X4 Pharmaceuticals : Investor Deck January 2022

Investor Presentation

January 2022

Forward-Looking Statements

This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by the words "may," "will," "could," "would," "should," "expect," "plan," "anticipate," "intend," "believe," "estimate," "predict," "project," "potential," "continue," "target," or other similar terms or expressions that concern X4's expectations, strategy, plans, or intentions. Forward-looking statements include, without limitation, statements regarding the clinical development and therapeutic potential of mavorixafor for the treatment of WHIM syndrome, Waldenström's macroglobulinemia, congenital neutropenia and other neutropenias and other primary immunodeficiencies, and of X4's other product candidates; X4's possible exploration of additional opportunities for mavorixafor; the expected duration of patent protection; the expected availability, content and timing of clinical data from X4's ongoing clinical trials of mavorixafor; anticipated regulatory filings; clinical trial design; and X4's cash runway and ability to satisfy covenants in agreements with third parties.

Any forward-looking statements in this presentation are based on management's current expectations and beliefs. Actual events or results may differ materially from those expressed or implied by any forward-looking statements contained herein, including, without limitation, uncertainties inherent in the initiation and completion of preclinical studies and clinical trials and clinical development; the risk that trials and studies may be delayed, including, but not limited to, as a result of the effects of the ongoing COVID-19 pandemic or delayed patient enrollment, and may not have satisfactory outcomes; the risk that the outcomes of preclinical studies or earlier clinical trials will not be predictive of later clinical trial results; the risk that initial or interim results from a clinical trial may not be predictive of the final results of the trial or the results of future trials; the potential adverse effects arising from the testing or use of mavorixafor or other product candidates; risks related to X4's ability to raise additional capital; risks related to the substantial doubt about X4's ability to continue as a going concern; and other risks and uncertainties, including those described in the section entitled "Risk Factors" in X4's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (SEC) on November 4, 2021, and in other filings X4 makes with the SEC from time to time. X4 undertakes no obligation to update the information contained in this presentation to reflect new events or circumstances, except as required by law.

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X4: Building On Success. Delivering Long-Term Growth.

Advancing innovative treatments for rare diseases caused by dysregulation of the immune system

Clinically proven Phase 3 candidate: Mavorixafor - a once-dailyoral CXCR4 antagonist

Advancing Mavorixafor to potentially treat >30,000 patients (US and EU Markets) in multiple indications Building a sustainable rare disease company with a growing pipeline

Key Value Drivers

• Strong Phase 2 PoC; Breakthrough Therapy Designation in lead indication (WHIM syndrome)
• Fully Enrolled global Phase 3 trial in WHIM; top-line data expected in 4Q 2022
• Positive Phase 1b data in Waldenstrom's macroglobulinemia (lymphoma); additional data 2H2022
• Positive Phase 1b data in Chronic Neutropenia; interim data 2/3Q 2022
• Pipeline of multiple pre-clinical compounds

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Advancing a Pipeline of Oral CXCR4 Antagonists

Candidate	Indication	Preclinical	Phase 1	Phase 2	Phase 3	Expected	Target Patient
Milestones	Populations
	WHIM (Warts, Hypogammaglobulinemia,								Top-line data
						Phase 3		4Q 2022	1,000-3,700 U.S.2
	Infections and Myelokathexis) syndrome1
								2H 2023 NDA
Mavorixafor	Waldenström's Macroglobulinemia								Add'l data /	2,000-3,000 U.S.3
	Phase 1b					clinical update
(WM)
								in 2H 2022
	Chronic Neutropenia (CN)								Add'l data /	5,000-10,000 U.S.4
		Phase 1b
							clinical update
									in 2Q/3Q 2022
										Other leukemias
X4P-002	Oncology indications	IND-							IND in 2H 2022	and lymphomas
enabling
										>25,0003
X4P-003	Primary immuno-deficiencies (PIDs)									Undisclosed

Potential to address the needs of >30,000 patients across multiple indications 2,3,4

1. Phase 2 open label extension (OLE) trial for WHIM ongoing 2. Company market research. Qessential market research, 2019 and IPM.ai artificial intelligence study, 2020. 3. WM
Epidemiology Analysis Nemetz Group. Data on file. 4. Estimate using Andersen et al. J Intern Med. 2016 Jun;279(6):566-75.	4

Seasoned Executive Leadership Team

PAULA RAGAN, Ph.D.

President & CEO

ADAM MOSTAFA

Chief Financial Officer

MARY DIBIASE, Ph.D.

Chief Operating Officer

DIEGO CADAVID, M.D.

Chief Medical Officer

ART TAVERAS, Ph.D.

Chief Scientific Officer

DEREK MEISNER, J.D.

Chief Legal Officer

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