SHANGHAI, China, April 9, 2026—IMPACT Therapeutics (“IMPACT”) today announced that it has received a milestone payment of US$5.0 million from Eikon Therapeutics, Inc. (Nasdaq: EIKN) (“EIKON”). The payment was triggered by the advancement of IMP1734 (also known as EIK1003 outside Greater China), one of the PARP1-selective inhibitors covered under the collaboration and license agreement between the two parties signed in May 2023, into Phase II clinical development.

IMP1734 was discovered by IMPACT’s scientists, and is a highly potent, next-generation PARP1-selective inhibitor, currently being evaluated as monotherapy and as combination therapies in a global Phase I/II trial for advanced solid tumors. By selectively targeting PARP1 while sparing PARP2, PARP1-selective inhibitors may offer a more refined therapeutic approach with improved safety, particularly reduced hematologic toxicity. This enhanced tolerability and broader therapeutic window may potentially allow for more flexible combination strategies, potentially enabling use in treatment settings previously inaccessible to PARP1/2 inhibitors.

IMP1734 has shown over 648-fold selectivity for PARP1 over PARP2, which may potentially translate to lower hematologic toxicity, improved safety, higher exposure, and broad opportunities to combine with other anti-tumor agents. In Phase I dose escalation studies, IMP1734 monotherapy shows a favorable pharmacokinetics (PK) profile and is well tolerated with mostly low-grade AEs that are manageable and/or self-limiting. We are also investigating IMP1734 in multiple combination regimens, with cohorts evaluating IMP1734 in combination with Abiraterone and Prednisone and with weekly Paclitaxel currently ongoing. 

Dr. Sui Xiong Cai, CEO of IMPACT, commented: “The receipt of this milestone payment underscores the significant progress in our partnership. We’re excited to work closely with our partner EIKON to accelerate the global development of this program, with the goal of bringing new treatment options to patients as soon as possible. IMPACT will focus on advancing synthetic lethality (SL)-based precision anti-cancer therapies globally, delivering innovative treatments to address the unmet medical needs of cancer patients.”

About the Collaboration

In May 2023, IMPACT and EIKON entered into an exclusive global licensing and collaboration agreement. Under the agreement, EIKON holds the exclusive rights to co-develop, register, manufacture, and commercialize IMP1734 and other PARP1-selective inhibitors in all territories outside of Greater China.

About IMP1734

IMP1734 is a novel PARP1-selective inhibitor with high potency of inhibiting PARP1 and low activity of inhibiting PARP2. Preclinical in vivo models demonstrated high anti-tumor activities and a wide therapeutic window. The improved therapeutic index of IMP1734 over currently marketed non-selective PARP1/2 inhibitors supports its development as monotherapy and in combination with other agents. Overall, phase I studies demonstrate hematologic toxicity to be uncommon, and clinical activity was observed at most doses tested, as evidenced by target lesion size reduction and durable responses. In addition, tolerability and efficacy are being evaluated in combination with Abiraterone and Paclitaxel, respectively, and results of these combination studies will be disclosed at future medical meetings. Additional information about the clinical trials of IMP1734 can be found at https://clinicaltrials.gov/study/NCT06253130.

About Eikon Therapeutics

Eikon Therapeutics is dedicated to advancing breakthrough therapies through the purposeful integration of science and engineering. Its research tools, including its proprietary SMT system, leverage Nobel Prize-winning super-resolution microscopy, bespoke automation, advanced data science, and software engineering to visualize and measure the real-time movement of proteins in living cells, with the goal of developing important innovative medicines to address serious unmet medical needs.

About IMPACT Therapeutics

Founded in 2009, we are a commercial-stage biotechnology company focused on advancing synthetic lethality (SL)-based precision anti-cancer therapies globally, delivering innovative treatments to address the unmet medical needs of cancer patients. We have in-house discovered and developed one of the most comprehensive and advanced SL franchises and are one of only three companies with both commercial-stage PARP1/2 inhibitors and clinical-stage next-generation PARP1-selective inhibitors worldwide.

Our core product, Senaparib (IMP4297), has already been commercialized, following its approval as 1L maintenance therapy for OC “all-comers” in China in January 2025, and is reimbursable for OC 1L “all-comers” since January 1, 2026. Senaparib also delivered the most favorable PFS outcome among PARP1/2 inhibitors (non head-to-head) for 1L maintenance therapy for OC “all-comers” in China, setting a new benchmark in this class.

Our continued growth is powered by an integrated R&D platform that enables innovation across both small molecules and emerging modalities, including ADCs and degraders. Additionally, we have forged partnerships with leading global biotech and China pharmaceutical companies to date, as validation of our pipeline and R&D platform.

Our major clinical pipeline drug candidates include the PARP1/2 inhibitor Senaparib (IMP4297), PARP1-selective inhibitors (IMP1734 and IMP1707, co-developed with Eikon Therapeutics), ATR inhibitor (IMP9064), WEE1 inhibitor (IMP7068), and multiple other synthetic lethality target inhibitors.

For additional information, please visit www.impacttherapeutics.com

IMPACT Therapeutics Contact:

+86 21 6841 1121

IR@impacttherapeutics.com

PR@impacttherapeutics.com