UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

Amendment No.: 0*

Name of Issuer: Collegium Pharmaceutical, Inc

Title of Class of Securities: Common Stock

CUSIP Number: 19459J104

Date of Event Which Requires Filing of this Statement: 12/31/2017

Check the appropriate box to designate the rule pursuant to which this
Schedule is filed.

[X] Rule 13d-1(b) [ ] Rule 13d-1(c) [ ] Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class
of securities, and for any subsequent amendment containing information
which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not
be deemed to be "filed" for the purpose of Section 18 of the Securities
Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of
that section of the Act but shall be subject to all other provisions of
the Act (however, see the Notes).

CUSIP No.: 19459J104

1. NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE
PERSON Janus Henderson Group plc EIN #00-0000000

2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP a. ___ b. ___ 3. SEC
USE ONLY

4. CITIZENSHIP OR PLACE OF ORGANIZATION Jersey, Channel Islands

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

5. SOLE VOTING POWER 0**

6. SHARED VOTING POWER 3,292,058**

7. SOLE DISPOSITIVE POWER 0**

8. SHARED DISPOSITIVE POWER 3,292,058**

9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
3,292,058**

10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
Not applicable

11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 10.1%**

12. TYPE OF REPORTING PERSON IA, HC

** See Item 4 of this filing

Item 1.

(a). Name of Issuer: Collegium Pharmaceutical, Inc ("Collegium")

(b). Address of Issuer's Principal Executive Offices:

780 Dedham Street, Suite 800 Canton, MA 02021

Item 2.

(a).-(c). Name, Principal Business Address, and Citizenship of
Persons Filing:

(1) Janus Henderson Group plc 201 Bishopsgate EC2M 3AE, United Kingdom
Citizenship: Jersey, Channel Islands

(d). Title of Class of Securities: Common Stock

(e). CUSIP Number: 19459J104

Item 3.

This statement is filed pursuant to Rule 13d-1 (b) or 13d-2(b) and the
person filing, Janus Henderson Group plc ("Janus Henderson")is a parent
holding company/control person in accordance with Section
240.13d-1(b)(ii)(G). See Item 4 for additional information.

Item 4. Ownership

The information in items 1 and 5 through 11 on the cover page(s) on
Schedule 13G is hereby incorporated by reference.

Janus Henderson has an indirect 100% ownership stake in Janus Capital
Management LLC ("Janus Capital"), INTECH Investment Management
("INTECH"), Perkins Investment Management LLC ("Perkins"), and Geneva
Capital Management LLC ("Geneva")(each an "Asset Manager" and
collectively as the "Asset Managers"). Due to the above ownership
structure, holdings for the Asset Managers are aggregated for purposes
of this filing. Each Asset Manager is a registered investment adviser,
each furnishing investment advice to various investment companies
registered under Section 8 of the Investment Company Act of 1940 and/or
to individual and institutional clients (collectively referred to herein
as "Managed Portfolios").

As a result of its ownership of the Asset Managers, Janus Henderson may
be deemed to be the beneficial owner of 3,292,058 shares or 10.1% of the
shares outstanding of Collegium Common Stock held by such Managed
Portfolios. However, Janus Henderson does not have the right to receive
any dividends from, or the proceeds from the sale of, the securities
held in the Managed Portfolios and disclaims any ownership associated
with such rights.

As a result of its role as investment adviser or sub-adviser to the
Managed Portfolios, Janus Capital may be deemed to be the beneficial
owner of 3,292,058 shares or 10.1% of the shares outstanding of
Collegium Common Stock held by such Managed Portfolios. However, Janus
Capital does not have the right to receive any dividends from, or the
proceeds from the sale of, the securities held in the Managed Portfolios
and disclaims any ownership associated with such rights.

Item 5. Ownership of Five Percent or Less of a Class

Not applicable.

Item 6. Ownership of More than Five Percent on Behalf of Another Person

The Managed Portfolios, set forth in Item 4 above, have the right to
receive all dividends from, and the proceeds from the sale of, the
securities held in their respective accounts.

The interest of any one such person does not exceed 5% of the class of
securities.

These shares were acquired in the ordinary course of business, and not
with the purpose of changing or influencing control of the Issuer.

Item 7. Identification and Classification of the Subsidiary Which
Acquired the Security Being Reported on by the Parent Holding Company

Janus Capital, INTECH, Perkins and Geneva are indirect subsidiaries of
Janus Henderson and are registered investment advisers furnishing
investment advice to Managed Portfolios.

Item 8. Identification and Classification of Members of the Group

Not applicable.

Item 9. Notice of Dissolution of Group

Not applicable.

Item 10. Certification

By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired in the ordinary course of
business and were not acquired for the purpose of and do not have the
effect of changing or influencing the control of the issuer of such
securities and were not acquired in connection with or as a participant
in any transaction having such purposes or effect.

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true,
complete and correct.

JANUS HENDERSON GROUP PLC

By /s/ Brennan Hughes 1/10/2018 Brennan Hughes,
Date Senior Vice President and Treasurer

JANUS CAPITAL MANAGEMENT LLC

By /s/ Brennan Hughes 1/10/2018 Brennan Hughes,
Date Senior Vice President and Treasurer