Financial Data and Key Metrics Changes - As of September 30, 2020, X4 Pharmaceuticals had $90.7 million in cash, cash equivalents, and restricted cash, which is expected to fund operations into early 2022 [22] - Research and development expenses increased to $11.4 million for Q3 2020 from $8.6 million in Q3 2019 [23] - General and administrative expenses rose to $5.6 million for Q3 2020 compared to $4.4 million for the same period in 2019 [23] - The net loss for Q3 2020 was $17.4 million, slightly improved from a net loss of $17.7 million in Q3 2019 [24] Business Line Data and Key Metrics Changes - The company continues to advance its Mavorixafor Clinical Development Program, with positive Phase 2 safety and efficacy data published for mavorixafor in WHIM syndrome [6][10] - Enrollment in the Phase 3 WHIM syndrome trial is ongoing, with expectations for top-line data in 2022 [14][32] Market Data and Key Metrics Changes - The company is diversifying its clinical trials across various sites and countries to mitigate COVID-19 impacts on patient enrollment [14] - The FDA granted Fast Track Designation for mavorixafor in WHIM syndrome, indicating significant unmet medical needs [12] Company Strategy and Development Direction - X4 Pharmaceuticals aims to become a global rare-disease company, focusing on advancing its clinical development programs and expanding its pipeline [19] - The company is implementing home-health visits for patients in chronic dosing studies, specifically for WHIM and Waldenstrom's trials, to address COVID-19 challenges [26] Management's Comments on Operating Environment and Future Outlook - Management acknowledges the ongoing challenges posed by the COVID-19 pandemic but remains focused on advancing clinical programs [5] - The company is confident in its plans to address the impact of COVID-19 on its studies and is optimistic about the long-term trajectory of mavorixafor [39] Other Important Information - The company appointed Dr. Art Taveras as the new Chief Scientific Officer, bringing significant expertise in drug discovery [17][19] - Alison Lawton was appointed to the Board of Directors, enhancing the board's strategic expertise [20] Q&A Session Summary Question: Is the home-health visit strategy being applied to WHIM and SCN trials? - Yes, home health visits are being implemented for WHIM and Waldenstrom's trials, but not for SCN due to the short treatment duration [26] Question: Updates on X4P-003 and X4P-002? - X4P-003 is approaching IND-enabling studies, while X4P-002 is in late-lead optimization [28] Question: Enrollment update for WHIM syndrome? - Enrollment is on track, and patients continue to enroll despite the pandemic [32] Question: How will Waldenstrom's data be rolled out? - The data will be presented in a robust format, aligned with key opinion leaders [35] Question: How does mavorixafor fit into the treatment paradigm if approved? - The study is exploring mavorixafor in treatment-naive and up to three prior lines of treatment patients [62] Question: Impact of the stock purchase agreement on cash runway? - The agreement serves as a downside protection tool, aiding in financial strategy [63] Question: Plans to broaden the pipeline with Art on board? - The company intends to leverage Art's expertise to explore additional indications and expand the pipeline [66]

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 _____________________________________________________________________________________ FORM 10-Q _____________________________________________________________________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2020 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the trans ...

Mavorixafor & Clinical Trials - Mavorixafor (X4P-001) is a first-in-class, oral, small molecule allosteric antagonist of chemokine receptor CXCR4 [6] - A global registrational Phase 3 trial of mavorixafor in WHIM syndrome is ongoing [6] - Phase 1b trials are underway in Waldenström's macroglobulinemia and Severe Congenital Neutropenia [6] - Phase 2 open label extension trial for WHIM is ongoing and Phase 3 trial initiated [18] WHIM Syndrome - In WHIM syndrome, infection rates decreased by 54% at 400 mg of mavorixafor [35] - Phase 2 trial data showed a 45-fold increase in TATANC versus lower doses [32] - The estimated U S WHIM population is over 3,500 [23] - The Phase 3 trial in WHIM has a primary endpoint of neutrophil count time above threshold (TAT) of 500 cells/uL [40] Waldenström's Macroglobulinemia (WM) - In Waldenström's Macroglobulinemia, 30-40% of patients have WHIM-like mutations in CXCR4 [47] - WM patients with CXCR4 mutations have ~4-fold likelihood of ibrutinib discontinuation [50] Severe Congenital Neutropenia (SCN) - Severe Congenital Neutropenia is characterized by abnormally low levels of neutrophils (<1,500 cell/ul) [62] Financials - X4 Pharmaceuticals had $1056 million in cash as of June 30, 2020, expected to fund operations into 2022 [85]

[PART I: FINANCIAL INFORMATION](index=3&type=section&id=PART%20I%3A%20FINANCIAL%20INFORMATION) [Financial Statements](index=6&type=section&id=Item%201.%20FINANCIAL%20STATEMENTS) The company's net loss widened to $26.3 million in H1 2020 due to higher expenses, while cash decreased to $103.7 million despite recognizing $3.0 million in license revenue [Condensed Consolidated Balance Sheets](index=6&type=section&id=Condensed%20Consolidated%20Balance%20Sheets) Condensed Consolidated Balance Sheet Highlights (in thousands) | Account | June 30, 2020 | December 31, 2019 | | :--- | :--- | :--- | | **Assets** | | | | Cash and cash equivalents | $103,744 | $126,184 | | Total current assets | $109,887 | $129,278 | | Total assets | $142,534 | $160,698 | | **Liabilities & Equity** | | | | Total current liabilities | $10,781 | $9,447 | | Long-term debt, net | $25,398 | $20,097 | | Total liabilities | $37,650 | $31,478 | | Total stockholders' equity | $104,884 | $129,220 | - Cash and cash equivalents decreased by **$22.4 million** in the first six months of 2020[18](index=18&type=chunk) - Total liabilities increased primarily due to a rise in long-term debt from **$20.1 million to $25.4 million**[18](index=18&type=chunk) [Condensed Consolidated Statements of Operations and Comprehensive Loss](index=7&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations%20and%20Comprehensive%20Loss) Statement of Operations Summary (in thousands, except per share data) | Metric | Three Months Ended June 30, 2020 | Three Months Ended June 30, 2019 | Six Months Ended June 30, 2020 | Six Months Ended June 30, 2019 | | :--- | :--- | :--- | :--- | :--- | | License revenue | $0 | $0 | $3,000 | $0 | | Research and development | $9,342 | $8,854 | $18,253 | $14,509 | | General and administrative | $5,316 | $4,560 | $9,986 | $9,343 | | Loss from operations | $(14,658) | $(13,414) | $(25,239) | $(23,852) | | Net loss | $(15,144) | $(13,383) | $(26,282) | $(24,256) | | Net loss per share | $(0.76) | $(1.02) | $(1.31) | $(3.32) | - The company recognized **$3.0 million in license revenue** during the six months ended June 30, 2020, which was not present in the prior year period[22](index=22&type=chunk) - Operating expenses increased for both the three and six-month periods year-over-year, driven by **higher R&D and G&A costs**[22](index=22&type=chunk) [Condensed Consolidated Statements of Cash Flows](index=10&type=section&id=Condensed%20Consolidated%20Statements%20of%20Cash%20Flows) Cash Flow Summary for the Six Months Ended June 30 (in thousands) | Activity | 2020 | 2019 | | :--- | :--- | :--- | | Net cash used in operating activities | $(26,986) | $(26,042) | | Net cash (used in) provided by investing activities | $(564) | $26,396 | | Net cash provided by financing activities | $5,049 | $86,791 | | Net (decrease) increase in cash | $(22,441) | $87,143 | - Net cash used in operating activities remained relatively stable year-over-year at approximately **$27.0 million**[34](index=34&type=chunk) - Financing activities in 2020 primarily consisted of **$4.9 million in net proceeds from borrowings**, compared to $86.8 million in 2019 which included proceeds from a common stock sale[34](index=34&type=chunk)[164](index=164&type=chunk) - Investing activities in 2019 included **$26.4 million in cash acquired from the merger with Arsanis**, a non-recurring event[34](index=34&type=chunk) [Notes to Condensed Consolidated Financial Statements](index=11&type=section&id=Notes%20to%20Condensed%20Consolidated%20Financial%20Statements) - The company is a clinical-stage biotech focused on mavorixafor, a CXCR4 inhibitor for rare diseases like WHIM syndrome, SCN, and WM[36](index=36&type=chunk) - As of June 30, 2020, the company had **$103.7 million in cash and cash equivalents** and believes it has sufficient funds for at least the next twelve months[37](index=37&type=chunk) - The **COVID-19 pandemic has caused disruptions**, including temporary closures of clinical trial sites and slower patient enrollment[40](index=40&type=chunk) - In March 2020, the company received a **$3.0 million milestone payment** from its license agreement with Abbisko, which was recognized as license revenue[66](index=66&type=chunk)[67](index=67&type=chunk) - In March 2020, the company amended its loan agreement with Hercules, increasing the total borrowing capacity to **$50.0 million** and drawing an additional $5.0 million, bringing the total principal to $25.0 million[80](index=80&type=chunk) [Management's Discussion and Analysis of Financial Condition and Results of Operations (MD&A)](index=31&type=section&id=Item%202.%20MANAGEMENT'S%20DISCUSSION%20AND%20ANALYSIS%20OF%20FINANCIAL%20CONDITION%20AND%20RESULTS%20OF%20OPERATIONS) Management discusses the impact of COVID-19 on clinical trial timelines, rising operating expenses, and the company's capital sufficiency for the next year [Overview and Pipeline](index=31&type=section&id=Overview%20and%20Pipeline) - The company is a clinical-stage biopharmaceutical firm focused on oral, small molecule antagonists of the CXCR4 receptor for treating rare diseases, including primary immunodeficiencies and certain cancers[131](index=131&type=chunk) - The lead product candidate, mavorixafor, is in a pivotal **Phase 3 trial for WHIM syndrome**, a Phase 1b trial for Severe Congenital Neutropenia (SCN), and a Phase 1b trial for Waldenström's macroglobulinemia (WM)[132](index=132&type=chunk)[133](index=133&type=chunk) - Due to the COVID-19 pandemic, the top-line data from the Phase 3 WHIM trial is now expected in **2022**, and initial data from the SCN trial is delayed into **2021**[132](index=132&type=chunk)[133](index=133&type=chunk) [COVID-19 Business Update](index=32&type=section&id=COVID-19%20Business%20Update) - The company has implemented business continuity measures, with its workforce transitioning to remote work in response to Massachusetts state orders[137](index=137&type=chunk) - Clinical development has been disrupted, leading to **delays in trial site initiation and patient enrollment**[138](index=138&type=chunk) - The company expects adequate global supply of mavorixafor through 2020 but acknowledges **potential future supply chain disruptions** if the pandemic persists[140](index=140&type=chunk) - Potential **delays in regulatory review** and interactions with the FDA and European Commission are anticipated due to the diversion of regulatory resources to COVID-19 related activities[141](index=141&type=chunk) [Results of Operations](index=33&type=section&id=Results%20of%20Operations) Comparison of Operating Results (in thousands) | Metric | Six Months Ended June 30, 2020 | Six Months Ended June 30, 2019 | Change | | :--- | :--- | :--- | :--- | | License revenue | $3,000 | $0 | $3,000 | | Research and development | $18,253 | $14,509 | $3,744 | | General and administrative | $9,986 | $9,343 | $643 | | Loss from operations | $(25,239) | $(23,852) | $(1,387) | - License revenue of **$3.0 million** was recognized in the first six months of 2020 due to achieving a financial milestone in the Abbisko agreement[144](index=144&type=chunk) - Research and development expenses **increased by $3.7 million** for the six months ended June 30, 2020, compared to the prior year, primarily due to increased compensation expenses from additional personnel[148](index=148&type=chunk) - General and administrative expenses increased for the six months ended June 30, 2020, mainly due to an **increase in G&A personnel** and higher stock-based compensation[150](index=150&type=chunk) [Liquidity and Capital Resources](index=36&type=section&id=Liquidity%20and%20Capital%20Resources) - As of June 30, 2020, the company had cash and cash equivalents of **$103.7 million**, which is believed to be sufficient to fund operations for at least the next twelve months[155](index=155&type=chunk) - The company has a loan facility with Hercules Capital, amended in March 2020, with **$25.0 million borrowed to date** and the potential to borrow up to an additional $25.0 million[156](index=156&type=chunk)[169](index=169&type=chunk) - The company entered into a 7-year lease for new headquarters in Allston, MA, with annual rent of approximately **$1.0 million**, commencing in May 2020[158](index=158&type=chunk) - Net cash used in operating activities was **$27.0 million** for the first six months of 2020, primarily resulting from the net loss of $26.3 million[160](index=160&type=chunk) [Quantitative and Qualitative Disclosures About Market Risk](index=42&type=section&id=Item%203.%20QUANTITATIVE%20AND%20QUALITATIVE%20DISCLOSURES%20ABOUT%20MARKET%20RISK) The company has elected scaled disclosure reporting obligations as a smaller reporting company and is therefore not required to provide the information for this item - As a smaller reporting company, X4 Pharmaceuticals is **not required to provide** quantitative and qualitative disclosures about market risk[180](index=180&type=chunk) [Controls and Procedures](index=42&type=section&id=Item%204.%20CONTROLS%20AND%20PROCEDURES) Management concluded that disclosure controls and procedures were effective as of June 30, 2020, with no material changes to internal controls during the quarter - Management evaluated the effectiveness of disclosure controls and procedures and concluded they were **effective as of June 30, 2020**[182](index=182&type=chunk) - **No changes in internal control over financial reporting** occurred during the quarter that materially affected, or are reasonably likely to materially affect, internal controls[183](index=183&type=chunk) [PART II: OTHER INFORMATION](index=43&type=section&id=PART%20II%3A%20OTHER%20INFORMATION) [Legal Proceedings](index=43&type=section&id=Item%201.%20LEGAL%20PROCEEDINGS) The company is not currently a party to any material legal proceedings - The company is **not currently involved** in any material legal proceedings[185](index=185&type=chunk) [Risk Factors](index=43&type=section&id=Item%201A.%20RISK%20FACTORS) The company faces significant financial, operational, and commercialization risks, including a history of losses, reliance on a single product, and clinical trial delays [Risks Related to Financial Position and Need for Additional Capital](index=43&type=section&id=Risks%20Related%20to%20Financial%20Position%20and%20Need%20for%20Additional%20Capital) - The company has a history of significant operating losses (**$158.3 million accumulated deficit** as of June 30, 2020) and expects to incur losses for the foreseeable future[187](index=187&type=chunk) - **Substantial additional funding will be required** to advance clinical development and potential commercialization, and the COVID-19 pandemic could disrupt access to capital markets[191](index=191&type=chunk)[193](index=193&type=chunk) - Raising additional capital may cause **significant dilution to existing stockholders** or require relinquishing rights to technologies on unfavorable terms[195](index=195&type=chunk) [Risks Related to Product Candidate Development](index=46&type=section&id=Risks%20Related%20to%20Product%20Candidate%20Development) - The company's business depends almost entirely on the success of its **lead product candidate, mavorixafor**[202](index=202&type=chunk)[203](index=203&type=chunk) - **Clinical trial delays**, such as those already experienced due to COVID-19 for the WHIM and SCN trials, could jeopardize the ability to receive approvals and generate revenue[222](index=222&type=chunk)[225](index=225&type=chunk) - The company may **fail to enroll a sufficient number of patients** in its clinical trials, particularly for rare diseases like WHIM, SCN, and WM, which could delay or prevent trial completion[224](index=224&type=chunk)[227](index=227&type=chunk) - The company relies on license agreements with Genzyme and others; **termination of these rights could materially harm the business**[213](index=213&type=chunk) [Risks Related to Marketing and Commercialization](index=53&type=section&id=Risks%20Related%20to%20Marketing%20and%20Commercialization) - A Breakthrough Therapy designation for mavorixafor **does not guarantee a faster review** or increase the likelihood of approval[238](index=238&type=chunk)[239](index=239&type=chunk) - The company must **build its own sales and marketing capabilities** or rely on third parties, both of which carry significant risks and costs[241](index=241&type=chunk)[254](index=254&type=chunk) - Commercial success depends on **market acceptance by physicians, patients, and payors**, as well as obtaining adequate reimbursement and favorable pricing[242](index=242&type=chunk)[267](index=267&type=chunk) - The company faces **substantial competition** from major pharmaceutical and biotech companies with greater resources[256](index=256&type=chunk)[260](index=260&type=chunk) [Risks Related to Dependence on Third Parties](index=63&type=section&id=Risks%20Related%20to%20Dependence%20on%20Third%20Parties) - The company is dependent on **single third-party manufacturers** for both the active pharmaceutical ingredient (API) and the finished drug product capsules for mavorixafor[289](index=289&type=chunk)[290](index=290&type=chunk) - Reliance on third-party Contract Research Organizations (CROs) to conduct clinical trials is critical; if these **CROs fail to perform**, regulatory approval could be delayed or denied[294](index=294&type=chunk) - **Disruptions in the supply chain**, including from the COVID-19 pandemic, could delay clinical trials and the potential commercial launch of products[298](index=298&type=chunk)[299](index=299&type=chunk) [Risks Related to Business Operations and Growth](index=73&type=section&id=Risks%20Related%20to%20Business%20Operations%20and%20Growth) - The **COVID-19 pandemic is adversely affecting business operations**, including causing delays in clinical trial enrollment and site activation[344](index=344&type=chunk)[346](index=346&type=chunk) - Future success depends on the ability to **attract and retain key executives** and qualified scientific personnel in a competitive environment[349](index=349&type=chunk) - The company relies significantly on information technology, and any **cybersecurity incident could compromise sensitive data** and disrupt operations[354](index=354&type=chunk)[356](index=356&type=chunk) - The ability to use net operating loss (NOL) carryforwards may be **limited by Section 382** of the Internal Revenue Code due to ownership changes[358](index=358&type=chunk)[359](index=359&type=chunk) [Unregistered Sales of Equity Securities and Use of Proceeds](index=82&type=section&id=Item%202.%20UNREGISTERED%20SALES%20OF%20EQUITY%20SECURITIES%20AND%20USE%20OF%20PROCEEDS) The company reported no unregistered sales of equity securities during the period - None[391](index=391&type=chunk)

Financial Data and Key Metrics Changes - As of June 30, 2020, X4 Pharmaceuticals had $105.6 million in cash, cash equivalents, and restricted cash, which is expected to fund operations into early 2022 [22][23] - Research and development expenses were $9.3 million for Q2 2020, compared to $8.9 million for the same period in 2019, while general and administrative expenses increased to $5.3 million from $4.6 million year-over-year [24] - The net loss for Q2 2020 was $15.1 million, up from a net loss of $13.4 million in Q2 2019 [24] Business Line Data and Key Metrics Changes - The company is conducting a pivotal Phase 3 trial for mavorixafor in patients with WHIM syndrome, with ongoing enrollment and progress noted as sites reopen due to COVID-19 [15] - A Phase 1b trial for mavorixafor in patients with severe congenital neutropenia is also ongoing, with initial data expected in 2021 [16] - The Phase 1b study for Waldenstrom's macroglobulinemia is expected to enroll between 12 and 18 patients, with initial results anticipated by the end of 2020 [19] Market Data and Key Metrics Changes - Updated research indicates that the estimated range of diagnosed and undiagnosed WHIM patients in the U.S. is greater than 3,500, significantly up from the previous estimate of approximately 1,000 genetically diagnosed patients [10] - The company has identified a concentrated target physician population primarily consisting of immunologists, hematologists, and infectious disease specialists [10] Company Strategy and Development Direction - The company aims to own and commercialize in the rare disease markets while remaining opportunistic regarding partnerships as situations arise [64] - The focus remains on advancing mavorixafor for WHIM syndrome and exploring its potential in other indications, including Waldenstrom's macroglobulinemia [19][20] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the ongoing clinical trials despite challenges posed by the COVID-19 pandemic, emphasizing patient safety and engagement [52][36] - The company plans to report topline Phase 3 results for WHIM in 2022, with further clarity on timelines for both WHIM and SCN expected in the future [15][16] Other Important Information - Dr. Renato Skerlj was promoted to Chief Scientific Officer, overseeing research and non-clinical development functions [20] - The collaboration with Invitae for generating genetic tests is ongoing, with no specific guidance yet on outputs [54] Q&A Session Summary Question: Any scenario for dose escalation beyond 600 mg in the Waldenstrom's trial? - Management indicated that while flexibility exists due to the drug's safety profile, they currently believe the 600 mg dose is sufficient [26] Question: Updates on potential collaborative partners for mavorixafor in solid tumors? - The partnership with Abbisko is progressing, but no updates on other strategic fronts outside of China [30] Question: Scope of the Phase 1b Waldenstrom's data? - The Phase 1b trial is a dose-escalating trial, with every patient starting at 200 mg and potentially escalating based on safety [33] Question: Enrollment status in clinical studies given the current environment? - Enrollment is maintaining guidance, with strong engagement from patients and physicians despite varying COVID-19 restrictions [52] Question: Thoughts on partnerships with new WHIM data and upcoming Waldenstrom's data? - The strategic focus remains on owning and commercializing in rare disease markets, with opportunistic partnerships considered as they arise [64]

Company Overview - X4 Pharmaceuticals is developing novel therapies targeting diseases resulting from CXCR4 pathway dysfunction to improve immune cell trafficking[6] - The lead product candidate, mavorixafor (X4P-001), is a first-in-class, oral, small molecule allosteric antagonist of chemokine receptor CXCR4[6] - The company is conducting multiple clinical trials, including a global registrational Phase 3 trial of mavorixafor in WHIM syndrome[6] Mavorixafor Clinical Trials and Indications - Mavorixafor is being investigated as a targeted treatment for diseases driven by immune-cell trafficking deficits, with lead indications including WHIM syndrome (Phase 3), Waldenström's Macroglobulinemia (Phase 1b), and Severe Congenital Neutropenia (Phase 1b)[11] - In a Phase 2 open-label extension study for WHIM syndrome, mavorixafor 400 mg orally once daily was well tolerated for over 2 years[33] - The Phase 2 WHIM trial demonstrated at least a 4.5-fold increase in TATANC (Time Above Threshold of Absolute Neutrophils Count) versus lower doses[34] - In the WHIM Phase 2 open-label extension, infection rates decreased from 4.63 to 2.14 (a 54% reduction) at the 400 mg dose[37] - The average wart burden was reduced by 75% after 14 months on 400 mg mavorixafor, compared to baseline[37] - A global registrational Phase 3 trial in WHIM syndrome is underway, randomizing patients 1:1 to mavorixafor (N=9) or placebo (N=9), with topline data expected in 2022[41, 42] - A Phase 1b trial of mavorixafor in combination with ibrutinib is underway in patients with MYD88 + CXCR4 mutations who have failed prior treatment for Waldenström's Macroglobulinemia, with initial data expected in 2H 2020[51] - A Phase 1b trial in Severe Congenital Neutropenia (SCN) is underway, enrolling up to 45 patients to assess responders to mavorixafor[61] Market Opportunity and Financials - The company estimates a significant market opportunity, targeting >10,000 total patients with rare diseases, including >3,500 with WHIM syndrome, 4,000-5,000 with CXCR4-mutant Waldenström's Macroglobulinemia, and 2,000-3,000 with Severe Congenital Neutropenia[64, 65, 67, 69] - As of March 31, 2020, the company had $117 million in cash, expected to fund operations into 2022[78]

Mavorixafor Clinical Trial & Results - Mavorixafor, a first-in-class CXCR4 antagonist, is being developed as a once-daily oral capsule targeting the mechanism of WHIM syndrome [19] - Phase 2 study data informed the design of the ongoing Phase 3 registration trial [42] - The Phase 3 trial uses a 400 mg orally once daily dose of Mavorixafor [29, 42] - The primary endpoint for the Phase 3 trial is TATANC (time above threshold for absolute neutrophil count) [29, 42] - Top-line Phase 3 data is expected in 2022 [45] Phase 2 Study Outcomes - At doses of 300 or 400 mg/day, the mean TATANC was 12.6 (±9.8) hours (N=7) compared to 2.8 (±3.5) hours or less for patients (N=4) treated at doses of 150 mg or lower [30] - The mean TATALc was 16.9 (±5.8) hours [30] - The yearly infection rate decreased from 4.63 events to 2.27 events on mavorixafor 300 mg and 400 mg once daily [35] - An average 75% reduction in the number of cutaneous warts was observed [40] WHIM Syndrome & Mavorixafor's Potential - There is a large unmet need for effective WHIM treatment [15, 45] - Mavorixafor is a promising targeted therapy that could lead to improved and durable clinical efficacy in patients with WHIM syndrome [45]

Company Overview - X4 Pharmaceuticals is developing novel therapies targeting diseases resulting from CXCR4 pathway dysfunction to improve immune cell trafficking[6] - Mavorixafor (X4P-001) is the company's lead product candidate, a first-in-class, oral, small molecule allosteric antagonist of chemokine receptor CXCR4[6] - The company has multiple clinical trials underway, including a global registrational Phase 3 trial of mavorixafor in WHIM syndrome[6] Mavorixafor and WHIM Syndrome - Mavorixafor is a targeted treatment for diseases driven by immune-cell trafficking deficits, with WHIM syndrome as a lead indication[11] - In a Phase 2 trial, 71% of patients achieved maximum Time Above Threshold (TAT) for neutrophil counts, and 85% achieved maximum TAT for lymphocyte counts[34] - Clinical yearly infection rates decreased from 4.63 to 2.41 (a 48% reduction) at 300 mg and 2.14 (a 54% reduction) at 400 mg of mavorixafor in the Phase 2 extension trial[37] - The company is conducting a global registrational Phase 3 trial in WHIM syndrome, with a primary endpoint of absolute neutrophil count time above threshold (TATANC) where the threshold is defined as 500 cells/uL[43] Other Indications and Financials - The company is also investigating mavorixafor in Waldenström's Macroglobulinemia (WM) and Severe Congenital Neutropenia (SCN) in Phase 1b trials[6, 11] - In Waldenström's Macroglobulinemia (WM), patients with CXCR4 mutations have a Very Good Partial Response (VGPR) rate of 9.5% compared to 44.4% for wild-type[51] - As of March 31, 2020, the company had $117.0 million in cash, expected to fund operations into 2022[82]

X4 Pharmaceuticals, Inc. (NASDAQ:XFOR) Q1 2020 Earnings Conference Call May 7, 2020 8:30 AM ET Company Participants Candice Ellis - Director of Corporate Communications & Investor Relations Paula Ragan - Chief Executive Officer Adam Mostafa - Chief Financial Officer Conference Call Participants Stephen Willey - Stifel Joel Beatty - Citi Swayampakula Ramakanth - H.C. Wainwright Laura Christianson - Cowen Trevor Allred - Oppenheimer Sahil Kazmi - B. Riley FBR Arlinda Lee - Canaccord Operator Greetings, and w ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 _____________________________________________________________________________________ FORM 10-Q _____________________________________________________________________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2020 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transitio ...