X4 Pharmaceuticals, Inc.

Greetings and welcome to the X4 Pharmaceuticals fourth quarter and full year 2023 financial and operating results conference call. At this time, all participants are in a listen-only mode. A question and answer session will follow the formal presentation. As a reminder, this conference is being recorded. It is now my pleasure to introduce your host, Dan Ferry from LifeSci Advisors. Please begin.

Thank you, Operator, and good morning, everyone. Presenting on today's call will be X4's Chief Executive Officer, Dr. Paula Regan, and Chief Financial Officer, Adam Mostafa. Following prepared remarks by each, we will open the call to your questions, and we'll be joined by Chief Commercial Officer, Mark Baldry, Chief Medical Officer, Dr. Christoph Arbit Engels, Chief Operating Officer, Mary DiPiase, and Chief Scientific Officer, Art Tavares. As a reminder on today's call, the company will be making forward-looking statements regarding regulatory and product development plans, as well as research activities. These statements are subject to risks and uncertainties that may cause actual results to differ from those forecasted. Description of these risks can be found in XFOR's most recent filings with the SEC, including this year's Form 10-K, which is expected to be filed after market close today. I'd now like to turn the call over to XFOR's President and CEO, Dr. Paula Regan. Paula?

Thanks, Dan. Good morning, everyone, and thank you for joining us on the call today. As we look ahead to 2024, we thought we'd take the time to reflect on all that we've accomplished over the past year. Milestones that have set the stage for what we expect will be an incredibly exciting and truly transformative year for X4, a year where we aim to become a fully integrated research, development, and commercialization company with the goal of delivering new options for rare disease patients. Throughout 2023, we hit several major milestones. Most importantly, submission and acceptance under FDA's priority review process of our NDA seeking approval of Maverick CIFOR, our oral targeted CXCR4 antagonist for the treatment of WHIM syndrome. As you may recall, WIM is a rare combined primary immunodeficiency caused by genetic variations to the CXCR4 receptor. The CXCR4 pathway helps regulate the migration of white blood cells, including neutrophils and lymphocytes, into the bloodstream. WIM is named for its four most common manifestations. Warts, which are typically caused by unresolved HPV infections. hypogamula globulinemia, or low levels of antibodies, infections, both viral and bacterial, and myelocathexis, or retention of white blood cells in the bone marrow. Diagnosis of WHIM has historically proven challenging because only a minority of patients actually experience all four manifestations in the acronym, although not all symptoms are required for diagnosis. The most challenging burden faced by people with WIM syndrome results from their low blood levels of neutrophils, or neutropenia, and low blood levels of lymphocytes, or lymphopenia, which research supports are experienced by essentially all WIM patients. As a consequence of neutropenia and lymphopenia, an estimated 92% of WIM patients experience frequent recurrent infections that significantly impact their health and quality of life. Over time, when patients with recurrent infections may experience debilitating and life-threatening complications, including increased cancer risk, irreversible end organ damage, and or sepsis. I mention this not only to emphasize the incredible burden of disease for these patients and their caregivers, but also to highlight that Mavericks 4 has been granted breakthrough therapy designation by the FDA indicating their recognition of Maverick Sephora as a product candidate with the potential to provide substantial improvement over the standard of care in the treatment, diagnosis, or prevention of a serious condition. So we were very pleased to have reported on the additional positive safety and efficacy results from our completed global pivotal phase three trial in WIM in May of last year and further analyses of the trial at several important medical meetings and congresses both last year and earlier this year. Publication of the full 4WIM trial results is currently pending at a highly respected international medical journal. As you know, the Phase III trial successfully met its primary endpoint and several key secondary endpoints, with participants on Mavericks 4 achieving statistically significant elevations in both their neutrophil and lymphocyte counts versus placebo, and importantly, statistically significant reductions in the rate of annualized infections, and clinically meaningful reductions in the severity and duration of infections versus placebo. Based on these results, we submitted our first NDA to the FDA in late August of last year, receiving notice of acceptance for priority review, setting a target PDUFA date of April 30th, which is fast approaching. As you can well appreciate, we've been incredibly busy preparing for this potential approval since we spoke with you last year. We've been having discussions with our payers, multiple meetings with FDA, and finalizing our supply and distribution arrangements to be ready in the event that we receive FDA approval. Our commercial and medical affairs organizations have grown meaningfully, although prudently, as we've continued to build our brand marketing and sales infrastructure to increase our presence at medical meetings and engage with our targeted hematologists and immunologists that we expect to have WIM patients under their care. We look forward to leveraging our rare disease commercial capabilities to start building the WIM market over time, with 2024 as the year to lay the foundation for future success, and looking beyond 2024 as we are successful in educating physicians, helping them identify WIM patients, and build demand for our product candidates. WHIM syndrome is a very rare form of combined immunodeficiency first described over 60 years ago in the medical literature. Given its rarity and lack of available therapies, disease awareness amongst our targeted physician audience has historically been quite low, with no approved treatments for WHIM and only supportive care for symptomatic management, not addressing the underlying cause of the disease. With our successful Phase III WHIM trial recently being presented at major medical conferences, we are very encouraged that the physician community is now gaining more awareness. Additionally, we've experienced strong engagement with our What If It's WHIM disease awareness campaign, which is also demonstrating an even broader interest in WHIM syndrome. At the ASH meeting in December, the organizers made a point of highlighting the need for new research and development in classical hematological diseases. At the meeting, our Chief Medical Officer, Dr. Christoph Arbett-Engels, gave a talk on the lack of innovation and the need for new treatments at the meeting. His presentation was enthusiastically welcomed by a standing-room-only audience. We're also pleased to report that at the recent Quad AI Immunology meeting in late February, not only was our abstract on the lymphocyte subset data from our FOR-WIM trial accepted as an oral presentation by Dr. Theresa Tarrant, an esteemed immunologist from Duke University, whom you've heard from our several past investor events. But Dr. Tarrant was also invited by the conference organizers to give a non-X4 sponsored talk on Mavericks 4 and WIM syndrome specifically. Both of her presentations were extremely well attended, as was our What If It's WIM booth, all of which served to increase our visibility and enable what we believe can result in a major leap forward for patients through physician awareness and education. The X4 team working on our Congress exhibition booths have recounted many stories of physicians thanking them for drawing their attention to this disorder. And they've reported that multiple physicians who approached us never before having heard of WIM syndrome left believing they might in fact have a WIM patient under their care. As you can imagine, we get the question often about the size of the market for WIM in the U.S. With rare diseases that have no treatments, it's always difficult to assess. These interactions with physicians serve to reinforce our belief that there may, in fact, be more WHAM patients out there beyond the thousand or so that we've estimated are diagnosed at present, based on claimed data and analyses. And while we eagerly await word from the FDA on our first NDA, we're continuing to advance our plans to seek approval for Maverick, Sephora, and WHAM outside of the U.S. as well. We've had productive interactions with regulators in Europe and now believe we may be able to submit for EMA approval in late 2024, early 2025. We've had discussions with potential partners on how best to leverage our U.S. approval if received across other geographies as well. More to come on that later this year. Now turning to our chronic utropenia program, we were able to make significant progress in advancing Mavericks for NCN during 2023 as well. Although our Phase II clinical trial was a little slower to enroll than we'd initially expected, we were able to learn and increase enrollment and achieve our target of at least 15 patients by early November, and we continue to expect to announce additional Phase II results in the 15-plus trial participants in the coming months. We expect that our data to be presented will include a meaningful number of patients who are receiving Maverick Sephora alone, without concomitant GCSF treatment, enabling the assessment of Mavericks IV as a potential monotherapy in those diagnosed with CM. We also expect that data to be presented will include information on additional participants being treated with the combination of Mavericks IV and GC-SF. Importantly, all of the preliminary data presented to date and other learnings from the Phase II trial, along with our interactions with the FDA, have enabled us to finalize the protocol for a global, pivotal, Phase III clinical trial of Mavericks IV and CN and advance the initiation of this important next trial in the first half of 2024. As we've previously discussed, we plan to enroll approximately 150 participants in the trial, which will be a 52-week double-blinded placebo-controlled trial with one-to-one randomization. We will be assessing the safety and efficacy of Mavericks for plus or minus concomitant GCSF treatment in those with congenital, autoimmune, or idiopathic neutropenia. The patients included into the study will also have to present with neutropenia and symptomatic infections despite current standard of care, including GCSF. There's a significant unmet medical need across this established phase three patient population, a U.S. market we estimate to represent approximately 15,000 people. The primary endpoint will be a two-component endpoint comprised of both the annualized infection rate and ANC responder analysis across the study population. Secondary endpoints will include the severity and duration of infections, antibiotic use, quality of life measurements, among others, and, of course, safety. We are in the process of initiating our global study sites and are looking forward to enrolling patients across a number of these sites beginning in the next few months. We are, as of now, planning to host a CN event before the end of June to update on both the phase two trial data and CN phase three trial progress. So stay tuned for more information on that. I'll now turn it over to our CFO, Adam Asafa, to review the fourth quarter and full year 2023 financials. Adam?