Ono Pharmaceutical Acquires Ionis' Antisense Oligonucleotide for Rare Blood Cancer in $280M Upfront Deal

Japan's Ono Pharmaceutical has entered into a licensing agreement with Ionis Pharmaceuticals, securing rights to sapablursen, a phase 2-stage antisense oligonucleotide targeting a rare form of blood cancer. The deal, announced on March 11, 2025, involves a substantial upfront payment of $280 million from Ono to Ionis, with the potential for additional milestone payments totaling up to $660 million.

Sapablursen: A Novel Approach to Treating Polycythemia Vera

Sapablursen is an RNA-targeted medicine designed to reduce the production of TMPRSS6, a protein involved in iron regulation. By decreasing TMPRSS6, the drug aims to increase the expression of hepcidin, the key regulator of iron homeostasis. This mechanism is believed to have therapeutic potential in various blood diseases, with the current focus on polycythemia vera (PV), a rare condition characterized by the overproduction of red blood cells.

The drug is currently undergoing a phase 2 clinical trial for PV, which Ionis will continue to manage as part of the licensing agreement. Following the completion of this trial, Ono will assume full responsibility for sapablursen's further development, regulatory filings, and commercialization efforts worldwide.

Strategic Implications for Both Companies

For Ionis Pharmaceuticals, this deal represents a significant milestone in its development strategy. Brett Monia, Ph.D., CEO of Ionis, expressed confidence in Ono's capabilities to maximize sapablursen's value and ensure broad access for PV patients. The agreement aligns with Ionis' recent transition to a commercial-stage company, following the approval of Tryngolza for familial chylomicronemia syndrome in December 2024.

Monia stated, "Ionis remains committed to advancing the wholly owned medicines we choose to commercialize ourselves, which includes our first independent launch currently underway and three additional anticipated launches in the next three years." He added that streamlining the company's portfolio provides financial flexibility to support investment in near and mid-term commercial opportunities.

For Ono Pharmaceutical, known for its co-development of the blockbuster cancer immunotherapy Opdivo with Bristol Myers Squibb, this acquisition strengthens its position in the hematology space. Toichi Takino, President and Chief Operating Officer of Ono, commented, "This partnership aligns with our strategy to strengthen our pipeline in hematology," and expressed optimism about sapablursen's potential to become a new treatment option for PV patients worldwide.

Financial Terms and Future Prospects

The licensing deal includes a $280 million upfront payment from Ono to Ionis, with the potential for up to $660 million in additional development, regulatory, and sales milestones. Ionis will also be eligible for mid-teen royalties on annual net sales of sapablursen.

This agreement follows Ono's recent activity in the oncology space, including a $700 million biobucks deal with LigaChem Biosciences in 2024 to expand its antibody-drug conjugate portfolio. The acquisition of sapablursen further demonstrates Ono's commitment to developing innovative treatments for hematological disorders and rare diseases.