IL-12 and Acute Radiation Syndrome (ARS) Pipeline

After a nuclear plant accident or a nuclear detonation, heavy radiation hits the bone marrow first. White cells and platelets fall, and patients die of infection and bleeding.

Drugs for this hematopoietic acute radiation syndrome (H-ARS) cannot be tested for efficacy in people. The FDA reviews them under the Animal Rule: efficacy comes from animal studies, and human studies only establish safety.

This page covers 13 assets: in ARS, 4 approved and 4 in clinical development; in IL-12 cancer immunotherapy, 4 in clinical development, 1 preclinical and 1 with rights returned. Libo Pharma's LIB-101, from Taiwan, appears in both groups.

01 | The four approved drugs each rescue one blood-cell line

• Neupogen (filgrastim): Amgen, 30 March 2015, the first H-ARS drug approved under the Animal Rule.
• Neulasta (pegfilgrastim): Amgen, 13 November 2015, the long-acting version.
• Leukine (sargramostim): Partner Therapeutics, 29 March 2018.
• Nplate (romiplostim): Amgen, January 2021, a TPO-receptor agonist.

The first three restore white cells and Nplate restores platelets. All four are existing blood-cell drugs whose labels were extended to ARS.

This is a government business. In October 2022, HHS's BARDA used Project BioShield funds to buy US$290 million of Nplate from Amgen. Amgen holds the stock as vendor-managed inventory, moving doses near expiry to the commercial market and replacing them for the government.

02 | LIB-101: one IL-12 dose for several blood-cell lines

LIB-101 is recombinant human interleukin-12 (IL-12). Libo Pharma says a single subcutaneous dose supports recovery across several blood-cell lineages, its main difference from the four approved drugs.

• Its predecessor, HemaMax (NM-IL-12), completed a 200-subject Phase 2 safety study in healthy volunteers in the US.
• BARDA has invested more than US$70 million in the program (2022 report).
• The Phase 3 plans about 300 healthy volunteers; as of March 2026, about 81 more were needed to finish enrollment.
• An investigator-initiated trial with Fukushima Medical University and TEPCO will make the drug in the US and store it in Fukushima for workers exposed at nuclear plants.

A nuclear plant operator willing to keep it on site is a second kind of buyer beyond government stockpiles.

03 | Rivals for the next stockpile order

• Entolimod (Tivic Health): a TLR5 agonist; met BARDA in January and March 2026 on funding and the Strategic National Stockpile.
• BIO 300 (Humanetics): oral, for prevention before exposure in military personnel and first responders. No FDA-approved drug prevents ARS before exposure.
• PLX-R18 (Pluri): placenta-derived cells in Phase 1; evaluated mass-production readiness in 2024.

LIB-101 and entolimod compete to save lives after exposure. BIO 300 targets the open gap of protection before exposure.

04 | IL-12 in cancer: big pharma is split

IL-12 can turn "cold" tumors hot and draw immune cells in, but systemic toxicity has long stalled development. The new approach is to make it act only inside the tumor:

• Xilio's efarindodekin alfa (XTX301) is activated in the tumor microenvironment. Gilead paid US$43.5 million upfront in 2024 with up to US$604 million more, and Phase 2 began in September 2025.
• Werewolf's WTX-330 is a conditionally activated prodrug. One gallbladder cancer patient had a partial response, but further development needs funding and the company is seeking partners.
• Ankyra's tolododekin alfa (ANK-101) is anchored in the tumor after injection; at ASCO 2026 it showed no dose-limiting toxicities.
• Dragonfly's DF6002: Bristol Myers Squibb licensed it in 2020 for US$475 million and returned it in February 2023.
• Audax's DAX-044: IL-12 fused to an antibody to concentrate it in the tumor microenvironment, still preclinical. On 27 October 2026 Astellas took an exclusive option to a worldwide license, with US$285 million in upfront and option-exercise payments and up to US$1.34 billion in total.

An IL-12 that has not yet reached patients drew US$285 million in upfront payments. After BMS walked away, Gilead and Astellas both paid in; big pharma is betting on designs that make IL-12 act only inside the tumor.

LIB-101 takes a different route: subcutaneous injection combined with radiotherapy. In a Phase 2a in cutaneous T-cell lymphoma (CTCL), the combination produced a 100% overall response rate in early-stage (IB) patients (company briefing). It has FDA and EMA orphan designations, and a multinational pivotal trial is planned. Diffuse large B-cell lymphoma (DLBCL) is in Phase 2.

05 | Taiwan: where Libo Pharma stands

Of the 13 assets on this page, LIB-101 is the only IL-12 in clinical development for both ARS and cancer, and the only Taiwanese asset.

Libo Pharma listed on Taiwan's emerging stock board (7888) on 23 December 2025 after raising about NT$850 million in a Series C in July 2025. It describes itself as a dual platform for defense-readiness medicine and immunotherapy: win ARS government procurement and nuclear-plant stockpiles first, then open the cancer market with a CTCL pivotal trial.

06 | Timeline

• Ongoing: LIB-101 Phase 3 enrollment (about 81 subjects short as of March 2026).
• Ongoing: entolimod funding and stockpile talks with BARDA.
• Planned: LIB-101 multinational pivotal trial in CTCL.
• Pending: efarindodekin alfa Phase 2 results and whether Gilead takes over development.
• 2027: DAX-044 expected to enter Phase 1.