrazolium dye-based viability assays while apoptosis was studied by flow-cytometry-based analysis after Annexin V staining. T cell functional status without and with urate was studied by exposing peripheral blood mononuclear cells isolated from healthy human donor blood to uric acid followed by flow cytometry-based analysis of exhaustion markers. Activation status of key signal transduction pathways was analyzed by Western blotting with phospho-specific antibodies.

Results: Uric acid stimulated growth in a concentration-dependent manner of MM.1S, NCI-H929, and ANBL-6 human-derived multiple myeloma cell lines as demonstrated by a 10-35% increase in viability. This was associated with activation of the p44/p42 Mitogen-activated protein kinase (MAPK) and the AKT/Protein kinase B signaling pathways, especially at 10 mg/dL, as evidenced by increased phospho-MAPK and phospho-AKT levels. In drug sensitivity studies, uric acid at up to 10 mg/dL reduced the anti-proliferative and pro-apoptotic activity of several conventional agents, including the corticosteroid dexamethasone and the alkylating agent 4-hydroperoxy-cyclophosphamide, the active metabolite of cyclophosphamide, but not that of melphalan. In the novel agent category, urate inhibited the activity of the proteasome inhibitors (PI) bortezomib and carfilzomib in association with an induction of Heat shock protein 70 (HSP70), a known mediator of PI resistance. Also, urate reduced the direct pro-apoptotic effects of the immunomodulatory agents lenalidomide and pomalidomide in these same myeloma cell lines. In the immunotherapy drug category, urate inhibited the activity of the B-cell maturation antigen (BCMA) x CD3 T-cell engager teclistamab as judged by reduced Annexin V staining. The latter was associated with enhanced levels of T-cell exhaustion, as shown by increased expression of T-cell immunoglobulin and mucin domain-3 (TIM-3), Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and Lymphocyte activation gene 3 (LAG-3). Studies are underway evaluating the effectiveness of the PI bortezomib in an in vivo model of hyperuricemic Vk*MYC transgenic mice generated by treatment with potassium oxonate (300 mg/kg), and these data will be presented at the meeting.

Conclusion: Our data demonstrate a heretofore unknown role of isolated elevated uric acid levels in promoting tumor proliferation and drug resistance through both myeloma cell intrinsic and tumor microenvironmental effects. Further validation of these findings may suggest that more aggressive treatment strategies targeting hyperuricemia clinically may be in order, in combination with other standard of care supportive care measures, in the setting of myeloma-directed therapy, and could hold promise for improving patient outcomes.

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2025
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