8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 21, 2017

Audentes Therapeutics, Inc.

(Exact name of Registrant as Specified in Its Charter)

Delaware	001-37833	46-1606174
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)
600 California Street, 17th Floor San Francisco, California		94108
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s Telephone Number, Including Area Code: (415) 818-1001

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instructions A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☒

Item 8.01 Other Events.

On September 21, 2017, Audentes Therapeutics, Inc. (the “Company”) announced it has commenced dosing of patients in ASPIRO, a Phase 1/2 clinical trial of AT132 for the treatment of X-Linked Myotubular Myopathy (XLMTM).  A copy of the press release issued by the Company related to this announcement is attached hereto as Exhibit 99.1.  ASPIRO is a multicenter, multinational, open-label, ascending dose study to evaluate the safety and preliminary efficacy of AT132 in approximately twelve XLMTM patients less than five years of age.  Preliminary data from ASPIRO is expected to be available in the fourth quarter of 2017.

On September 27, 2017, the Company announced that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease and Fast Track designations for AT132 for the treatment of XLMTM.  In addition to these two new designations, AT132 has also received Orphan Drug designation from both the FDA and European Medicines Agency.  A copy of the press release issued by the Company related to this announcement is attached hereto as Exhibit 99.2.  

On September 27, 2017, the Company presented the preliminary data from INCEPTUS in the investor presentation attached hereto as Exhibit 99.3. INCEPTUS is a prospective natural history run-in study intended to characterize the clinical condition of children with XLMTM, identify subjects for potential enrollment in ASPIRO, and serve as a longitudinal baseline and within-patient control for ASPIRO.

The Company plans to present the information in the investor presentation attached hereto as Exhibit 99.4 at the LEERINK Partners Roundtable Series: Rare Disease & Immuno-Oncology Conference on September 27, 2017.

Item 9.01 Financial Statements and Exhibits

(d) Exhibits.

Exhibit

Number      Description

99.1              Press Release issued by Audentes Therapeutics, Inc. dated September 21, 2017.

99.2              Press Release issued by Audentes Therapeutics, Inc. dated September 27, 2017.

99.3              Investor Presentation (INCEPTUS).

99.4              Investor Presentation (LEERINK Conference).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	Audentes Therapeutics, Inc.
Date: September 27, 2017	By:	/s/ Thomas Soloway
		Thomas Soloway
		Chief Financial Officer

EX-99.1

Exhibit 99.1

Audentes Therapeutics Announces Dosing of First Patient in ASPIRO,
a Phase 1/2 Clinical Trial of AT132 for the Treatment of X-Linked Myotubular Myopathy

Preliminary data from ASPIRO expected to be available in the fourth quarter of 2017

SAN FRANCISCO, Sept. 21, 2017 / PRNewswire/ -- Audentes Therapeutics, Inc. (Nasdaq: BOLD), a biotechnology company focused on developing and commercializing gene therapy products for patients living with serious, life-threatening rare diseases, today announced it has commenced dosing of patients in ASPIRO, a Phase 1/2 clinical trial of AT132 for the treatment of X-Linked Myotubular Myopathy (XLMTM).  ASPIRO is a multicenter, multinational, open-label, ascending dose study to evaluate the safety and preliminary efficacy of AT132 in approximately twelve XLMTM patients less than five years of age.  Preliminary data from ASPIRO is expected to be available in the fourth quarter of 2017.

"XLMTM is a severe rare disease characterized by profound muscle weakness, respiratory failure and early death,” stated Suyash Prasad, M.D., Senior Vice President and Chief Medical Officer.  “Over 50 percent of the boys affected by XLMTM do not live to celebrate their second birthday, and no currently approved treatment options exist for these patients, their families and care-givers.”

Dr. Prasad continued, “We are grateful to the many expert collaborators, patient advocacy organizations and parents who have supported Audentes and helped guide our efforts.  Most of all we are thankful to the children and families affected by XLMTM for their participation in ASPIRO. We look forward to working together with our partners to advance AT132 as a potentially transformative therapy to treat this devastating disease.”

In addition to ASPIRO, the clinical development program for AT132 includes RECENSUS, a retrospective medical chart review, for which Audentes has previously announced data from an initial analysis of 112 male subjects.  This analysis confirmed and expanded upon the understanding of the significant disease burden of XLMTM on patients, families and the healthcare system.  Audentes is also conducting INCEPTUS, a prospective natural history run-in study.  The primary objectives of INCEPTUS are to characterize the clinical condition of children with XLMTM, identify subjects for potential enrollment in ASPIRO, and serve as a longitudinal baseline and within-patient control for ASPIRO.  Audentes plans to announce preliminary data from INCEPTUS in the third quarter of 2017.

About AT132 for X-Linked Myotubular Myopathy

AT132 is the Audentes product candidate being developed to treat XLMTM, a rare monogenic disease characterized by extreme muscle weakness, respiratory failure andearly death, with an estimated 50% mortality rate by 18 months of age.  XLMTM is caused by mutations in the MTM1 gene, which encodes a protein called myotubularin.  Myotubularin plays an important role in the development, maintenance and function of skeletal muscle cells.  AT132 is comprised of an AAV8 vector containing a functional copy of the MTM1 gene.  Multiple studies in animal models of XLMTM have demonstrated that a single administration of AT132 improved disease symptoms and survival rates, with no significant AT132-related adverse events or safety findings.  In one study these effects have lasted more than four and a half years years.  Audentes is developing AT132 in collaboration with Genethon (www.genethon.fr).

About ASPIRO, the Phase 1/2 Clinical Study of AT132

ASPIRO is designed as a multicenter, multinational, open-label, ascending dose study to evaluate the safety and preliminary efficacy of AT132 in approximately 12 XLMTM patients less than five years of age. The study is expected to include nine AT132 treated subjects and three delayed-treatment concurrent control subjects.  Primary endpoints include safety (adverse events and certain laboratory measures) and efficacy (assessments of neuromuscular and respiratory function).  Secondary endpoints include the burden of disease and health related quality-of-life, and muscle tissue histology and biomarkers.  The primary efficacy analysis is expected to be conducted at 12 months, with interim evaluations expected to be conducted at earlier time points. After the primary 12-month assessment, subjects are expected to be followed for another four years to assess long term safety, durability of effect and developmental progression.

About Audentes Therapeutics, Inc.

Audentes Therapeutics (Nasdaq: BOLD) is a biotechnology company focused on developing and commercializing gene therapy products for patients living with serious, life-threatening rare diseases.  We have four product candidates in development, AT132 for the treatment of X-Linked Myotubular Myopathy (XLMTM), AT342 for the treatment of Crigler-Najjar Syndrome, AT982 for the treatment of Pompe disease, and AT307 for the treatment of the CASQ2 subtype of Catecholaminergic Polymorphic Ventricular Tachycardia (CASQ2-CPVT).  We are a focused, experienced and passionate team committed to forging strong, global relationships with the patient, research and medical communities.

For more information regarding Audentes, please visit www.audentestx.com.

About Genethon

Genethon, located in Evry, France, is a non-profit R&D organization dedicated to the development of biotherapies for orphan genetic diseases, from research to clinical validation. Genethon is specialized in the discovery and development of gene therapy drugs and has multiple ongoing programs at clinical, preclinical and research stage for neuromuscular, blood, immune system, liver and eye diseases.

Discover Genethon’s pipeline: http://www.genethon.fr/produits/

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to: the timing of preliminary data from ASPIRO, the timing of data presentation from INCEPTUS and the ability of INCEPTUS to serve as a longitudinal baseline and within patient control for ASPIRO, and the potential of AT132 to be a transformative therapy for patients living with XLMTM.  All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Although the company believes that the expectations reflected in such forward-looking statements are reasonable, the company cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. Forward-looking statements are subject to risks and uncertainties that may cause the company's actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties related to the company's ability to advance its product candidates, obtain regulatory approval of and ultimately commercial its product candidates, the timing and results of preclinical and clinical trials, the company's ability to fund development activities and achieve development goals, the company's ability to protect

intellectual property and other risks and uncertainties described under the heading "Risk Factors" in documents the company files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and the company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof.

Audentes Contacts:

Investor Contact:
Thomas Soloway, CFO
415.818.1040
ir@audentestx.com

Media Contact:
Paul Laland
415.519.6610
media@audentestx.com

EX-99.2

Exhibit 99.2

Audentes Therapeutics Announces Rare Pediatric Disease and Fast Track Designations for AT132 for the Treatment of X-Linked Myotubular Myopathy

Preliminary data from ASPIRO, the Phase 1/2 study of AT132, expected to be available in the fourth quarter of 2017

SAN FRANCISCO,  September 27, 2017 / PRNewswire/ -- Audentes Therapeutics, Inc. (Nasdaq: BOLD), a biotechnology company focused on developing and commercializing gene therapy products for patients living with serious, life-threatening rare diseases, today announced that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease and Fast Track designations for AT132, the company’s gene therapy product candidate being developed to treat X-Linked Myotubular Myopathy (XLMTM).  In addition to these two new designations, AT132 has also received Orphan Drug designation from both the FDA and European Medicines Agency.

Matthew R. Patterson, President and Chief Executive Officer of Audentes, stated, “The incentives provided by the Rare Pediatric Disease and Fast Track designations are significant and include opportunities to work with FDA to expedite the development of AT132, and the potential to obtain a valuable Rare Pediatric Disease Priority Review Voucher upon approval.  We are eager to leverage these benefits and to work closely with the FDA and XLMTM patient community as we pursue our goal of developing AT132 to treat this devastating rare disease.”

Audentes recently announced the enrollment of the first patient in ASPIRO, the Phase 1/2 clinical trial of AT132 in patients with XLMTM.  Preliminary data from ASPIRO is expected to be available in the fourth quarter of 2017.  In addition to ASPIRO, the clinical development program for AT132 includes RECENSUS, a retrospective medical chart review, for which Audentes has previously announced data from an initial analysis of 112 male subjects.  This analysis confirmed and expanded upon the understanding of the significant disease burden of XLMTM on patients, families and the healthcare system.  Audentes is also conducting INCEPTUS, a prospective natural history and run-in study.  The primary objectives of INCEPTUS are to characterize the clinical condition of children with XLMTM, identify subjects for potential enrollment in ASPIRO, and serve as a longitudinal baseline and within-patient control for ASPIRO.

About the Rare Pediatric Disease Priority Review Voucher and Fast Track Programs

A Rare Pediatric Disease designation may be granted by the FDA to drugs and biologics intended to treat orphan diseases affecting fewer than 200,000 patients in the United States, primarily age 18 years or younger. The designation provides incentives to advance the development of rare disease drugs, including access to the FDA's expedited review and approval programs. In addition, under the FDA's Rare Pediatric Disease Priority Review Voucher program, a sponsor that receives approval for a biologics license application for a rare pediatric disease may be eligible to receive a voucher for a priority review of a subsequent marketing application for a different product. The priority review voucher may be used by the sponsor, sold or transferred.

The Fast Track program was created by the FDA to facilitate the development and expedite the review of new drugs which show promise in treating a serious or life-threatening disease and address an unmet medical need. Drugs that receive this designation benefit from more frequent communications and meetings with FDA to review the drug's development plan including the design of the proposed clinical trials, use of biomarkers and the extent of data needed for approval. Drugs with Fast Track Designation may qualify for priority review to expedite the FDA review process, if relevant criteria are met.

About AT132 for X-Linked Myotubular Myopathy

AT132 is the Audentes product candidate being developed to treat XLMTM, a rare monogenic disease characterized by extreme muscle weakness, respiratory failure andearly death, with an estimated 50% mortality rate by 18 months of age.  XLMTM is caused by mutations in the MTM1 gene, which encodes a protein called myotubularin.  Myotubularin plays an important role in the development, maintenance and function of skeletal muscle cells.  AT132 is comprised of an AAV8 vector containing a functional copy of the MTM1 gene.  Multiple studies in animal models of XLMTM have demonstrated that a single administration of AT132 improved disease symptoms and survival rates, with no significant AT132-related adverse events or safety findings.  In one study these effects have lasted more than four and a half years to date.  Audentes is developing AT132 in collaboration with Genethon (www.genethon.fr).

About Audentes Therapeutics, Inc.

Audentes Therapeutics (Nasdaq: BOLD) is a biotechnology company focused on developing and commercializing gene therapy products for patients living with serious, life-threatening rare diseases.  We have four product candidates in development, AT132 for the treatment of X-Linked Myotubular Myopathy (XLMTM), AT342 for the treatment of Crigler-Najjar Syndrome, AT982 for the treatment of Pompe disease, and AT307 for the treatment of the CASQ2 subtype of Catecholaminergic Polymorphic Ventricular Tachycardia (CASQ2-CPVT).  We are a focused, experienced and passionate team committed to forging strong, global relationships with the patient, research and medical communities.

For more information regarding Audentes, please visit www.audentestx.com.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to: whether Audentes will eventually receive approval of AT132, whether it will receive a Rare Pediatric Disease Voucher, whether such voucher will have value in the form of expediting the review of other Audentes products or have value to other companies seeking such a voucher, and whether benefits afforded by the FDA’s Fast Track designation will help facilitate the development and expedited review of AT132.  All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Although the company believes that the expectations reflected in such forward-looking statements are reasonable, the company cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. Forward-looking statements are subject to risks and uncertainties that may cause the company's actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties related to the company's ability to advance its product candidates, obtain regulatory approval of and ultimately commercial its product candidates, the timing and results of preclinical and clinical trials, the company's ability to fund development activities and achieve development goals, the company's ability to protect intellectual property and other  risks and uncertainties described under the heading "Risk Factors" in

documents the company files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and the company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof.

Audentes Contacts:

Investor Contact:
Thomas Soloway, CFO
415.818.1040
ir@audentestx.com

Media Contact:
Paul Laland
415.519.6610
media@audentestx.com

EX-99.3

AT132 for X-Linked Myotubular Myopathy INCEPTUS Study Interim Results Exhibit 99.3

CONFIDENTIAL Safe Harbor Except for statements of historical fact, any information contained in this presentation may be a forward-looking statement that reflects the Company’s current views about future events and are subject to risks, uncertainties, assumptions and changes in circumstances that may cause events or the Company’s actual activities or results to differ significantly from those expressed in any forward-looking statement. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “plan,” “expect,” “estimate,” “anticipate,” “intend,” “goal,” “strategy,” “believe” and similar expressions and variations thereof. Forward-looking statements include statements regarding the Company’s business strategy; potential growth opportunities; clinical development activities; the timing and results of Investigational New Drug application and Clinical Trial Authorisation submissions; the timing and results of preclinical studies and clinical trials; the nature and timing of potential regulatory approvals; and the likelihood of future commercialization of product candidates. Although the Company believes that the expectations reflected in such forward-looking statements are reasonable, the Company cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including those described under the heading “Risk Factors” in documents the Company has filed with the SEC. These forward-looking statements speak only as of the date of this presentation, and the Company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof. Certain information contained in this presentation may be derived from information provided by industry sources. We believe such information is accurate and that the sources from which it has been obtained are reliable. However, we cannot guarantee the accuracy of, and have not independently verified, such information. The trademarks included herein are the property of the owners thereof and are used for reference purposes only. Such use should not be construed as an endorsement of such products.

Serious, life-threatening rare disease Significant impairment of respiratory and neuromuscular function Estimated 50% mortality by 18 months Incidence: 1 in 50K newborn males Monogenic, well-understood biology MTM1 gene encodes myotubularin, an enzyme required for normal development and function of skeletal muscle Target for AAV gene therapy AAV8 effectively penetrates skeletal muscle Muscle tissue is otherwise reasonably healthy and exhibits no dystrophic or inflammatory change Clear clinical measures Respiratory function measured by maximum inspiratory pressure (MIP) Neuromuscular function as measured by validated scales Muscle biopsy XLMTM Overview A Fatal Disease with no Treatment Options Source: Hnia, Beggs, et al. J Clin Invest. 2011, Joshua Frase Foundation. McEntagart, 2002

AT132 Clinical Development Program INCEPTUS Prospective Natural History Run-in Study in XLMTM Patients N≈16 Longitudinal baseline and within-patient control for ASPIRO Facilitates enrollment in and operational aspects of ASPIRO ASPIRO A Phase 1/2 Gene Therapy Study in XLMTM Patients N=12 Assessment of safety and tolerability and preliminary efficacy Focus on neuromuscular & respiratory measurements RECENSUS A Medical Chart Review of Patients with XLMTM N=112 Characterize aspects of the disease and medical management of XLMTM Identify potential outcome measures for ASPIRO Initial presentation Q1:17; Publication planned Q4:17 Preliminary data available from on-going study First patient dosed Q3:17; Prelim. data expected YE:17 Orphan Drug Designation received from FDA and EMA Rare Pediatric Disease and Fast Track designations granted

INCEPTUS: beginning…

Objectives To characterize the natural history of children with XLMTM, with a specific focus on respiratory and neuromuscular measurements To assess the burden of disease in XLMTM subjects and caregivers INCEPTUS Study Overview Inclusion Criteria Subject is male < 4 yrs. old Genetically confirmed XLMTM Requires ventilator support Design Prospective, Natural History Run-in Study N≈16 Assessments every 3 months up to 2 years, or rollover into ASPIRO Baseline

INCEPTUS Clinical Study Sites Plan to use same study sites in ASPIRO

INCEPTUS Enrollment and Follow-up Duration As of September 14, 2017 Note: Interim data as of September 14, 2017

23 Serious Adverse Events 89 Adverse Events 1 patient death High frequency of hospitalizations and life-threatening events due to respiratory tract infections Approximately 100 cumulative hospitalization days in patients with SAEs INCEPTUS: Non-treatment Serious Adverse Events High frequency of life-threatening adverse events Total=23 NT-SAEs Note: Interim data as of September 14, 2017

INCEPTUS Measures of Neuromuscular function

CHOP-INTEND Designed to assess motor function in congenital myopathies Used in non-ambulant children up to 3 years of age Assessments include: Spontaneous movement of upper and lower extremities Rolling elicited from legs and arms Head control Max score of 64 is reached in first 3-6 mos. in healthy children To be conducted in all patients Motor Function Measure 20 (MFM-20) Designed to assess motor function in neuromuscular diseases Used in non-ambulant and ambulant children 2-7 years of age Evaluation of motor strength in 3 dimensions of muscle tone Standing and transfers Axial, proximal and distal motor function To be conducted in all patients > 2 years of age Key Neuromuscular Function Measures

CHOP-INTEND Scores All patients have severely impaired motor abilities and have missed all major gross motor milestones (rolling, standing, walking) Maximum score of 64 points normally reached in healthy children by 3 to 6 months of age Note: Interim data as of September 14, 2017 Age Range: 8 mos. to 4 yrs.

MFM-20 Scores All patients scoring well below normal on neuromuscular function Normal score in healthy children over 2 years of age Note: Interim data as of September 14, 2017 Age Range: 8 mos. to 4 yrs.

INCEPTUS Respiratory function, strength, and endurance

Key Respiratory Function Measures Ventilator dependence and settings Ventilator dependence over the previous 24 h Changes in ventilator settings (rate and pressure) Key measures: O2 saturation, CO2 levels, serum bicarbonate Respiratory sprinting test Time that patient is able to sustain effective respiration without ventilator support Maximal inspiratory pressure (MIP) Peak pressure generated during inspiration Measure of diaphragm, abdominal and accessory muscle strength Additional spirometric measures being captured

Ventilator Dependence Within the Previous 24 Hours Majority of patients require continuous (24/7) ventilator support Invasive Ventilation N=13/18 Non-Invasive Respiratory Support (Bi-PAP) N=5/18 Note: Interim data as of September 14, 2017

Respiratory Sprinting Test – Median Time Off Ventilator Most patients cannot tolerate more than 10 min off ventilator Note: Only patients on invasive ventilator support undergo a sprinting test Note: Interim data as of September 14, 2017

Maximum Inspiratory Pressures Respiratory strength of patients as measured by maximum inspiratory pressure is consistently well below normal levels Normal minimal pressures in healthy children Note: Interim data as of September 14, 2017

ASPIRO: to aspire…

ASPIRO Phase 1/2 Clinical Study Baseline AT132 Administration Subjects from INCEPTUS Weeks 1 – 4 Prednisolone Weeks 5–9 Taper Extension study Baseline Assessments Neuromuscular Respiratory Biopsy Assessments Neuromuscular Respiratory Biopsy Assessments Neuromuscular Respiratory Biopsy Assessments Neuromuscular Respiratory 3 mos. 6 mos. 12 mos. Inclusion Criteria Subject is male <5 yrs old, or enrolled in INCEPTUS Genetically confirmed XLMTM Requires ventilator support Key Efficacy Assessments Neuromuscular CHOP INTEND MFM-20 Bayley III Muscle biopsy Respiratory Ventilator use Respiratory sprinting Max Inspiratory Pressure (MIP) Design N=12, roll-over from INCEPTUS 3 ascending-dose cohorts (3 active plus a delayed treatment concurrent control) Doses: 1x1014, 3x1014, 5x1014 vg/kg Open-label, Ascending-Dose, Safety and Preliminary Efficacy Study

ASPIRO Phase 1/2 Clinical Study Cohort #1 control Cohort #3 control Cohort #2 control All control subjects treated after optimal dose is determined Cohort #1: Patient 1 Cohort #1: Patients 2 & 3 Cohort #2: Patient 1 Cohort #2: Patient 2 & 3 Cohort #3: Patient 1 Cohort #3: Patients 2 & 3 Optimal dose decided on the basis of 6-month data Primary efficacy assessment at 12 months Five-year follow-up period Preliminary data from Cohort #1 available year end 2017

INCEPTUS study of XLMTM key findings to date High frequency of life-threatening events Severely impaired neuromuscular motor development and function Permanent ventilator dependence in many patients Findings are generally consistent across age range under study Implications for ASPIRO Planned efficacy assessments should be reliable and sensitive measures of treatment effect All outcome measures assess domains that are clinically relevant in XLMTM patients Program next steps Preliminary cohort #1 data expected to be available by year-end Data updates expected throughout 2018 as dose escalation progresses INCEPTUS Key Findings and Program Next Steps

AT132 for X-Linked Myotubular Myopathy INCEPTUS Study Interim Results

EX-99.4

Audentes Corporate Overview September 27, 2017 Exhibit 99.4

Except for statements of historical fact, any information contained in this presentation may be a forward-looking statement that reflects the Company’s current views about future events and are subject to risks, uncertainties, assumptions and changes in circumstances that may cause events or the Company’s actual activities or results to differ significantly from those expressed in any forward-looking statement. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “plan,” “expect,” “estimate,” “anticipate,” “intend,” “goal,” “strategy,” “believe” and similar expressions and variations thereof. Forward-looking statements include statements regarding the Company’s business strategy; potential growth opportunities; clinical development activities; the timing and results of Investigational New Drug application and Clinical Trial Authorisation submissions; the timing and results of preclinical studies and clinical trials; the nature and timing of potential regulatory approvals; and the likelihood of future commercialization of product candidates. Although the Company believes that the expectations reflected in such forward-looking statements are reasonable, the Company cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including those described under the heading “Risk Factors” in documents the Company has filed with the SEC. These forward-looking statements speak only as of the date of this presentation, and the Company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof. Certain information contained in this presentation may be derived from information provided by industry sources. We believe such information is accurate and that the sources from which it has been obtained are reliable. However, we cannot guarantee the accuracy of, and have not independently verified, such information. The trademarks included herein are the property of the owners thereof and are used for reference purposes only. Such use should not be construed as an endorsement of such products. Safe Harbor

Multi-product pipeline based on focused selection criteria Proven leadership team with significant experience Internal cGMP manufacturing provides core strategic advantage Targeting indications with limited or no treatment options Preliminary clinical data from lead programs expected end of 2017 Audentes Therapeutics A clinical-stage biotechnology company developing gene therapy products to treat serious, life-threatening rare diseases

Experienced and Passionate Team Audentes Therapeutics 117 employees based in the San Francisco Bay Area as of June 30, 2017 Matthew Patterson President and Chief Executive Officer Natalie Holles Senior VP and Chief Operating Officer Thomas Soloway Senior VP and Chief Financial Officer Suyash Prasad, M.D. Senior VP and Chief Medical Officer John Gray, Ph.D. Senior VP and Chief Scientific Officer Mary Newman Senior VP, Regulatory Affairs David Nagler Senior VP, Human Resources and Corporate Affairs

Robust Pipeline AT132 AT342 AT307 AT982 Applying world-class AAV science to monogenic diseases with high potential for transformative clinical benefits IndicationStage of DevelopmentCommercial RightsProof-of-ConceptIND EnablingPhase 1/2XLMTMCrigler-Najjar SyndromePompe DiseaseCASQ2-CPVT

Audentes Internal cGMP Manufacturing Leadership Position in AAV Manufacturing Superior control over timelines, cost and IP Enables rapid addition of new programs 38,000 square feet in South San Francisco 2 x 500L scale ongoing to supply clinical trials In-house QC lab for critical release assays Additional capacity (~5,000L) possible in existing lease footprint Facility and process designed to meet global regulatory requirements and support commercialization Designed for seamless transition from IND enabling studies through commercial launch Advantages of internal cGMP manufacturing Commercial readiness Large-scale cGMP capacity Natural host for AAV Significant regulatory history with HEK293 Industrial scale serum-free suspension culture system Mammalian cell-based production platform

AT132 X-linked myotubular myopathy

XLMTM A Fatal Disease with no Treatment Options Significant impairment of respiratory and neuromuscular function Estimated 50% mortality by 18 months Incidence: 1 in 50K newborn males AAV8 effectively penetrates skeletal muscle Muscle tissue is otherwise reasonably healthy and exhibits no dystrophic or inflammatory change MTM1 gene encodes myotubularin, an enzyme required for normal development and function of skeletal muscle Respiratory function measured by maximum inspiratory pressure (MIP) Neuromuscular function as measured by validated scales Muscle biopsy Hnia, Beggs, et al. J Clin Invest. 2011, Joshua Frase Foundation. McEntagart, 2002 Serious, life-threatening rare disease Target for AAV gene therapy Clear clinical measures Monogenic, well-understood biology

Normal (n=13) XLMTM (n=2) XLMTM+AT132 (n=3) 0 50 100 150 0 50 100 Percent survival Single injection of 2 x 1014 vg/kg AT132 in 3 week and 5 week old MTM1 KO mice M. K. Childers et al., Sci Transl Med, 2014; Buj-Bello, et al. Human Molecular Genetics, 2008; Note: vector dosing numbers have been adjusted from publication as a result of improvements in titration methodology Normal Mice + Placebo MTM + Placebo MTM + AT132 Prototype P ≤ 0.001 P ≤ 0.001 XLMTM Canine Model MTM1 KO Mouse Model Weeks of age Untreated MTM1 KO Mice + Placebo, n = 10 MTM1 KO + AT132 (5 weeks), n = 11 MTM1 KO + AT132 (3 weeks), n = 8 Normal Mice + Placebo, n = 10 Single injection of 2 x 1014 vg/kg AT132 A Single Treatment with AT132 Results In Dramatic Improvement & Survival in XLMTM Mouse and Dog Models P ≤ 0.001

*Dogs 3, 4 and 5, the three dogs treated in the proof-of-concept canine study, achieved a statistically significant improvement in survival. Treatment with AT132 Results in Dramatic Improvement and Survival in XLMTM Dogs

AT132 Clinical Development Program INCEPTUS Prospective Natural History Run-in Study in XLMTM Patients N≈16 Longitudinal baseline and within-patient control for ASPIRO Facilitates enrollment in and operational aspects of ASPIRO ASPIRO A Phase 1/2 Gene Therapy Study in XLMTM Patients N=12 Assessment of safety and tolerability and preliminary efficacy Focus on neuromuscular & respiratory measurements RECENSUS A Medical Chart Review of Patients with XLMTM N=112 Characterize aspects of the disease and medical management of XLMTM Identify potential outcome measures for ASPIRO Initial presentation Q1:17; Publication planned Q4:17 Preliminary data available from on-going study First patient dosed Q3:17; Prelim. data expected YE:17 Orphan Drug Designation received from FDA and EMA Rare Pediatric Disease and Fast Track designations granted

INCEPTUS: Key Findings Prospectively collected natural history data confirm poor clinical outcomes of children living with XLMTM (n=18) Key Findings Data High frequency of life- threatening events 89 Adverse Events, 23 Serious Adverse Events, 1 patient death Approximately 100 cumulative hospitalization days in patients with SAEs, primarily due to respiratory complications Severely impaired motor development and function CHOP-INTEND and MFM-20 functional scores well below normal No patient has achieved rolling, standing or walking milestones Highly compromised respiratory function Majority of patients require permanent 24/7 ventilation All patients score significantly below normal on key respiratory measures

CHOP-INTEND Scores All patients have severely impaired motor abilities and have missed all major gross motor milestones (rolling, standing, walking) Note: Interim data as of September 14, 2017 Age Range: 8 mos. to 4 yrs.

MFM-20 Scores All patients scoring well below normal on neuromuscular function Normal score in healthy children over 2 years of age Note: Interim data as of September 14, 2017 Age Range: 8 mos. to 4 yrs.

Ventilator Dependence Within the Previous 24 Hours Majority of patients require continuous (24/7) ventilator support Invasive Ventilation N=13/18 Non-Invasive Respiratory Support (Bi-PAP) N=5/18 Note: Interim data as of September 14, 2017

Respiratory Sprinting Test – Median Time Off Ventilator Most patients cannot tolerate more than 10 min off ventilator Note: Only patients on invasive ventilator support undergo a sprinting test Note: Interim data as of September 14, 2017

Maximum Inspiratory Pressures Respiratory strength of patients as measured by maximum inspiratory pressure is consistently well below normal levels Normal minimal pressures in healthy children Note: Interim data as of September 14, 2017

ASPIRO Phase 1/2 Clinical Study Baseline AT132 Administration Subjects from INCEPTUS Weeks 1 – 4 Prednisolone Weeks 5–9 Taper Extension study Baseline Assessments Neuromuscular Respiratory Biopsy Assessments Neuromuscular Respiratory Biopsy Assessments Neuromuscular Respiratory Biopsy Assessments Neuromuscular Respiratory 3 mos. 6 mos. 12 mos. Inclusion Criteria Subject is male <5 yrs old, or enrolled in INCEPTUS Genetically confirmed XLMTM Requires ventilator support Key Efficacy Assessments Neuromuscular CHOP INTEND MFM-20 Bayley III Muscle biopsy Respiratory Ventilator use Respiratory sprinting Max Inspiratory Pressure (MIP) Design N=12, roll-over from INCEPTUS 3 ascending-dose cohorts (3 active plus a delayed treatment concurrent control) Doses: 1x1014, 3x1014, 5x1014 vg/kg Open-label, Ascending-Dose, Safety and Preliminary Efficacy Study

AT342 Crigler-Najjar syndrome

Crigler-Najjar Syndrome A Rare Disease that Leads to Neurological Damage and Death Significant bilirubin accumulation that can lead to irreversible neurological damage and death Current treatments: > 12 hours/day of phototherapy, liver transplant Estimated incidence of 1 in 1 million newborns AAV8 effectively penetrates the liver In the majority of patients, liver tissue is otherwise healthy UGT1A1 gene encodes enzyme required for bilirubin metabolism and excretion Serum bilirubin Time on phototherapy Serious, life-threatening rare disease Target for AAV gene therapy Clear clinical measures Monogenic, well-understood biology Bortolussi et. al, Human Gene Therapy, 2014; Orphanet.com

AT342 Rapidly Reduces Bilirubin Levels in Crigler-Najjar Mouse Model A single tail vein injection of AT342 in a knockout mouse model rapidly reduced and normalized bilirubin levels for the duration of the study Previously published study with AAV8-UGT1A1 in a knockout mouse shows durable effect out to 17 months Total Bilirubin Levels (mg/dL) Days 1.5 x 1010 vg/kg (n=5) 1.5 x 1011 vg/kg (n=5) 1.5 x 1012 vg/kg (n=5) 1.5 x 1013 vg/kg (n=5) Vehicle Control Bortolussi et. al, Human Gene Therapy

AT342 Development Program LUSTRO Prospective Natural History Run-in Study in Crigler-Najjar Patients (N=16 to 18) Longitudinal baseline and within-patient control for VALENS Facilitates enrollment in and operational aspects of VALENS VALENS A Phase 1/2 Gene Therapy Study in Crigler-Najjar Patients N=12 Assessment of safety and tolerability and preliminary efficacy Focus on serum bilirubin & phototherapy use Preliminary data available Q4:17 Plan to initiate VALENS Q4:17; Prelim. data expected YE:17 Orphan Drug Designation received from FDA and EMA

VALENS Phase 1/2 Clinical Study Open-Label, Ascending-Dose, Safety & Preliminary Efficacy Study Assessments Initial assessments Liver biopsy Weeks 5–9 Taper Weeks 13 – 17 Weaning Weeks 1 – 4 Prednisolone Assessments ∆ Bilirubin Weeks 1 – 12 Normal prescribed phototherapy dose Assessments Liver biopsy AT342 Administration Subjects from LUSTRO Assessments ∆ Bilirubin ∆ Phototherapy Extension study Design N=12, roll-over from LUSTRO 3 ascending-dose cohorts (3 active plus a delayed treatment concurrent control) Doses: 1.5x1012, 6.0x1012, 1.5x1013 vg/kg Key Assessments ∆ bilirubin from baseline (BL) to 12 wks. ∆ bilirubin from BL to 18 wks. ∆ phototherapy (PT) from BL to 18 wks. Successful weaning from PT Liver biopsy Inclusion Criteria Genetically confirmed Crigler-Najjar ≥ 1 year of age Subject receives daily phototherapy for ≥6 hours within a 24 hour period Baseline Week 12 Week 18 Week 24

AT982 Pompe disease

Pompe Disease A Rare, Severe, Progressive Neuromuscular Disease Severe muscle weakness, respiratory failure, and in infants, increased cardiac mass and heart failure Spectrum of disease from severe (infantile/early-onset) to more attenuated (juvenile/late-onset) Estimated incidence of 1 in 40K Efficacy of ERT limited by poor cellular uptake, no neuronal exposure, and immune reaction to exogenous GAA Published animal Proof-of-Concept utilizing both muscle- and liver-directed AAV approaches Gene encodes lysosomal enzyme acid alpha-glucosidase (GAA), deficiency leads to accumulation of lysosomal glycogen Respiratory function by MIP Neuromuscular function as measured by validated scales Muscle biopsy Serious, life-threatening rare disease Target for AAV gene therapy Clear clinical measures Monogenic, well-understood biology Lipinksi, Shawn. Molecular Genetics and Metabolism, 2012; Lacana, et al., Amer. J. Medical Genetics, 2012; International Pompe Association, Pompe Community and United Pompe Foundation

AT982 Development Path to planned phase 1/2 clinical study Activity Overview and Achievements Preclinical studies Proof of concept established in murine model Comprehensive construct selection study ongoing - Muscle, neuronal and liver-directed vectors, AAV8 & AAV9 Functional, biochemical, immunological endpoints Regulatory Orphan Drug Designation granted by FDA and EMA IND planned H1:18 Chemistry, Mfg. & Controls (CMC) Leverages existing AT132 and AT342 process and methods Clinical supply manufacturing preparations underway Clinical development Phase 1/2 study planned H2:18

AT307 Catecholaminergic polymorphic ventricular tachycardia (CPVT)

CASQ2-CPVT A Life-Threatening Inherited Arrhythmia Ventricular arrhythmias and sudden death in response to stress and/or exercise Prevalence estimated at > 6,000 in addressable markets with mortality of 30-50% by age 30 AAV9 vector capsid effectively penetrates heart tissue Heart tissue is otherwise healthy Autosomal recessive form (CASQ2) : gene encodes calsequestrin 2, essential for normal calcium homeostasis in cardiac myocytes Electrocardiogram during exercise stress test Episodes of VT and/or syncope Serious, life-threatening rare disease Target for AAV gene therapy Clear clinical measures Monogenic, well-understood biology Cerrone et al., Circulation Cardiovascular Genetics, 2012; Napolitano et al., Circulation, 2012; Priori et al. Europace, 2013; GeneReviews: http://www.ncbi.nlm.nih.gov/books/NBK1289/

A single administration of an AT307 prototype achieved: Near normal levels of CASQ2 protein expression Reduction in pre-arrhythmic events and ventricular tachycardia to normal levels in both newborn and adult mice Denegri et al., Circulation, 2014 Newborn Mice P < 0.001 P < 0.001 P < 0.001 P < 0.001 P < 0.001 P < 0.05 Adult Mice P < 0.001 P < 0.05 AT307 Prototype Prevents VT in Newborn Mice and Reverses VT in Adult Mice

Financial Overview & Summary

Jun. 30, 2017 cash, equivalents & short-term investments: $145M Funded to achieve key value inflection milestones: XLMTM: Interim results from the ASPIRO study Crigler-Najjar: Interim results from the planned VALENS study Pompe disease: File IND, initiate Phase 1/2 study for systemic administration of AT982 CASQ2-CPVT: File IND and initiate Phase 1/2 study of AT307 Q1:17 (Unaudited) Q2:17 (Unaudited) R&D Expense $14.3M $18.8 G&A Expense $ 3.9M $4.1 Loss from Ops. $(18.2M) $(22.8) Financial Overview

Audentes Highlights Treating devastating diseases with high unmet medical need Potential for transformational disease impact Compelling Pipeline AAV Gene Therapy Leadership Team with significant rare disease and gene therapy expertise Robust internal research, analytical and large-scale cGMP manufacturing capabilities Catalysts Catalysts Preliminary AT132 clinical data planned Q4:17 Preliminary AT342 clinical data planned Q4:17 Plan to file AT307 IND year-end 2017 Plan to file AT982 systemic administration IND H1:18 US and EU Orphan Drug Designation for all programs Establish large-scale cGMP manufacturing AT132 first patient dosed AT342 IND active ✓ ❐ ✓ ❐ ✓ ❐ ✓ ❐ ❐ ❐ ❐ ❐

Audentes Corporate Overview September 27, 2017