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

                                  SCHEDULE 13G
                    Under the Securities Exchange Act of 1934

			      Celsion Corporation
                                (Name of Issuer)

                                   Common Stock
                          (Title of Class of Securities)

                                    15117N305
                                 (CUSIP Number)

                                December 31, 2011

             (Date of Event Which Requires Filing of this Statement)

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. 15117N305




       1.    Names of Reporting Persons.
             I.R.S. Identification Nos. of above persons (entities only).

             OrbiMed Advisors LLC

       2.    Check the Appropriate Box if a Member Of a Group (See Instructions)

             [ ] (a)
             [ ] (b)

       3.    SEC Use Only

       4.    Citizenship or Place of Organization

             Delaware

       5.    Sole Voting Power: 0
Number of
Shares           6.  Shared Voting Power: 1,182,771
Beneficially
Owned by         7.  Sole Dispositive Power:  0
Each Reporting
Person With      8.  Shared Dispositive Power: 1,182,771

       9.    Aggregate Amount Beneficially Owned by Each Reporting Person
             1,182,771

       10.   Check if the Aggregate Amount in Row (9) Excludes Certain Shares
             (See Instructions)

       11.   Percent of Class Represented by Amount in Row (9) 3.49%

       12.   Type of Reporting Person (See Instructions) IA






                               CUSIP No. 15117N305



       1.    Names of Reporting Persons.
             I.R.S. Identification Nos. of above persons (entities only).

             OrbiMed Capital LLC

       2.    Check the Appropriate Box if a Member of a Group (See Instructions)

             [ ] (a)
             [ ] (b)

       3.    SEC Use Only

       4.    Citizenship or Place of Organization

             Delaware

       5.    Sole Voting Power: 0
Number of
Shares           6.  Shared Voting Power: 1,087,500
Beneficially
Owned by         7.  Sole Dispositive Power: 0
Each Reporting
Person With      8.  Shared Dispositive Power:  1,087,500

       9.    Aggregate Amount Beneficially Owned by Each Reporting Person
             1,087,500

       10.   Check if the Aggregate Amount in Row (9) Excludes Certain Shares
             (See Instructions)

       11.   Percent of Class Represented by Amount in Row (9) 3.20%

       12.   Type of Reporting Person (See Instructions) IA




                               CUSIP No. 15117N305



       1.    Names of Reporting Persons.
             I.R.S. Identification Nos. of above persons (entities only).

             Samuel D. Isaly

       2.    Check the Appropriate Box if a Member of a Group (See Instructions)

             [ ] (a)
             [ ] (b)

       3.    SEC Use Only

       4.    Citizenship or Place of Organization

             United States

       5.    Sole Voting Power: 0
Number of
Shares           6.  Shared Voting Power: 2,270,271
Beneficially
Owned by         7.  Sole Dispositive Power: 0
Each Reporting
Person With      8.  Shared Dispositive Power: 2,270,271

       9.    Aggregate Amount Beneficially Owned by Each Reporting Person:
             2,270,271

       10.   Check if the Aggregate Amount in Row (9) Excludes Certain Shares
             (See Instructions)

       11.   Percent of Class Represented by Amount in Row (9) 6.69%

       12.   Type of Reporting Person (See Instructions) HC




Item 1. (a)  Issuer: Celsion Corporation

             1.      Address:

		     997 Lenox Drive, Suite 100
		     Lawrenceville, NJ 08648


Item 2. (a)  Name of Person Filing:
             OrbiMed Advisors LLC
             OrbiMed Capital LLC
             Samuel D. Isaly

        (b)  Address of Principal Business Offices:

             601 Lexington Avenue, 54th Floor
	     New York, NY 10022

        (c)  Citizenship:
             Please refer to Item 4 on each cover sheet for each filing person

        (d)  Title of Class of Securities
             Common stock

        (e)  CUSIP Number: 15117N305


Item 3. OrbiMed Advisors LLC and OrbiMed Capital LLC are investment
advisors in accordance with ss.240.13d-1(b)(1)(ii)(E). Samuel D. Isaly is
a control person in accordance with ss.240.13d-1(b)(1)(ii)(G).

Item 4.  Ownership

         Please see Items 5 - 9 and 11 for each cover sheet for each filing
separately

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.

	 Reporting persons are holding 6.69% (3.49% in the case of
         OrbiMed Advisors LLC and 3.20% in the case of OrbiMed Capital LLC) of
         the shares and share equivalents issuable from warrants on behalf
	 of other persons who have the right to receive or the power to
	 direct the receipt of dividends from, or proceeds from sale of,
	 such securities. No one such other person's interest in the
	 securities whose ownership is reported here relates to more than
	 five percent of the class.






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

         Not Applicable

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 and held in the ordinary
course of business and were not acquired and are not held for the purpose of or
with the effect of changing or influencing the control of the issuer of the
securities and were not acquired and are not held in connection with or as a
participant in any transaction having that purpose or effect.





                               SIGNATURE

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.

Date: February 14, 2012
                                       OrbiMed Advisors LLC

                                       By: /s/ Samuel D. Isaly
                                       --------------------------
                                       Name:  Samuel D. Isaly
                                       Title: Managing Member

                                       OrbiMed Capital LLC

                                       By: /s/ Samuel D. Isaly
                                       --------------------------
                                       Name:  Samuel D. Isaly
                                       Title: Managing Member


                                       By: /s/ Samuel D. Isaly
                                       --------------------------
                                       Name:  Samuel D. Isaly


			JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on this Schedule 13G, dated
February 14, 2012 (the "Schedule 13G"), with respect to the Common Stock,
par value $.01 per share, of Celsion Corporation is filed on
behalf of each of us pursuant to and in accordance with the provisions of
Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, and
that this Agreement shall be included as an Exhibit to this Schedule 13G.
Each of the undersigned agrees to be responsible for the timely filing of the
Schedule 13G, and for the completeness and accuracy of the information
concerning itself contained therein. This Agreement may be executed in any
number of counterparts, all of which taken together shall constitute one and
the same instrument.

        IN WITNESS WHEREOF, the undersigned have executed this Agreement as
of the 14th day of February 2012.


                                          OrbiMed Advisors LLC

                                          By: /s/ Samuel D. Isaly
                                          ---------------------------
                                          Name:  Samuel D. Isaly
                                          Title: Managing Member


                                          OrbiMed Capital LLC

                                          By: /s/ Samuel D. Isaly
                                          ----------------------------
                                          Name:  Samuel D. Isaly
                                          Title: Managing Member


                                          By: /s/ Samuel D. Isaly
                                          ----------------------------
                                          Name:  Samuel D. Isaly


		    Statement of Control Person

The Statement on this Schedule 13G dated February 14, 2012 with respect
to the common stock, $.01 par value per share, of Celsion Corporation
is filed by Samuel D. Isaly in accordance with the provisions of
Rule 13d-1(b) and Rule 13d-1(k),respectively,as control person (HC) of
OrbiMed Advisors LLC and OrbiMed Capital LLC.

OrbiMed Advisors LLC and OrbiMed Capital LLC file this statement on
Schedule 13G in accordance with the provisions of Rule 13d-1(b) and
Rule 13d-1(k), respectively, as investment advisors (IA).