Exhibit 10.51

Confidential Materials omitted and filed separately with the

Securities and Exchange Commission. Asterisks
denote omissions.

THIRD AMENDMENT TO LICENSE, SUPPLY AND DISTRIBUTION AGREEMENT

THIS THIRD AMENDMENT TO LICENSE, SUPPLY AND DISTRIBUTION AGREEMENT is made and entered into as of this 19th day of December, 2006 (Effective Date) by and between
F.Hoffmann-La Roche Ltd. (FHLR) having a principal office at Grenzacherstrasse 124, Basel, Switzerland and 454 Life Sciences Corporation (454) having a principal office at 20 Commercial Street, Branford, CT 06405, USA.

RECITALS

WHEREAS, the Parties
have entered into a written License, Supply and Distribution Agreement dated May 11, 2005, as amended by the First Amendment to License, Supply and Distribution Agreement dated December 19, 2005 and the Second Amendment to License, Supply
and Distribution Agreement dated October 27, 2006 (License Agreement); and

WHEREAS, the Parties desire to sell a refurbished Rev.
1.0 (Rev. 1.0 is currently marketed under the product name GS 20) instrument as a Licensed Product under the Agreement.

NOW THEREFORE,
in consideration of the covenants and mutual promises set forth herein, the receipt and sufficiency of which are hereby acknowledged, the Parties agree as follows:

1. According to Section 3.3 (b) of the License Agreement the Parties hereby amend Exhibit 2 by adding as Licensed Product a Refurbished GS20 instrument (GS 20-R), with an initial estimated Average Sales Price of
$[**] (US):

(See attached document.)

GS 20-R has the same
Specification as Rev 1.0 instrument and will be assembled by 454 by adding a new camera to a Rev 1.0 (GS20) instrument returned as part of an Upgrade to a GS FLX instrument. It is agreed between the Parties that all Exhibits of the License Agreement
referring to Rev. 1.0 instrument shall equally apply to GS 20-R.

2. The third paragraph of Section 3.3 (e) is deleted in its entirety and
replaced by:

Based on its 2006 forecast, FHLR has ordered [**] Rev. 1.0 instruments from 454. The Parties agree that 454 will fill the order
with GS 20-R in accordance with the terms of the License Agreement. GS 20-R is warranted by 454 to FHLR for [**] from the date of delivery. This warranty may be extended by FHLR or its Affiliates to the customer.

An Upgrade of a GS 20-R to a GS FLX as provided in the first two paragraphs of this Section 3.3. (e) will be available to customers after one year of
ownership, except that the initial estimated AUUP for the Upgrade of a Refurbished GS20 shall be [**] US Dollars (US $ [**]) instead of [**] US Dollars (US $ [**]).



---

Section 3.4 (d) of the Original Agreement is amended to read as follows:

During the Initial Term of this Agreement FHLR shall pay minimum royalties on the 30th day of the first Contract Year and before the last day of the Contract Year
prior to each of the three subsequent Contract Years as follows:

1st Contract Year: US$ [**]
(Payment before January 30th2006)

2nd Contract Year: US$ [**] (Payment before December 31st2006)

3rd
Contract Year: US$ [**] (Payment before December 31st2007)

4th Contract Year: US$ [**] (Payment before December 31st2008).

454 has no right to ask for earlier payment than the
dates agreed on in this Section.

Such minimum royalties shall be fully applied to and deductible
from royalties due for Net Sales during the relevant Contract Year (relevant Contract Year for the 1stContract Year
payment is 2006, for the 2ndContract Year payment it is 2007 for the 3rdContract Year payment it is 2008 and for the 4thContract Year Payment it is 2009) provided that such minimum royalties shall be due only if Rev. 1.0 is available for Commercial Launch at FHLR in 2005, Rev. 1.1 is available for Commercial Launch at FHLR in 2006 and Rev.
2.0 is available for Commercial Launch at FHLR in 2008. Otherwise and in each case the amount of minimum royalties will have to be negotiated between the Parties in good faith.

IN WITNESS WHEREOF, each of the Parties has caused this Third Amendment to the Original Agreement to be executed by its duly authorized representative.



|                         |  |                         |  |                   |  |        |  |                          
|------------------------ |  | ----------------------- |  | ----------------- |  | ------ |  | -------------------------
|Basel,                   |  |                         |  | Branford,        
|F. Hoffmann-La Roche Ltd |  |                         |  | 454 Life Sciences
|                         |  |                         |  |                  
|By:                      |  | /s/ P. Saladin          |  |                   |  | By:    |  | /s/ Christopher K. McLeod
|Name:                    |  | P. Saladin              |  |                   |  | Name:  |  | Christopher K. McLeod    
|Title:                   |  | Head of Diag. Licensing |  |                   |  | Title: |  | President & CEO          
|Date:                    |  | Dec. 20, 2006           |  |                   |  | Date:  |  | December 19, 2006        



|       |  |                        |  |  |  |  |  | 
|------ |  | ---------------------- |  |  |  |  |  | 
|       |  |                        |  | 
|By:    |  | /s/ Claus Ruetsch      |  |  |  |  |  | 
|Name:  |  | Claus Ruetsch          |  |  |  |  |  | 
|Title: |  | Head Legal Diagnostics |  |  |  |  |  | 
|Date:  |  | Dec. 22, 2006          |  |  |  |  |  | 



---

|            |  |                                                                |  |      |  |                     |  |                                                         
|----------- |  | -------------------------------------------------------------- |  | ---- |  | ------------------- |  | --------------------------------------------------------
|Instrument 
|Cat. No.    |  | Product                                                        |  | ASP$ |  | Transfer Price$     |  | Transfer Price (incl Training Kits + Installation Kits)$
|            |  | Refurbished GS 20 Instrument                                   |  | [**] |  | [**]                |  | [**]                                                    
|            |  | including:                                                     |  |      |  |                     |  |                                                         
|04777115001 |  | Counterweight for the Bead Deposition Devices                  |  |      |  |                     |  |                                                         
|04777018001 |  | Camera Faceplate Guard                                         |  |      |  |                     |  |                                                         
|04777026001 |  | Nebulizer Holder                                               |  |      |  |                     |  |                                                         
|04777034001 |  | Medium Bead Deposition Device, Complete                        |  |      |  |                     |  |                                                         
|04777042001 |  | Medium Bead Deposition Device, Complete - 8 lanes              |  |      |  |                     |  |                                                         
|04777069001 |  | Large Bead Deposition Device, Complete (2 Regions)             |  |      |  |                     |  |                                                         
|04840712001 |  | Large Bead Deposition Device, Complete (4 Regions)             |  |      |  |                     |  |                                                         
|04840682001 |  | Large Bead Deposition Device, Complete (16 Regions)            |  |      |  |                     |  |                                                         
|            |  | Medium PicoTiterPlate Cartridge  40 x 75 format              |  |      |  |                     |  |                                                         
|            |  | Large PicoTiterPlate Cartridge  70 x 75 format               |  |      |  |                     |  |                                                         
|            |  | Swinlock Filter Unit                                           |  |      |  |                     |  |                                                         
|            |  | 16 Gauge Blunt Needles                                         |  |      |  |                     |  |                                                         
|            |  | Plastic Economy Forceps                                        |  |      |  |                     |  |                                                         
|            |  | Zeiss Tissue (Box)                                             |  |      |  |                     |  |                                                         
|            |  | Wash Tube Holder                                               |  |      |  |                     |  |                                                         
|            |  | Extra Fluidics Waste Tank and Bottle Support                   |  |      |  |                     |  |                                                         
|            |  | GS 20 DNA Library Preparation Kit Users Manual                |  |      |  |                     |  |                                                         
|            |  | GS 20 DNA Library Preparation Kit Quick Guide                  |  |      |  |                     |  |                                                         
|            |  | GS 20 emPCR Kit Users Guide                                   |  |      |  |                     |  |                                                         
|            |  | GS 20 emPCR Kit Quick Guide                                    |  |      |  |                     |  |                                                         
|            |  | Genome Sequencer 20 Operators Manual                          |  |      |  |                     |  |                                                         
|            |  | Genome Sequencer 20 Quick Guide                                |  |      |  |                     |  |                                                         
|            |  | GS 20 Data Processing Software Manual                          |  |      |  |                     |  |                                                         
|            |  | Genome Sequencer 20 Site Preparation Guide                     |  |      |  |                     |  |                                                         
|            |  | Genome Sequencer 20 Software                                   |  |      |  |                     |  |                                                         
|            |  |                                                                |  |     
|            |  | Additional items which must be ordered seperately              |  |      |  |                     |  |                                                         
|            |  |                                                                |  |     
|            |  | Training                                                       |  |      |  | Unit Transfer Price |  | Total Transfer Price                                    
|04852265001 |  | GS 20 DNA Library Preparation Kit                              |  |      |  | [**]                |  | [**]                                                    
|04852290001 |  | GS 20 emPCR Kit (3 units)                                      |  |      |  | [**]                |  | [**]                                                    
|04853342001 |  | GS 20 Sequencing Kit (70x75)                                   |  |      |  | [**]                |  | [**]                                                    
|04852419001 |  | GS 20 Sequencing Kit (40x75) (3 units)                         |  |      |  | [**]                |  | [**]                                                    
|04852427001 |  | GS 20 PicoTiterPlate Kit (70x75)                               |  |      |  | [**]                |  | [**]                                                    
|04746813001 |  | GS 20 PicoTiterPlate Kit (40x75) (3 units)                     |  |      |  | [**]                |  | [**]                                                    
|            |  |                                                                |  |     
|            |  | Installation                                                   |  |      |  |                     |  |                                                         
|04852389001 |  | GS 20 Installation Kit                                         |  |      |  | [**]                |  | [**]                                                    
|04853342001 |  | GS 20 Sequencing Kit (70x75)                                   |  |      |  | [**]                |  | [**]                                                    
|04852427001 |  | GS 20 PicoTiterPlate Kit (70x75)                               |  |      |  | [**]                |  | [**]                                                    
|            |  | Upgrade of GS20R to GS FLX: Transfer price as per Amendfment 2 |  | [**] |  | [**]                |  | [**]