13G Filing: James E. Flynn and Proteon Therapeutics Inc (PRTO)

74371L109

Proteon
Therapeutics, Inc.

200 West Street

Waltham, MA 02451

James
E. Flynn, Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Management Company, L.P., Deerfield Special Situations Fund,
L.P., Deerfield Partners, L.P., Deerfield International
Master Fund, L.P. and Deerfield Private Design Fund III, L.P.

James E. Flynn, Deerfield Mgmt, L.P., Deerfield
Mgmt III, L.P., Deerfield Management Company, L.P., Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield
International Master Fund, L.P. and Deerfield Private Design Fund III, L.P., 780 Third Avenue, 37th Floor, New York, NY 10017

Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield
Management Company, L.P., Deerfield Private Design Fund III, L.P., Deerfield Special Situations Fund, L.P. and Deerfield Partners,
L.P. – Delaware limited partnerships;

Deerfield International Master Fund, L.P. –
British Virgin Islands limited partnership;

James E. Flynn – United States citizen

Common Stock

74371L109

If This Statement is Filed Pursuant to
Rule 13d-1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a:

Broker or dealer registered under Section 15 of the
Exchange Act.

Insurance company as defined in Section 3(a)(19) of
the Exchange Act.

Investment company registered under Section 8 of the
Investment Company Act.

An employee benefit plan or endowment fund in accordance
with Rule 13d-1(b)(1)(ii)(F);