PTC Therapeutics restructures Censa earn-out with $225M cash, capped milestones

Rhea-AI Filing Summary

On 5 Aug 2025, PTC Therapeutics (PTCT) entered a Rights Satisfaction Agreement with holders of roughly 90% of former Censa Pharmaceuticals equity. The deal cancels the royalty-style Net Sales Payments—8% on annual sepiapterin sales ≤ $250 M, 10% on sales > $250 M ≤ $500 M, and 12% on sales > $500 M—originally embedded in the 2020 Censa merger.

In exchange, PTC paid an up-front cash consideration of ≈ $225 M at closing and agreed to up to five additional milestone payments of ≈ $90 M each $3 B, $5 B, $7 B, $9 B and $11 B achieved within rolling periods of 3–11 consecutive years. Any former Censa holder that later joins the agreement will receive its pro-rata share of the up-front and any future milestones.

The arrangement only affects the specified Net Sales Payments; all other contingent obligations under the original merger agreement remain intact. The agreement contained customary reps, warranties and covenants and closed simultaneously with signing.

Positive

• Royalty elimination: Cancels 8–12% variable Net Sales Payments on sepiapterin, potentially enhancing future gross margins.
• High holder participation: 90% of former Censa securityholders agreed, minimizing residual obligations to non-participants.
• Capped liability: Future payouts are fixed at ≈$450 M and contingent on ambitious multi-billion-dollar sales thresholds.

Negative

• Immediate cash impact: Requires an up-front payment of ≈$225 M, reducing near-term liquidity.
• Remaining milestones: PTCT still faces up to ≈$450 M in additional payments if sales milestones are met.

Insights

Sell-Side Pharmaceutical Analyst

TL;DR Replaces uncapped royalties with capped cash and milestones; improves long-term gross margin but increases near-term cash burn.

Analysis: Eliminating an 8–12% royalty on global sepiapterin sales could meaningfully lift eventual product margins if commercialization succeeds. The immediate $225 M outflow is material—≈14% of PTCT’s 2024 year-end cash—but provides cost certainty and removes a drag on peak profitability. The $450 M milestone ceiling is only triggered at multibillion-dollar sales levels, aligning payouts with strong revenue performance. Overall impact is moderately positive given the trade-off between liquidity and long-term economics.

M&A Structuring Specialist

TL;DR Classic earn-out buy-down: high participation (90%) lowers residual tail risk; terms appear market-standard.

The agreement converts an open-ended royalty into a finite earn-out, simplifying PTCT’s capital structure and easing forecasting. 90% holder consent limits hold-out exposure, while the joinder mechanic sweeps in any late signatories. Milestone sizing (≈$90 M each) scales at ~3% of the respective sales thresholds, materially lower than the canceled top-slice royalty, indicating favorable economics for PTCT if sepiapterin becomes a blockbuster. The simultaneous sign-and-close structure mitigates execution risk.

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UNITED STATES

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SECURITIES AND EXCHANGE COMMISSION

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WASHINGTON, D.C. 20549

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FORM 8-K

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CURRENT REPORT

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Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

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Date of Report (Date of earliest event reported): August 5, 2025

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PTC THERAPEUTICS, INC.

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(Exact Name of Company as Specified in Charter)

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Delaware		001-35969		04-3416587
(State or Other Jurisdiction	​	(Commission	​	(IRS Employer
of Incorporation)	​	File Number)	​	Identification No.)

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500 Warren Corporate Center Drive	​		​
Warren, NJ	​	​	07059
(Address of Principal Executive Offices)	​	​	(Zip Code)

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Registrant’s telephone number, including area code: (908) 222-7000

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Not applicable

(Former Name or Former Address, if Changed Since Last Report)

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Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

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☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

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☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

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☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

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☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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Securities registered pursuant to Section 12(b) of the Act:

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Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, $0.001 par value per share	​	PTCT	​	Nasdaq Global Select Market

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Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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Emerging growth company ☐

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If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

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Item 1.01. Entry into a Material Definitive Agreement.

On August 5, 2025, PTC Therapeutics, Inc. (the “Company”), certain of the former securityholders of Censa Pharmaceuticals, Inc., a Delaware corporation (“Censa”), and, for the limited purposes set forth in the agreement, Shareholder Representative Services LLC, a Colorado limited liability company (“SRS”), entered into a Rights Satisfaction Agreement (the “Rights Satisfaction Agreement”), pursuant to which such former securityholders of Censa (the “Participating Rightsholders”) agreed to the cancellation and forfeiture of their rights to receive certain payments based on worldwide annual net sales by the Company of products containing sepiapterin (“Net Sales of Product”) under that certain Agreement and Plan of Merger, dated May 5, 2020, by and among the Company, Censa, Hydro Merger Sub, Inc., a Delaware corporation, and SRS, solely in its capacity as the representative, agent and attorney-in-fact of the securityholders of Censa, (the “Merger Agreement”), in exchange for the consideration set forth in the Rights Satisfaction Agreement and further detailed below.

Pursuant to the terms of the Rights Satisfaction Agreement, the Participating Rightsholders have canceled and forfeited their rights under the Merger Agreement to receive a percentage of annual net sales during the applicable payment term equal to (i) 8% of annual Net Sales of Product for that portion of annual Net Sales of Product less than or equal to $250.0 million, (ii) 10% of annual Net Sales of Product for that portion of annual Net Sales of Product greater than $250.0 million but less than $500.0 million and (iii) 12% of annual Net Sales of Product for that portion of annual Net Sales of Product greater than $500.0 million (collectively, the “Net Sales Payments”).

In consideration of the foregoing, the Company agreed to pay to the Participating Rightsholders an aggregate amount in cash up to $250.0 million (the “Upfront Consideration”) upon the consummation of the transactions contemplated by the Rights Satisfaction Agreement (the “Closing”) and potential milestone payments (each an “Additional Milestone Payment”) of up to $100.0 million each (or up to $500.0 million in the aggregate) based on the achievement of specified Net Sales Thresholds (as defined in the Merger Agreement). The amount of the Upfront Consideration and the Additional Milestone Payments was subject to adjustment in the Rights Satisfaction Agreement based on the number of Participating Rightsholders.

At the Closing, based on the participation of former Censa securityholders holding approximately 90% of Censa’s equity securities prior to the consummation of the transactions contemplated by the Merger Agreement, the Company paid an aggregate amount of Upfront Consideration in cash of approximately $225.0 million. Additionally, the Company is obligated to make Additional Milestone Payments in an amount equal to approximately $90.0 million upon achievement of each of the (i) first occurrence of a three or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $3.0 billion, (ii) first occurrence of a five or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $5.0 billion, (iii) first occurrence of a seven or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $7.0 billion, (iv) first occurrence of a nine or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $9.0 billion and (v) first occurrence of an 11 or fewer consecutive calendar year period in which aggregate Net Sales of Product are greater than $11.0 billion. If, after the Closing, any additional former securityholder of Censa executes and delivers a joinder to the Rights Satisfaction Agreement and becomes a party thereto, the Company will pay such former securityholder an amount in cash equal to such former securityholder’s applicable pro rata share of the Upfront Consideration (less any Net Sale Payments previously received) and any Additional Milestone Payments that become payable to Participating Rightsholders under the Rights Satisfaction Agreement.

The Rights Satisfaction Agreement has no effect on the Merger Agreement other than to provide for the cancellation and forfeiture of the Participating Rightsholders’ rights to receive the Net Sales Payments described above. As a result, all other rights and obligations under the Merger Agreement remain in effect pursuant to their terms, including, without limitation, the Company's obligation to pay certain contingent payments upon the achievement of certain development and Net Sales of Product milestones.

The Rights Satisfaction Agreement contains customary representations, warranties and covenants of the Company and the Participating Rightsholders and provided for a simultaneous signing and closing.

The foregoing description of the Rights Satisfaction Agreement is not complete and is qualified in its entirety by reference to the full text of the Rights Satisfaction Agreement, a copy of which will be filed as an exhibit to the Company’s Quarterly Report on Form 10-Q for the fiscal quarter ending September 30, 2025.

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this Report to be signed on its behalf by the undersigned hereunto duly authorized.

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​	PTC Therapeutics, Inc.
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Date: August 7, 2025	By:	/s/ Pierre Gravier
​	Name:	Pierre Gravier
​	Title:	Chief Financial Officer

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FAQ

What did PTC Therapeutics (PTCT) announce on 5 Aug 2025?

It entered a Rights Satisfaction Agreement to cancel certain sepiapterin sales-based royalty payments owed to former Censa securityholders.

How much up-front cash will PTCT pay under the agreement?

Approximately $225 million was paid at closing based on 90% holder participation.

What royalty rates were canceled by the agreement?

Royalties of 8% on annual sales ≤ $250 M, 10% on sales > $250 M ≤ $500 M, and 12% on sales > $500 M.

What are the potential milestone payments and triggers?

Up to five payments of ≈$90 M each, triggered when cumulative net sales exceed $3 B, $5 B, $7 B, $9 B, and $11 B within set timeframes.

Does the agreement affect other contingent payments in the 2020 merger?

No. All other obligations under the original merger agreement remain unchanged.