On November 7, 2025 Akeso, Inc. (HKEX: 9926.HK) reported the preclinical research data for its novel antagonistic monoclonal antibody targeting IL-1RAP, AK135, at the 40th Annual Meeting of the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) held in National Harbor, Maryland.

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The results demonstrated that AK135 effectively targets IL-1RAP and blocks three key pro-inflammatory signaling pathways—IL-1, IL-33, and IL-36 at their source, thereby halting the transmission of inflammatory signals. In preclinical models, AK135 provided significant pain relief in neuropathy, exhibiting dose-dependent efficacy, while also showing good tolerability and safety profiles.

In vitro Results:

ELISA, Fortebio molecular interaction technology, and flow cytometry (FACS) results demonstrated that AK135 has high affinity for IL-1RAP, with binding activity comparable to or superior to that of the control antibody CAN04.
Reporter gene assays further confirmed that AK135 effectively inhibits the activation of IL-1, IL-33, and IL-36 signaling pathways, showing excellent half-maximal inhibitory concentration (IC50) values in each of the pathways.
In tumor cell models, AK135 significantly reduced the secretion of pro-inflammatory cytokines (such as IL-6 and IL-8) induced by IL-1, IL-33, and IL-36.
In vivo Results:

The in vitro experiments confirmed the high affinity and potent neutralizing activity of AK135. To further evaluate its in vivo efficacy, the research team established a Chemotherapy-induced peripheral neuropathy (CIPN) mouse model and assessed the pharmacological effects of AK135 through intermittent low-dose paclitaxel administration.
Following AK135 treatment, the paw withdrawal threshold (PWT) in the CIPN model was significantly increased, indicating that AK135 effectively alleviated mechanical allodynia, with a dose-dependent efficacy.
Throughout the treatment period, mice in all dose groups maintained stable body weight, with no significant signs of toxicity, demonstrating good tolerance.
CIPN is a prevalent and dose-limiting side effect of chemotherapy, affecting 50-90% of treated patients, of which 30-40% progressing to chronic neuropathic pain. Despite its clinical significance, effective treatment options remain limited, and the underlying mechanisms are not fully understood. Emerging evidence suggests that pro-inflammatory cytokines released by the damaged neurons play a key role in CIPN pathogenesis. IL-1 receptor accessory protein (IL-1RAP/IL-1RAcP) is a critical mediator of inflammatory signaling, amplifying responses through the interleukin-1 (IL-1), interleukin-33 (IL-33), and interleukin-36 (IL-36) pathways. Akeso developed AK135, a novel antagonistic monoclonal antibody targeting IL-1RAP, to alleviate the peripheral neuralgia by inhibiting these proinflammatory signaling pathways.

About AK135 (IL-1RAP Targeting Antibody)
AK135 is a novel antagonistic antibody targeting IL-1RAP, internally developed by Akeso, aimed at treating chemotherapy-induced peripheral neuropathy (CIPN). By precisely blocking IL-1RAP, this product simultaneously inhibits the three core inflammatory signaling pathways—IL-1, IL-33, and IL-36, providing relief from neuroinflammatory responses at their source. Preclinical studies have shown that AK135 significantly alleviates neuropathic pain in a dose-dependent manner, while also demonstrating good tolerance. Currently, AK135 is in Phase I clinical trials for the treatment of CIPN.

(Press release, Akeso Biopharma, NOV 7, 2025, View Source [SID1234659653])