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

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                                  SCHEDULE 13G

                                 (Rule 13d-102)

                INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
             TO Section 240.13d-1(b), (c), AND (d) AND AMENDMENTS THERETO 
                      FILED PURSUANT TO Section 240.13d-2


                    Under the Securities Exchange Act of 1934
                                (Amendment No. 4)


                              MEDIDATA SOLUTIONS INC
                  ----------------------------------------------
                                (Name of Issuer)


                                   COMMON STOCK 
                 -----------------------------------------------
                         (Title of Class of Securities)


                                    58471A105
                              ---------------------
                                 (CUSIP Number)


                                DECEMBER 31, 2017
                             ---------------------
             (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)



                                 Page 1 of 5 Pages



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CUSIP No.:  58471A105                   13G                   Page 2 of 5 Pages

................................................................................

1.       Names of Reporting Persons

         Sands Capital Management, LLC

................................................................................

2.       Check the Appropriate Box if a Member of a Group               (a) [ ]
                                                                        (b) [ ] 

         NOT APPLICABLE  

................................................................................

3.       SEC Use Only

................................................................................

4.       Citizenship or Place of Organization

         Delaware, United States

................................................................................

Number of       5.     Sole Voting Power: 2,382,759                  
Shares
Beneficially    ................................................................
Owned by Each
Reporting       6.     Shared Voting Power: -0-               
Person With     ................................................................

                7.     Sole Dispositive Power: 3,554,159      
                ................................................................

                8.     Shared Dispositive Power: -0-           
................................................................................

9.       Aggregate Amount Beneficially Owned by Each Reporting Person

         3,554,159
................................................................................

10.      Check if the Aggregate Amount in Row (9) Excludes Certain Shares   [ ]
         

         NOT APPLICABLE
................................................................................

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

         6.1% (1)

................................................................................


12.      Type of Reporting Person:

         IA 


______________________________ 

(1)  Based on 58,460,955 shares of common stock outstanding as reported in the
     Issuer's Form 10-Q as of October 30, 2017.




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CUSIP No.:  58471A105                   13G                   Page 3 of 5 Pages


Item 1(a) Name of Issuer:

	MEDIDATA SOLUTIONS INC


Item 1(b) Address of Issuer's Principal Executive Offices: 

  	350 Hudson Street, 9th Floor, New York, NY 10014
 

Item 2(a) Name of Person Filing: 

   	SANDS CAPITAL MANAGEMENT, LLC
 

Item 2(b) Address of Principal Business Office, or if None, Residence:
 
   	1000 WILSON BLVD., SUITE 3000, ARLINGTON, VA 22209
 

Item 2(c) Citizenship:

   	DELAWARE, UNITED STATES
 

Item 2(d) Title of Class of Securities:

   	COMMON STOCK
 

Item 2(e) CUSIP Number: 58471A105
 

Item 3 If this statement is filed pursuant to Sections 240.13d-1(b) or 
240.13d-2(b) or (c), check whether the person filing is a:

 
	(a) [ ] Broker or dealer registered under section 15 of the Act 
	    	(15 U.S.C. 78o);

	(b) [ ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

	(c) [ ] Insurance company as defined in section 3(a)(19) of the Act 
		(15 U.S.C. 78c);

	(d) [ ] Investment company registered under section 8 of the Investment 
		Company Act of 1940 (15 U.S.C 80a-8);

	(e) [X] An investment adviser in accordance with Section 
		240.13d-1(b)(1)(ii)(E);

	(f) [ ] An employee benefit plan or endowment fund in accordance with 
		Section 240.13d-1(b)(1)(ii)(F);

	(g) [ ] A parent holding company or control person in accordance with 
		Section 240.13d-1(b)(1)(ii)(G);

	(h) [ ] A savings association as defined in Section 3(b) of the Federal 
		Deposit Insurance Act (12 U.S.C. 1813);

	(i) [ ] A church plan that is excluded from the definition of an
                investment company under section 3(c)(14) of the Investment
                Company Act (15 U.S.C. 80a-3);

	(j) [ ] A non-U.S. institution in accordance with Section 
		240.13d-1(b)(1)(ii)(J);

	(k) [ ] Group, in accordance with Section 240.13d-1(b)(1)(ii)(K). 

	If filing as a non-U.S. institution in accordance with Section
        240.13d-1(b)(1)(ii)(J), please specify the type of institution: ____

 

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CUSIP No.:  58471A105                   13G                   Page 4 of 5 Pages

  
Item 4. Ownership

Provide the following information regarding the aggregate number and 
percentage of the class of securities of the issuer identified in Item 1.

(a) Amount beneficially owned: 3,554,159

(b) Percent of class: 6.1%

(c) Number of shares as to which the person has:

	(i) Sole power to vote or to direct the vote: 2,382,759

	(ii) Shared power to vote or to direct the vote: None

	(iii) Sole power to dispose or to direct the disposition of: 3,554,159

	(iv) Shared power to dispose or to direct the disposition of: None

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

	If this statement is being filed to report the fact that as of the 
	date hereof the reporting person has ceased to be the beneficial 
	owner of more than 5 percent of the class of securities, check the 
	following [   ].
	

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

 
	Securities reported on this Schedule 13G are beneficially owned by 
	clients of Sands Capital Management, LLC.  Sands Capital Management, 
	LLC's clients include pension plans, endowments, foundations, 
	corporations, mutual and UCITS funds, charities, sovereign wealth
        funds, foreign funds, state and municipal government entities,
	Taft-Hartley plans, private investment funds, families,
	and individuals.
	
	The advisory clients of Sands Capital Management, LLC do not 
	individually own more than 5% of the outstanding shares.
 

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

	Not Applicable.
 

Item 8. Identification and Classification of Members of the Group.
 

	Not Applicable.
 

Item 9. Notice of Dissolution of Group.
 

	Not Applicable. 
  
 

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CUSIP No.:  58471A105                   13G                   Page 5 of 5 Pages

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 are 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, other than 
activities solely in connection with a nomination under Section 240.14a-11.
 

                                   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.

                                        Sands Capital Management, LLC


                                        Date:     February 14, 2018

                                        By:       /s/ Lisa M. Grozio
                                                  ----------------------
                                        Name:     Lisa M. Grozio
                                        Title:    Chief Compliance Officer