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             Chiasma, Inc. 
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             (Name of Issuer) 
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             Common Stock 
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             (Title of Class of Securities) 
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             16706W102 
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             (CUSIP Number) 
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             December 31, 2019 
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             (Date of Event Which Requires Filing of this Statement) 
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                 CUSIP No.   16706W102 
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                 13G 
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                 Page 2 of 6 Pages 
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| Item 1(a). | Name of Issuer | 
| Item 1(b). | Address of Issuer's Principal Executive Offices | 
| Item 2(a). | Name of Person Filing | 
| Item 2(b). | Address of Principal Business Office or, if none, Residence | 
| Item 2(c). | Citizenship | 
| Item 2(d). | Title of Class of Securities | 
| Item 2(e). | CUSIP Number | 
| Item 3. | 
                 If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a: 
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| Item 4. | Ownership | 
| Item 5. | Ownership of Five Percent or Less of a Class | 
| Item 6. | Ownership of More Than Five Percent on Behalf of Another Person | 
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                     CUSIP No.   16706W102 
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                     13G 
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                     Page 3 of 6 Pages 
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| Item 7. | 
                 Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company 
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| Item 8. | Identification and Classification of Members of the Group | 
| Item 9. | Notice of Dissolution of Group | 
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                   Item 10. 
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                   Certification 
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               CUSIP No.   16706W102 
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               13G 
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               Page 4 of 6 Pages 
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             ARCH VENTURE FUND VI, L.P. 
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             By:   ARCH Venture Partners VI, L.P. 
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| its General Partner | 
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                By:   ARCH Venture Partners VI, LLC 
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                                 its General Partner 
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                 By:                   *                                           
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                                         Keith Crandell 
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                                         Managing Director 
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                 ARCH VENTURE PARTNERS VI, L.P. 
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                 By:   ARCH Venture Partners VI, LLC 
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| its General Partner | 
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                    By:                    *                                           
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                                     Keith Crandell 
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| Managing Director | 
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               ARCH VENTURE PARTNERS VI, LLC 
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               By:                       *                                           
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| Keith Crandell | |
| Managing Director | 
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                                                      *                                           
                       | 
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| Keith Crandell | 
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                                                          *                                           
                           | 
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                             Robert Nelsen 
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                                                            *                                           
                             | 
                          |
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                               Clinton Bybee 
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               * By:  /s/ Mark McDonnell                              
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            ||
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                          Mark McDonnell as  
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                          Attorney-in-Fact 
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               CUSIP No.   16706W102 
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               13G 
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               Page 5 of 6 Pages 
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               Dated:    February 13, 2020 
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               ARCH VENTURE FUND VI, L.P. 
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               By:   ARCH Venture Partners VI, L.P. 
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          |
| its General Partner | 
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                  By:   ARCH Venture Partners VI, LLC 
               | 
            |
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                                   its General Partner 
               | 
            
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                   By:                   *                                           
               | 
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                                           Keith Crandell 
               | 
            |
| 
                                           Managing Director 
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                   ARCH VENTURE PARTNERS VI, L.P. 
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              |
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                   By:   ARCH Venture Partners VI, LLC 
                 | 
              |
| its General Partner | 
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                      By:                    *                                           
                   | 
                |
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                                       Keith Crandell 
                   | 
                |
| Managing Director | 
| 
                 ARCH VENTURE PARTNERS VI, LLC 
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            |
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                 By:                       *                                           
               | 
            |
| Keith Crandell | |
| Managing Director | 
| 
                                                            *                                           
                             | 
                          |
| Keith Crandell | 
| 
                                                                *                                           
                                 | 
                              |
| 
                                   Robert Nelsen 
                                 | 
                              
| 
                                                                  *                                           
                                   | 
                                |
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                                     Clinton Bybee 
                                   | 
                                
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                 * By:  /s/ Mark McDonnell                              
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              ||
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                            Mark McDonnell as  
               | 
              ||
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                           Attorney-in-Fact 
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               CUSIP No.   16706W102 
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               13G 
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               Page 6 of 6 Pages 
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               ARCH VENTURE FUND VI, L.P. 
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          |
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               By:   ARCH Venture Partners VI, L.P. 
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          |
| its General Partner | 
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                  By:   ARCH Venture Partners VI, LLC 
               | 
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                                   its General Partner 
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                   By:  /s/ Keith Crandell                                
                     
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                                           Managing Director 
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                   ARCH VENTURE PARTNERS VI, L.P. 
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              |
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                   By:   ARCH Venture Partners VI, LLC 
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| its General Partner | 
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                      By:   /s/ Keith Crandell                                  
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| Managing Director | 
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                 ARCH VENTURE PARTNERS VI, LLC 
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                 By:   /s/ Keith Crandell                                  
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| Managing Director | 
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                   /s/ Keith Crandell                                          
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| Keith Crandell | 
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                       /s/ Robert Nelsen                                          
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                       Robert Nelsen 
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                         /s/ Clinton Bybee                                          
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                         Clinton Bybee 
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