Good morning. Welcome to the Passage Bio Remix Therapeutics merger agreement announcement conference call. I would like to remind you that this call is being recorded for replay. I will now turn the conference call over to Kathleen Borthwick, Chief Financial Officer of Passage Bio. Please go ahead.
Thank you, operator. Good morning, everyone. Before we begin, I'd like to remind you that today's call may include forward-looking statements, including statements related to the expected timing and completion of proposed merger, financing, clinical development plans, and future performance. These statements are subject to risks and uncertainties described in our SEC filings, which we urge you to read. With that, I'll now turn the call over to Dr. Will Chou, President and Chief Executive Officer of Passage Bio.
Thank you, Kathleen. Good morning. Earlier today, Passage Bio issued a press release outlining a definitive merger agreement with Remix Therapeutics, as well as a concurrent private placement financing led by a syndicate of leading biotechnology investors supporting Remix's novel pipeline programs. This financing is expected to close immediately prior to the completion of the merger. This all-stock transaction represents an important moment for Passage shareholders and follows a comprehensive evaluation of strategic alternatives by our board of directors with a disciplined focus on delivering value to our shareholders. We are excited to enter into this merger agreement with Remix, a company with a compelling pipeline and the potential to bring meaningful therapies to patients in need. Remix has built a highly differentiated and clinically advanced platform centered on reprogramming RNA processing to address disease at its source.
This approach enables the targeting of disease drivers that have historically been beyond the reach of conventional drug discovery, including oncogenic transcription factors such as MYB, which is implicated across multiple cancers. Remix's lead program, REM-422, is an oral mRNA degrader targeting MYB with preliminary clinical data demonstrating excellent therapeutic potential. REM-422 is currently in the clinic in multiple indications, including in an ongoing registrational study for adenoid cystic carcinoma, and the program is expected to deliver on multiple clinical data readouts over the coming quarters. The combined company will be supported by an oversubscribed private placement and is expected to have cash runway into 2028, providing a strong financial position to execute against meaningful clinical milestones. Under the terms of the transaction, pre-merger Passage Bio shareholders are expected to own approximately 7% of the combined company at closing.
Pre-merger Remix shareholders, inclusive of those participating in the private placement, are expected to own approximately 93% of the combined company at closing. The percentage of the combined company that Passage shareholders will own at closing is subject to adjustments based on the estimated amount of Passage's net cash immediately prior to the closing date, which is expected to take place in the fourth quarter of 2026. In addition to receiving a portion of the new combined company, Passage shareholders may continue to participate in the success of Passage's pediatric gene therapy programs, currently sub-licensed to GEMMA Biotherapeutics, via contingent value rights entitling holders to a portion of net proceeds, if any, received for certain milestone payments. On behalf of Passage Bio, I would like to thank our employees, collaborators, patients and shareholders for their support and dedication.
With unanimous support from board members at both companies, we are excited to enter into this merger and look forward to the progress of the combined company under the dedicated and talented Remix leadership team. With that, I'll turn the call over to Pete Smith, CEO of Remix Therapeutics.
Thank you, Will, and thank you all for joining us today. Today marks a transformational milestone for Remix Therapeutics as we take this step to become a publicly traded company through our merger with Passage Bio. At Remix, our mission is to reprogram RNA processing to address disease drivers at its origin. For decades, drug discovery has focused primarily on proteins, leaving many important disease drivers largely inaccessible by conventional approaches. We take a fundamentally different approach by targeting RNA processing directly, which could allow us to control gene expression upstream of protein production and unlock new therapeutic possibilities. We believe this represents a meaningful shift in the way medicines can be discovered and developed, enabling new ways to intervene in disease biology.
This transaction is structured to accelerate that vision. It provides immediate access to the public markets, enabling us to expand our investor base and scale our efforts. Importantly, it is supported by an oversubscribed private placement led by new investor Decheng Capital, with participation from leading institutional investors that will result in total gross proceeds of over $100 million. Combined with the capital from Passage Bio, we expect to have cash runway into 2028, allowing us to execute against key clinical milestones across our pipeline. At the core of our company is the REMaster platform, which integrates deep expertise in data science, biomolecular sciences, and chemistry to rationally design small molecules that modulate RNA processing.
This platform allows us to create highly specific and selective orally available therapies against disease-driving targets that have proven challenging to address with conventional approaches, while also serving as a scalable discovery engine for generating multiple new programs over time. Our lead program REM-422 is a clear example of this strategy in action. REM-422 is an orally available mRNA degrader targeting MYB, an oncogenic transcription factor implicated across multiple cancers, starting with our work in adenoid cystic carcinoma, or ACC, and acute myeloid leukemia and high-risk myelodysplastic syndromes, or AML/high-risk MDS. Rather than attempting to directly inhibit the MYB protein, REM-422 induces the inclusion of a poison exon in the MYB mRNA transcript, leading to its degradation through nonsense-mediated decay. Thus, we are inhibiting MYB's function by preventing it from being expressed through an RNA degradation mechanism.
This represents a powerful mechanism of action and a new way to approach previously inaccessible targets. REM-422 has received Orphan Drug Designation for AML and ACC, as well as Fast Track designation for ACC from the FDA, reinforcing both the unmet medical need in these indications and the potential importance of this therapy. REM-422 is currently being evaluated in a phase I/II clinical trial in patients with ACC and a phase I study in AML and high-risk MDS. In ACC, this includes both a phase I dose escalation phase in 69 patients designed to determine the maximum tolerated dose and recommended phase II dose, and a phase II confirmatory cohort targeting 40-50 patients, which will further evaluate safety and efficacy in biomarker-positive patients.
The phase I study is completed, and our ARIA study is currently enrolling in the phase II portion, which is an open label, non-randomized multicenter trial. A CC is a solid tumor with over 1,500 new cases seen each year in the U.S. and a prevalent population of 13,000-16,000 people. It most commonly arises in the salivary glands and is characterized by frequent recurrence, perineural invasion, and dysregulation of the MYB oncogene. Approximately 60%-65% of ACC patients are MYB poison exon biomarker positive and potential candidates for REM-422 treatment. Depending on tumor location, patients may experience symptoms such as facial numbness, difficulty swallowing, vision changes, or difficulty breathing. Despite multiple therapeutic approaches being explored, including chemotherapy, kinase inhibitors, and immunotherapy, clinical outcomes have historically been modest.
There are currently no approved treatment options, which underscores the significant unmet need and opportunity for innovation in these patients. We recently reported encouraging clinical data from the ongoing ARIA study in patients with ACC at the 2026 ASCO annual meeting. REM-422 demonstrated dose proportional increases in exposure across all dose levels tested and reduction of MYB mRNA and protein levels in tumor biopsies taken from patients. REM-422 has demonstrated favorable safety and tolerability data with no dose-limiting toxicities observed to date and primarily low-grade adverse events such as anemia, fatigue, and epistaxis. The recommended phase II dose of 24 milligrams was generally well tolerated, with several patients approaching two years of treatment and ongoing. In the biomarker-positive cohort treated at the recommended phase II dose.
An overall response rate of 43% was observed, with durable responses exceeding one year and ongoing. We also observed a 100% disease control rate. Responses were observed across molecular subtypes, various histologies, and regardless of prior lines of therapy, including in patients previously treated with antibody-drug conjugates, highlighting the potential breadth of activity even in a heavily pretreated patients population. These results are compelling and unprecedented in this disease, given that there are no systemic treatment options for this life-threatening cancer. Of note, we have aligned with the FDA on the recommended phase II dose, use of biomarker selection that is an assay designed to identify patients that are MYB poison exon positive performed in collaboration with Tempus, and also the design of the phase II study.
Enrollment in the phase II study is proceeding very well, with over 50% of the planned study size already enrolled since the trial opened in late Q4 of 2025. Looking ahead, we are excited to progress our programs and pipeline, including advancing REM-422 through clinical development and generating key data that we believe can meaningfully inform its potential. We expect to have initial data from our ongoing phase II cohorts for REM-422 and ACC in mid-2027. We have also started enrollment in the phase I study of REM-422 in AML high-risk MDS and have observed strong preliminary antitumor activity during dose escalation. Dose escalation is ongoing to determine the recommended phase II dose for REM-422 in AML MDS, and we expect to have top-line data in mid-2027.
Furthermore, we expect to progress our discovery pipeline with nomination of a development candidate for our mRNA degrader program targeting MYB-dysregulated cancers in 2027. The transaction announced today will fund the company through these milestones with cash runway into 2028. Upon closing of the transaction, I will continue to serve as Chief Executive Officer, working alongside an experienced leadership team and board of directors. Together, this team brings deep expertise in RNA biology, drug development, and company building with a shared commitment to translating innovative science into impactful medicines. Taking a step back to reflect, this transaction is transformative as it positions Remix to lead in the new category of RNA-targeted therapeutics, advance a differentiated clinical pipeline, and deliver important milestones in the near and mid-term.
Most importantly, it strengthens our ability to bring meaningful new treatment options to patients with significant unmet medical needs. We are excited about the opportunity ahead and grateful for the continued support of our investors, employees, and partners. Thank you for joining us today.
Ladies and gentlemen, this concludes today's event. You may now disconnect.