October 20, 2020 Panacea Acquisition Corp. Floor 3 San Francisco, CA 94103 Re: Lock-Up Agreement for EcoR1 Panacea Holdings, LLC and PA Co-Investment LLC Ladies and Gentlemen:

Exhibit 10.4

Execution Version

October 20, 2020

Panacea Acquisition Corp.

000 Xxxxxx Xxxxxx

Xxxxx 0

Xxx Xxxxxxxxx, XX 00000

Re: Lock-Up Agreement for EcoR1 Panacea Holdings, LLC and PA Co-Investment LLC

Ladies and Gentlemen:

This letter (this “Letter Agreement”) is being delivered to you in accordance with the Agreement and Plan of Merger (the “MA”) entered into by and among Panacea Acquisition Corp., a Delaware corporation (the “Company”), Panacea Merger Subsidiary Corp., a Delaware corporation (“Merger Sub”) and Nuvation Bio Inc., a Delaware corporation (“Nuvation”), pursuant to which, among other things, Merger Sub will be merged with and into Nuvation on the date hereof (the “Merger”), with Nuvation surviving the Merger as a wholly owned subsidiary of the Company.

In order to induce the Company to proceed with the Merger and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the undersigned (the “Securityholder”) hereby agrees with the Company as follows:

1. Subject to the exceptions set forth herein, the Securityholder agrees not to, without the prior written consent of the board of directors of the Company, (i) sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option, right or warrant to purchase or otherwise transfer, dispose of or agree to transfer or dispose of, directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the Securities and Exchange Commission promulgated thereunder, any currently outstanding Class B Common Stock, par value $0.0001 per share, of the Company (the “Existing Class B Common Stock”) issued in connection with the public offering of the Company (or shares of Class A Common Stock, par value $0.0001 per share, of the Company (the “Class A Common Stock”) issuable upon conversion of the Existing Class B Common Stock) held by it immediately after the effective time of the Merger (the “Lock-up Shares”), (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any of the Lock-up Shares, whether any such transaction is to be settled by delivery of such securities, in cash or otherwise or (iii) publicly announce any intention to effect any transaction specified in clause (i) or (ii) (the actions specified in clauses (i)-(iii), collectively, “Transfer”) until 365 days after the closing date of the Merger (the “Lock-Up Period”), subject to the early release provisions set forth in Section 3 below.

2. The restrictions set forth in paragraph 1 shall not apply to:

(i) in the case of an entity, (A) to another entity that is an affiliate (as defined in Rule 405 promulgated under the Securities Act of 1933, as amended) of the undersigned, or to any investment fund or other entity controlling, controlled by, managing or managed by or under common control with the undersigned or affiliates of the undersigned or who shares a common investment advisor with the undersigned or (B) as part of a distribution to members, partners or shareholders of the undersigned;

(ii) in the case of an individual, Transfers by gift to members of the individual’s immediate family (as defined below) or to a trust, the beneficiary of which is a member of one of the individual’s immediate family, an affiliate of such person or to a charitable organization;

(iii) in the case of an individual, Transfers by virtue of laws of descent and distribution upon death of the individual;

(iv) in the case of an individual, Transfers by operation of law or pursuant to a court order, such as a qualified domestic relations order, divorce decree or separation agreement;

(v) in the case of an individual, Transfers to a partnership, limited liability company or other entity of which the undersigned and/or the immediate family (as defined below) of the undersigned are the legal and beneficial owner of all of the outstanding equity securities or similar interests;

(vi) in the case of an entity that is a trust, to a trustor or beneficiary of the trust or to the estate of a beneficiary of such trust;

(vii) in the case of an entity, Transfers by virtue of the laws of the state of the entity’s organization and the entity’s organizational documents upon dissolution of the entity;

(viii) Transfers of any shares of Class A Common Stock or Class B Common Stock, par value $0.001 per share of the Company with such rights and characteristics as are described in the certificate of incorporation of the Company as in effect immediately following the Merger (the “Class B Common Stock” and together with the Class A Common Stock, the “Common Stock”) or other securities acquired as part of the PIPE (as defined in the MA) or issued in exchange for, or on conversion or exercise of, any securities issued as part of the PIPE;

(ix) transactions relating to Common Stock or other securities convertible into or exercisable or exchangeable for Common Stock acquired in open market transactions after the effective time of the Merger, provided that no such transaction is required to be, or is, publicly announced (whether on Form 4, Form 5 or otherwise, other than a required filing on Schedule 13F, 13G or 13G/A) during the Lock-Up Period;

(x) the exercise of stock options or warrants to purchase shares of Common Stock or the vesting of stock awards of Common Stock and any related transfer of shares of Common Stock to the Company in connection therewith (x) deemed to occur upon the “cashless” or “net” exercise of such options or warrants or (y) for the purpose of paying the exercise price of such options or warrants or for paying taxes due as a result of the exercise of such options or warrants, the vesting of such options, warrants or stock awards, or as a result of the vesting of such shares of Common Stock, it being understood that all shares of Common Stock received upon such exercise, vesting or transfer will remain subject to the restrictions of this Letter Agreement during the Lock-Up Period;

(xi) Transfers to the Company pursuant to any contractual arrangement in effect at the effective time of the Merger that provides for the repurchase by the Company or forfeiture of Common Stock or other securities convertible into or exercisable or exchangeable for Common Stock in connection with the termination of the Securityholder’s service to the Company;

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(xii) the entry, by the Securityholder, at any time after the effective time of the Merger, of any trading plan providing for the sale of shares of Common Stock by the Securityholder, which trading plan meets the requirements of Rule 10b5-1(c) under the Exchange Act, provided, however, that such plan does not provide for, or permit, the sale of any shares of Common Stock during the Lock-Up Period and no public announcement or filing is voluntarily made or required regarding such plan during the Lock-Up Period;

(xiii) transactions in the event of completion of a liquidation, merger, stock exchange or other similar transaction which results in all of the Company’s securityholders having the right to exchange their shares of Common Stock for cash, securities or other property; and

(xiv) transactions to satisfy any U.S. federal, state, or local income tax obligations of the Securityholder (or its direct or indirect owners) arising from a change in the U.S. Internal Revenue Code of 1986, as amended (the “Code”), or the U.S. Treasury Regulations promulgated thereunder (the “Regulations”) after the date on which the MA was executed by the parties, and such change prevents the Merger from qualifying as a “reorganization” pursuant to Section 368 of the Code (and the Merger does not qualify for similar tax-free treatment pursuant to any successor or other provision of the Code or Regulations taking into account such changes), in each case solely and to the extent necessary to cover any tax liability as a direct result of the transaction.

provided, however, that (A) in the case of clauses (i) through (vii), these permitted transferees must enter into a written agreement, in substantially the form of this Letter Agreement (it being understood that any references to “immediate family” in the agreement executed by such transferee shall expressly refer only to the immediate family of the Securityholder and not to the immediate family of the transferee), agreeing to be bound by these Transfer restrictions. For purposes of this paragraph, “immediate family” shall mean a spouse, domestic partner, child (including by adoption), father, mother, brother or sister of the undersigned, and lineal descendant (including by adoption) of the undersigned or of any of the foregoing persons; and “affiliate” shall have the meaning set forth in Rule 405 under the Securities Act of 1933, as amended.

3. In the event that the Company releases or waives, in full or in part, any party from a lock-up agreement entered into in connection with the closing of the Merger, then the same percentage of Lock-up Shares held by the undersigned as the percentage of Lock-up Shares (or such equivalent term as defined in such lock-up agreement) held by such released party to such party’s aggregate number of Lock-up Shares that are the subject of such waiver or release shall be immediately and fully released on the same terms from the applicable prohibition(s) set forth herein. The foregoing provisions of this paragraph will not apply if the release or waiver is granted to a holder of Common Stock in connection with a follow-on public offering of Common Stock pursuant to a registration statement filed with the SEC, whether or not such offering or sale is wholly or partially a secondary offering of the Common Stock, and the undersigned, only to the extent the undersigned has a contractual right to demand or require the registration of the undersigned’s Common Stock or “piggyback” on a registration statement filed by the Company for the offer and sale of its Common Stock, has been given an opportunity to participate on a basis consistent with such contractual rights in such follow-on offering. In the event that the Company changes, amends, modifies or waives (other than to correct a typographical error) any particular provision of any other lock-up agreement entered into in connection with the closing of the Merger, then the undersigned shall be offered the option (but not the requirement) to make a corresponding change, amendment, modification or waiver to this Letter Agreement.

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4. The Lock-Up Period shall terminate upon the earlier of (i) 365 days after the closing date of the Merger, (ii) the closing of a merger, liquidation, stock exchange, reorganization or other similar transaction after the closing date of the Merger that results in all of the public stockholders of the Company having the right to exchange their shares of Common Stock for cash securities or other property, or (iii) the day after the date on which the closing price of the Class A Common Stock equals or exceeds $12.00 per share (as adjusted for share splits, share capitalizations, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing at least 150 days after the closing date of the Merger.

5. In furtherance of the foregoing, the Company, and any duly appointed transfer agent for the registration or transfer of the securities described therein, are hereby authorized to decline to make any transfer of securities if such transfer would constitute a violation or breach of this Letter Agreement.

6. This Letter Agreement replaces Section 7(a) of that certain Letter Agreement, dated June 30, 2020, among the Company, the Sponsor, Xxxxx Investments and the Company’s officers and directors, which Section 7(a) shall be terminated and of no further effect with respect to Securityholder upon the Closing of the Merger, and constitutes the entire agreement and understanding of the parties hereto in respect of the subject matter hereof and supersedes all prior understandings, agreements or representations by or among the parties hereto, written or oral, to the extent they relate in any way to the subject matter hereof or the transactions contemplated hereby. This Letter Agreement may not be changed, amended, modified or waived (other than to correct a typographical error) as to any particular provision, except by a written instrument executed by the undersigned (i) Securityholder and (ii) the Company.

7. No party hereto may assign either this Letter Agreement or any of its rights, interests or obligations hereunder without the prior written consent of the other party. Any purported assignment in violation of this paragraph shall be void and ineffectual and shall not operate to transfer or assign any interest or title to the purported assignee. This Letter Agreement shall be binding on the Securityholder and each of its respective successors, heirs and assigns and permitted transferees.

8. This Letter Agreement shall be governed by and construed and enforced in accordance with the laws of the State of Delaware, without giving effect to conflicts of law principles that would result in the application of the substantive laws of another jurisdiction. The parties hereto (i) all agree that any action, proceeding, claim or dispute arising out of, or relating in any way to, this Letter Agreement shall be brought and enforced in the Delaware Chancery Court, and irrevocably submit to such jurisdiction and venue, which jurisdiction and venue shall be exclusive and (ii) waive any objection to such exclusive jurisdiction and venue or that such courts represent an inconvenient forum.

9. This Letter Agreement shall terminate on the earlier of (i) the expiration of the Lock-up Period and (ii) the liquidation of the Company.

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Very truly yours,

If stockholder is an individual:

Signature:

Print Name:

If stockholder is an entity:

Name of Stockholder:  

Signature:

Name:

Title:

Agreed and Acknowledged:
Panacea Acquisition Corp
By:	/s/
	Name:
	Title:

[Signature Page to Lock-Up Agreement]