Background: Relapsed/refractory (R/R) Hodgkin lymphoma (HL) remains difficult to treat, with particularly poor outcomes following relapse post-autologous stem cell transplant and check point inhibitors, and limited treatment options. The shift of active agents into the frontline setting further underscores the need for new therapies in R/R HL. B-cell lymphoma 2 inhibition (BCL2i) has shown activity, but remains underexplored, particularly in combination strategies. Similarly, Bruton’s tyrosine kinase inhibitors (BTKI) have demonstrated preliminary efficacy in R/R HL. Thus, we aimed to evaluate BCL2i with venetoclax (ven) in combination with other agents, including BTKi, to assess cytotoxic effects in HL cell lines.
Methods: HL cell lines L1236, L428 and L540 were utilized for this analysis. Ven was combined with Ibrutinib (ibr), acalabrutinib (acal), zanubrutinib (zanu), pirtobrutinib (pir), brentuximab vedotin (bv) and doxorubicin (doxo) to assess synergistic cytotoxicity. HL cells were exposed for 48 hours. Cell viability changes were determined by measuring adenosine triphosphate content using Cell Titer-Glo Assay. The half maximal inhibitory concentration (IC50) was calculated with Graph Pad Prism Software. Experiments were performed in triplicates on three separate occasions. Data was analyzed using SPSS 21.0 software. Synergy coefficients for ven combinations were calculated by CalcuSyn software.
Results: Ven monotherapy demonstrated activity across all three HL cell lines, with the lowest IC50 observed in L540 (Fig 1A). Ven was subsequently combined with dox producing synergistic cytotoxicity across all cell lines, with the lowest IC50 in L428 (Fig 1B & 1C). Ven was then paired with bv with similar synergistic killing of all HL cells, with the lowest IC50 seen in L540 (Fig 1D & 1E). Ven also showed synergistic activity when combined with multiple BTKis, all of which showed synergistic efficacy in HL cell killing, with the lowest IC50 values observed with ibr and pir (Figure 1F-1M).
Conclusions: In this study, we evaluated the synergistic activity and potential efficacy of BCL2i (ven) in combination with other agents in HL cell lines. We found that ven combined with doxo, bv, and multiple BTKi’s consistently produced synergistic cytotoxicity across HL models. These findings highlight BCL2i-based combinations as a potential therapeutic approach for R/R HL and support further investigation to enable progression toward clinical trials.
Alex Niu, Noah Brosnick, Cory Mavis, Matthew Cortese, Francisco Hernandez-Ilizaliturri