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Background: Folate Receptor alpha (FRa) is a validated cell surface cancer target that is prevalently expressed in multiple cancers with high unmet need, including ovarian cancer and other gynecological cancers, while exhibiting minimal expression in normal tissues. Due to FRa’s favorable expression profile, multiple antibody-drug conjugates (ADCs) are being explored in this setting. Here we present the preclinical characterization of a new anti-FRa ADC, ZW191. ZW191 is an antibody drug conjugate (ADC) comprised of a humanized IgG1 antibody conjugated to a novel camptothecin-based topoisomerase 1 inhibitor payload, ZD06519, via a maleimidocaproyl (MC) anchor and a glycyl glycyl phenylalanyl glycine (GGFG)-aminomethyl (AM) cleavable linker at a drug-to-antibody ratio (DAR) of 8. Materials and Methods: The novel antibody and drug-linker components of ZW191 were generated, characterized, and optimally integrated. The apparent binding affinity and cellular internalization of the ZW191 antibody, and the intracellular concentration of the released camptothecin payload, ZD06519, were determined in FRa-expressing cells. Additionally, the binding specificity of the ZW191 antibody was determined using a cell microarray technology to test for binding against over 6,000 full length proteins that are individually over-expressed in human cells. Tumor spheroid cancer cell cultures were utilized to determine the cytotoxicity of ZW191 and the ability of ZW191 to penetrate the layers of the three-dimensional (3D) spheroid. The bystander activity of ZW191 was assessed using antigen positive and negative co-culture experiments. The anti-tumor activity of ZW191 was evaluated in a panel of cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) ovarian cancer models spanning a range of FRa expression. ZW191 was evaluated in toxicology and pharmacokinetic (PK) studies performed in rodents and non-human primates (NHP). Results: The antibody component of ZW191 features a favorable binding profile with strong and exclusive binding to FRa, and drives superior tumor spheroid penetration, cellular internalization, and payload delivery compared to FRa targeted antibodies used in other ADCs. ZW191 demonstrates potent activity in FRa expressing 3D tumor spheroid cultures and effective bystander activity. In a panel of CDX and PDX models representing a range of FRa expression, ZW191 demonstrates compelling anti-tumor activity at exposures that are estimated to be readily achievable in the clinic. ZW191 was tolerated up to 200 mg/kg in a two-dose rat study and at 30 mg/kg in a two-dose NHP study, with favorable PK. The promising efficacy, tolerability, and PK supports the potential of ZW191 as a novel therapeutic agent that may help address unmet need in patients with high and low FRa-expressing cancers. Citation Format: Sam Lawn, Andrea Hernandez Rojas, Raffaele Colombo, Dayananda Siddappa, Jodi Wong, Kaylee Wu, Vincent Fung, Dunja Urosev, Luying Yang, Jamie R. Rich, Stuart D. Barnscher. ZW191, a novel FRa-targeting antibody drug conjugate bearing a topoisomerase 1 inhibitor payload [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2641.

Pancreatic cancer is often diagnosed at advanced stages and responds poorly to chemotherapy. Because high tumor T cell infiltration corresponds with better clinical outcomes in pancreatic cancer patients, immunotherapy has gained significant interest over the last decade for the treatment of recurrent pancreatic cancer. IL-12 is a proinflammatory cytokine with pleiotropic effects including activation of CD8+ T cells and NK cells. Unfortunately, systemic high dose IL-12 administration led to severe toxicities in clinical trials which has limited further development of this cytokine as a cancer therapeutic. To address this limitation, we developed an implantable cytokine delivery platform to allow for local administration of IL-12. These cytokine factories, composed of genetically engineered epithelial cells encapsulated in biocompatible polymers, allow for safe and controlled dosing in vivo. Tumor adjacent administration of IL-12-based cytokine factories caused reduction of intraperitoneal pan02 tumor burden by 80% after only 1 week of treatment in mice with pancreatic cancer. Single cell RNAseq of the tumor adjacent immune cells at this time point showed 2x more T and NK cells present in the IL-12 treated mice than untreated mice suggesting modulation of the tumor microenvironment via immune cell infiltration. Importantly, the necessary IL-12 dose was well tolerated in all mice without signs of toxicity for 180 days. In efforts to evaluate the translatability of this platform, we further tested IL-12-based cytokine factories in a non-human primate. The cytokine factories produced a high local IL-12 concentration without substantial leakage into the systemic circulation and were well tolerated by the primates as shown by the lack of fever or weight loss, as well as the lack of renal or liver toxicity. Our findings highlight the therapeutic potential of IL-12 treatments when administered locally via cytokine factories in preclinical animal models. Further, these findings provide rationale for future development and clinical testing of cytokine factories for treatment of a wide range of metastatic peritoneal cancers in humans. Citation Format: Amanda Nash, Samira Aghlara-Fotovat, Bertha Castillo, Annie Nguyen, Andrew Cui, Andrea Hernandez, Peter Rios, Sofia Ghani, Ira Joshi, Chunyu Xu, Rahul Sheth, Weiyi Peng, Jose Oberholzer, Amir Jazaeri, Omid Veiseh. IL-12-based cytokine factories modulate tumor microenvironment to eradicate pancreatic tumors in mice and are well tolerated in non-human primates [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3547.

Pro-inflammatory cytokines have been approved as a cancer immunotherapy for treatment of metastatic melanoma and renal carcinoma for over 30 years. However, widespread use of cytokine therapy in the clinic is limited by its short half-life in circulation and the associated toxicities that emerge as a result of high systemic exposure. To overcome these limitations, we developed a clinically translatable cytokine delivery platform, called cytokine factories, composed of genetically engineered epithelial cells encapsulated in biocompatible polymers. These cells are able to produce a wide range of natural cytokines (IL2, IL7, IL10, or IL12) and allow for controlled and predictable dosing in vivo. In vivo administration of cytokine factories created a high local cytokine concentration (IP space) without substantial leakage into the systemic circulation. Local, or tumor adjacent, administration of pro-inflammatory (IL-2-based) cytokine factories caused reduction of tumor burden by 70% after only 1 week of treatment when delivered as a monotherapy to mice with malignant pleural mesothelioma (MPM). Importantly, when administered in combination with local anti-PD1 injections, these cytokine factories lead to eradication of these highly aggressive tumors in 7/7 treated mice. To validate the translatability of this platform, we evaluated the safety profile in non-human primates. Significantly, this platform produced local and systemic T cell biomarker profiles that predict efficacy without renal, liver, or general toxicity in non-human primates. Our findings demonstrate the safety and efficacy of cytokine factories in preclinical animal models and provide rationale for future clinical testing for the treatment of metastatic peritoneal cancers in humans. Citation Format: Amanda Nash, Samira Aghlara-Fotovat, Andrea Hernandez, Bertha Castillo, Alexander Lu, Aarthi Pugazenthi, Peter Rios, Sofia Ghani, Ira Joshi, Douglas Isa, Chunyu Xu, Rahul Sheth, Weiyi Peng, Jose Oberholzer, Amir Jazaeri, Hee-Jin Jang, Bryan Burt, Hyun-Sung Lee, Ravi Ghanta, Omid Veiseh. Evaluation of implantable cytokine factories in combination with checkpoint inhibitors for eradication of malignant pleural mesothelioma (MPM) tumors in mice with safe and predictable dosing in non-human primates [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4189.

Therapies targeting HER2 have transformed the treatment of patients with HER2-expressing breast and gastric cancers. Unfortunately, many patients recur following HER2-targeted treatments and new therapies are needed. Multiple antibody-drug conjugate (ADC) technologies are being explored in this setting, some of which utilize the anti-HER2 antibody trastuzumab. Here we present the preclinical characterization of a new anti-HER2 biparatopic ADC, ZW49, which is generated from the conjugation of a novel N-acyl sulfonamide auristatin payload to the inter-chain disulfide bond cysteines of the bispecific anti-HER2 IgG1 antibody ZW25, via a protease cleavable linker. A series of in vitro and in vivo experiments were performed to characterize ZW49 as a potential therapeutic candidate. In cellular binding assays, it was confirmed that the payload conjugation to ZW25 did not affect the antibody's binding to HER2-expressing cells. ZW49 displayed potent in vitro cytotoxicity in multiple cancer cell lines expressing HER2 and was efficacious in multiple patient-derived xenograft (PDX) models. In mice bearing the HBCx-13b HER2 3+ PDX, two doses of ZW49 administered two weeks apart generated tumor regressions. Furthermore, preliminary results from PDX models with lower levels of HER2 expression treated with ZW49 also generated regressions. In nonhuman primates ZW49 administered intravenously every two weeks for three doses was well tolerated. Based on these findings, we are proceeding with further development of ZW49 as a therapeutic candidate in HER2-expressing cancers. Citation Format: Kevin J. Hamblett, Phil W. Hammond, Stuart D. Barnscher, Vincent K. Fung, Rupert H. Davies, Grant R. Wickman, Andrea Hernandez, Tong Ding, Adam S. Galey, Geoffrey C. Winters, Jamie R. Rich, John S. Babcook. ZW49, a HER2-targeted biparatopic antibody-drug conjugate for the treatment of HER2-expressing cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3914.

Antibody drug conjugates (ADCs) combine the specificity of monoclonal antibodies with potent antineoplastic small molecules, and promise efficacy without the systemic toxicity of chemotherapy. Despite this tremendous potential, most clinical ADCs have failed to provide sufficient therapeutic benefit before the onset of off-target dose-limiting platform toxicities. Here we report the development of proprietary protease cleavable N-acyl sulfonamide linked hemiasterlin and auristatin payloads, Zymelink, that allow the generation of an efficacious ADC platform with improved tolerability. Both Zymelink drug-linkers were conjugated via maleimides to endogenous cysteines. As Zymelink drug-linkers are more polar than maleimide valine citrulline monomethyl auristatin E drug-linker, the resulting ADCs can be produced with potential advantages in PK, efficacy and safety. The resulting ADCs exhibit potent in vitro cytotoxicity. A trastuzumab-based ADC prepared with Zymelink drug-linker and demonstrated at least equivalent efficacy compared to a trastuzumab-based ADC prepared with MMAE, promoting durable complete regressions in a patient-derived xenograft model. Zymelink hemiasterlin and auristatin ADCs were tolerated at 5-6 fold higher doses compared to a MMAE ADC in cynomolgus monkeys. The maximum tolerated dose of the MMAE ADC was just 3 mg/kg based on severe neutropenia. Zymelink hemiasterlin ADC was tolerated at 15 mg/kg with no evidence of neutropenia or elevations in transaminases. Zymelink auristatin ADC was tolerated at 18 mg/kg based on increased levels of transaminases at 24 mg/kg. Moreover, Zymelink ADCs exhibited greater serum exposure at equivalent doses. These results suggest Zymelink ADCs have a greatly expanded therapeutic window compared to MMAE conjugates. Citation Format: Stuart Barnscher, John Babcook, Jamie Rich, Geoff Winters, Graham Garnett, Andrea Hernandez, Vincent Fung, Kevin Yin, Kevin Hamblett, Rupert Davies. Zymelink drug conjugate platform: redefining the therapeutic window for ADCs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 61. doi:10.1158/1538-7445.AM2017-61