1cBio and Lee’s Pharm partnership illustration featuring a cancer cell, DNA, drug molecule, Asia map, San Francisco and Hong Kong, representing the OC-3 PARP1 inhibitor licensing agreement.

1cBio Licenses PARP1 Inhibitor OC-3 to Lee’s Pharm in $27 Million Asia Deal

September 11, 2026 3 Min Read

1cBio has struck a regional licensing deal with Hong Kong-based Lee’s Pharmaceutical Holdings to advance OC-3, its next-generation selective PARP1 inhibitor, across Greater China and parts of Southeast Asia.

Under the agreement announced September 9, Lee’s Pharm receives exclusive rights to develop and commercialize OC-3 in China and certain Southeast Asian markets. 1cBio is eligible for an upfront payment together with development and sales milestones worth up to $27 million, plus royalties on future net sales. (PR Newswire)

The deal gives 1cBio something particularly valuable for an early-stage oncology program: a regional partner that can take on a substantial portion of the development and manufacturing work while generating data that can also support the drug’s broader global development.

OC-3 Takes Aim at a More Selective Generation of PARP Inhibition

OC-3 is currently in preclinical development and is designed as a next-generation, PARP1-selective inhibitor for tumors with defects in homologous recombination repair, or HRR.

That biology has already been validated by existing PARP inhibitors, particularly in tumors carrying mutations in DNA-repair genes such as BRCA1, BRCA2 and PALB2. 1cBio sees potential applications for OC-3 across prostate, ovarian, breast and pancreatic cancers with these molecular characteristics. The company says OC-3 has demonstrated potent antitumor activity in preclinical models of DNA-repair-deficient cancers. (PR Newswire)

What makes OC-3 potentially interesting is its selectivity.

Existing PARP inhibitors have demonstrated meaningful efficacy across several cancers, but hematologic toxicity can constrain dosing and complicate combination strategies. 1cBio is developing OC-3 to selectively inhibit PARP1 while largely sparing PARP2 at anticipated therapeutic exposures, with the goal of preserving antitumor activity while reducing bone-marrow toxicity. (1cBio)

According to 1cBio, OC-3 is a potent PARP1 inhibitor with moderate PARP1 trapping. The company believes this profile could eventually provide greater flexibility both as a monotherapy and in combination regimens.

That remains a hypothesis to be tested clinically, however. OC-3 has not yet entered human trials, so its safety and efficacy advantages over established PARP inhibitors or other PARP1-selective candidates have yet to be demonstrated.

Lee’s Pharm Takes the Lead in China and Southeast Asia

The partnership goes beyond a straightforward commercialization license.

Lee’s Pharm will be responsible for Good Laboratory Practice (GLP) safety studies and manufacturing activities required to support regulatory approval of OC-3 within the licensed territories. The transaction also includes a drug-supply manufacturing agreement. (PR Newswire)

For 1cBio, an important part of the structure is access to the resulting development data. The company retains rights to use data generated under the collaboration to support its planned U.S. Investigational New Drug application.

1cBio currently says it intends to file a U.S. IND for OC-3 in 2027, while seeking additional partnerships to support the drug’s broader global development. (1cBio)

The arrangement therefore gives the small San Francisco Bay Area biotech a way to advance OC-3 on parallel tracks: Lee’s Pharm can move the program toward clinical development in Asia while 1cBio uses the resulting work to help prepare for U.S. development.

A Strategic Fit for Both Companies

For 1cBio, the transaction brings non-dilutive funding, development resources and regional manufacturing capabilities to its lead oncology program without surrendering the drug’s broader global opportunity.

1cBio CEO Andrew Protter highlighted Lee’s Pharm’s oncology infrastructure and manufacturing capabilities as important factors behind the partnership, saying the collaboration should provide additional resources as 1cBio works toward its U.S. IND and eventual clinical trials in solid tumors. (1cBio)

Lee’s Pharm, meanwhile, adds an early-stage precision-oncology asset built around an already clinically validated DNA-damage-repair pathway.

The timing is notable as drug developers increasingly explore whether PARP1-selective inhibitors can improve upon the therapeutic window of first-generation PARP1/2 inhibitors. The central question is whether greater PARP1 selectivity can maintain—or improve—anticancer activity while reducing hematologic toxicity sufficiently to allow higher exposures or more effective combination regimens.

OC-3 will ultimately have to demonstrate those advantages in patients.

For now, the Lee’s Pharm agreement provides 1cBio with both financing and an operational partner capable of helping move the program from preclinical development toward the clinic. If the program reaches its planned U.S. IND filing in 2027, the coming year should begin to show whether OC-3 can translate its preclinical profile into a differentiated clinical PARP1 program.