Sean McCarthy
Analyst · Mizuho Group. Please go ahead. Your line is open
Thanks, Chris, and good afternoon, everyone. Thanks for joining us for an update on recent progress at CytomX. On today's call, I'll provide an overview of the company's therapeutic pipeline, including status updates for our emerging programs, CX-904, CX-801 and CX-2051. I'll also cover recent developments within our CD71 targeting program and additional updates on our corporate partnerships. At CytomX, we believe that as biologic anticancer therapies become more and more potent, the need for localizing empowered modalities such as antibody-drug conjugates, T-cell engagers and cytokines into cancer tissue becomes increasingly important as a way to improve therapeutic window. Indeed, we believe that localization will be the future of biologics. CytomX vision is to transform lives with safer, more effective therapies. We aim to realize our vision for the benefit of patients by leveraging our Probody platform to create high impact therapeutics that are localized to diseased tissue, thereby reducing systemic toxicities and maximizing overall benefit. 2022 was an important year of transition for our company in which we restructured and repositioned CytomX for future success by prioritizing our earlier stage portfolio that incorporates learning from our experience with the first wave of Probody therapeutics that we pioneered and advanced into the clinic. Since our early years, CytomX has pursued a consistent strategy focused on long-term company build around the Probody platform and maximizing impact for patients. Our substantial investments to date have allowed for broad clinical evaluation of our platform, have resulted in a uniquely strong scientific foundation and a deep pipeline of therapeutic candidates positioned to deliver significant near and long-term value. We currently have more than 15 active Probody therapeutic programs, including three clinical stage molecules and we expect to file two new INDs for wholly owned programs later this year. Additionally, through our collaborations, we have substantially extended the reach of our science. CytomX entered 2023 with robust financial resources and funding into 2025, positioning the company to execute towards multiple milestones over the next 12 months to 24 months. Moving now to our pipeline. I'd like to start with T-cell engaging bispecifics and our company is expanding efforts with this modality. T-cell engagers hold tremendous promise for the treatment of solid tumors. However, the very potency of this modality can lead to widespread activation of the immune system imposing constraints on therapeutic window. Localization of the powerful anticancer activity of this class of drugs could unlock enormous potential for patients by enhancing therapeutic window. CytomX and our partners believe the Probody platform to be ideally suited to addressing this challenge. Our lead program in this area is CX-904, a clinical stage Probody T-cell engager targeting EGFR and CD3 partnered with Amgen in a global co-development alliance. EGFR is a highly validated and broadly expressed cancer target and we see a compelling opportunity to leverage this target to localize anti-tumor T cell responses preferentially to the tumor microenvironment. Our published preclinical data show that a localized bispecific EGFR CD3 Probody has a widened therapeutic window compared to its unmasked counterpart. These preclinical data led to the advancement of CX-904 and we're now well underway with Phase 1 dose escalation. The Phase 1 study has advanced from initial single patient cohorts into the 3+3 phase of dose escalation. The primary goal of dose escalation for this drug candidate is to assess safety and we aim to reach dose levels and exposures by the end of 2023, which we can start enrollment into back law cohorts in certain EGFR positive tumors. Looking ahead to 2024, a key milestone on the horizon will be the selection of recommended Phase 2 dose and the potential decision to initiate Phase 1b expansion cohorts in EGFR positive tumors. This decision will be taken in conjunction with our partner Amgen. CytomX would then be responsible for the execution of expansion cohorts and upon the conclusion of the expansion phase, Amgen will take over global development with CytomX retaining certain co-funding, co-development and co-commercialization rights. We look forward to providing additional CX-904 updates as the program advances. Staying with T cell engagers, we were delighted that in January 2023, our partner Astellas nominated the first collaboration clinical candidate triggering a $5 million milestone payment to CytomX. CytomX and Astellas are also collaborating on additional T cell engagers and CytomX is eligible to receive future preclinical, clinical and commercial milestones across these programs. We also retain the option to select U.S. development and commercial rights within the Astellas collaboration. Continuing with T cell bispecifics. In November 2022, CytomX has had a multi-target R&D collaboration with Regeneron to discover and develop new bispecific immunotherapies. Regeneron has considerable efforts in T cell bispecifics and both companies see opportunities to broaden the reach of T cell engagers by utilizing CytomX platform to localize these highly potent agents to tumor tissue, widening therapeutic window. This shared vision formed the basis of our discussions last year, leading to the deal we announced in November. Given Regeneron's acknowledged high bar for external innovation, this collaboration is yet another point of validation of CytomX scientific and platform expertise. Moving now to our upcoming INDs for next generation molecules CX-2051 and CX-801. Starting with CX-2051, our conditionally active Probody ADC targeting EpCAM. EpCAM has been regarded as a high potential target for decades and has been clinically validated by others, but clinical activity has only been achieved with local administration. CX-2051 is tailored to optimize therapeutic index for EpCAM expressing epithelial cancers by matching the target with payload mechanism of action and tumor sensitivity. We have optimized masking, protease cleavability, and we have selected a camptothecin derivative, topoisomerase 1 inhibitor in the [indiscernible] class as the payload for this program and with a drug antibody ratio of 8. The EpCAM (ph) payload class has shown exciting clinical results with ADCs, including N HER2 and Trodelvy, and we really think this payload is an optimal choice for this program. Although locally administered anti-EpCAM therapeutics have shown promise, efforts to generate systemic anti-EpCAM therapeutics have to date not been successful. CX-2051, however, when systemically administered has demonstrated a wide predicted therapeutic index and strong preclinical activity in multiple preclinical models including colorectal cancer. We anticipate filing an IND for this novel ADC in the second half of 2023. Turning now to CX-801, our dually masked interferon alpha-2b, the lead program within our broad efforts in the cytokine field. We believe there's enormous potential to harness the powerful anti-cancer activity of cytokines by using our localization strategies to direct their activity towards tumor tissue and away from systemic immune system activation. Interferon alpha-2b is an approved immunotherapeutic that has demonstrated clinical activity in multiple cancer types, and we believe provides a potentially superior approach to activating anti-tumor immune responses than cytokines such as IL-2, IL-12 and IL-15. Interferon alpha stimulates antigen-presenting cells to activate cytotoxic T cells and combines effectively with checkpoint inhibition, offering tremendous potential to unlock checkpoint refractory and/or resistant cancers. Interferon alpha also has direct tumor cell killing activity, providing a dual mechanism of action. However, the powerful anti-cancer activity of interferon alpha has thus far been difficult to harness due to its systemic toxicity. In data presented at 16, 2022, we demonstrated that CX-801 has a wide therapeutic index and an enhanced tolerability profile compared to unmasked interferon. Our data have highlighted CX-801's preferential activity in the tumor microenvironment as well as the potential for synergistic effects when combined with checkpoint inhibitors. We believe CX-801 has the potential to become a unique centerpiece of combination therapy for a wide range of tumor types and we aim to rapidly advance this potentially best-in-class program towards clinical evaluation with an IND filing targeted for the second half of 2023. Let me turn now to our CD71 program. At CytomX, we have had a long-standing interest in leveraging the unique molecular properties of CD71, the transferrin receptor as an anti-cancer target. Our goal is to use our Probody platform to open a therapeutic window for this high potential, but previously undruggable target. And as such, we have developed an antibody drug conjugate to CD71 that we call CX-2029. We partnered the program with AbbVie, [indiscernible] back to 2016 and that was focused on the advancement of CX-2029 into IND-enabling and clinical studies. Under the collaboration agreement, CytomX was responsible for early development up to the completion of cohort expansions and with AbbVie being responsible for later-stage development. We have made substantial progress since this alliance started, and in January this year, we announced updated results from the cohort expansions, which included encouraging clinical activity in unselected heavily pretreated patients with tumors of squamous histologies, including a 21% confirmed response rate in squamous esophageal cancer. Grade 3 anemia remains the most common treatment-related adverse event. Strategies for management of anemia have included transfusions, dose delays and dose reductions. And patients who have responded to CX-2029 have been actively managed through the use of anemia mitigation measures. Our January data update for CX-2029 essentially marks the conclusion of CytomX's responsibilities for execution of the clinical program within the AbbVie alliance, and the data has been under evaluation at AbbVie in recent months. AbbVie informed us on March 21 that they do not plan to advance CX-2029 into further clinical studies for strategic portfolio reasons, and the alliance will conclude. CytomX regains full rights to CD71 and has an exclusive option to reacquire full rights to CX-2029, and these discussions are underway. While we are disappointed with AbbVie's decision, in our work to date on CD71, we have pushed new scientific boundaries and demonstrated for the first-time that targeting CD71 with an antibody drug conjugate can lead to tumor shrinkage in late-stage cancer patients. Going forward, CytomX will be evaluating next steps for CX-2029 while also continuing to pursue next-generation strategies to targeting CD71. We would like to thank AbbVie for their partnership in helping us bring CX-2029 and our CD71 program to this stage in its development. I'd like to now briefly update on our collaborative work with Bristol Myers Squibb and Moderna. Our alliance with BMS has continued to make progress, and I would like to take a few minutes to cover the latest updates on the CTLA-4 program. We have worked with BMS on two CTLA-4 Probody approaches. The first is a Probody version of ipilimumab that's called 249. We're also working with BMS on a Probody version of their non-fucosylated anti-CTLA-4 antibody designed to be a more potent version of ipi. This Probody named 288 is designed to be a safer, more effective version of the non-fucosylated ipi. At their earnings call a few weeks ago, BMS announced their prioritization and advancement of the non-fucosylated Probody, 288, which is now the leading edge of their next-generation CTLA-4 program. At SITC in 2022, BMS presented Phase 1 data on 218, which is the non-fucosylated antibody that underlies 288, showing intriguing activity, including in microsatellite-stable colorectal cancer. The 288 Probody is being advanced to Phase 2, and we look forward to future updates from BMS. Lastly, I'd like to reemphasize our most recent collaboration with Moderna, which highlights CytomX's continued innovation, breadth and pioneering efforts in the field of conditional activation and also our continued ability to leverage partnering as a financing vehicle for our company. We're excited to have already kicked off this collaboration, which brings together two leading platforms to research and develop mRNA-encoded conditionally activated biologics. CytomX and Moderna share a vision of investing at the intersection of biology and technology to transform the lives of patients in oncology and also in non-oncology therapeutic areas, and we look forward to doing great things together. Let me now turn the call over to Chris to provide you with a financial overview for the quarter.