13D Filing: James E. Flynn and AveXis Inc (AVXS)

CUSIP No.  05366U100

13D/A

Page 10 of 15 Pages

This Amendment No. 4 (this “Amendment”)
to Schedule 13D amends the Schedule 13D (as previously amended, the “Schedule 13D”) filed by (i) Deerfield Mgmt,
L.P. (“Deerfield Mgmt”), (ii) Deerfield Special Situations Fund, L.P. (“Deerfield Special Situations
Fund”), (iii) Deerfield Management Company, L.P. (“Deerfield Management”), (iv) Deerfield Private
Design Fund III, L.P. (“Deerfield Private Design Fund III”), (v) Deerfield Partners, L.P. (“Deerfield
Partners”), (vi) Deerfield International Master Fund, L.P. (“Deerfield International Master Fund”),
(vii) Deerfield Mgmt III, L.P. (“Deerfield Mgmt III”) and (viii) James E. Flynn, a natural person (“Flynn”
and collectively with Deerfield Mgmt, Deerfield Special Situations Fund, Deerfield Management, Deerfield Private Design Fund III,
Deerfield Partners, Deerfield International Master Fund and Deerfield Mgmt III, the “Reporting Persons”), with
respect to the securities of AveXis, Inc. (the “Company”), on February 19, 2016, as amended by Amendment Nos.
1, 2 and 3 to the Schedule 13D filed on February 2, 2017, May 31, 2017 and August 22, 2017. Deerfield Special Situations Fund,
Deerfield Private Design Fund III, Deerfield Partners and Deerfield International Master Fund are collectively referred to herein
as the “Funds.”

Capitalized terms used herein but not otherwise
defined herein shall have the meanings ascribed to them in the Schedule 13D.

Item 5.

Interest in Securities of the Issuer.

Items 5(a), (b) and (c) of the Schedule 13D are hereby amended
and restated in their entirety as follows:

(a)

(1)       Deerfield
Mgmt

Number of shares:

502,014 (comprised of shares held by Deerfield Special Situations Fund, Deerfield Partners and Deerfield International Master Fund)

Percentage of shares: 1.57%*

(2)       Deerfield
Management

Number of shares:

1,857,862 (comprised of shares held by Deerfield Special Situations Fund, Deerfield Private Design Fund III, Deerfield Partners and Deerfield International Master Fund, and shares held directly by Deerfield Management)

Percentage of shares: 5.82%*

(3)       Deerfield
Special Situations Fund

Number of shares: 230,585

Percentage of shares: 0.72%*

(4)       Deerfield
Private Design Fund III

Number of shares: 1,343,202

Percentage of shares: 4.21%*