X4 Pharmaceuticals, Inc. · NASDAQ:XFOR
X4 Pharmaceuticals — Investor Day (October 2026)
34 slides from X4 Pharmaceuticals's investor day presentation, Oct 29, 2026
Slide 1: Virtual Investor Day October 29, 2026
Virtual Investor Day October 29, 2026 Nasdaq: XFOR Exhibit 99.1
Slide 2: Forward-looking statements
2 This presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question-and-answer sessions and any documents or materials distributed at or in connection with the presenta
Slide 3: Introduction & Corporate Overview
Introduction & Corporate Overview Adam Craig, MD, PhD Executive Chairman
Slide 4: Meet the Speakers
4 cAdam Craig, MD PHD Executive Chair Meet the Speakers cDavid Kirske Chief Financial Officer cJohn Volpone President and COO cMichael Massello, MBA SVP Market Strategy and Development cShreyans Gandhi, MBBS, MD, FRCPath c Julia Warren, MD, PhD
Slide 5: Agenda
5 Agenda Topic Speaker Introduction & Corporate Overview Dr. Adam Craig Mavorixafor Clinical Program John Volpone Market Opportunity in Primary Chronic Neutropenia Michael Massello KOL Fireside Chat Dr. Adam Craig, Dr. Shreyans Gandhi & Dr. Julia Warren Question & Answer Session
Slide 6: Delivering on the Promise of CXCR4 Antagonist Mavorixafor
6 Delivering on the Promise of CXCR4 Antagonist Mavorixafor Focused on improving the lives of people with rare hematology diseases • Underwent corporate transformation in 2025/2026 • Focused on completing the Pivotal Phase 3 4WARD Primary Chronic Neutropenia trial • Full enrollment (N=126) expected
Slide 7: Mavorixafor: An Oral Agent Designed to Alleviate Neutropenia
7 Mavorixafor: An Oral Agent Designed to Alleviate Neutropenia Targeted Mechanism • CXCR4 regulates movement of white blood cells throughout the body2 • CXCR4 antagonism results in the migration of white blood cells from the bone marrow3,4 Modified figure from reference1 Orally active CXCR4 Antagoni
Slide 8: Mavorixafor Pipeline
8 Mavorixafor Pipeline Indication Key MilestonesPhase 1 Phase 2 Phase 3 Approved PRIMARY CHRONIC NEUTROPENIA (Congenital, Autoimmune, Idiopathic) Phase 3 · Ongoing Pivotal trial in PCN patients experiencing recurrent and/or serious infections 4WARD Global Pivotal Full Enrollment End Q4 2026 Topline
Slide 9: Mavorixafor Clinical Program
Mavorixafor Clinical Program John Volpone President & Chief Operating Officer
Slide 10: Pivotal Phase 3 4WARD Trial in Primary Chronic Neutropenia
10 Pivotal Phase 3 4WARD Trial in Primary Chronic Neutropenia (PCN) Mavorixafor (50%) +/- G-CSF Placebo (50%) +/- G-CSF Global, Double-Blind, Placebo-Controlled Trial Screening Baseline Visit and 1:1 Randomization N=126 ANC assessments at baseline and months 1, 2, 3, 6, 9, and 12 months Key Inclusio
Slide 11: 4WARD Baseline Characteristics
11 4WARD Baseline Characteristics AGE 36 years Median age SEX 70% Female BASELINE ANC 483 cells/µL Median ANC INFECTION HISTORY 68% of patients with 3+ infections at baseline DISEASE SEVERITY Evenly divided between moderate and severe disease Blinded, pooled data as of September 2026. G-CSF USE 37%
Slide 12: 4STEPS: A Phase 2b G-CSF Dose Reduction Trial with Mavorixafor
12 4STEPS: A Phase 2b G-CSF Dose Reduction Trial with Mavorixafor DESIGN Phase 2b Single-arm, open-label, multicenter study ENROLLMENT CRITERIA ≥ 1000 cells/μL Baseline ANC ESTIMATED ENROLLMENT ~25 patients On stable G-CSF therapy at study entry TOTAL SITES ~25 In the U.S. and UK OBJECTIVE To invest
Slide 13: 4STEPS Trial Designed to Evaluate G-CSF Dose Reduction
13 4STEPS Trial Designed to Evaluate G-CSF Dose Reduction When Treating with Mavorixafor OBSERVATION 4 weeks G-CSF only RUN-IN 8 weeks Mavorixafor added STEPWISE G-CSF REDUCTION 16–20 weeks MAINTENANCE 24 weeks FINAL ANALYSIS Durability PRIMARY ANALYSIS STEP 1 ≥ 25% reduction STEP 2 ≥ 50% reduction
Slide 14: Primary Chronic Neutropenia Development Timelines
14 Primary Chronic Neutropenia (PCN) - Development Timelines 4WARD Phase 3 Full enrollment (N=126) Q4 2026 4STEPS Phase 2b First Patient First Visit 4WARD Pivotal Phase 3 Topline data Potential FDA Approval in PCN Q1 2027 Q1 2028 Late 2028 / Early 2029 4STEPS Phase 2b Topline data H1 2028
Slide 15: Mavorixafor Commercial Opportunity
Mavorixafor Commercial Opportunity Michael Massello SVP Market Strategy and Development
Slide 16: High Disease Impact & Limited Treatment Options in PCN
16 High Disease Impact & Limited Treatment Options in Primary Chronic Neutropenia (PCN) Rare, chronic blood disorder • Neutrophil counts <1,500 cells/µL for >3 months • Idiopathic, congenital, cyclic and autoimmune Heterogeneous disease with a large underserved market that is often underdiagnosed an
Slide 17: Market Research Establishing the PCN Commercial Opportunity
17 Market Research Establishing the PCN Commercial Opportunity Claims Analysis Veeva claims analysis 2023-2025 Identified the symptomatic PCN population Komodo claims analysis 2023-2025 Independently confirmed the symptomatic PCN population Longitudinal claims analysis Mapped the Patient Journey fro
Slide 18: PCN Disease Burden: Infections & Symptoms
18 Mouth and throat oral ulcers, gingivitis, periodontitis, pharyngitis Lungs pneumonia, bronchiectasis Skin cellulitis, abscesses, slow wound healing Blood bacteremia and sepsis risk with severe or prolonged neutropenia Ears and sinuses otitis media, sinusitis Whole body fever, fatigue, pain Gut an
Slide 19: PCN is a High-Burden Disease with Significant Patient Desire for Better Options
19 PCN is a High-Burden Disease with Significant Patient Desire for Better Treatment Options Profound emotional impact Social withdrawal and feelings of isolation from fear of the next infection High motivation to manage disease Patients want to control their disease given challenges with injections
Slide 20: Adults Living with PCN Restrict Everyday Life to Avoid Infection
20 Avoided crowded places such as restaurants or large events Felt especially alert or on guard around others Avoided public transportation Avoided social gatherings Avoided traveling or vacations Adults Living with PCN Restrict Everyday Life to Avoid Infection Because of worry about infection, adul
Slide 21: Adults with PCN Report a Significant Impact on Work
21 Missed Work (n=51/80) Mean 9.6 workdays missed in Past Year Adults with PCN Report a Significant Impact on Work Missed a Promotion or Chose to Not Pursue a New Role (n=16/80) Reduced Work Hours (n=43/80) 64% 20%54% X4 Burden of Illness survey in primary CN 206 (n=110): 80 adults and 30 adolescent
Slide 22: PCN has Profound Emotional Impact on Adolescents and Children
22 Avoided interacting with others (n=18/30) Reduced participation in afterschool activities (n=16/30) Missed school days (n=18/30) 60% 60%53% PCN has Profound Emotional Impact on Adolescents and Children X4 Burden of Illness survey in primary CN 2026 (n=110): 80 adults and 30 adolescents/children r
Slide 23: Management of Symptomatic PCN
23 Management of Symptomatic PCN Some patients use bothG-CSF Injections The only treatment that increases neutrophil counts (approved 1994) Antibiotics Used to treat (prevent) bacterial infections without improving neutropenia Two main therapeutic options exist today with no new therapies in 30 year
Slide 24: G-CSF Injections Carry Significant Burden
24 G-CSF Injections Carry Significant Burden The Burden of G-CSF injections Injection burden • Frequent, painful • 66% of G-CSF patients have injection fatigue¹ Peaks and troughs: gaps in protection Neutrophil counts rise and fall between doses² Long-term safety 20%+ of secondary malignancies with h
Slide 25: Antibiotics Do Not Address the Underlying Neutropenia
25 Antibiotics Can Treat Infections But Do Not Address the Underlying Neutropenia The Burden of Antibiotics Disease not addressed Treats infections but does not raise neutrophil counts1 Toxicity Cumulative exposure carries its own side effects and drug interactions2 Drug resistance Long-term use can
Slide 26: The PCN Patient Journey and Where Care is Delivered
26 The PCN Patient Journey and Where Care is Delivered The Patient Journey 01 Initial Consultation Patients typically first visit Primary Care Provider (PCP) 02 Diagnosis Confirmatory diagnosis by a hematologist/ oncologist (heme/onc) 03 Treatment G-CSF is primarily prescribed by heme/oncs; antibiot
Slide 27: Hematologists and Patients are Aligned on Key Drivers for a New Treatment
27 Hematologists and Patients are Aligned on the Key Drivers for a New Treatment "We are so frustrated for patients who have no other treatments than just a few modalities…ready to embrace anything new to treat this disease.“ “Oral would be a game-changer in PCN” – Hematologist, Advisory Board, Sept
Slide 28: Mavorixafor is a Highly Differentiated Therapy in Development for PCN
28 Mavorixafor is a Highly Differentiated Therapy in Development for PCN Once-daily oral therapy CXCR4 antagonist that mobilizes neutrophils into circulation Well tolerated, mild GI toxicity1 Being evaluated as monotherapy and in combination with G-CSF First and only oral therapy in development for
Slide 29: Hematologists View Mavorixafor as Differentiated From Standard of Care
29 Hematologists View Mavorixafor as Differentiated From Current Standard of Care and Intend to Use It as the Dominant Agent for PCN #2 ~90% 87%#1 Greater infection control1 Oral route of administration1,2 Report intent to prescribe mavorixafor3 Rated mavorixafor favorably (>5/7)3 Differentiator Dif
Slide 30: U.S. Prevalence of PCN
30 U.S. Prevalence of PCN Consistent and validated across multiple platforms 2+ infection episodes ANC < 1,000 cells/µL ~15,000 patients 2+ infection episodes in 2025 (symptomatic), includes ER visits and hospitalizations 1+ infection episodes ANC <1,000 cells/µL ~30,000 patients 1+ infection episod
Slide 31: X4 is Well Positioned to Capture the ~15,000 Patient Base Case
31 X4 is Well Positioned to Capture the ~15,000 Patient Base Case 4WARD includes patients spanning the base case: Enrolls patients age 12+ with recurrent infections, on or off G-CSF 1 Patients live with recurrent infections: Every patient in the base case has two or more infections a year. 2 Infecti
Slide 32: Mavorixafor Represents a Significant Initial Market Opportunity
32 Mavorixafor Represents a Significant Initial Market Opportunity with Potential Upside • ANC < 1,000 cells/µL • 1+ Infections • Symptomatic • ANC < 1,000 cells/µL • 2+ Infections • Symptomatic Patient Profile Patient Profile ~15K Patients ~30K Patients Source: Komodo Healthcare longitudinal claims
Slide 33: Fireside Chat
Fireside Chat Dr. Adam Craig Dr. Shreyans Gandhi Dr. Julia Warren
Slide 34: X4 on Track to Deliver Pivotal Phase Data in 2028
34 X4 on Track to Deliver Pivotal Phase 3 Data in 2028 • Large market opportunity for mavorixafor in PCN in the US • Approximately 15,000 patients with moderate and severe disease • Clear medical need for well tolerated oral agent - monotherapy or in combination with G-CSF • C-Suite team experienced