Document:

EX-10.23

 Exhibit 10.23 

CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY
WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. 

LETTER WAIVER 
 Dated as of
June 10, 2014 
 MMS Funding LLC 
 c/o Life Sciences
Alternative Funding LLC 
 50 Main Street, Suite 1000 
 White
Plains, New York 10606 
 Attention: Richard Gumer and Stephen DeNelsky 

E-mail: rich@lsafunding.com; steve@lsafunding.com 

with a copy to: 
 Wilmer Cutler Pickering Hale and Dorr
LLP 
 7 World Trade Center 
 250 Greenwich
Street 
 New York, New York 10007 
 Attention: Jennifer C.
Berrent and George W. Shuster, Jr. 
 E-mail: Jennifer.Berrent@wilmerhale.com; George.Shuster@wilmerhale.com 

 

	RE:	Loan Agreement, dated as of June 25, 2013, between MMS Funding LLC, successor in interest to Life Sciences Alternative Funding LLC, as Lender (“Lender” or “you”), and Mevion Medical Systems,
Inc., as Borrower (“Borrower”), as amended by Amendment No. 1 to the Loan Agreement, dated as of February 7, 2014, between Lender and the Borrower and by the Letter Agreement dated as of February 7, 2014 between the Borrower
and Lender, (such Loan Agreement, as so amended, the “Loan Agreement”) 

 Ladies and Gentlemen: 

We refer to the Loan Agreement. Capitalized terms not otherwise defined in this letter agreement (this “Letter Waiver”) have the
same meanings as specified in the Loan Agreement; references to Articles, Sections, Schedules or Exhibits are references to Articles, Sections, Schedules or Exhibits to the Loan Agreement. 

1. Background 
 Borrower
is party to contracts referenced on Annex 1 hereto (the “Affected Contracts”) (A) pursuant to which (i) the Contract Parties thereto are beneficiaries of Rights of Setoff against future amounts payable to Borrower or its
Subsidiaries (as listed under Part 1 of Annex 1) (each a “Setoff”), (ii) the Contract Parties thereto have a field of exclusivity (as listed under Part 2 of Annex 1) (each, “Exclusivity”), or (iii) the Contract Parties
thereto are beneficiaries of most favored nation provisions (each, a “MFN”) (as listed in Part 3 of Annex 1) or (B) that is or may be deemed to be a Material Contract (as listed in Part 4 of Annex 1) (each, an “MC Affected
Contract”). Information was not included (A) relating to the Exclusivity, the MFNs or the Setoffs in the Affected Contracts, as applicable, on Schedule 8.19(k), and accordingly, for such 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 
reason alone (except as expressly provided in this Letter Waiver), the representations and warranties made under Section 8.06(a), 8.19(e)(iii) and 8.19(k), and under each Loan Document under
which such representations were made, confirmed or repeated, including the certificates delivered on June 25, 2013 and February 7, 2014 pursuant to Section 7.01(m) and Section 7.02(j), respectively (collectively, the
“Funding Date Certificates”), were not correct when made, and (B) relating to the MC Affected Contract on Schedule 8.19(a) and accordingly, for such reason alone (except as expressly provided in this Letter Waiver), the
representations and warranties made under Section 8.06(a) and 8.19(a), and under each Loan Document under which such representations were made, confirmed or repeated, including the Funding Date Certificates, were not correct when made (such
breaches, collectively, the “8.19 Rep Breaches”). 
 Borrower will restate its annual financial statements for fiscal years 2012
and 2013 based on a corrected September 30, 2011 balance sheet, which restatement is caused by, and which corrections are limited to, [***] which are reflected in the draft restated consolidated balance sheet and related statements of income,
stockholders’ equity and cash flows for the years ending September 30, 2012 and September 30, 2013 excerpted from the Borrower’s draft Registration Statement on Form S-1 dated as of June [10], 2014 (the “Draft Restated
Financials”), a copy of which is attached hereto as Annex 5 hereto. Solely with respect to (and including, with respect to later occurring periods, as a consequence of) the modifications reflected in the Draft Restated Financials, the
Financial Statements, Initial Forecast and all of the other financial information delivered on or in connection with the Tranche A Funding Date, the Tranche B Funding Date and on November 15, 2013, December 24, 2013 and February 12, 2014 pursuant to
Section 9.03 were not complete and correct as represented under Section 8.06(a) and Section 8.09, and under each Loan Document under which such representations were made, confirmed or repeated, including without limitation each of the compliance
certificates delivered pursuant to Section 9.03(c) (each, a “Compliance Certificate”) on December 24, 2013 and February 12, 2014 and each of the Funding Date Certificates (such breaches, collectively, the “Restated F/S Rep
Breaches”). 
 Each reference to the “MIT License” in the Schedules was incorrect in that such reference failed to include a
reference to the First Amendment, dated October 22, 2013, between Massachusetts Institute of Technology and Borrower, a copy of which was delivered to Lender with the Funding Date Certificate dated February 7, 2014. Accordingly, solely with respect
to such omission, the representations made with respect to Section 8.06(a) and 8.18 under the Funding Date Certificate dated February 7, 2013, were incorrect (such breach of representation, the “License Reference Breach”). 

As Lender is aware, and following, in each case conversations with Lender: (i) Borrower did not deliver the quarterly financial information
required to be delivered to Lender pursuant to Sections 9.03(a) for the fiscal quarter ending June 30, 2013 or the compliance certificate required to be delivered to Lender therewith pursuant to Section 9.03(c) because such fiscal quarter ended only
five days after the Tranche A Funding Date; (ii) Borrower did not deliver within the time period required the quarterly financial information required to be delivered to Lender pursuant to Sections 9.03(a), or the compliance certificate required to
be delivered to Lender therewith pursuant to Section 9.03(c), for the fiscal quarter ending September 30, 2013, and instead delivered on November 15, 2013 drafts of the financial information required to be delivered with respect to such quarter end,
and, on December 24, 2013, delivered the audited annual financial information required to be delivered to Lender under 9.03(b) with the compliance certificate required to be delivered therewith pursuant to Section 9.03(c) for the fiscal year ending
September 30, 2013; (iii) Borrower did not include statements of stockholders equity in the quarterly financial information delivered to Lender pursuant to Section 9.03(a) for the fiscal quarter ending December 31, 2014; and Borrower did not
delivered the quarterly financial information required to be delivered to Lender pursuant to Sections 9.03(a), or the compliance certificate required to be delivered to Lender therewith pursuant to Section 9.03(c), for the fiscal quarter ending
March 31, 2104 (the breaches described in the foregoing clauses (i)-(iv), collectively, the “F/S Delivery Breaches”). 
 The
representation that no Default or Event of Default had occurred and is continuing was incorrect [***] (such breaches of representations described in clauses (a) and (b), collectively, the “Certificate Breaches”, and, together with
the 8.19 Rep Breaches and the Restated F/S Rep Breaches, the “Representation Breaches”). 
 2. Events of Default 

Each Representation Breach gives rise to an Event of Default under Section 11.01(c), and Borrower’s failure to provide notices of the
foregoing as required under Section 9.03(f) and Section 9.08(a), gives rise to Events of Default under Section 11.01(d) and (e), respectively (such Events of Default under Section 11.01(c), (d) and (e) with respect to the Representation Breaches,
the “Existing Representation Events of Default”). Each F/S Delivery Breach gives rise to an Event of Default under Section 11.01(d), and Borrower’s failure to provide notices of the foregoing as required under Section 9.08(a), gives
rise to an Event of Default under Section 11.01(e) (such Events of Default under Section 11.01(d) and 11.01(e) with respect to the F/S Delivery Breaches, together with the Existing Representation Events of Default, the “Existing Events of
Default”). 
 3. Waiver and Consent 

Borrower hereby requests that you waive, effective as of the date hereof, the Existing Events of Default. By your execution of this Letter
Waiver, and subject to the terms of this Letter Waiver and in reliance on the representations and warranties and covenants contained herein, you hereby irrevocably and unconditionally waive the Existing Events of Default, effective as of the date
hereof. 
 Borrower hereby requests that Lender consent to the amendment of the Contract with [***] attached as Annex 4 hereto, and
Lender hereby irrevocably and unconditionally consents to such amendment. 
 4. Acknowledgements, Representations and Warranties, and
Covenants 
 Borrower represents and warrants to Lender that (i) the descriptions of the Existing Events of Default set forth in
this Letter Waiver are true, correct, and complete, (ii) no Defaults or Events of Default other than the Existing Events of Default have occurred and are continuing as of the date hereof, (iii) Borrower has not breached its obligations
with respect to a field of exclusivity, or any “uptime” warranty, afforded any Contract Party under a Material Contract, (iv) Borrower has not received or delivered any notice regarding termination of any Material Contract that is a
sole-source supplier contract, [***] (vi) after giving effect to the Letter Agreement, dated as of the date hereof, between Lender and Borrower, Schedule 8.19(a) is complete and accurate, (vii) as of the Tranche B Funding Date, and on
the basis of the Draft Restated Financials, the Profit Condition and the Patient Treatment Condition were satisfied, and (viii) since February 7, 2104, no Material Adverse Effect has occurred, and, as of the date of this Agreement, there
are no events, circumstance, changes, actions, proceedings or claims pending or threated that would reasonably be expected to have, individually or in the aggregate, a Material Adverse Effect. 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Borrower acknowledges and agrees that, as of May 31, 2014, the principal balance of the
outstanding Obligations under the Loan Agreement is at least $30,650,000.00, which amount does not include Fixed Interest and Revenue Participation, fees, expenses and other amounts that are chargeable or otherwise reimbursable under the Loan
Agreement. Borrower is in compliance with the payment schedule attached hereto as Annex 3. Borrower agrees that it will pay on a timely basis all interest and other amounts due to Lender under the Loan Agreement or other Loan Documents.
Borrower hereby agrees to pay Lender a wavier fee of $[***], which fee shall be fully earned upon Lender’s execution and delivery of this Letter Waiver. 

Borrower confirms, acknowledges and agrees that all of the Obligations, including those set forth above, are valid and outstanding, and
Borrower does not have any rights of Setoff, defenses, claims or counterclaims with respect to any of the Obligations. Borrower hereby indemnifies, holds harmless, and forever releases Lender from any and all Liens, claims, interests and causes of
action of any kind or nature that Borrower or any Third Party now has or may hereafter have against Lender that relate to the Loan Agreement or other Loan Documents based on facts existing on or before the date hereof or that are related to or arise
in connection with this Letter Waiver, other than a breach hereof by Lender. 
 Borrower confirms, acknowledges and agrees that, with the
exception of the limited waiver described in this Letter Waiver which is subject to the terms and conditions hereof, Lender has now and will have the right to accelerate the Obligations and exercise other rights and remedies based upon the
occurrence and continuance of any Event of Default (other than the Existing Events of Default) that occurs, and that this Letter Waiver and the waivers described herein is of substantial value to Borrower. Without limiting the foregoing, Borrower
confirms, acknowledges and agrees that any information provided to Lender (or its agents) with respect to the Master Purchase Agreement by and between Mevion Medical Systems, Inc. and Storrington Industries Limited, dated as of May 10, 2012 (the
“Storrington Contract”) in connection with this Letter Waiver is not, and shall not be deemed to be a modification of Schedule 8.19(e) and shall be disregarded for determining whether any breach under, or termination of, the Storrington
Contract, gives rise to an Event of Default under Section 11.01(l), or whether any modification of the Storrington Contract results in an Event of Default under Section 11.01(e) with respect to a breach of Section 9.11. 

The Loan Agreement, the Notes and each of the other Loan Documents, except to the extent of the waiver specifically provided above, are and
shall continue to be in full force and effect and are hereby in all respects ratified and confirmed. Without limiting the generality of the foregoing, the Security Agreement and all of the Collateral described therein do and shall continue to secure
the payment of all Obligations of Borrower Parties under the Loan Documents. 
 Except as expressly provided herein, the execution and
delivery of this Letter Waiver shall not: (i) constitute an extension, modification, or waiver of any term, provision or aspect of, or any right, power or remedy of Lender under, the Loan Agreement or any of the other Loan Documents;
(ii) extend the terms of the Loan Agreement or the due date of any of the Obligations; (iii) give rise to any obligation on the part of Lender to extend, amend, waive or otherwise modify any term or condition of the Loan Agreement or any
of the other Loan Documents; or (iv) give rise to any defenses or counterclaims to the right of Lender to compel payment of the Obligations or to otherwise enforce its rights and remedies under the Loan Agreement and the other Loan Documents.
Except as expressly set forth in the third section of this Letter Waiver, Lender hereby expressly reserves all of its rights and remedies under the Loan Agreement and the other Loan Documents and under applicable Law with respect to the Existing
Events of Default and otherwise. 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 5. Miscellaneous 

If you agree to the terms and provisions of this Letter Waiver, please evidence such agreement by executing and returning a copy of this Letter
Waiver by electronic mail, and promptly thereafter by national courier two counterparts of this Letter Wavier, to: 
 Mevion Medical
Systems, Inc. 
 300 Foster Street 

Littleton, Massachusetts 01460 

Attention: Chief Financial Officer 

E-mail: dmelson@mevion.com 
 with
a copy to: 
 Goodwin Procter LLP 

Exchange Place 
 53 State
Street 
 Boston, Massachusetts 02109 

Attention: Anna E. Dodson 

E-mail: adodson@goodwinprocter.com 

Without limiting Section 5.02 of the Loan Agreement, Borrower agrees to pay on demand all reasonable costs and expenses of Lender,
including but not limited to the reasonable fees and out-of-pocket expenses of counsel to Lender. In partial payment of such fees and expenses, Borrower shall pay Lender on the date of this Letter Waiver an amount equal to $[***] in fees and
expenses estimated to have been incurred to date, and Lender will provide Borrower copies of invoices against which such amount shall be applied. 

This Letter Waiver is subject to the provisions of Section 13.05 of the Loan Agreement and is a “Loan Document” for all
purposes under the Loan Agreement and Loan Documents, including Article XII. 
 This Letter Waiver may be executed in any number of
counterparts and by different parties hereto in separate counterparts, each of which when so executed shall be deemed to be an original and all of which taken together shall constitute one and the same agreement. Delivery of an executed counterpart
of a signature page to this Letter Waiver by telecopier shall be effective as delivery of a manually executed counterpart of this Letter Waiver. 

This Letter Waiver shall be governed by and construed in accordance with the Laws of the State of New York (without giving effect to any
conflict of laws principles that would require application of the Laws of another jurisdiction). 
 [Signature page follows.] 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 
			
	Very truly yours,
	
	MEVION MEDICAL SYSTEMS, INC.
		
	By:	 	/s/ Joseph Jachinowski
	Name:	 	Joseph Jachinowski
	Title:	 	President and CEO

 Agreed as of the date first above written: 
  

			
	MMS FUNDING LLC
		
	By:	 	/s/ Ian C. Wildgoose Brown
	Name:	 	Ian C. Wildgoose Brown
	Title:	 	Authorized Person

 [Signature Page to Letter Waiver] 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 CONSENT 

Dated as of June 10, 2014 

The undersigned, Mevion Medical Systems UK, LLC, a Delaware limited liability company, as Guarantor under the Guarantee Agreement and a
Grantor under the Security Agreement (the “Guarantor”), each in favor of Lender party to the Loan Agreement referred to in the foregoing Letter Waiver (capitalized terms used herein and not defined herein have the meaning ascribed thereto
in such Loan Agreement), hereby consents to such Letter Waiver and hereby confirms and agrees that (a) notwithstanding the effectiveness of such Letter Waiver, each of the Guarantee Agreement and the Security Agreement is, and shall continue to
be, in full force and effect and is hereby ratified and confirmed in all respects, and (b) the Security Agreement and all of the Collateral described therein do, and shall continue to, secure the payment of all of the Obligations. 

 

			
	
	MEVION MEDICAL SYSTEMS UK LLC
		
	By:	 	/s/ Joseph Jachinowski
	Name:	 	Joseph Jachinowski
	Title:	 	President and CEO

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Annex 1 

Affected Contracts 
 [***] 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

  
 Part 2 (Exclusivity) 

 

			
	 Customer/Supplier/Vendor (Contract Date)
	  	
	 Robert Wood Johnson University Hospital (May 4, 2006)
	  	System Build Contract by and between Still River Systems, Inc. and Robert Wood Johnson University Hospital, dated as of May 4, 2006.
		
	 Techprecision Corp. (December 4, 2012)
	  	Master Purchase Agreement by and between Mevion Medical Systems, Inc., dated as of December 4, 2012. (Section 4)
		
	 Storrington Industries Limited (May 10, 2012)
	  	Master Purchase Agreement by and between Mevion Medical Systems, Inc. and Storrington Industries Limited, dated as of May 10, 2012. (Section 4)
		
	 [***]
	  	[***]
		
	 [***]
	  	[***]
		
	 [***]
	  	[***]
		
	[***][***Two pages redacted***]	  	

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Annex 2 

Summary of Corrections in Draft Restatements 

Prior to Fiscal Year 2012 
 1. Recorded a loss accrual/inventory
write-down for BJH due to the $[***] penalty in the amount of $[***]. Of this, $[***] was recorded as a write-down to inventories and the remainder was recorded to accrued contract losses. This was also reflected as an adjustment to the opening
accumulated deficit of fiscal year 2012. 
 2. Approximately $[***] of other miscellaneous adjustment recorded to the opening accumulated deficit for fiscal
year 2012. 
 Fiscal Year 2012 
 1. $[***] of BJH installation
costs that were previously recorded in the statement of operations for fiscal year 2012 were removed from the statement of operations and charged against the accrued contract losses that was established prior to fiscal year 2012 as noted above. 

2. Other miscellaneous adjustments netting to an unfavorable statement of operations impact of $[***].

Fiscal Year 2013 
 1. $[***] of BJH installation costs that were
previously recorded in the statement of operations for fiscal year 2013 were removed from the statement of operations and charged against the accrued contract losses that was established prior to fiscal year 2012 as noted above. 

2. $[***] of favorable contract loss adjustments for [***] that were recorded to the statement of operations in fiscal year 2013 had $[***] pushed back to
September 30, 2011. The remaining $[***] was for the [***] that the Company had excluded from its loss accrual assessment but feels should now be recorded after further review of the contract. 

3. Other miscellaneous adjustments netting to an unfavorable statement of operations impact of $[***]. 

4. A balance sheet reclassification adjustment to accumulated deficit from additional paid in capital of $[***] to reflect the excess of fair value over
carrying value for preferred stock that was forced to convert to common stock during fiscal year 2013. 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Annex 3 

Updated Payment Schedule 
 [***] 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Annex 4 

[***] Contract Amendment 
 [***][***Three
pages redacted***] 

  

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Annex 5 

Restated Financial Statements 

Mevion Medical Systems, Inc. and Subsidiaries 

Index to Consolidated Financial Statements 
  

			
	 	  	Pages
	 Reports of Independent Registered Public Accounting Firms
	  	F-2
	 Consolidated Balance Sheets as of September 30, 2013 and 2012 and as of March 
31, 2014 (unaudited), Actual and Pro Forma
	  	F-4
	 Consolidated Statements of Operations for the Years Ended September 
30, 2013 and 2012 and the Six Months Ended March 31, 2014 and 2013 (unaudited)
	  	F-5
	 Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Deficit for the Years Ended
 September 30, 2013 and 2012 and the Six Months Ended March 31, 2014 (unaudited)
	  	F-6
	 Consolidated Statements of Cash Flows for the Years Ended September 
30, 2013 and 2012 and the Six Months Ended March 31, 2014 and 2013 (unaudited)
	  	F-9
	 Notes to Consolidated Financial Statements
	  	F-10

  
 F-1 

 Report of Independent Registered Public Accounting Firm 

The Board of Directors and Stockholders 
 Mevion Medical Systems,
Inc. and Subsidiaries 
 We have audited the accompanying consolidated balance sheet of Mevion Medical Systems, Inc. and Subsidiaries as of
September 30, 2013, and the related consolidated statements of operations, redeemable convertible preferred stock and stockholders’ deficit, and cash flows for the year then ended. These financial statements are the responsibility of the
Company’s management. Our responsibility is to express an opinion on these financial statements based on our audit. 
 We conducted our
audit in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of
material misstatement. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audit included consideration of internal control over financial reporting as a basis for
designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion. An
audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall
financial statement presentation. We believe that our audit provides a reasonable basis for our opinion. 
 In our opinion, the consolidated
financial statements referred to above present fairly, in all material respects, the financial position of Mevion Medical Systems, Inc. and Subsidiaries as of September 30, 2013, and the results of its operations and its cash flows for the year
then ended, in conformity with U.S. generally accepted accounting principles. 
 /s/ McGladrey LLP 

Boston, Massachusetts 
 June 10, 2014 

  
 F-2 

 Report of Independent Registered Public Accounting Firm 

The Board of Directors and Stockholders 
 Mevion Medical Systems,
Inc. and Subsidiaries 
 We have audited the accompanying consolidated balance sheet of Mevion Medical Systems, Inc. and Subsidiaries as of
September 30, 2012, and the related consolidated statements of operations, redeemable convertible preferred stock and stockholders’ deficit, and cash flows for the year then ended. These financial statements are the responsibility of the
Company’s management. Our responsibility is to express an opinion on these financial statements based on our audit. 
 We conducted our
audit in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of
material misstatement. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audit included consideration of internal control over financial reporting as a basis for
designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion. An
audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall
financial statement presentation. We believe that our audit provides a reasonable basis for our opinion. 
 In our opinion, the consolidated
financial statements referred to above present fairly, in all material respects, the financial position of Mevion Medical Systems, Inc. and Subsidiaries as of September 30, 2012, and the results of their operations and their cash flows for the
year then ended, in conformity with U.S. generally accepted accounting principles. 
 /s/ HEIN & ASSOCIATES LLP 

Denver, Colorado 
 June 10, 2014 

  
 F-3 

 Mevion Medical Systems, Inc. and Subsidiaries 

Consolidated Balance Sheets 

(In thousands) 
  

																	
	 	  	September 30,
2013	 	 	September 30,
2012	 	 	March 31,
2014	 	 	Pro Forma
March 31,
2014	 
	 	  	 	 	 	 	 	 	(unaudited)	 
	 Assets
	  				 				 				 			
	 Current assets:
	  				 				 				 			
	 Cash and cash equivalents
	  	$	12,058	  	 	$	19,084	  	 	$	18,559	  	 	$	18,559	  
	 Accounts receivable
	  	 	—  	  	 	 	—  	  	 	 	1,086	  	 	 	1,086	  
	 Inventories
	  	 	39,819	  	 	 	26,539	  	 	 	47,041	  	 	 	47,041	  
	 Deposits on inventory purchases
	  	 	1,858	  	 	 	3,729	  	 	 	1,481	  	 	 	1,481	  
	 Prepaid expenses
	  	 	366	  	 	 	356	  	 	 	610	  	 	 	610	  
	 Other current assets
	  	 	19	  	 	 	75	  	 	 	255	  	 	 	255	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total current assets
	  	 	54,120	  	 	 	49,783	  	 	 	69,032	  	 	 	69,032	  
	 Property and equipment, net
	  	 	6,072	  	 	 	5,178	  	 	 	5,756	  	 	 	5,756	  
	 Deferred financing costs, net
	  	 	1,035	  	 	 	—  	  	 	 	1,243	  	 	 	1,243	  
	 Other assets
	  	 	183	  	 	 	198	  	 	 	162	  	 	 	162	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total Assets
	  	$	61,410	  	 	$	55,159	  	 	$	76,193	  	 	$	76,193	  
	 Liabilities, Redeemable Convertible Preferred Stock, and Stockholders’ Deficit
	  				 				 				 			
	 Current liabilities:
	  				 				 				 			
	 Accounts payable
	  	$	2,104	  	 	$	2,938	  	 	$	3,111	  	 	$	3,111	  
	 Accrued expenses
	  	 	934	  	 	 	585	  	 	 	845	  	 	 	845	  
	 Accrued compensation and benefits
	  	 	1,883	  	 	 	1,484	  	 	 	1,883	  	 	 	1,883	  
	 Deferred revenue
	  	 	—  	  	 	 	—  	  	 	 	4,052	  	 	 	4,052	  
	 Customer deposits
	  	 	38,040	  	 	 	38,630	  	 	 	50,540	  	 	 	50,540	  
	 Contract loss accruals
	  	 	2,234	  	 	 	2,086	  	 	 	3,938	  	 	 	3,938	  
	 Other liabilities
	  	 	—  	  	 	 	—  	  	 	 	4,720	  	 	 	4,720	  
	 Accrued financing fees, current portion
	  	 	128	  	 	 	—  	  	 	 	171	  	 	 	171	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total current liabilities
	  	 	45,323	  	 	 	(45,723	  	 	 	69,260	  	 	 	69,260	  
	 Long-term liabilities:
	  				 				 				 			
	 Long term debt, net
	  	 	19,817	  	 	 	—  	  	 	 	29,635	  	 	 	29,635	  
	 Deferred revenue
	  	 	357	  	 	 	357	  	 	 	1,329	  	 	 	1,329	  
	 Accrued financing fees, net of current portion
	  	 	246	  	 	 	—  	  	 	 	753	  	 	 	753	  
	 Warrant liability
	  	 	1,787	  	 	 	1,278	  	 	 	3,529	  	 	 	—  	  
	 Other non-current liabilities
	  	 	244	  	 	 	143	  	 	 	264	  	 	 	264	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total liabilities
	  	 	67,774	  	 	 	(47,501	  	 	 	104,770	  	 	 	101,241	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Commitments and contingencies (Note 15)
	  				 				 				 			
	 Redeemable convertible preferred stock, $0.01 par value—aggregate liquidation preference of $158,131, $140,958, and $158,131 at
September 30, 2013, September 30, 2012, and March 31, 2014 (unaudited), respectively
	  	 	155,533	  	 	 	(138,263	  	 	 	155,914	  	 	 	—  	  
	 Stockholders’ deficit:
	  				 				 				 			
	 Common stock, $0.001 par value—authorized 12,000 shares; issued and outstanding, 471 shares, 141 shares, 473 shares, and 9,377
shares at September 30, 2013, September 30,2012, March 31, 2014 (unaudited), and March 31, 2014 pro forma (unaudited), respectively
	  	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	9	  
	 Additional paid-in capital
	  	 	1,147	  	 	 	492	  	 	 	903	  	 	 	160,337	  
	 Accumulated deficit
	  	 	(163,044	) 	 	 	(131,097	) 	 	 	(185,394	) 	 	 	(185,394	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total stockholders’ deficit
	  	 	(161,897	) 	 	 	(130,605	) 	 	 	(184,491	) 	 	 	(25,048	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total Liabilities, Redeemable Convertible Preferred Stock, and Stockholders’ Deficit
	  	$	61,410	  	 	$	55,159	  	 	$	76,193	  	 	$	76,193	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 

 See accompanying notes to consolidated financial statements. 

  
 F-4 

 Mevion Medical Systems, Inc. and Subsidiaries 

Consolidated Statements of Operations 

(In thousands, except per share data) 
  

																	
	 	  	September 30,	 	 	Six Months Ended
March 31,	 
	 	  	2013	 	 	2012	 	 	2014	 	 	2013	 
	 	  	 	 	 	 	 	 	(unaudited)	 
	 Revenue
	  	$	—  	  	 	$	—  	  	 	$	—  	  	 	$	—  	  
	 Cost of revenue
	  	 	—  	  	 	 	—  	  	 	 	4,408	  	 	 	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Gross loss
	  	 	—  	  	 	 	—  	  	 	 	(4,408	) 	 	 	—  	  
	 Operating expenses:
	  				 				 				 			
	 Research and development
	  	 	26,155	  	 	 	18,921	  	 	 	8,614	  	 	 	10,846	  
	 Selling and marketing
	  	 	3,779	  	 	 	2,473	  	 	 	1,660	  	 	 	1,768	  
	 General and administrative
	  	 	7,804	  	 	 	7,276	  	 	 	4,009	  	 	 	4,154	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total operating expenses
	  	 	37,738	  	 	 	28,670	  	 	 	14,283	  	 	 	16,768	  
	 Gain on termination of contracts
	  	 	—  	  	 	 	750	  	 	 	—  	  	 	 	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Loss from operations. Other income (expense):
	  	 	(37,738	) 	 	 	(27,920	) 	 	 	(18,691	) 	 	 	(16,768	) 
	 Interest expense
	  	 	(1,117	) 	 	 	(144	) 	 	 	(1,897	) 	 	 	(150	) 
	 (Loss) gain on revaluation of warrants
	  	 	(44	) 	 	 	1,514	  	 	 	(1,742	) 	 	 	(3	) 
	 Other (expense) income, net
	  	 	(7	) 	 	 	14	  	 	 	(20	) 	 			
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Total other (expense) income, net
	  	 	(1,168	) 	 	 	1,384	  	 	 	((3,659	) 	 	 	(153	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net loss
	  	 	(38,906	) 	 	 	(26,536	) 	 	 	(22,350	) 	 	 	(16,921	) 
	 Accretion of redeemable convertible preferred stock to redemption value
	  	 	(659	) 	 	 	(572	) 	 	 	(381	) 	 	 	(296	) 
	 Gain on extinguishment of redeemable convertible preferred stock
	  	 	6,959	  	 	 	—  	  	 	 	—  	  	 	 	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net loss attributable to common stockholders
	  	$	(32,606	) 	 	$	(27,108	) 	 	$	(22,731	) 	 	$	(17,217	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net loss per share attributable to common stockholders—basic and diluted
	  	$	(118.68	) 	 	$	(207.10	) 	 	$	(49.00	) 	 	$	(129.02	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Weighted-average common shares used in computing net loss per share attributable to common stockholders—basic and diluted
	  	 	275	  	 	 	131	  	 	 	464	  	 	 	133	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Pro forma net loss per share attributable to common stockholders—basic and diluted (unaudited)
	  	$	(4.60	) 	 				 	$	(2.39	) 	 			
		  	  
	  
	 	 				 	  
	  
	 	 			
	 Pro forma weighted-average number of common shares used in net loss per share applicable to common stockholders—basic and diluted
(unaudited)
	  	 	8,465	  	 				 	 	9,368	  	 			
		  	  
	  
	 	 				 	  
	  
	 	 			

 See accompanying notes to consolidated financial statements. 

  
 F-5 

 Mevion Medical Systems, Inc. and Subsidiaries 

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Deficit 

(In thousands) 
  

																																																																					
	 	 	Series E
Redeemable
Convertible
Preferred
Stock	 	 	Series D-1
Redeemable
Convertible
Preferred
Stock	 	 	Series D
Redeemable
Convertible
Preferred
Stock	 	 	Series A
Redeemable
Convertible
Preferred
Stock	 	 	Series B
Redeemable
Convertible
Preferred
Stock	 	 	Series C
Redeemable
Convertible
Preferred
Stock	 	 	Common
Stock	 	 	 	 	 	 	 	 	 	 	 	 	 
	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Additional
Paid-in
Capital	 	 	Accumulated
Deficit	 	 	Total
Stockholders’
Deficit	 
	 Balance, September 30, 2011
	 	 	—  	  	 	$	 —  	  	 	 	827	  	 	$	11,561	  	 	 	2,915	  	 	$	49,727	  	 	 	72	  	 	$	4,700	  	 	 	119	  	 	$	10,081	  	 	 	161	  	 	$	16,850	  	 	 	133	  	 	$	 —  	  	 	$	641	  	 	$	(104,561	) 	 	$	(103,920	) 
	 Issuance of restricted common stock
	 				 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 				 	 	8	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 			
	 Exercise of stock options
	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	3	  	 	 	—  	  	 	 	3	  
	 Exercise of warrants to purchase Series D-1 preferred stock
	 				 	 	—  	  	 	 	5	  	 	 	44	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 				 				 				 				 				 				 	 	—  	  	 	 	—  	  
	 Stock-based compensation
	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	420	  	 	 	—  	  	 	 	420	  
	 Issuance of Series E preferred stock, net of issuance costs
	 	 	2,802	  	 	 	44,728	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 				 				 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 				 				 				 	 	—  	  	 	 	—  	  	 	 	—  	  
	 Accretion of preferred stock to redemption value
	 				 	 	36	  	 	 	—  	  	 	 	473	  	 				 	 	54	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	9	  	 	 	—  	  	 	 	—  	  	 	 	(572	) 	 				 	 	(572	) 
	 Net loss
	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	(26,536	) 	 	 	(26,536	) 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Balance, September 30, 2012
	 	 	2,802	  	 	$	44,764	  	 	 	832	  	 	$	12,078	  	 	 	2,915	  	 	$	49,781	  	 	 	72	  	 	$	4,700	  	 	 	119	  	 	$	10,081	  	 	 	161	  	 	$	16,859	  	 	 	141	  	 	$	 —  	  	 	$	492	  	 	$	(131,097	) 	 	$	(130,605	) 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 

  
 F-6 

 Mevion Medical Systems, Inc. and Subsidiaries 

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Deficit 

(In thousands) 
  

																																																																					
	 	 	Series E
Redeemable
Convertible
Preferred
Stock	 	 	Series D-1
Redeemable
Convertible
Preferred
Stock	 	 	Series D
Redeemable
Convertible
Preferred
Stock	 	 	Series A
Redeemable
Convertible
Preferred
Stock	 	 	Series B
Redeemable
Convertible
Preferred
Stock	 	 	Series C
Redeemable
Convertible
Preferred
Stock	 	 	Common
Stock	 	 	 	 	 	 	 	 	 	 
	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Numberof
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Additional
Paid-in
Capital	 	 	Accumulated
Deficit	 	 	Total
Stockholders’
Deficit	 
	 Balance, September 30, 2012
	 	 	2,802	  	 	$	44,764	  	 	 	832	  	 	$	12,078	  	 	 	2,915	  	 	$	49,781	  	 	 	72	  	 	$	4,700	  	 	 	119	  	 	$	10,081	  	 	 	161	  	 	$	16,859	  	 	 	141	  	 	$	 —  	  	 	$	492	  	 	$	(131,097	) 	 	$	(130,605	) 
	 Issuance of restricted common stock
	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	7	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  
	 Stock-based compensation
	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	446	  	 	 	—  	  	 	 	446	  
	 Issuance of Series E preferred stock, net of issuance costs
	 	 	1,557	  	 	 	24,438	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  
	 Accretion of preferred stock to redemption value
	 	 	—  	  	 	 	110	  	 	 	—  	  	 	 	482	  	 	 	—  	  	 	 	51	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	16	  	 	 	—  	  	 	 	—  	  	 	 	(659	) 	 	 	—  	  	 	 	(659	) 
	 Gain on extinguishment and conversion of preferred stock
	 	 	(19	) 	 	 	(305	) 	 	 	—  	  	 	 	—  	  	 	 	(145	) 	 	 	(2,500	) 	 	 	—  	  	 	 	—  	  	 	 	(29	) 	 	 	(2,405	) 	 	 	(25	) 	 	 	(2,617	) 	 	 	323	  	 	 	—  	  	 	 	868	  	 	 	6,959	  	 	 	7,827	  
	 Net loss
	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	(38,906	) 	 	 	(38,906	) 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Balance, September 30, 2013
	 	 	4,340	  	 	$	69,007	  	 	 	832	  	 	$	12,560	  	 	 	2,770	  	 	$	47,332	  	 	 	72	  	 	$	4,700	  	 	 	90	  	 	$	7,676	  	 	 	136	  	 	$	14,258	  	 	 	471	  	 	$	 —  	  	 	$	1,147	  	 	$	(163,044	) 	 	$	(161,897	) 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 

  
 F-7 

 Mevion Medical Systems, Inc. and Subsidiaries 

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Deficit 

(In thousands) 
  

																																																																					
	 	 	Series E
Redeemable
Convertible
Preferred
Stock	 	 	Series D-1
Redeemable
Convertible
Preferred
Stock	 	 	Series D
Redeemable
Convertible
Preferred
Stock	 	 	Series A
Redeemable
Convertible
Preferred
Stock	 	 	Series B
Redeemable
Convertible
Preferred
Stock	 	 	Series C
Redeemable
Convertible
Preferred
Stock	 	 	Common Stock	 	 	 	 	 	 	 	 	 	 
	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Number
of
Shares	 	 	Amount	 	 	Additional
Paid-in
Capital	 	 	Accumulated
Deficit	 	 	Total
Stockholders’
Deficit	 
	 Balance, September 30, 2013
	 	 	4,340	  	 	$	69,007	  	 	 	832	  	 	$	12,560	  	 	 	2,770	  	 	$	47,332	  	 	 	72	  	 	$	4,700	  	 	 	90	  	 	$	7,676	  	 	 	136	  	 	$	14,258	  	 	 	471	  	 	$	–  	  	 	$	1,147	  	 	$	(163,044	) 	 	$	(161,897	) 
	 Exercise of stock options (unaudited)
	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	2	  	 	 	–  	  	 	 	8	  	 	 	–  	  	 	 	8	  
	 Stock-based compensation (unaudited)
	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	129	  	 	 	–  	  	 	 	129	  
	 Accretion of preferred stock to redemption value (unaudited)
	 	 	–  	  	 	 	104	  	 	 	–  	  	 	 	248	  	 	 	–  	  	 	 	26	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	3	  	 	 	–  	  	 	 	–  	  	 	 	(381	) 	 	 	–  	  	 	 	(381	) 
	 Net loss (unaudited)
	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 				 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	–  	  	 	 	(22,350	) 	 	 	(22,350	) 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Balance, March 31, 2014 (Unaudited)
	 	 	4,340	  	 	$	69,111	  	 	 	832	  	 	$	12,808	  	 	 	2,770	  	 	$	47,358	  	 	 	72	  	 	$	4,700	  	 	 	90	  	 	$	7,676	  	 	 	136	  	 	$	14,261	  	 	 	473	  	 	$	–  	  	 	$	903	  	 	$	(185,394	) 	 	$	(184,491	) 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 

 See accompanying notes to consolidated financial statements. 

  
 F-8 

 Mevion Medical Systems, Inc. and Subsidiaries 

Consolidated Statements of Cash Flows 

(In thousands) 
  

																	
	 	  	Year Ended September 30,	 	 	Six Months Ended March 31,	 
	 	  	2013	 	 	2012	 	 	2014	 	 	2013	 
	 	  	 	 	 	 	 	 	(unaudited)	 
	 Cash flows from operating activities:
	  				 				 				 			
	 Net loss
	  	$	(38,906	) 	 	$	(26,536	) 	 	$	(22,350	) 	 	$	(16,921	) 
	 Adjustments to reconcile net loss to net cash used in operating activities:
	  				 				 				 			
	 Stock-based compensation
	  	 	446	  	 	 	420	  	 	 	129	  	 	 	251	  
	 Depreciation and amortization
	  	 	2,122	  	 	 	1,658	  	 	 	1,211	  	 	 	1,038	  
	 Loss on disposal of property and equipment
	  	 	79	  	 	 	15	  	 	 	86	  	 	 	85	  
	 Provision for inventory write-downs
	  	 	1,916	  	 	 	402	  	 	 	988	  	 	 	—  	  
	 Amortization of deferred financing fees
	  	 	68	  	 	 	—  	  	 	 	107	  	 	 	—  	  
	 Gain (loss) on revaluation of warrants
	  	 	44	  	 	 	(1,514	) 	 	 	1,742	  	 	 	—  	  
	 Non-cash interest expense
	  	 	442	  	 	 	—  	  	 	 	434	  	 	 	10	  
	 Changes in assets and liabilities:
	  				 				 				 			
	 Accounts receivable
	  	 	—  	  	 	 	—  	  	 	 	(1,086	) 	 	 	—  	  
	 Inventories
	  	 	(17,197	) 	 	 	(13,347	) 	 	 	(8,737	) 	 	 	(10,447	) 
	 Deposits on inventory purchases
	  	 	1,871	  	 	 	(2,108	) 	 	 	377	  	 	 	1,420	  
	 Prepaid expenses and other current assets
	  	 	45	  	 	 	39	  	 	 	(480	) 	 	 	(194	) 
	 Other long term assets
	  	 	126	  	 	 	(198	) 	 	 	10	  	 	 	24	  
	 Accounts payable
	  	 	(445	) 	 	 	1,001	  	 	 	1,007	  	 	 	(824	) 
	 Accrued expenses
	  	 	748	  	 	 	799	  	 	 	(117	) 	 	 	(88	) 
	 Customer deposits
	  	 	(590	) 	 	 	16,460	  	 	 	12,500	  	 	 	2,062	  
	 Deferred revenue
	  	 	—  	  	 	 	—  	  	 	 	5,022	  	 	 	—  	  
	 Contract loss accruals
	  	 	147	  	 	 	(640	) 	 	 	1,706	  	 	 	(537	) 
	 Other liabilities
	  	 	(74	) 	 	 	(282	) 	 	 	4,703	  	 	 	171	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net cash used in operating activities
	  	 	(49,158	) 	 	 	(23,831	) 	 	 	(2,748	) 	 	 	(23,950	) 
	 Cash flows from investing activities:
	  				 				 				 			
	 Purchases of property and equipment
	  	 	(1,050	) 	 	 	(2,298	) 	 	 	(444	) 	 	 	(1,080	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net cash used in investing activities
	  	 	(1,050	) 	 	 	(2,298	) 	 	 	(444	) 	 	 	(1,080	) 
	 Cash flows from financing activities:
	  				 				 				 			
	 Proceeds from issuance of long-term debt
	  	 	20,000	  	 	 	—  	  	 	 	10,000	  	 	 	—  	  
	 Proceeds from issuance of convertible notes payable
	  	 	10,000	  	 	 	5,000	  	 	 	—  	  	 	 	10,000	  
	 Proceeds from issuance of Series E preferred stock and warrants, net
	  	 	14,285	  	 	 	39,008	  	 	 	—  	  	 			
	 Payments for long-term debt financing costs
	  	 	(1,103	) 	 	 	—  	  	 	 	(315	) 	 	 	—  	  
	 Proceeds from the exercise of stock options and warrants
	  	 	—  	  	 	 	3	  	 	 	8	  	 	 	—  	  
	 Repayment of capital lease obligation
	  	 	—  	  	 	 	(9	) 	 	 	—  	  	 	 	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net cash provided by financing activities
	  	 	43,182	  	 	 	44,002	  	 	 	9,693	  	 	 	10,000	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Net (decrease) increase in cash and cash equivalents
	  	 	(7,026	) 	 	 	17,873	  	 	 	6,501	  	 	 	(15,030	) 
	 Cash and cash equivalents, beginning of period
	  	 	19,084	  	 	 	1,211	  	 	 	12,058	  	 	 	19,084	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Cash and cash equivalents, end of period
	  	$	12,058	  	 	$	19,084	  	 	$	18,559	  	 	$	4,054	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Supplemental disclosure of cash flow information:
	  				 				 				 			
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Cash paid for interest
	  	$	626	  	 	$	—  	  	 	$	1,389	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Supplemental disclosure of noncash investing and financing activities:
	  				 				 				 			
	 Conversion of notes payable and accrued interest to preferred stock
	  	$	10,229	  	 	$	5,174	  	 	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Conversion of preferred stock to common stock
	  	$	7,827	  	 	$	—  	  	 	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Conversion of accounts payable to preferred stock
	  	$	389	  	 	$	546	  	 	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Inventory transferred to property and equipment, net
	  	$	2,001	  	 	$	1,020	  	 	$	524	  	 	$	28	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Accretion of preferred stock to redemption value
	  	$	659	  	 	$	572	  	 	$	381	  	 	$	296	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Gain on extinguishment of preferred stock
	  	$	6,959	  	 	$	—  	  	 	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Debt discount
	  	$	374	  	 	$	—  	  	 	$	578	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Asset retirement obligation establishment
	  	$	155	  	 	$	—  	  	 	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Reclassification of fair value of liability-classified warrants upon exercise
	  	$	—  	  	 	$	44	  	 	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 

 See accompanying notes to consolidated financial statements. 

  
 F-9 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	1.	BACKGROUND AND ORGANIZATION 

 Mevion Medical Systems, Inc. and Subsidiaries (the
“Company”), a medical technology company headquartered in Littleton, Massachusetts, was incorporated in the state of Delaware on February 26, 2004. The Company is engaged in the development, sale, and service of proton beam radiation
therapy systems. The Company has two wholly-owned subsidiaries, Mevion Medical Systems Asia, K.K., and Mevion Medical Systems UK LLC, which were incorporated in September 2008 and May 2012, respectively. The Company reports its financial condition
and results of operations on a fiscal year basis ending on September 30th of each year. 
 Since inception, the Company has devoted
substantially all of its efforts toward product research and development, initial sales and market development, raising capital and preparing for the production and shipment of the MEVION S250, which is a proton radiation therapy device not
customized to customer specifications. In March of 2012, the Company was granted the CE mark to sell its products in the European Community countries. In July of 2012, the Company was granted 510(k) clearance from the U.S. Food and Drug
Administration (“FDA”) to sell its products domestically. On December 13, 2013, the MEVION S250 received its first clinical acceptance at a customer site and the first patient treatment with that system was performed on
December 19, 2013. Upon the first patient treatment, the Company exited the development stage. 
 Liquidity 

The Company has funded its operations primarily through the issuance of preferred stock, debt, and payments from customers. As of
March 31, 2014, the Company had an accumulated deficit of $185,394. The Company believes that its cash resources of $18,559 at March 31, 2014, will be sufficient to allow the Company to fund its current operating plan through
December 31, 2014. As the Company continues to incur losses, transition to profitability is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company may never achieve profitability, and
unless and until doing so, the Company will continue to need to raise additional capital. Management intends to fund future operations through additional private or public debt or equity offerings, and may seek additional capital through
arrangements with strategic partners or from other sources. There can be no assurances, however, that additional funding will be available on terms acceptable to the Company or if at all. 

 

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES 

 The accompanying consolidated financial
statements reflect the application of certain significant accounting policies, as described below and elsewhere in the accompanying notes to the consolidated financial statements. 

Principles of Consolidation 
 The
consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. The functional currency of all its foreign
wholly-owned subsidiaries is the U.S. dollar and therefore the Company has not recorded any currency translation adjustments. 
 Foreign Currency

 The foreign currency translation gains and losses resulting from exchange rate fluctuations of transactions denominated in a currency
other than functional currency are included in other (expense) income in the consolidated statements of operations. Such amounts are not material for fiscal 2013 and fiscal 2012 and the six months ended March 31, 2014 and 2013. 

  
 F-10 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 Use of Estimates 

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires
management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amount of expenses during the
reporting period. Such management estimates include those relating to revenue recognition, inventory write-downs to reflect net realizable value, assumptions used in the valuation of stock-based awards and warrants, accruals for contract losses, and
valuation allowances against deferred tax assets. Actual results could differ from those estimates. 
 Unaudited Interim Financial Information 

The accompanying consolidated balance sheet as of March 31, 2014, statements of operations and of cash flows for the six months ended
March 31, 2014 and 2013, and the statements of changes in redeemable convertible preferred stock and stockholders’ deficit for the six months ended March 31, 2014 are unaudited. The interim unaudited consolidated financial statements
have been prepared on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s
financial position as of March 31, 2014 and the results of its operations and its cash flows for the six months ended March 31, 2014 and 2013. The financial data and other information disclosed in these notes related to the six months
ended March 31, 2014 and 2013 are also unaudited. The results for the six months ended March 31, 2014 are not necessarily indicative of results to be expected for the year ending September 30, 2014, any other interim periods, or any
future year or period. 
 Unaudited Pro Forma Information 

Upon the completion of a qualified initial public offering (“IPO”), all of the redeemable convertible preferred stock (see Note 7)
will automatically convert into 8,904 shares of common stock. The accompanying unaudited pro forma balance sheet as of March 31, 2014 has been prepared to give effect to such conversions as if the conversions had occurred on March 31,
2014. In addition, the preferred stock warrant of $3,529 has been reclassified to additional paid-in capital. Unaudited pro forma basic and diluted net loss per share allocable to common stockholders for the year ended September 30, 2013 and
the six months ended March 31, 2014 has been prepared to give effect to the conversions as if the conversions had occurred on October 1, 2012 or the date of issuance, if later. 

Revenue Recognition 
 The Company’s
product contains both software and non-software components that together deliver essential functionality. As a result, the Company will recognize revenue for product sales under the non-software accounting guidance. Sales generally involve multiple
deliverables of equipment, installation and related services. At the inception of a sales agreement, the Company allocates the contract value to each deliverable based on its relative selling price. 

  
 F-11 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 The Company determines selling prices using vendor specific objective evidence
(“VSOE”), if it exists, or third party evidence (“TPE”). If neither VSOE nor TPE exists for a deliverable, the Company uses estimated selling price (“ESP”). VSOE is generally limited to the price charged when the same
or similar products or services are sold separately or, if applicable, the stated substantive renewal rate in the agreement. TPE is determined based on the prices charged by competitors for a similar deliverable when sold separately. Typically, the
Company is not able to use TPE as it is difficult to obtain sufficient information on competitor pricing. If the Company is unable to establish selling price using VSOE or TPE, the Company uses ESP. The objective of ESP is to determine the price at
which the Company would sell a product or service on a standalone basis. 
 In order to determine ESP, the Company considers the cost to
produce the deliverable, the anticipated margin on that deliverable, the selling price and profit margin for similar parts and the Company’s ongoing pricing strategy and policies. 

The Company will recognize revenue related to equipment when title and risk of loss is passed to the customer, provided that there is
persuasive evidence of an arrangement, the sales price is fixed or determinable, collection of the related receivable is reasonably assured and customer acceptance criteria have been successfully demonstrated. The Company does not sell any products
that are designed to customer specifications. 
 The Company’s sales contracts, which require that the Company perform the
installation, transfer title and risk of loss to the customer once the installation of the product is completed and the customer has accepted the product. Products that are sold with customer acceptance criteria are classified as either
“new” or “established” products. Products are initially classified as new and are only classified as established once post customer acceptance provisions have been determined to be routine and there is a demonstrated history of
achieving the final acceptance provisions without extraordinary effort. In determining when a proton radiation system is considered “established”, the Company considers the following factors: (i) achieving the satisfactory uptime
performance of installed systems and (ii) experiencing clinical commissioning post customer acceptance with minimal Company support. The Company believes that reaching these criteria at several customer sites will demonstrate that there are no
material uncertainties regarding customer acceptance of the system. 
 For established proton radiation systems, the Company will recognize
revenue when the customer accepts the installed unit and title and risk of loss transfers to the customer, provided all other revenue recognition criteria have been met. Customer acceptance is defined as the point when the installation has been
completed and the customer acknowledges that the unit operates in accordance with the contractually defined specifications. For contracts of proton radiation systems considered to be new or containing post customer acceptance milestones with
substantive performance conditions, product revenue will be recorded upon the achievement of such performance conditions. 
 Typically,
sales agreements include payment milestones that extend beyond the point of customer acceptance and generally represent 20% or less of the total contract value. These milestones are essentially payment holdbacks based on the customer achieving their
work requirements and any efforts required by the Company are normally perfunctory. The Company will exclude these holdbacks from the revenue that will be recorded upon customer acceptance. Revenue from post customer acceptance milestones will be
recognized as those milestones are achieved. To the extent that any contract contains a post customer acceptance milestone with substantive performance conditions, no revenue will be recognized until all such performance conditions are met. 

  
 F-12 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 For proton radiation systems that the Company does not install, such as those sold to
distributors who are trained, responsible for installation and have a demonstrated track record of installing without Company support, the Company will recognize product revenue upon delivery of the final system component to the distributor,
provided that title and risk of loss have passed to the distributor with no rights of return and any distributor acceptance criteria have been met. The Company’s sales contracts with distributors generally provide for the distributor to accept
title and risk of loss once the final component is shipped by the Company to the distributor, which is normally 12 to 18 months before installation is completed by the distributor. Revenue will not be recognized in excess of milestones payments
billed. For sales to distributors with acceptance criteria that are not successfully demonstrated upon delivery, revenue will be recognized upon the distributor’s customer acceptance similar to when the Company is responsible for installation.

 The Company generally receives non-refundable milestone payments that are initially recorded as customer deposits on the balance sheet.
When a customer fails to perform its contractual obligations and such failure continues after notice of breach and a cure period, the Company may terminate the contract and the customer may be liable for contractual damages. At the time of
termination, the Company includes in income from operations any non-refundable deposits, deferred revenue, deferred costs and any costs associated with terminating the contract including excess inventory or unrecoverable vendor advances. 

With each MEVION S250, the Company provides a warranty that normally ranges from 12 to 24 months and may be extended for a limited number of
additional months subject to certain performance criteria. The warranty includes not only the costs to repair and replace defective parts, but also any costs of required maintenance during the warranty period. The Company separates the estimated
value of these services and will recognize the revenue on a straight-line basis over the warranty period. 
 The Company will classify
shipping and handling charges as revenue and the related costs in cost of revenue. 
 Deferred revenue includes amounts that have been
billed per the contractual terms but have not yet been recognized as revenue. 
 Fair Value of Financial Instruments 

The Company’s financial instruments include cash and cash equivalents, accounts receivable, accounts payable, and accrued expenses.
Because of their short maturity, the carrying amount of these financial instruments approximates fair value. 
 The Company’s financial
instruments also include long-term debt, for which the carrying value approximates fair value at September 30, 2013 and March 31, 2014 as the long-term debt was recently obtained and the interest rates approximate market rates. The
disclosure of the estimated fair value of the long-term debt was determined using level 2 inputs in the fair value hierarchy (Note 8). 
 Cash and
Cash Equivalents 
 The Company considers all short-term, highly liquid investments with original maturities of 90 days or less to be
cash equivalents. Cash equivalents primarily consist of investments in money market accounts. 
 Concentration of Credit Risk 

The Company maintains its cash in bank deposit accounts which, at times, may exceed federally insured limits. The Company has not experienced
any losses in such accounts. The Company believes it is not exposed to any significant credit risk on cash and cash equivalents. Concentration of credit risk, with respect to cash and cash equivalents, is limited because the Company places its
investments in highly rated institutions. 

  
 F-13 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 Inventories 

Inventory costs are stated at the lower of cost or market. Certain manufacturing and installation costs incurred prior to the commencement of
commercial operations are included in research and development expenses in the consolidated statements of operations. 
 Management assesses
the recoverability of inventory based on types and levels of inventory, estimated inventory costs related to incomplete contracts as compared to expected contract revenue, product life cycle, and changes in technology. Inventory write-downs are
based upon the age of the inventory, estimated net realizable value, and other significant management judgments concerning future demands for the inventory. The Company continues to assess the net realizable value of its inventory and could be
required to write-off previously capitalized costs upon a change in the various judgments noted above. All inventories, including amounts expected to be on hand for more than one year, are classified as a current asset. 

Inventories consist of the following: 
  

													
	 	  	September 30,	 	  	 	 
	 	  	2013	 	  	2012	 	  	March 31, 2014	 
	 	  	 	 	  	 	 	  	(unaudited)	 
	 Raw materials
	  	$	15,732	  	  	$	10,827	  	  	$	15,350	  
	 Work-in-process
	  	 	24,087	  	  	 	15,712	  	  	 	31,691	  
		  	  
	  
	 	  	  
	  
	 	  	  
	  
	 
		  	$	39,819	  	  	$	26,539	  	  	$	47,041	  
		  	  
	  
	 	  	  
	  
	 	  	  
	  
	 

 Approximately $16,312, $8,836, and $22,847 of the inventory balance at September 30, 2013 and 2012 and
March 31, 2014, respectively, represents the costs of equipment being installed at customer sites. 
 Property and equipment: 

Property and equipment is recorded at cost and depreciated using the straight-line method over its estimated useful life. Property and
equipment consisted of the following: 
  

															
	 	  	 	  	September 30,	 
	 	  	Estimated Useful
Lives	  	2013	 	 	2012	 	 	March 31, 2014	 
	 	  	 	  	 	 	 	 	 	 	(unaudited)	 
	 Property and equipment:
	  		  				 				 			
	 Machinery and equipment
	  	5years	  	$	5,248	  	 	$	4,384	  	 	$	5,525	  
	 Research and development capital
	  	5years	  	 	4,321	  	 	 	2,376	  	 	 	4,579	  
	 Leasehold improvements
	  	Lessor of lease
term or useful life
of asset	  	 	2,318	  	 	 	2,140	  	 	 	2,318	  
	 Computer hardware and office equipment
	  	3-5years	  	 	964	  	 	 	842	  	 	 	1,069	  
	 Software
	  	3-5years	  	 	653	  	 	 	631	  	 	 	656	  
	 Furniture and fixtures
	  	5years	  	 	411	  	 	 	279	  	 	 	411	  
	 Construction in progress
	  		  	 	75	  	 	 	411	  	 	 	129	  
		  		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 
		  		  	 	13,990	  	 	 	11,063	  	 	 	14,687	  
	 Less: accumulated depreciation and amortization
	  		  	 	(7,918	) 	 	 	(5,885	) 	 	 	(8,931	) 
		  		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 
		  		  	$	6,072	  	 	$	5,178	  	 	$	5,756	  
		  		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 

  
 F-14 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 Depreciation and amortization expense for fiscal 2013 and fiscal 2012 and the six months
ended March 31, 2014 and 2013 was $2,078, $1,658, $1,199 and $1,013, respectively. 
 Upon retirement or disposal, the cost of the
asset disposed of and the related accumulated depreciation are removed from the accounts and any gain or loss is reflected in the Company’s consolidated statements of operations. Expenditures for maintenance and repairs are charged to expense
when incurred while the costs of significant improvements, which extend the life of the underlying asset, are capitalized. 
 Impairment of Long-Lived
Assets 
 Long-lived assets are reviewed for impairment when circumstances indicate the carrying value of an asset may not be
recoverable. For assets that are to be held and used, impairment is recognized when the estimated undiscounted cash flows associated with the asset or group of assets is less than their carrying value. If impairment exists, an adjustment is made to
write the asset down to its fair value, and a loss is recorded as the difference between the carrying value and fair value. Fair values are determined based on quoted market values, discounted cash flows or internal and external appraisals, as
applicable. Assets to be disposed of are carried at the lower of carrying value or estimated net realizable value. 
 Research and Development Costs

 Expenditures, including payroll, contractor expenses, and supplies, for research and development of products and manufacturing
processes are expensed as incurred. 
 Software development costs incurred subsequent to establishing technological feasibility are
capitalized through the general release of the products that contain the embedded software elements. Technological feasibility is demonstrated by the completion of a working model. The Company has not capitalized any software development costs as of
March 31, 2014 since the costs incurred subsequent to achieving technological feasibility and completing the research and development for the hardware components were immaterial. 

Segment Information 
 The Company operates
in one business segment, which is the manufacturing, sale and service of proton radiation therapy systems. Operating segments are identified as components of an enterprise about which separate discrete financial information is available for
evaluation by the chief operating decision maker in making decisions regarding resource allocation and assessing performance. To date, the chief operating decision maker has made such decisions and assessed performance at the company level, as one
segment. The Company’s chief operating decision maker is the Chief Executive Officer. 
 Asset Retirement Obligation 

The Company records obligations associated with its lease obligations, the retirement of tangible long-lived assets and the associated
asset-retirement costs in accordance with authoritative guidance on asset retirement obligations. The Company reviews legal obligations associated with the retirement of long-lived assets that result from contractual obligations or the acquisition,
construction, development and/or normal use of assets. If it is determined that a legal obligation exists, the fair value of the liability for an asset retirement obligation is recognized in the period in which it is incurred, if a reasonable
estimate of fair value can be made. When the 

  
 F-15 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 
liability is initially recorded, the Company capitalizes the cost of the asset retirement obligation. Over time, the liability is accreted to its present value, and the capitalized cost
associated with the retirement obligation is depreciated over the useful life of the related asset. 
 Convertible Instruments 

The Company evaluates and accounts for conversion options embedded in its convertible instruments in accordance with professional standards.
Professional standards generally provide three criteria that, if met, require companies to bifurcate conversion options from their host instruments and account for them as free standing derivative financial instruments. These three criteria include
circumstances in which (a) the economic characteristics and risks of the embedded derivative instruments are not clearly and closely related to the economic characteristics and risks of the host contract, (b) the hybrid instrument that
embodies both the embedded derivative instrument and the host contract is not re-measured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur and (c) a
separate instrument with the same terms as the embedded derivative instrument would be considered a derivative instrument. 
 Income Taxes 

The Company assesses income taxes for federal, state, local and foreign jurisdictions. Income taxes are accounted for under the liability
method. Deferred taxes are determined based on the difference between the financial reporting and tax basis of assets and liabilities, using enacted tax rates in effect in the years in which the differences are expected to reverse. Due to
uncertainty of realization of the tax benefits, the Company has provided a valuation allowance for the full amount of its net deferred tax assets. 

The Company accounts for uncertain tax positions using a “more-likely-than-not” threshold for recognizing and resolving uncertain
tax positions. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters
subject to audit, new audit activity and changes in facts or circumstances related to a tax position. The Company evaluates these tax positions on an annual basis. The Company also accrues for potential interest and penalties related to unrecognized
tax benefits in income tax expense (see Note 10). 
 The Company recognizes the tax benefit of tax positions to the extent that the
benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and
circumstances. 
 Debt Financing Costs and Discounts 

Direct and incremental costs, as well as debt discounts, incurred in obtaining loans or in connection with the issuance of long-term debt are capitalized and amortized to interest expense over the terms of the related debt agreements using the effective interest rate method. 

Redeemable Convertible Preferred Stock 

The Company reviews the rights and preferences of its equity securities for any changes in terms, rights or preferences to determine if such
change is a modification or an extinguishment. The Company evaluates amendments to equity securities using a qualitative method which considers the business purpose for the 

  
 F-16 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 
amendment and whether it adds, deletes or significantly changes a substantive contractual term or the nature of the equity securities. An amendment that changes a substantive contractual term or
fundamentally changes the nature of the share of preferred stock is considered an extinguishment. If considered an extinguishment, the Company accounts for the removal of the carrying value of the old securities and recognizes the new securities at
their current fair value in accordance with the guidance in ASC 470-50, Debt—Modifications and Extinguishments. An amendment that does not meet these criteria is a modification. A modification would be accounted for in accordance with
the guidance in ASC 718-20, Compensation—Stock Compensation, in which the Company estimates the fair value of the equity security pre- and post- modification and recognizes the incremental fair value, if any, resulting from the modified
terms. 
 Stock-Based Compensation 
 The
Company accounts for all stock options and awards, including modifications to awards, granted to employees and non-employees, using a fair value method. The Company has elected to use the Black-Scholes option pricing model to determine the fair
value of stock options granted. In accordance with the accounting standard, the Company recognizes the compensation cost of stock-based awards on a straight-line basis over the vesting period of the award. 

The fair value of common stock has been determined by the Board of Directors at each award grant date based upon a variety of factors,
including the results obtained from independent third-party valuations, the Company’s financial position and historical financial performance, an evaluation of benchmark of the Company’s competition, the current climate in the marketplace,
the effect of the rights and preferences of the preferred stockholders and the prospects of a liquidity event, among others. 
 The interest
rate was based on the U.S. Treasury bond rate at the date of grant with a maturity approximately equal to expected term. The Company has estimated the expected term of its employee stock options using the “simplified” method, whereby, the
expected term equals the arithmetic average of the vesting term and the original contractual term of the option due to its lack of sufficient historical data. Expected volatility for the Company’s common stock was based on an average of the
historical volatility of a peer group of similar public companies. The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. In developing a forfeiture rate estimate, the Company has
considered its historical experience to estimate pre-vesting forfeitures for service-based awards. The estimation of stock-based awards that will ultimately vest requires judgment, and to the extent actual results differ from the Company’s
estimates, such amounts will be recorded as an adjustment in the period estimates are revised. 
 Warrants to Purchase Redeemable Convertible Preferred
Stock 
 The Company reviews the terms of all warrants issued in connection with the applicable accounting guidance and classifies
warrants as a long-term liability on the consolidated balance sheets if the warrant may conditionally obligate the Company to transfer assets, including repurchase of the issuer’s shares, at some point in the future. Warrants to purchase shares
of redeemable convertible preferred stock meet these criteria and therefore require liability-classification. The Company classifies warrants within stockholders’ equity on the consolidated balance sheets if the warrants are considered to be
indexed to the Company’s own stock, and otherwise would be recorded in stockholders’ equity. 

  
 F-17 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	2.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued) 

  

 Liability-classified warrants are subject to re-measurement at each balance sheet date, and
any change in fair value is recognized as a component of other income (expense) in the consolidated statements of operations. The Company estimates the fair value of these warrants at issuance and each balance sheet date thereafter using the
Black-Scholes option-pricing model as described in the stock-based compensation section above, based on the estimated market value of the underlying redeemable convertible preferred stock at the valuation measurement date, the remaining contractual
term of the warrant, risk-free interest rates, expected dividends and expected volatility of the price of the underlying redeemable convertible preferred stock. 
  

	3.	RECENT ACCOUNTING PRONOUNCEMENTS 

 In July 2013, the Financial Accounting Standards Board
(“FASB”) issued Accounting Standards Update (“ASU”) No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exist. ASU 2013-11 amends
the presentation requirements of ASC 740, Income Taxes, and requires an unrecognized tax benefit to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, similar tax loss, or a tax
credit carryforward. To the extent the tax benefit is not available at the reporting date under the governing tax law or if the entity does not intend to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented
as a liability and not combined with deferred tax assets. The ASU is effective for annual periods, and interim periods within those years, beginning after December 15, 2013, which is fiscal 2014 for the Company. The amendments are to be applied
to all unrecognized tax benefits that exist as of the effective date and may be applied retrospectively to each prior reporting period presented. The adoption of this standard did not have a material impact on our consolidated financial statements.

 In May 2014, the FASB issued ASU No. 2014-09—Revenue from Contracts with Customers (Topic 606). ASU 2014-09 supersedes most of
the existing guidance on revenue recognition in Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition. The core principle of the revenue model is that an entity recognizes revenue to depict the transfer of promised goods
or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In applying the revenue model to contracts within its scope, an entity will need to
(i) identify the contract(s) with a customer (ii) identify the performance obligations in the contract (iii) determine the transaction price (iv) allocate the transaction price to the performance obligations in the contract and
(v) recognize revenue when (or as) the entity satisfies a performance obligation. ASU No. 2014-09 is effective for public entities for annual and interim periods beginning after December 15, 2016. The ASU allows for either full
retrospective adoption, where the standard is applied to all of the periods presented, or modified retrospective adoption, where the standard is applied only to the most current period presented in the financial statements. The Company is currently
assessing the impact of this standard to its consolidated financial statements. 
  

	4.	CUSTOMER CONTRACTS AND CONCENTRATIONS 

 Customer Revenue and Accounts Receivable 

The Company had one customer that accounted for 92% of the accounts receivable balance at March 31, 2014. 

Customer Deposits 
 Customer deposits
represent refundable and non-refundable payments from customers upon achievement of certain milestones in the delivery of the product, as defined by individual contracts with the customers. All customer deposits, including those that are expected to
be a deposit for more than one year, are classified as 

  
 F-18 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	4.	CUSTOMER CONTRACTS AND CONCENTRATIONS (continued) 

  

 
current liabilities. Customer deposits for equipment are initially classified as deposits, and then reclassified to deferred revenue when title and risk of loss passes or services have been
provided, but revenue has not been recognized. At September 30, 2013 and 2012, non-refundable deposits from 14 customers totaled $33,040 and $30,630 respectively. At March 31, 2014, non-refundable deposits from 13 customers totaled
$47,540. 
 Refundable deposits at September 30, 2013 and 2012 and March 31, 2014 from two customers, three customers, and one
customer totaled $5,000, $8,000, and $3,000, respectively. 
 In fiscal year 2013, the Company terminated a sales contract and refunded the
customer $3,000 of a deposit held by the Company at September 30, 2012. In fiscal year 2012, the Company terminated a sales contract and refunded the customer $250 of a $1,000 deposit. The remaining $750 was recognized as a gain on termination
of contracts in the consolidated statements of operations in fiscal year 2012. 
  

	5.	DEBT 

 On June 25, 2013, the Company entered into a Loan Agreement and a Security
Agreement (collectively, the “Loan Agreement”) with Life Sciences Alternative Funding LLC (“LSAF”) that includes two tranches at an annual interest rate of 14.75%. The Company will make monthly interest payments at an annual rate
of 11.75% and the remaining 3.00% will be added to the principal balance for the first thirty-six months of the Loan Agreement. Beginning in June 2016, the Company will begin repaying the principal balance compounded daily for accrued interest in
twenty-four monthly installments. Penalties ranging from 1.00% to 5.00% will be incurred for any outstanding principal prepayments made prior to June 25, 2018. Tranche A was executed on June 25, 2013 and the Company received $20,000 and
Tranche B was executed for $10,000 on February 6, 2014. 
 In executing Tranche B, the term of the loan was extended one year to
June 25, 2019 and the Company will begin repaying the outstanding principal balance for Tranches A and B in thirty monthly installments beginning in December 2016. 

During the term of the Loan Agreement, the Company will make revenue participation payments to LSAF of 0.30% and 0.15% of the cash collected
from its customers for Tranches A and B, respectively, with a maximum amount of $1,000 and $500, respectively. The Company incurred $374 and $578 during fiscal 2013 and the six months ending March 31, 2014, respectively, for the estimated
revenue participation payments the Company believes are probable of being paid. The $374 and $578 have been recorded as a discount to the $20,000 and $30,000 long-term debt at September 30, 2013 and March 31, 2014, respectively, and are
being accreted over the term of the Loan Agreement using the effective interest rate method. During fiscal year 2013 and the six months ended March 31, 2014, $31 and $45, respectively, of the discount was accreted as interest expense in the
consolidated statements of operations. During the six months ended March 31, 2014, $29 of revenue participation payments were made to LSAF. The unamortized balance of the discount at September 30, 2013 and March 31, 2014 was $343 and
$876, respectively. 
 Borrowings under the Loan Agreement may be used for general corporate purposes, including permitted acquisitions.
Under the Loan Agreement, all tangible and intangible assets of the Company serve as collateral for borrowings under the Loan Agreement. Any failure to comply with the operating covenants of the Loan Agreement or a change in control of the Company,
as defined in the Loan Agreement, would constitute a default, permitting LSAF, among other things, to accelerate repayment of outstanding borrowings, including all accrued interest and fees, and to terminate the Loan Agreement. In May 2014, the
Company determined that it had breached certain representations and warranties under the Loan Agreement during the periods presented. In June 2014, the Company secured a waiver covering these breaches. 

  
 F-19 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	5.	DEBT (continued) 

  

 In connection with entering into the Loan Agreement, the Company incurred $1,103 and $315 of
transaction costs for Tranches A and B, respectively, which have been deferred and are being expensed using the effective interest rate method over the term of the Loan Agreement. Total amortization expense of these transaction costs recognized as
interest expense in the consolidated statements of operations in fiscal year 2013 and the six months ended March 31, 2014 was $68 and $107, respectively. The unamortized balance of the deferred financing fees at September 30, 2013 and
March 31, 2014 was $1,035 and $1,243, respectively. 
 The aggregate maturities of long-term debt outstanding at September 30,
2013 and March 31, 2014 are as follows: 
  

									
	 Fiscal year
	  	September 30, 2013	 	  	March 31, 2014	 
	 	  	 	 	  	(unaudited)	 
	 2016
	  	$	2,193	  	  	$	—  	  
	 2017
	  	 	9,697	  	  	 	8,004	  
	 2018
	  	 	8,270	  	  	 	12,162	  
	 2019
	  	 	—  	  	  	 	10,332	  
		  	  
	  
	 	  	  
	  
	 
	 Total
	  	$	20,160	  	  	$	30,498	  
		  	  
	  
	 	  	  
	  
	 

  

	6.	NOTES PAYABLE TO STOCKHOLDERS 

 In October 2011, the Company entered into a Note Purchase
and Security Agreement with certain stockholders to issue convertible promissory notes for aggregate proceeds up to $10,000. In October 2011, the Company issued $5,000 of these convertible promissory notes with a stated interest rate of 13% per
annum and secured by all of the Company’s assets. These notes were immediately convertible into series D-1 redeemable convertible preferred stock (“Series D-1 Preferred Stock”) or into shares of a new class of preferred stock sold in
connection with a qualified financing (as defined in the agreement). During fiscal year 2012, the Company recorded interest expense of $174. In January 2012, in connection with the sale of a new class of preferred stock, Series E redeemable
convertible preferred stock (“Series E Preferred Stock”), the principal balance and accrued interest of $174 were converted into Series E Preferred Stock. 

On February 13, 2013, the Company entered into a Note Purchase Agreement with certain stockholders to issue convertible promissory notes
for aggregate proceeds of $10,000. The notes bore interest of 12% per annum and matured in one year, at which time accrued interest would be paid. In the event that the Company consummated a qualified equity financing, as defined in the
agreement, then the notes and all accrued interest thereon would automatically convert into the equity securities of such financing. On April 2, 2013, in connection with a sale of Series E Preferred Stock, the principal balance and accrued
interest of $229 were converted into Series E Preferred Stock. In fiscal year 2013, the Company recorded interest expense of $229. See Note 7 below for further disclosures of the above note issuances. 

 

	7.	STOCKHOLDERS’ DEFICIT AND REDEEMABLE CONVERTIBLE PREFERRED STOCK 

 Authorized Capital Stock

 On April 2, 2013, the Company amended its Certificate of Incorporation via a Certificate of Amendment of the Sixth Amended and
Restated Certificate of Incorporation to increase the number of shares of common stock and Series E Preferred Stock which the Company is authorized to issue to 12,000 and 5,500 shares, respectively. 

  
 F-20 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	7.	STOCKHOLDERS’ DEFICIT AND REDEEMABLE CONVERTIBLE PREFERRED STOCK (continued) 

  

 In addition, the amended Certificate of Incorporation now specifies that if a stockholder does not purchase
their pro-rata portion of a qualified financing, as defined therein, then such stockholder’s shares of preferred stock will automatically be converted to common stock. 

At September 30, 2013, the Company has reserved shares of common stock for issuance as follows: 

 

					
	 Conversion of preferred stock
	  	 	8,904	  
	 Exercise of outstanding stock options
	  	 	1,046	  
	 Available to grant under stock option plans
	  	 	242	  
	 Exercise and conversion of warrants
	  	 	236	  
	 Total
	  	 	10,428	  

 Common Stock 

In fiscal year 2012, the Company granted 8 shares of restricted stock to directors for services performed. The shares had a grant date fair
value of $2.69 per share and vest 25% after one year, and then monthly for the remaining vesting period of approximately three years. The Company recorded $7, $1, $3, and $3 of compensation expense related to the vesting of these shares for fiscal
years 2013 and 2012 and the six months ended March 31, 2014 and 2013, respectively. 
 In fiscal year 2013, the Company granted 7
shares of restricted stock to directors for services performed. The shares had a grant date fair value of $2.69 per share and vest 25% after one year, and then monthly for the remaining vesting period of approximately three years. The Company
recorded $6, $3, and $3 of compensation expense related to the vesting of these shares for fiscal year 2013 and the six months ended March 31, 2014 and 2013, respectively. 

Redeemable Convertible Preferred Stock 

Between March 8, 2011 and April 14, 2011, the Company issued 827 shares of Series D-1 Preferred Stock for aggregate proceeds of
$14,100, net of issuance costs of $86. In connection with this sale of preferred stock, the Company issued warrants to purchase 165 shares of Series D-1 Preferred Stock with an exercise price of $0.01 per share which expire after at the earliest of
(i) five years after issuance, (ii) immediately upon the closing of the Company’s initial public offering of its securities, or (iii) immediately upon the closing of a sale event. Because the warrants allow the holder to purchase
redeemable preferred stock, the warrants were classified as liabilities as they embodied a conditional obligation to transfer assets in the future. The Company recorded the warrants at their initial grant-date fair value and allocated the remaining
net proceeds to Series D-1 Preferred Stock. In January 2012, 5 of the warrants were exercised and the Company issued Series D-1 Preferred Stock. 

Between January 12, 2012 and July 19, 2012, the Company issued 2,802 shares of Series E Preferred Stock for an aggregate purchase
price of $44,728, net of issuance costs of $271, of which $39,008 was received in cash, $546 from the cancellation of indebtedness and $5,174 from the conversion of convertible promissory notes and accrued interest. 

Between April 25, 2013 and May 22, 2013, the Company issued 1,557 shares of Series E Preferred Stock for an aggregate purchase price
of $24,903, net of issuance costs of $97, of which $14,285 was received in cash, $389 from the cancellation of indebtedness and $10,229 from the conversion of convertible promissory notes and accrued interest (Note 6). In connection with these
issuances, the Company also issued warrants to purchase 66 additional shares of Series E Preferred Stock with an exercise price of $16.06 per share which expire at the 

  
 F-21 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	7.	STOCKHOLDERS’ DEFICIT AND REDEEMABLE CONVERTIBLE PREFERRED STOCK (continued) 

  

 earliest of (i) five years after issuance, (ii) immediately upon the closing of the Company’s
initial public offering of its securities, or (iii) immediately upon the closing of a sale event. Because the warrants allow the holder to purchase redeemable preferred stock, the warrants were classified as liabilities. At issuance, the Series
E warrants were valued at $465, which was estimated using Black-Scholes using the following assumptions: risk free interest rate, 0.91%; expected dividend yield, 0%; expected life, five years; expected volatility, 50.71%. The Company recorded the
warrants at their initial grant-date fair value and allocated the remaining net proceeds to the Series E Preferred Stock. 
 In connection
with this Series E Preferred Stock financing in April 2013 and in accordance with the 
 Company’s amended Certificate of
Incorporation, the following shares of Series B, C, D, and E Preferred Stock held by preferred stockholders who did not participate in that financing were converted to common stock: 

 

									
	 	  	Shares of
Preferred Stock	 	  	Shares of
Common Stock	 
	 Series B
	  	 	29	  	  	 	79	  
	 Series C
	  	 	25	  	  	 	76	  
	 Series D
	  	 	145	  	  	 	149	  
	 Series E
	  	 	19	  	  	 	19	  
		  				  	 	323	  

 The Company has accounted for this transaction as an extinguishment of the preferred stock. Accordingly, the
Company recorded an aggregate gain of $6,959 within accumulated deficit equal to the difference between the fair value of the newly issued common stock and the carrying amount of the preferred stock. The gain on extinguishment is reflected in the
calculation of net loss attributable to common stockholders in accordance with FASB ASC Topic 260, Earnings Per Share. 
 At
September 30, 2013 and 2012 and March 31, 2014, the shares authorized, issued, and outstanding as well as the liquidation preference for each class of redeemable convertible preferred stock are as follows: 

 

																	
	 	  	September 30, 2013	 
	Class	  	Shares
Authorized	 	  	Shares Issued	 	  	Shares
Outstanding	 	  	Liquidation
Preference	 
	 Series E
	  	 	5,500	  	  	 	4,359	  	  	 	4,340	  	  	$	69,695	  
	 Series D-1
	  	 	993	  	  	 	832	  	  	 	832	  	  	 	14,281	  
	 Series D
	  	 	2,915	  	  	 	2,915	  	  	 	2,770	  	  	 	47,500	  
	 Series A
	  	 	72	  	  	 	72	  	  	 	72	  	  	 	4,700	  
	 Series B
	  	 	119	  	  	 	119	  	  	 	90	  	  	 	7,675	  
	 Series C
	  	 	161	  	  	 	161	  	  	 	136	  	  	 	14,280	  
		
	 	  	September 30, 2012	 
	Class	  	Shares
Authorized	 	  	Shares Issued	 	  	Shares
Outstanding	 	  	Liquidation
Preference	 
	 Series E
	  	 	2,802	  	  	 	2,802	  	  	 	2,802	  	  	$	45,000	  
	 Series D-1
	  	 	993	  	  	 	832	  	  	 	832	  	  	 	14,281	  
	 Series D
	  	 	2,915	  	  	 	2,915	  	  	 	2,915	  	  	 	50,000	  
	 Series A
	  	 	72	  	  	 	72	  	  	 	72	  	  	 	4,700	  
	 Series B
	  	 	119	  	  	 	119	  	  	 	119	  	  	 	10,080	  
	 Series C
	  	 	161	  	  	 	161	  	  	 	161	  	  	 	16,897	  

  
 F-22 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	7.	STOCKHOLDERS’ DEFICIT AND REDEEMABLE CONVERTIBLE PREFERRED STOCK (continued) 

  

																	
	 	  	March 31, 2014	 
	 	  	(unaudited)	 
	 Class
	  	Shares
Authorized	 	  	Shares Issued	 	  	Shares
Outstanding	 	  	Liquidation
Preference	 
	 Series E
	  	 	5,500	  	  	 	4,359	  	  	 	4,340	  	  	$	69,695	  
	 Series D-1
	  	 	993	  	  	 	832	  	  	 	832	  	  	 	14,281	  
	 Series D
	  	 	2,915	  	  	 	2,915	  	  	 	2,770	  	  	 	47,500	  
	 Series A
	  	 	72	  	  	 	72	  	  	 	72	  	  	 	4,700	  
	 Series B
	  	 	119	  	  	 	119	  	  	 	90	  	  	 	7,675	  
	 Series C
	  	 	161	  	  	 	161	  	  	 	136	  	  	 	14,280	  

 The rights and preferences of the Series A, Series B, Series C, Series D, Series D-1, and Series E Preferred
Stock (collectively “Preferred Stock”) are as follows: 
 Dividends 

The holders of Preferred Stock are entitled to receive a dividend when declared by the Board of Directors based on the stockholders pro rata
share of the stock outstanding. The dividend accrues only when declared by the Board of Directors. Through March 31, 2014, no dividends have been declared or paid by the Company. 

Voting Rights 
 Each holder of the
Preferred Stock is entitled to vote on all matters and is entitled to the number of votes equal to the number of shares of common stock into which each share of Preferred Stock can be converted. Except as otherwise required by law, the holders of
Preferred Stock shall be entitled to vote on all matters submitted to a vote of the holders of the common stock together with such holders of common stock. 

Conversion 
 Each share of the Series A,
Series B, Series C, Series D, Series D-1 and Series E Preferred Stock is convertible into 2.4568, 2.7905, 3.0435, 1.0221, 1.0679 and 1 share of common stock, respectively, at the stockholder’s option at any time after the date of issuance
subject to adjustment for certain events, as defined in the Certificate of Incorporation. The Preferred Stock will automatically convert to common stock at the then-effective conversion price of such series of Preferred Stock upon the closing of an
initial public offering for which the proceeds are at least $50,000 and the price paid by the public for such shares are at least three times the Series E original purchase price of $16.06 per share, subject to adjustment. The holders of Preferred
Stock are entitled to anti-dilution protection in which the conversion rate may be reduced upon the occurrence of certain events. 
 Liquidation
Preference 
 In the event of liquidation, the holders of Series E Preferred Stock will be paid out of the assets of the Company
available for distribution to its stockholders before any payment shall be made to the holders of any other class of preferred stock and common stock at an amount per share of $16.06, plus all declared and unpaid dividends. Holders of Series D and
Series D-1 Preferred Stock will have preferential status over Series A, Series B and Series C Preferred Stock, and common stock, and be paid $17.15 per share. Holders of Series A, Series B, and Series C Preferred Stock shall be paid $64.86, $85.00,
and $105.00 per share, respectively, plus all declared and unpaid dividends before payment is made to common stockholders. 

  
 F-23 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	7.	STOCKHOLDERS’ DEFICIT AND REDEEMABLE CONVERTIBLE PREFERRED STOCK (continued) 

  

 If the assets of the Company available for distribution to its stockholders are insufficient
to pay the holders of Series E Preferred Stock, the holders will share ratably in any distribution of the assets available for distribution in proportion to the respective amounts in respect to shares held by the holders of Series E Preferred Stock.
If the assets of the Company available for distribution to its stockholders are insufficient to pay the holders of Series D and Series D-1 Preferred Stock, the holders will share ratably in any distribution of the assets available for distribution
in proportion to the respective amounts in respect to shares held by them. If, after the payment to the holders of Series D and Series D-1 Preferred Stock, the assets of the Company are insufficient to pay the holders of Series A, Series B, and
Series C Preferred Stock, the assets will be distributed pro rata to the holders of Preferred Stock in accordance with the respective amounts which would have been distributed to such stockholders if the assets had been sufficient. 

Redemption Rights 
 The Preferred
Stockholders, with the approval of a majority of all such Preferred Stockholders, may, by giving notice to the Company on January 12, 2017 and each of the two one-year anniversaries thereafter, require the Company to redeem all of the
outstanding shares of Preferred Stock in three equal installments on those same dates. 
 The redemption price per share shall be equal to
$64.86, $85.00, $105.00, $17.15, $17.15 and $16.06 per share for Series A, Series B, Series C, Series D, Series D-1, and Series E Preferred Stock, respectively, plus any declared and unpaid dividends on such shares. 

The Preferred Stock is classified outside of stockholders’ equity due to the contingent redemption features but is not considered
mandatorily redeemable. 
  

	8.	FAIR VALUE MEASUREMENTS 

 In accordance with U.S. generally accepted accounting
standards, fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between
market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The standard describes a fair value hierarchy based on three levels
of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value which are the following: 

Level 1—Quoted prices in active markets for identical assets or liabilities. 

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or
liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. 

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or
liabilities. 

  
 F-24 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	8.	FAIR VALUE MEASUREMENTS (continued) 

  

 The assets or liabilities fair value measurement level within the fair value hierarchy is
based on the lowest level of any input that is significant to the fair value measurement. Valuation techniques used need to maximize the use of observable inputs and minimize the use of unobservable inputs. 

The warrant liability was measured at fair value on a recurring basis and has inputs categorized as Level 3 in the fair value hierarchy. The
warrant liability was valued using the Black-Scholes option pricing model. The Company revalued the outstanding Series D-1 and Series E warrants on September 30, 2013 and March 31, 2014 and the Series D-1 warrants on September 30,
2012 using the following assumptions: 
  

													
	 	  	September 30,	 	  	 	 
	 	  	2013	 	  	2012	 	  	March 31, 2014	 
	 	  	 	 	  	 	 	  	(Unaudited)	 
	 Risk-free interest rate
	  	 	0.5% - 1.3%	  	  	 	0.4% - 0.4%	  	  	 	0.4% - 1.4%	  
	 Expected dividend yield
	  	 	0%	  	  	 	0%	  	  	 	0%	  
	 Volatility factor
	  	 	45.6% - 48.3%	  	  	 	51.3% - 51.5%	  	  	 	49.0% - 53.1%	  
	 Expected life of warrant
	  	 	2.4 years - 4.6 years	  	  	 	3.4 years - 3.5 years	  	  	 	1.9 years - 4.1 years	  

 As the outstanding Series D-1 warrants have a nominal exercise price, the assumptions used as inputs in the
model for the remaining contractual term, risk-free interest rate, expected dividend yield and expected volatility had no material impact on the fair value of the warrants. 

The table below sets forth a summary of changes in the fair value of the Company’s level 3 liability (warrants) for fiscal years 2013 and
2012 and the six months ended March 31, 2014: 
  

					
	 Balance at September 30, 2011
	  	$	 2,836	  
	 Exercise of warrants
	  	 	(44	) 
	 Gain on revaluation of warrants
	  	 	(1,514	) 
		  	  
	  
	 
	 Balance at September 30, 2012
	  	 	1,278	  
	 Fair value of warrants issued
	  	 	465	  
	 Loss on revaluation of warrants
	  	 	44	  
		  	  
	  
	 
	 Balance at September 30, 2013
	  	 	1,787	  
	 Loss on revaluation of warrants (unaudited)
	  	 	1,742	  
		  	  
	  
	 
	 Balance at March 31, 2014 (unaudited)
	  	$	3,529	  
		  	  
	  
	 

 The resulting gain or loss on revaluation was recorded as other income (expense) in the consolidated
statements of operations. 
 Warrants to purchase 225 shares, 160 shares, and 225 shares of Preferred Stock were outstanding for fiscal
years 2013 and 2012 and the six months ended March 31, 2014, respectively. 
  

	9.	STOCK-BASED COMPENSATION 

 During calendar year 2005, the Company established the 2005
Stock Option and Incentive Plan (the “Plan”), subsequently amended and restated, under which a maximum of 1,336 shares of the Company’s authorized and available common stock may be issued in the form of incentive stock options and
other equity interests. 

  
 F-25 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	9.	STOCK-BASED COMPENSATION (continued) 

  

 Under the terms of the Plan, options and other equity interests may be granted to employees,
officers, directors, consultants and advisors of the Company. The exercise price of each incentive stock option (“ISO”) or Non-Qualified Stock Option (“NQSO”) shall be the fair market value at the time each option is granted. The
Company has granted restricted stock awards, service-based options and performance-based options under the Plan. Service-based options granted under the Plan generally vest as follows: 25% of the shares vest one calendar year from the vesting start
date and the remainder vest ratably over the following 36 calendar months. The options granted under the Plan generally expire in 10 years. 

The fair value of stock options issued to employees for all periods were measured with the following assumptions: 

 

																	
	 	  	Fiscal Year	 	 	Six Months Ended	 
	 	  	2013	 	 	2012	 	 	March 31, 2014	 	 	March 31, 2013	 
	 	  	 	 	 	 	 	 	(Unaudited)	 
	 Risk-free interest rate
	  	 	1.1	% 	 	 	1.1	% 	 	 	1.8	% 	 	 	1.1	% 
	 Expected dividend yield
	  	 	0	% 	 	 	0	% 	 	 	0	% 	 	 	0	% 
	 Volatility factor
	  	 	53.6	% 	 	 	51.7	% 	 	 	50.9	% 	 	 	53.6	% 
	 Expected life of options
	  	 	6 years	  	 	 	6 years	  	 	 	6 years	  	 	 	6 years	  

 The weighted-average fair value of stock options granted during the fiscal years 2013 and 2012 and the six
months ended March 31, 2014 and 2013, as determined by the Black-Scholes option pricing model, was $1.36, $1.32, $0.88 and $1.36 per stock option, respectively. 

During fiscal year 2010, performance-based stock options were granted under the Plan subject to vesting based on the occurrence of certain
events. The exercise price for these performance-based options is $6.00 per share. The terms of these stock options are as follows: 1) up to 68 shares will vest upon the earlier of (i) the closing of a Change in Control of the Company; or
(ii) the date which is 12 months following the effective date of an initial public offering; 2) 17 shares vested in fiscal year 2012 upon approval by the FDA of a 510(k) to market the Company’s MEVION S250 proton beam radiotherapy system;
and 3) 17 option shares vested upon the first customer acceptance of the Company’s MEVION S250 proton beam radiotherapy system in the six months ended March 31, 2014. The Company recorded $24 of compensation expense related to the vesting
of these performance-based stock options for fiscal year 2012, based on the probability of vesting. 
 During fiscal year 2012,
performance-based stock options exercisable for 30 shares were granted under the Plan, subject to vesting based on the achievement of certain sales criteria. The exercise price for these performance-based options is $2.69 per share. During fiscal
year 2013, 15 of these performance-based stock options were cancelled since the performance metric was not achieved. The Company recorded $(16) and $16 of compensation (income) expense related to the vesting of these performance-based stock options
for fiscal years 2013 and 2012, respectively. 

  
 F-26 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	9.	STOCK-BASED COMPENSATION (continued) 

  

 As of September 30, 2013, 242 shares were available for grant under the Plan. Stock
option activity for all periods is as follows: 
  

													
	 	  	Number
of
Options	 	 	Weighted-
Average
Exercise
Price	 	  	Weighted-
Average
Remaining
Life in
Years	 
	 Outstanding at September 30, 2012
	  	 	931	  	 	$	4.90	  	  	 	8.56	  
	 Options granted
	  	 	144	  	 	 	2.69	  	  			
	 Options cancelled and forfeited
	  	 	(29	) 	 	 	5.71	  	  			
		  	  
	  
	 	 	  
	  
	 	  	  
	  
	 
	 Outstanding at September 30, 2013
	  	 	1,046	  	 	 	4.57	  	  	 	7.80	  
	 Options granted (unaudited)
	  	 	178	  	 	 	1.76	  	  			
	 Options exercised (unaudited)
	  	 	(2	) 	 	 	4.74	  	  			
	 Options cancelled and forfeited (unaudited)
	  	 	(29	) 	 	 	3.90	  	  			
		  	  
	  
	 	 	  
	  
	 	  	  
	  
	 
	 Outstanding at March 31, 2014 (unaudited)
	  	 	1,193	  	 	 	4.17	  	  	 	7.45	  
		  	  
	  
	 	 	  
	  
	 	  	  
	  
	 
	 Exercisable at September 30, 2013
	  	 	509	  	 	 	5.92	  	  	 	7.08	  
	 Vested and expected to vest at September 30, 2013
	  	 	1,005	  	 	 	4.58	  	  	 	7.80	  
	 Exercisable at March 31, 2014 (unaudited)
	  	 	613	  	 	 	5.46	  	  	 	6.50	  
	 Vested and expected to vest at March 31, 2014 (unaudited)
	  	 	1,087	  	 	 	4.12	  	  	 	7.51	  

 For the fiscal years 2013 and 2012 and the six months ended March 31, 2014, the Company recorded total
stock-based compensation expense in the consolidated statement of operations as follows: 
  

																	
	 	  	Fiscal Year	 	  	Six Months Ended	 
	 	  	2013	 	  	2012	 	  	March 31, 2014	 	  	March 31, 2013	 
	 	  	 	 	  	 	 	  	(unaudited)	 
	 Cost of revenue
	  	$	 —  	  	  	$	 —  	  	  	$	 20	  	  	$	—  	  
	 Research and development
	  	 	140	  	  	 	—  	  	  	 	25	  	  	 	—  	  
	 Selling and marketing
	  	 	13	  	  	 	—  	  	  	 	14	  	  	 	—  	  
	 General and administrative
	  	 	293	  	  	 	420	  	  	 	70	  	  	 	251	  
		  	  
	  
	 	  	  
	  
	 	  	  
	  
	 	  	  
	  
	 
	 Total
	  	$	446	  	  	$	420	  	  	$	129	  	  	$	251	  
		  	  
	  
	 	  	  
	  
	 	  	  
	  
	 	  	  
	  
	 

 The breakdown of stock-based compensation expense between the various awards types in fiscal years 2013 and
2012 and the six months ended March 31, 2014 was as follows: 
  

																	
	 	  	Fiscal Year	 	  	Six Months Ended	 
	 	  	2013	 	 	2012	 	  	March 31, 2014	 	  	March 31, 2013	 
	 	  	 	 	 	 	 	  	(unaudited)	 
	 Service-based options
	  	$	436	  	 	$	346	  	  	$	125	  	  	$	237	  
	 Performance-based options
	  	 	(15	) 	 	 	40	  	  	 	—  	  	  	 	(5	) 
	 Restricted stock awards
	  	 	25	  	 	 	34	  	  	 	4	  	  	 	19	  
		  	  
	  
	 	 	  
	  
	 	  	  
	  
	 	  	  
	  
	 
	 Total
	  	$	446	  	 	$	420	  	  	$	129	  	  	$	251	  
		  	  
	  
	 	 	  
	  
	 	  	  
	  
	 	  	  
	  
	 

  
 F-27 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	9.	STOCK-BASED COMPENSATION (continued) 

  

 As of September 30, 2013 and March 31, 2014, there was $557 and $545 respectively,
of unrecognized compensation expense related to non-vested stock option awards that is expected to be recognized over a weighted-average period of 2.31 years and 2.54 years, respectively. 

The total fair value of stock options that vested during fiscal years 2013 and 2012 and the six months ended March 31, 2014 and 2013 was
$454, $342, $132, and $215, respectively. 
 The options had no intrinsic value in any of the periods presented. 

To date, the Company has issued 46 shares of restricted stock awards under the Plan and 2 shares of restricted stock awards outside of the
Plan. 
 The following table, including shares granted under the Plan and outside the Plan, summarizes the status of the Company’s
non-vested restricted common shares as of September 30, 2013 and 2013 and March 31, 2014 and changes during fiscal year 2013 and the six months ended March 31, 2014: 

 

									
	 	  	Number
of
Shares	 	 	Weighted-
Average
Grant
Date Fair
Value	 
	 Non-vested at September 30, 2012
	  	 	8	  	 	$	3.36	  
	 Granted
	  	 	7	  	 	 	2.69	  
	 Vested during the year
	  	 	(6	) 	 	 	3.62	  
		  	  
	  
	 	 	  
	  
	 
	 Non-vested at September 30, 2013
	  	 	9	  	 	$	2.69	  
	 Vested during the year (unaudited)
	  	 	(2	) 	 	 	2.69	  
		  	  
	  
	 	 	  
	  
	 
	 Non-vested at March 31, 2014 (unaudited)
	  	 	7	  	 	$	2.69	  
		  	  
	  
	 	 	  
	  
	 

 As of September 30, 2013 and March 31, 2014, there was $27 and $22, respectively, of unrecognized
compensation expense related to non-vested restricted common stock that is expected to be recognized over a weighted-average period of 2.81 years and 2.31 years, respectively. The total estimated fair value of restricted common stock vested during
fiscal years 2013 and 2012 and the six months ended March 31, 2014 and 2013 were $22, $30, $5, and $14, respectively. 
  

	10.	INCOME TAXES 

 Loss before provision for income taxes was as follows: 

 

									
	 	  	Fiscal Year	 
	 	  	2013	 	 	2012	 
	 United States
	  	$	(37,580	) 	 	$	(26,133	) 
	 Foreign
	  	 	(1,326	) 	 	 	(403	) 
		  	  
	  
	 	 	  
	  
	 
	 Total
	  	$	(38,906	) 	 	$	(26,536	) 
		  	  
	  
	 	 	  
	  
	 

  
 F-28 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	10.	INCOME TAXES (continued) 

  

 The following reconciles the differences between income taxes computed at the federal tax
rate and the provision for income taxes: 
  

									
	 	  	Fiscal Year	 
	 	  	2013	 	 	2012	 
	 Expected income tax benefit at the federal statutory rate
	  	 	(34.0	)% 	 	 	(34.0	)% 
	 State taxes, net of federal benefit
	  	 	(5.2	)% 	 	 	(5.5	)% 
	 Non-deductible items and other
	  	 	0.6	% 	 	 	(1.4	)% 
	 Federal and state credits
	  	 	(2.9	)% 	 	 	(0.9	)% 
	 Change in valuation allowance
	  	 	41.5	% 	 	 	41.8	% 
		  	  
	  
	 	 	  
	  
	 
		  	 	—	% 	 	 	—	% 
		  	  
	  
	 	 	  
	  
	 

 Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets
and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s net deferred tax assets consisted of the following at September 30, 2013 and 2012: 

 

									
	 	  	September 30,	 
	 	  	2013	 	 	2012	 
	 Net operating loss carryforwards
	  	$	42,645	  	 	$	28,053	  
	 Net capitalized start-up costs
	  	 	14,030	  	 	 	15,175	  
	 Research and Investment Tax Credits
	  	 	4,964	  	 	 	3,452	  
	 Net capitalized R&D expenses
	  	 	2,641	  	 	 	3,067	  
	 Reserves and accruals
	  	 	4,793	  	 	 	3,850	  
	 Depreciation
	  	 	592	  	 	 	494	  
	 Other
	  	 	351	  	 	 	313	  
		  	  
	  
	 	 	  
	  
	 
	 Total deferred tax assets
	  	 	70,016	  	 	 	54,404	  
	 Deferred tax asset valuation allowance
	  	 	(70,016	) 	 	 	(54,404	) 
		  	  
	  
	 	 	  
	  
	 
	 Net deferred tax assets
	  	$	—  	  	 	$	—  	  
		  	  
	  
	 	 	  
	  
	 

 The Company maintains a valuation allowance related to its deferred tax asset position when management
believes it is more likely than not that the net deferred tax assets will not be realized in the future. Our valuation allowance increased by approximately $15,612 during fiscal 2013. 

At September 30, 2013, the Company had federal net operating loss carryforwards of approximately $111,102 which begin to expire in
calendar year 2025 and state net operating loss carryforwards of approximately $92,237 which begin to expire in fiscal 2014. The Company had federal research and development tax credit carryforwards of approximately $3,226 and $2,079 for fiscal 2013
and fiscal 2012, respectively. The Company also had state research and development tax credit carryforwards of $2,404 and $1,888 for fiscal 2013 and 2012, respectively. These federal and state credits expire at various dates through 2033. 

Under the provisions of the Internal Revenue Code (“IRC”), net operating loss and credit carryforwards, and other tax attributes,
may be subject to limitation if there has been a significant change in ownership of the Company (as defined by the IRC). The Company has performed an analysis of its carryforwards and has determined that there are no limitations as of
September 30, 2013. Future owner or equity shifts, including the initial public offering, could result in limitations on net operating losses and credit carryforwards. 

  
 F-29 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	10.	INCOME TAXES (continued) 

  

 The Company’s federal tax returns since calendar year 2004 are open to examination due
to unused net operating loss carryforwards generated in those years. The Company’s state returns since calendar year 2008 are similarly open. 

In October 2010, the Company received $270 from the Commonwealth of Massachusetts under a Massachusetts Life Sciences Center Tax Incentive
agreement. Upon the anticipated achievement of specified annual requirements through fiscal 2015, the Company will recognize income related to the credit ratably over the same period. In both fiscal 2013 and 2012, the Company recognized $54 in other
income related to this credit. In August 2011, the Company received another $266 from the Commonwealth of Massachusetts under the same program. However, as of December 31, 2011, the Company did not meet the specified annual requirements and, as
a result, the Company was unable to continue to recognize income related to the credit. In fiscal year 2012, the Company repaid the $266 and recognized expense of $40 for previously recognized income related to this credit. 

The Company accounts for uncertain tax positions using a “more-likely-than-not” threshold. The evaluation of uncertain tax positions
is based on factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity and changes in facts or
circumstances related to a tax position. The Company evaluates these tax positions on an annual basis. In addition, the Company also accrues for potential interest and penalties related to unrecognized tax benefits in income tax expense. As of
September 30, 2013 and 2012, the Company had unrecognized tax benefits related to research credits in the amounts of $1,375 and $1,287, respectively. 

The following is a tabular reconciliation of the total amounts of unrecognized tax benefits: 

 

									
	 	  	For Year Ended September 30,	 
	 	  	2013	 	  	2012	 
	 Unrecognized benefit — October 1
	  	$	1,287	  	  	$	1,270	  
	 Gross increases — tax positions in prior period positions
	  	 	24	  	  	 	—  	  
	 Gross increases — tax positions in current period positions
	  	 	64	  	  	 	17	  
		  	  
	  
	 	  	  
	  
	 
	 Unrecognized benefit — September 30
	  	$	1,375	  	  	$	1,287	  
		  	  
	  
	 	  	  
	  
	 

  

	11.	NET LOSS PER SHARE 

 Historical Loss Per Share 

Basic net loss per share is computed using the weighted average number of shares of common stock outstanding during the period. Unvested
restricted stock awards, although legally issued and outstanding, are not considered outstanding for purposes of calculating basic net income per share. Diluted net loss per share is computed using the sum of the weighted average number of common
shares outstanding during the period and, if dilutive, the weighted average number of potential shares of common stock, including unvested restricted stock awards and the assumed exercise of stock options. The Company applied the two-class method to
calculate its basic and diluted net loss per share available to common stockholders, as its redeemable convertible preferred stock and common stock are participating securities. The two-class method is an earnings allocation formula that treats a
participating security as having rights to earnings that otherwise would have been available to common stockholders. However, the two-class method does not impact the net loss per share of common stock as the Company was in a net loss position for
each of the periods presented and preferred stockholders do not participate in losses. 

  
 F-30 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	11.	NET LOSS PER SHARE (continued) 

  

 The calculations of shares used to compute basic and diluted net loss per share are as
follows: 
  

																	
	 	  	Fiscal Year	 	 	Six Months Ended
March 31,	 
	 	  	2013	 	 	2012	 	 	2014	 	 	2013	 
	 	  	 	 	 	 	 	 	(unaudited)	 
	 Net loss attributable to common stockholders
	  	$	(32,606	) 	 	$	(27,108	) 	 	$	(22,731	) 	 	$	(17,217	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Weighted average number of common shares outstanding-basic
	  	 	275	  	 	 	131	  	 	 	464	  	 	 	133	  
	 Effect of dilutive securities:
	  				 				 				 			
	 Stock options, restricted stock awards, preferred stock and preferred stock warrants
	  	 	—  	  	 	 	—  	  	 	 	—  	  	 	 	—  	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Weighted average number of common shares outstanding-diluted
	  	 	275	  	 	 	131	  	 	 	464	  	 	 	133	  
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 Basic and diluted net loss per share:
	  	$	(118.68	) 	 	$	(207.10	) 	 	$	(49.00	) 	 	$	(129.02	) 
		  	  
	  
	 	 	  
	  
	 	 	  
	  
	 	 	  
	  
	 

 The Company’s potential dilutive securities, which include stock options, restricted stock awards,
preferred stock, and warrants to purchase preferred stock have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares
outstanding is used to calculate both basic and diluted net loss per share are the same. The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated because including them would
have had an anti-dilutive effect: 
  

																	
	 	  	Fiscal Year	 	  	Six Months Ended
March 31,	 
	 	  	2013	 	  	2012	 	  	2014	 	  	(2013	 
	 	  	 	 	  	 	 	  	(unaudited)	 
	 Redeemable convertible preferred shares (as converted)
	  	 	8,904	  	  	 	7,670	  	  	 	8,904	  	  	 	7,670	  
	 Options to purchase common stock
	  	 	1,046	  	  	 	931	  	  	 	1,193	  	  	 	1,075	  
	 Preferred stock warrants (as converted)
	  	 	236	  	  	 	171	  	  	 	236	  	  	 	171	  
	 Restricted stock awards
	  	 	10	  	  	 	8	  	  	 	8	  	  	 	13	  

 Unaudited Pro Forma Loss per Share 

Upon closing of the IPO contemplated in this Form S-1, all shares of redeemable convertible preferred stock will automatically convert into
8,904 shares of common stock. The unaudited pro forma net loss per share, basic and diluted, for the fiscal year 2013 and the six month period ending March 31, 2014 has been computed to give effect to the redeemable convertible preferred stock
conversions as if such conversions had occurred on October 1, 2012 or the date of issuance, if later. The unaudited pro forma net income attributable to common stockholders used in the calculation of unaudited basic and diluted pro forma net
loss per share attributable to common stockholders does not include the effects of the accretion to redemption value of the redeemable convertible preferred stock and the gain on extinguishment of redeemable convertible preferred stock because it
assumes that the conversion of the redeemable convertible preferred stock had occurred at the beginning of the period. 

  
 F-31 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	11.	NET LOSS PER SHARE (continued)  

  

 A reconciliation of the numerator and denominator used in the calculation of unaudited pro
forma basic and diluted loss per share is as follows: 
  

									
	 	  	Unaudited Pro forma	 
	 	  	Fiscal Year
2013	 	 	Six Months
Ended March
31, 2014	 
	 Net loss
	  	$	(38,906	) 	 	$	(22,350	) 
		  	  
	  
	 	 	  
	  
	 
	 Weighted average number of common shares outstanding-basic
	  	 	275	  	 	 	464	  
	 Pro forma adjustment for assumed conversion of redeemable convertible preferred stock
	  	 	8,190	  	 	 	8,904	  
		  	  
	  
	 	 	  
	  
	 
	 Number of shares used for pro forma basic EPS computation
	  	 	8,465	  	 	 	9,368	  
	 Dilutive effect of share equivalents resulting from stock options and warrants
	  	 	—  	  	 	 	—  	  
		  	  
	  
	 	 	  
	  
	 
	 Number of shares used for pro forma dilutive EPS computation
	  	 	8,465	  	 	 	9,368	  
		  	  
	  
	 	 	  
	  
	 
	 Pro forma basic and diluted net loss per share:
	  	$	(4.60	) 	 	$	(2.39	) 
		  	  
	  
	 	 	  
	  
	 

  

	12.	EMPLOYEE BENEFIT PLAN 

 The Company has an employee benefit plan under
Section 401(k) of the IRC (the “401(k) Plan”). The 401(k) Plan allows employees to make pretax contributions up to the maximum allowable amount set by the Internal Revenue Service. Under the 401(k) Plan, the Company may match a
portion of the employee contribution. The Company has not made any contributions to the 401(k) Plan since its inception. 
  

	13.	RELATED PARTY TRANSACTIONS 

 The Company has a vendor (“Shareholder A”) that
has a minor ownership interest in the Company of less than 5% at September 30, 2013 and 2012 and March 31, 2014. During fiscal years 2013 and 2012 and the six months ended March 31, 2014 and 2013, the Company purchased materials and
value added services with a total cost of $2,426, $3,026, $1,568, and $1,307, respectively, from Shareholder A. In addition, at March 31, 2014 the Company has entered into purchase commitments with Shareholder A for the fiscal year ended
September 30, 2014 of approximately $2,861 (see Note 15). 
 The Company also has a customer (“Shareholder B”) that has a
minor ownership interest in the Company of less than 1% at March 31, 2014. In calendar year 2007, Shareholder B contracted with the Company to purchase three MEVION S250’s along with the installation of each system. The Company has
received $3,000 of non-refundable deposits from Shareholder B for these contracts. 
 In calendar year 2008, the Company entered into a
System Development and Supply Agreement (the “Development Agreement”) with a vendor (“Shareholder C”), who has a minor ownership interest in the Company of less than 1% at March 31, 2014. Through September 30, 2013, the
Company has paid $750 to Shareholder C for services under the Development Agreement. Shareholder C is required to pay a royalty to the Company under the Development Agreement for each system Shareholder C sells with the developed software interface
to the MEVION S250. 

  
 F-32 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	14.	GEOGRAPHIC DATA 

 The Company operates in one operating segment. Total long-lived assets
held outside of the United States were immaterial for all periods presented. 
  

	15.	COMMITMENTS, CONTINGENCIES, AND GUARANTEES 

 Leases and Other Commitments 

The Company entered into a three year operating lease agreement for its research and administrative facility commencing in April 2012. During
fiscal year 2013, the lease term was extended through March 2016. At September 30, 2013, the Company had an asset retirement obligation of approximately $111 and $177, respectively, included in other non-current assets and other non-current
liabilities in the consolidated balance sheets to return the facility to its original condition. At March 31, 2014, the Company had an asset retirement obligation of approximately $99 and $214, respectively, included in other non-current assets
and other non-current liabilities in the consolidated balance sheets to return the facility to its original condition. Amortization expense of the related asset in fiscal year 2013 and the six months ended March 31, 2014 and 2013 was $44, $12,
and $25, respectively. 
 During fiscal year 2012, the Company also entered into office lease agreements in the United Kingdom for a one
year term and Japan for a two year term. 
 Rental expense under operating leases was $1,416, $1,305, $726 and $730 for fiscal years 2013
and 2012 and the six months ended March 31, 2014 and 2013, respectively. At September 30, 2013, the future minimum lease payments under the non-cancelable leases are as follows: 

 

					
	 Fiscal Year
	  	 	 
	 2014
	  	$	1,420	  
	 2015
	  	 	1,394	  
	 2016
	  	 	709	  
		  	  
	  
	 
		  	$	3,523	  
		  	  
	  
	 

 At March 31, 2014, the Company had certain purchase commitments for fiscal year 2014, fiscal year 2015,
and fiscal year 2016 amounting to $6,906, $5,131, and $4,512, respectively, some of which require the Company to purchase multiple pieces of equipment and to enter into one year service agreements for such equipment. The deposits on inventory
purchases at September 30, 2013, September 30, 2012, and March 31, 2014 of $1,858, $3,729, and 1,481, respectively, are non-refundable. 

Contract Loss Accruals 
 The Company
regularly evaluates customer contracts for situations where the estimated costs to fulfill contractual obligations (typically equipment installation, and related service) exceed the expected total contract revenue. Any such amounts are recorded as
charge to the consolidated statements of operations and are allocated between inventory writedowns and contract loss accruals. During fiscal years 2013 and 2012, the Company recorded charges to research and development in the consolidated statements
of operations of $2,434 and $221, respectively. During the six months ended March 31, 2014, the Company recorded a charge in the consolidated statements of operations of $2,221, of which $1,520 was recorded to cost of revenue and $701 was
recorded to research and development. The charge recorded in the six months ended March 31, 2014 includes $1,593 arising under the contracts with Shareholder B. 

  
 F-33 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	15.	COMMITMENTS, CONTINGENCIES, AND GUARANTEES (continued) 

  

 Legal Claims 

From time to time, the Company may be exposed to litigation in connection with its products and operations. The Company’s policy is to
assess the likelihood of any adverse judgments or outcomes related to legal matters, as well as ranges of probable losses, and to provide such losses and related disclosures when appropriate. 

In December 2010, Massachusetts Institute of Technology (“MIT”) filed two lawsuits in federal district court against the Company. In
the first lawsuit MIT alleged that a patent of the Company should be corrected to add one of its staff as a co-inventor. That same lawsuit requested that MIT be declared the owner of the Company patent. Litigation was completed on December 17,
2012 when the special master ruled in favor of the Company as sole inventor. On March 4, 2013, the court formally adopted the Special Master’s Report in its entirety as an order of the court. The court also entered a final judgment
expressly confirming that the Company remains the sole owner of the patent. The outcome of the litigation does not affect the Company’s right to use the patent or result in any further obligation to the Company. 

In the second lawsuit, MIT alleged that the Company infringed three MIT patents based on the claim that the Company was no longer licensed
under those patents and that the Company breached a research contract between the parties. The second lawsuit was settled in fiscal year 2011 and the Company paid $888, which was recorded in research and development expense in the consolidated
financial statements during that year. 
 In connection with the settlement, the Company entered into a license agreement (the “License
Agreement”) with MIT which was effective on June 30, 2011. The License Agreement required a license issue fee of $300 which was paid in calendar year 2011 and future minimum license fees due each fiscal year until the expiration or
termination of the last valid claim within the patent rights, which is currently estimated to be in fiscal year 2027, unless terminated earlier based on provisions in the License Agreement. The License Agreement also requires a royalty to be paid by
the Company based on sales and sub-license income. The license fees may be credited against royalties payable to MIT in the year in which they are earned. 

The Company is expensing the license payments made in the period they are due unless they are estimated to be used as a credit against a
future royalty. During fiscal years 2013 and 2012, the Company paid license fees and the only milestone payment under the License Agreement for the receipt of FDA approval of the MEVION S250 of $250 and $600, respectively, which were recorded in
research and development expense in the consolidated statements of operations for fiscal years 2013 and 2012, respectively. No milestone payments were made during the six month period ending March 31, 2014. The Company recognized royalty
expense of $375 paid to MIT during the six month period ending March 31, 2014 which was recorded in cost of revenue in the consolidated statements of operations. 

  
 F-34 

 Mevion Medical Systems, Inc. and Subsidiaries 

Notes to consolidated financial statements (continued) 

Amounts as of March 31, 2014 and for the six months ended March 31, 2014 and 2013 are unaudited 

(In thousands, except per share data) 
  

	15.	COMMITMENTS, CONTINGENCIES, AND GUARANTEES (continued) 

  

 At September 30, 2013, future minimum license fees due to MIT and another unrelated
party under license agreements are as follows: 
  

					
	 Fiscal Year
	  	 	 
	 2014
	  	$	450	  
	 2015
	  	 	575	  
	 2016
	  	 	575	  
	 2017
	  	 	500	  
	 2018
	  	 	500	  
	 Thereafter
	  	 	4,500	  
		  	  
	  
	 
		  	$	7,100	  
		  	  
	  
	 

  

	16.	RISKS AND UNCERTAINTIES 

 The Company is subject to risks common to companies in the
medical device industry. These risks, which could have a material and negative impact on the Company’s business, financial condition, and results of operations, include, but are not limited to, loss of any significant customer, patent
infringement, dependence on key suppliers, and United States and foreign regulatory clearances and approvals. 
  

	17.	SUBSEQUENT EVENTS 

 The Company has evaluated subsequent events through the date of this
prospectus and determined that no additional subsequent events occurred that would require recognition in the consolidated financial statements or disclosure in the notes thereto. 

  
 F-35EX-10.28

 Exhibit 10.28 

CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY
WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. 

AMENDMENT NO. 1 TO LOAN AGREEMENT 

This Amendment No. 1 dated as of February 7, 2014 (this “Amendment”) to the Loan Agreement dated as of
June 25, 2013 (the “Existing Loan Agreement”) is entered into between Life Sciences Alternative Funding LLC, a Delaware limited liability company, as lender (“Lender”), Mevion Medical Systems,
Inc., a Delaware corporation, as borrower (“Borrower”), and Mevion Medical Systems UK, LLC, a Delaware limited liability company, as guarantor (“Guarantor”), pursuant to and in accordance with
Section 13.05 of the Existing Loan Agreement. Capitalized terms used herein that are not otherwise defined shall have the meanings ascribed to them in the Existing Loan Agreement. 

The Parties hereby agree as follows: 

ARTICLE I 

AMENDMENT 

Section 1.01. Addition of Definitions. Section 1.01 of the Existing Loan Agreement is hereby amended to add the following
defined terms: 
 “ “Allocated Contract Cost” means (a) $[***], with respect to any U.S.
Included Product Agreement, and (b) $[***], with respect to any Non-U.S. Included Product Agreement. 

“Non-U.S. Included Product Agreement” means any Included Product Agreement pursuant to which Borrower agrees
to sell and deliver Included Product(s) to a Person not located in the United States. 
 “Gross Contract
Value” means, with respect to any Included Product Agreement, the total gross amount received or receivable by Borrower during the term of such Included Product Agreement pursuant such Included Product Agreement, including milestone
payments (defined under the applicable Included Product Agreement as “Price” or otherwise), amounts received or receivable from royalties, minimum royalty payments, profit payments or distributions, and license fees. 

“Included Product Agreement” means any Included License Agreement and any other Contract pursuant to which
Borrower and/or any of its Subsidiaries agrees to sell, directly or indirectly, Included Product(s) to Third Parties that are end-users, out-licensors, distributors or other Third Parties. 

“Margin” means, with respect to each Included Product Agreement, the Gross Contract Value less the Allocated
Contract Cost. 
 “Margin Requirement” means, at any time of determination on or after the Tranche B Funding
Date, the aggregate Margin for all Terminated Included Product Agreements at such time is equal to or less than the Margin Threshold in effect at such time. 

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 “Margin Threshold” means, as of any time of determination on
or after the Tranche B Funding Date, [***]. 
 “New Included Product Agreement” means any Included Product
Agreement entered into by Borrower on or after the Tranche B Funding Date. 
 “Terminated Included Product
Agreement” means any Included Product Agreement that is terminated in its entirety by any party thereto at any time on or after the Tranche B Funding Date. 

“Termination Payments” means, with respect to any Included Product Agreement, (a) all payments paid or
payable to a party to such Included Product Agreement (other than Borrower or any of its Subsidiaries) in respect of the termination, amendment or replacement of such Included Product Agreement, including any refunds, settlement payments, judgment
payments and securities, and any collections, recoveries, payments, supplements or other compensation, any other remuneration of any kind paid, and any other amounts (including damages, awards, interest and penalties) of any kind or nature paid or
payable by Borrower or any of its Subsidiaries (other than to Borrower or any of its Subsidiaries) in substitution or compensation for, or otherwise in respect of, such termination, plus all reasonable and documented out-of-pocket costs and expenses
(including documented attorneys’ fees) actually incurred by Borrower or any of its Subsidiaries in connection with such termination at any time on or after the Tranche B Funding Date, and (b) the amount of any other reduction in Gross
Contract Value in respect of such Included Product Agreement, including (without duplication) pursuant to a termination in part by any party thereto at any time on or after the Tranche B Funding Date. 

“U.S. Included Product Agreement” means any Included Product Agreement pursuant to which Borrower agrees to
sell and deliver Included Product(s) solely to Persons located in the United States.” 

  
 -2- 

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Section 1.02. Material Adverse Effect. The definition of “Material Adverse
Effect” set forth in Section 1.01 of the Existing Loan Agreement is hereby amended [***] 
 Section 1.03. Notice of Margin
Requirement Compliance. Section 9.03(c) of the Existing Loan Agreement is hereby amended to add the following as a new subsection (iv): 

“(iv) The Margin Requirement shall have been satisfied as of the date of the certificate and at all times during the
period covered by the financial statements delivered to Lender (and, for the avoidance of doubt, only at such times that are on and after the Tranche B Funding Date).” 

Section 1.04. Compliance with Laws and Contracts. Section 9.07(a) of the Existing Loan Agreement is hereby amended to add the
following at the end thereof: 
 “; provided that this Section 9.07(a) shall not prohibit Borrower from
terminating any Included Product Agreement so long as before and after giving effect thereto, the Margin Requirement shall be satisfied” 

Section 1.05. Additional Covenants of Borrower. Section 9.11 of the Existing Loan Agreement is hereby amended to add the
following at the end thereof: 
 “; provided that this Section 9.11 shall not prohibit Borrower from
terminating any Included Product Agreement so long as before and after giving effect thereto, the Margin Requirement shall be satisfied” 

Section 1.06. Activities of Borrower. Section 10.01 of the Existing Loan Agreement is hereby amended to add the following at
the end thereof: 
 “; provided that this Section 10.01 shall not prohibit Borrower from terminating any
Included Product Agreement so long as before and after giving effect thereto, the Margin Requirement shall be satisfied” 

Section 1.07. Transactions with Affiliates. Section 10.06 of the Existing Loan Agreement is hereby deleted and amended and
restated in its entirety as follows: 
 “Section 10.06. Limitation on Transactions with Affiliates. 

Borrower shall not, and shall cause its Subsidiaries not to, directly or indirectly, enter into any transaction or series of related
transactions or participate in any arrangement (including any Transfer or purchase or the rendering of any service) with, or for the benefit of, any Affiliate that is not a Borrower Party (and, in the case of a Borrower Party that is a Subsidiary,
that is not a Subsidiary Guarantor who has complied with the terms hereof, including the execution and delivery of the applicable Security Documents), other than (a) the Loan Documents, (b) Permitted Intercompany Transfers, (c)(i) in
the ordinary course of business of Borrower and (ii) upon fair and reasonable terms no less favorable to Borrower than it would obtain in a 

  
 -3- 

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 
comparable arm’s-length transaction with a non-Affiliate, and (d) sales of equity securities by Borrower to existing investors of Borrower in bona fide financing transactions which do
not result in the occurrence of a Change of Control and are otherwise permitted under this Agreement.” 
 Section 1.08. Other
Indebtedness and Agreements; Preferred Stock. Section 10.12(b) of the Existing Loan Agreement is hereby amended to add the following at the end thereof: 

“; provided further that this Section 10.12(b) shall not prohibit Borrower from terminating any Included
Product Agreement so long as before and after giving effect thereto, the Margin Requirement shall be satisfied” 
 Section 1.09.
Event of Default. Section 11.01 of the Existing Loan Agreement is hereby amended to add the following as a new subsection (s): 

“(s) Borrower fails at any time after the Tranche B Funding Date to satisfy the Margin Requirement.” 

ARTICLE II 

ADDITIONAL REPRESENTATION AND WARRANTY 

Borrower, with respect to itself and each of its Subsidiaries, as applicable, hereby represents and warrants to Lender that, except as set
forth on Schedule A attached hereto, neither Borrower nor any of its Subsidiaries has received any written notice or, to the Knowledge of Borrower, oral communication, (i) of the intention or threat of any party to any Included Product
Agreement (other than Borrower or any of its Subsidiaries) to terminate such Included Product Agreement in whole or in part or (ii) requesting any amendment, alteration or modification of such Included Product Agreement or any license,
sublicense or assignment thereunder that (A) has not either been withdrawn in writing or reflected in such Included Product Agreement, or (B) if implemented would reasonably be expected to have, individually or in the aggregate, a Material
Adverse Effect. 

  
 -4- 

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 ARTICLE III 

MISCELLANEOUS 

Section 3.01. Effect of Amendment. Except as specifically amended by this Amendment, the Existing Loan Agreement shall remain in
full force and effect. All references in the Existing Loan Agreement to “this Agreement” or “herein” shall mean the Existing Loan Agreement as amended by this Amendment. 

Section 3.02. Governing Law. This Amendment shall be governed by and construed in accordance with the Laws of the State of New
York (without giving effect to any conflict of laws principles that would require application of the Laws of another jurisdiction). 

Section 3.03. Counterparts; Facsimile Signatures. This Amendment may be executed and delivered by facsimile signature (including
PDF) and in any number of counterparts, each of which shall be deemed an original but all of which together shall constitute one and the same instrument. 

[The remainder of this page is intentionally left blank.] 

  
 -5- 

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 The undersigned executed this Amendment as of the date first set forth above. 

 

			
	Life Sciences Alternative Funding LLC,
	as Lender
		
	By:	 	/s/ Stephen J. DeNelsky
	Name:	 	Stephen J. DeNelsky
	Title:	 	President
	
	Mevion Medical Systems, Inc.,
	as Borrower
		
	By:	 	/s/ Joseph Jachinowski
	Name:	 	Joseph Jachinowski
	Title:	 	President and CEO
	
	Mevion Medical Systems UK, LLC,
	as Guarantor
		
	By:	 	/s/ Joseph Jachinowski
	Name:	 	Joseph Jachinowski
	Title:	 	President and CEO

  
 -6- 

 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH “[***]”. A COMPLETE
VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIAL TREATMENT UNDER RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

  

 Schedule A 

Material Contract Notices 

[***] 

  
 -7-

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