Corporate Presentation Leader in AAV Gene Therapy June 16, 2020 Forward-looking statements This presentation includes "forward-looking statements," within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These statements express a belief, expectation or intention and are generally accompanied by words that convey projected future events or outcomes such as "believe," "may," "will," "estimate," "continue," "anticipate," ...

Financial Data and Key Metrics Changes - As of March 31, 2020, cash, cash equivalents, and marketable securities totaled $356.6 million, down from $400 million as of December 31, 2019, primarily due to net cash used in operating activities of $35.6 million and cash used for property and equipment purchases of $4.6 million [38] - Revenues for Q1 2020 were $17.6 million, a significant increase from $900,000 in Q1 2019, driven by $10 million in royalty revenue from Zolgensma and $7.2 million in license revenue from a new agreement with Ultragenyx [39] - Research and development expenses rose to $37 million in Q1 2020 from $25.2 million in Q1 2019, attributed to increased personnel costs and clinical trial expenses [41] - General and administrative expenses increased to $14.8 million in Q1 2020 from $11.6 million in Q1 2019, mainly due to higher personnel-related costs and professional fees [42] - The net loss for Q1 2020 was $40 million, or $1.08 per share, compared to a net loss of $32.2 million, or $0.89 per share, in Q1 2019 [43] Business Line Data and Key Metrics Changes - The RGX-314 gene therapy program demonstrated stable and consistent results, with 73% of patients remaining anti-VEGF injection-free nine months after a single administration [15][24] - The company is advancing its internal gene therapy pipeline, with ongoing trials for RGX-121 and RGX-111, and expects to provide updates in mid-2020 [16][28] Market Data and Key Metrics Changes - Novartis reported over $530 million in net sales of Zolgensma as of the end of Q1 2020, indicating progress towards the $1 billion milestone that would trigger an $80 million payment to REGENXBIO [40] Company Strategy and Development Direction - The company is focused on improving lives through gene therapy and has made significant progress in its NAV Technology Platform, with over 20 partnered product candidates [30][36] - REGENXBIO is expanding its gene therapy pipeline and has plans to initiate trials for RGX-314 using a suprachoroidal delivery approach in 2020 [25][30] Management's Comments on Operating Environment and Future Outlook - Management expressed optimism about the potential of gene therapy to provide safer treatment alternatives during the COVID-19 pandemic, highlighting the importance of single administration treatments [50][51] - The company anticipates regulatory updates and continued progress in its clinical programs throughout 2020 [36][52] Other Important Information - The construction of a GMP production facility in Rockville is ongoing and expected to be operational in 2021, which will enhance production capabilities [18] Q&A Session Summary Question: Regarding the suprachoroidal data and initiation in the first half of this year - Management confirmed that they are targeting to start the suprachoroidal delivery development program for wet AMD by the end of the first half of 2020 and will provide updates based on data available at that time [55][56] Question: Concerns about inflammation with the suprachoroidal approach - Management acknowledged the potential for inflammation but noted that preclinical data with their proprietary NAV technology showed no inflammation with suprachoroidal delivery, providing comfort regarding this route [64][66] Question: Financial aspects regarding CapEx build-out and Abeona license agreement - Management clarified that the CapEx for the new headquarters and GMP facility will be in the tens of millions over the life of the program and confirmed that there are outstanding amounts due from Abeona due to a breach of contract [84][86]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q 9600 Blackwell Road, Suite 210 Rockville, MD 20850 (Address of principal executive offices) (Zip Code) (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 transition period from ___ to ___ Commission File Number 001 ...

Financial Data and Key Metrics Changes - As of December 31, 2019, the company had cash, cash equivalents, and marketable securities totaling $400 million, down from $470.6 million as of December 31, 2018, primarily due to cash used in operating activities during 2019 [44] - Revenues for Q4 2019 were $11.8 million, and for the full year, revenues were $35.2 million, compared to $40.8 million and $218.5 million for the same periods in 2018, respectively [45] - The net loss for Q4 2019 was $26.5 million, and for the full year, it was $94.7 million, compared to a net income of $4.3 million and $99.9 million for the same periods in 2018 [50] Business Line Data and Key Metrics Changes - The company reported $10.7 million and $20.8 million of royalty revenue from the net sales of ZOLGENSMA during Q4 and the full year of 2019, respectively [47] - Research and development expenses increased to $33.8 million for Q4 2019 and $124.2 million for the full year, compared to $24.3 million and $83.9 million for the same periods in 2018 [48] - General and administrative expenses rose to $14.5 million for Q4 2019 and $51.8 million for the full year, compared to $11.1 million and $36.9 million for the same periods in 2018 [49] Market Data and Key Metrics Changes - The company is eligible to receive a milestone payment of $80 million from AveXis upon the achievement of $1 billion in cumulative net sales of ZOLGENSMA [47] - The NAV Technology platform is currently being applied in one marketed product, ZOLGENSMA, and more than 20 partnered product candidates, with 15 in active clinical development [40] Company Strategy and Development Direction - The company aims to improve lives through the curative potential of gene therapy based on its proprietary NAV technology platform, focusing on both AAV-mediated antibody delivery and AAV-mediated monogenic gene replacement [10][11] - The construction of a CGMP production facility in Rockville, Maryland, is on track to be operational in 2021, which will support early and late-stage programs [21] - The company is expanding its internal gene therapy pipeline and advancing key programs, including RGX-314 for wet AMD and RGX-121 for MPS II [12][31] Management's Comments on Operating Environment and Future Outlook - Management expressed optimism about the clinical results of RGX-314 and plans to report longer-term data in 2020, which will inform the next steps for the program [13] - The company remains committed to addressing unmet needs in rare diseases and believes in the promise of NAV Technology for rare disease treatments [24] - Management highlighted the importance of partnerships with groups like Novartis to realize the potential of NAV Technology [42] Other Important Information - The company acknowledged the risks and uncertainties associated with forward-looking statements regarding financial outlook and product development plans [4][5] - Management emphasized the importance of maintaining and protecting intellectual property rights in the context of ongoing disputes [60][62] Q&A Session Summary Question: What kind of data would change thoughts on trial design for RGX-314? - Management indicated that while they do not foresee dramatic changes, having a full twelve months of data will help enhance and fine-tune the trial design [56] Question: Will the company wait for data from the wet AMD suprachoroidal study before starting the diabetic retinopathy trial? - Management confirmed that they will take advantage of data from the ongoing wet AMD study to inform the diabetic retinopathy trial [58] Question: Can the company provide more details on the IP dispute? - Management acknowledged sending a letter to protect intellectual property rights and stated that they have a strong and broad intellectual property portfolio [60][62] Question: What is the path forward for RGX-121 regarding approval? - Management expressed optimism about the correlation between biomarker changes and clinical outcomes, indicating ongoing exploration of pharmacology [71][73] Question: Is there potential for an ex-U.S. partner for RGX-314? - Management stated they are prepared to move forward with the program and are open to exploring partnerships if necessary [89][90]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-37553 REGENXBIO Inc. (Exact name of registrant as specified in its charter) Delaware 47-1851754 (State or other ju ...

REGENXBIO, Inc. (NASDAQ:RGNX) Q3 2019 Earnings Conference Call November 5, 2019 4:30 PM ET Company Participants Patrick Christmas - Senior Vice President and General Counsel Kenneth Mills - President and Chief Executive Officer Stephen Pakola - Chief Medical Officer Vittal Vasista - Chief Financial Officer Conference Call Participants Gena Wang - Barclays PLC Mani Foroohar - SVB Leerink Kostas Biliouris - Morgan Stanley Operator Good afternoon, and welcome to the REGENXBIO Third Quarter 2019 Earnings Confer ...

Table of Contents 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, 2019 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ___ to ___ Commission File Number 001-37553 REGENXBIO Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 47-1851754 (S ...

Corporate Presentation Leader in AAV Gene Therapy September 6, 2019 Forward-looking statements This presentation includes "forward-looking statements," within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These statements express a belief, expectation or intention and are generally accompanied by words that convey projected future events or outcomes such as "believe," "may," "will," "estimate," "continue," "anticipat ...

Regenxbio, Inc. (NASDAQ:RGNX) Q2 2019 Earnings Conference Call August 7, 2019 4:30 PM ET Company Participants Sara Garon Berl - Vice President of Law and Policy for REGENXBIO Kenneth Mills – Chief Executive Offier, President and Director Vittal Vasista - Chief Financial Officer Steve Pakola - Chief Medical Officer Conference Call Participants Mani Foroohar - SVB Leerink Gena Wang - Barclays Operator Good afternoon and welcome to the REGENXBIO Second Quarter 2019 Earnings Conference Call. At this time, all p ...

Table of Contents ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) For the quarterly period ended June 30, 2019 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ___ to ___ Commission File Number 001-37553 REGENXBIO Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 47-1851754 (State ...