CBIO Catalyst Biosciences Inc

      CUSIP No.                 14888D208

          1.Names of Reporting Persons.

             Laurence W.Lytton

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

                USA

      5.Sole Voting Power       282,000 (1)

      6.Shared Voting Power

      7.Sole Dispositive Power  282,000 (1)

      8.Shared Dispositive Power


      9.Aggregate Amount Beneficially Owned by Each Reporting
      Person                    282,000 (1)


       (1) includes 194,500 common shares, and 250 Series A Pfd Stock
       convertible into 50,000 common shares and warrants to purchase
       37,500 shares at an exercise price of $5.50 per share.


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


      11.Percent of Class Represented by Amount in Row (9)
                                6.5% (2)

       (2) Based on 4,260,161 shares of common stock outstanding as of
       April 20, 2017, as reported in the Issuers Form 8-K filed with
       the SEC on April 24, 2017, plus the assumed conversion of reporting
       persons Series A Pfd Stock (50,000 shares if converted) and
       warrants (37,500 shares if converted).



      12.Type of Reporting Person (See Instructions)

                        IN

            Item 1.

      (a)Name of Issuer         Catalyst Biosciences, Inc.

      (b)Address of Issuer's Principal Executive Offices

                        260 Littlefield Ave.
                        South San Francisco, California




              Item 2.

      (a)Name of Person Filing  Laurence W. Lytton

      (b)Address of Principal Business Office or, if none, Residence

                467 CPW
                N.Y., NY  10025

      (c)Citizenship                    USA

      (d)Title of Class of Securities   Common

      (e)CUSIP Number                   14888D208

      Item 3.   not applicable


      Item 4.Ownership.

      (a)Amount beneficially owned:    282,000 (1).

      (b)Percent of class:              6.5%

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

      (i)Sole power to vote or to direct the vote       282,000 (1).

      (ii)Shared power to vote or to direct the vote

      (iii)Sole power to dispose or to direct the disposition of  282,000 (1).

      (iv)Shared power to dispose or to direct the disposition of


      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.

                        Not applicable

      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 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.
      ___5/1/17____________________________
      Date
      ____s/ Laurence W. Lytton____________________________
      Signature
      _____Laurence W. Lytton___________________________
      Name/Title