Opaganib (ABC294640) Induces Immunogenic Tumor Cell Death and Enhances Checkpoint Antibody Therapy

Abstract

Antibody-based cancer drugs that target the checkpoint proteins CTLA-4, PD-1 and PD-L1 provide marked improvement in some patients with deadly diseases such as lung cancer and melanoma. However, most patients are either unresponsive or relapse following an initial response, underscoring the need for further improvement in immunotherapy. Certain drugs induce immunogenic cell death (ICD) in tumor cells in which the dying cells promote immunologic responses in the host that may enhance the in vivo activity of checkpoint antibodies. Sphingolipid metabolism is a key pathway in cancer biology, in which ceramides and sphingosine 1-phosphate (S1P) regulate tumor cell death, proliferation and drug resistance, as well as host inflammation and immunity. In particular, sphingosine kinases are key sites for manipulation of the ceramide/S1P balance that regulates tumor cell proliferation and sensitivity to radiation and chemotherapy. We and others have demonstrated that inhibition of sphingosine kinase-2 by the small-molecule investigational drug opaganib (formerly ABC294640) kills tumor cells and increases their sensitivities to other drugs and radiation. Because sphingolipids have been shown to regulate ICD, opaganib may induce ICD and improve the efficacy of checkpoint antibodies for cancer therapy. This was demonstrated by showing that in vitro treatment with opaganib increases the surface expression of the ICD marker calreticulin on a variety of tumor cell types. In vivo confirmation was achieved using the gold standard immunization assay in which B16 melanoma, Lewis lung carcinoma (LLC) or Neuro-2a neuroblastoma cells were treated with opaganib in vitro and then injected subcutaneously into syngeneic mice, followed by implantation of untreated tumor cells 7 days later. In all cases, immunization with opaganib-treated cells strongly suppressed the growth of subsequently injected tumor cells. Interestingly, opaganib treatment induced crossover immunity in that opaganib-treated B16 cells suppressed the growth of both untreated B16 and LLC cells and opaganib-treated LLC cells inhibited the growth of both untreated LLC and B16 cells. Next, the effects of opaganib in combination with a checkpoint antibody on tumor growth in vivo were assessed. Opaganib and anti-PD-1 antibody each slowed the growth of B16 tumors and improved mouse survival, while the combination of opaganib plus anti-PD-1 strongly suppressed tumor growth and improved survival (p < 0.0001). Individually, opaganib and anti-CTLA-4 antibody had modest effects on the growth of LLC tumors and mouse survival, whereas the combination of opaganib with anti-CTLA-4 substantially inhibited tumor growth and increased survival (p < 0.001). Finally, the survival of mice bearing B16 tumors was only marginally improved by opaganib or anti-PD-L1 antibody alone but was nearly doubled by the drugs in combination (p < 0.005). Overall, these studies demonstrate the ability of opaganib to induce ICD in tumor cells, which improves the antitumor activity of checkpoint antibodies.

Proteomics and lipidomic analysis reveal dysregulated pathways associated with loss of sacsin

“…To summarize, our proteomics and lipidomic study in fibroblasts from ARSACS patients highlighted altered levels of ceramides and DGs, which may potentially be involved in impaired cell signaling in ARSACS etiopathogenesis. Confirmation of these findings in motor neurons would allow us to speculate on targets for treatments ( Maines et al, 2023 ) or monitor disease severity through surrogates of metabolic status in ARSACS.…”

Opaganib Downregulates N-Myc Expression and Suppresses In Vitro and In Vivo Growth of Neuroblastoma Cells

“…Therefore, we evaluated the antitumor activity of opaganib in combination with irinotecan (IRIN) plus temozolomide (TMZ) because IRIN + TMZ is the backbone for treatment of recurrent or refractory NB alone or in combination with additional potential therapies [110,111]. C57BL/6 mice bearing LLC tumors were selected for the initial exploratory study because of their established tumor growth rates and responsiveness to opaganib [45]. This study demonstrated a significantly increased efficacy of opaganib + IRIN + TMZ relative to vehicle-and IRIN +TMZ-treated mice.…”

“…Despite limited success in NB therapy, targeting checkpoint proteins continues to be explored in clinical trials of this disease [27]. We have previously demonstrated that opaganib promotes immunogenic cell death (ICD) in tumor cells, including Neuro-2a cells [45], which can enhance therapeutic responses to checkpoint antibodies. Additionally, both c-Myc [112] and N-Myc [113] have been shown to modulate anti-tumor immune suppression, and so a combination of Myc inhibitors with cancer immunotherapy may improve NB patient survival.…”

“…In contrast, mice treated with oral opaganib had substantially reduced rates of tumor growth, indicating antitumor activity against human NB cells with amplified MYCN. Further experiments were conducted in immunocompetent syngeneic mouse model systems because of their importance to the host immune response and the impact of opaganib treatment on immune responsiveness [45].…”

“…We have previously demonstrated that opaganib promotes immunogenic cell death (ICD) in tumor cells, including Neuro-2a cells [45], which can enhance therapeutic responses to checkpoint antibodies. Therefore, we conducted studies on the antitumor activity of opaganib when combined with antibodies against either murine PD-1, PD-L1, or CLTA-4 toward Neuro-2a tumors growing in syngeneic A/J mice.…”