Company: HURA
Filing Date: 2025-05-23
Form Type: 424B3
Source: 0001193125-25-125499
Chunk: 563

Company: TuHURA Biosciences, Inc./NV
Filing Date: 2025-05-23
Form: 424B3
Chunk 563
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 By enhancing the immune response, it is now possible to obtain dramatic and long-lasting tumor regressions, even in patients with advanced or otherwise incurable cancers. There exist today four broad categories of marketed immunotherapies:

| • |     | Cell-based therapies (e.g., CAR T cells); |

| • |     | Vaccines (e.g., BCG); |

| • |     | Oncolytic viruses (e.g., T-Vec); and |

| • |     | Immunomodulators (e.g., CPIs). |

Immune checkpoint inhibitors (CPIs) The most widely prescribed and effective group of treatments are the CPIs. Since 2011, ten CPIs have been approved in the United States, primarily for the treatment of advanced or metastatic solid tumors. CPIs that have been approved by the FDA only have a few different mechanisms of action. They either block the interaction of PD1 with its ligands (PD-L1or -L2),or they block the interaction of CTLA4 with its ligands (CD80 or CD86), or they block the interaction of LAG-3to its canonical MHC Class II ligand. Since PD1, CTLA4 and LAG-3serve as breaks on the T-cell-drivenimmune response, antibodies that block these interactions enhance the activation of effector T cells. The first LAG-3inhibitor was FDA approved only in combination with a PD1 inhibitor in March 2022. Because there is such a large population of advanced cancer patients for whom there are few available treatments, the CPIs have become widely used, and this is reflected in the commercial success of the group. However, despite more than a decade of development, existing CPIs still address only two distinct mechanisms of action and are effective in only a fraction of treated patients. Several key CPI deficiencies have become apparent from the clinical data:

| • |     | CR rates for most tumor types, either as a single agent or in combination with other drugs, are low and sometimes 
 similar to conventional chemotherapy. There are very few instances where CR rates exceed 10%.                     |

| • |     | Most patients have no response or PR and do not achieve durable remission of disease. There are few or no options 
 for subsequent immunotherapy treatment of these patients.                                                         |

| • |     | Only a few CPI mechanisms are FDA approved, limiting combination therapy options. |

| • |     | CPIs are not labeled or show poor efficacy in the