BIOCEPT, INC. FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT

Exhibit 10.18.1

BIOCEPT, INC.

FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT

This FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT (this “Amendment”), amending the Note and Warrant Purchase Agreement by and among BIOCEPT, INC., a California corporation (the “Company”) and the investors listed on the Schedule of Investors attached thereto (the “Investors”) dated as of February 1, 2011 (the “Purchase Agreement”), is entered into as of July 1, 2011 by and among the Company and the Investors. Capitalized terms used herein which are not defined herein shall have the definition ascribed to them in the Purchase Agreement.

RECITALS

WHEREAS, the Company and the Investors have previously entered into the Purchase Agreement;

WHEREAS, Section 6.7 of the Purchase Agreement provides that the Purchase Agreement may be amended with the written consent of (i) the Company and (ii) the holders of at least a majority in interest of the outstanding Securities (the “Required Holders”); and

WHEREAS, the undersigned constitute (i) the Company and (ii) the Required Holders.

AGREEMENT

NOW, THEREFORE, in consideration of the foregoing and the promises and covenants contained herein and in the Purchase Agreement, and for other good and valuable consideration, the receipt of which is hereby acknowledged, the parties hereto agree as follows:

1.        Recitals.    The reference to “$5,000,000” in the “whereas” clause contained in the recitals of the Purchase Agreement is hereby amended and restated such that it shall be “$6,000,000.”

2.        Section 2.5 of the Purchase Agreement.    The first sentence of Section 2.5 of the Purchase Agreement shall be amended and restated to read in its entirety as follows:

“On June 1, 2011, the fifth closing of the purchase and sale of the Notes in the principal amounts set forth opposite each Investor’s name under the heading “Fifth Closing Principal Amount of Note” on the Schedule of Investors attached hereto (the “Fifth Closing”) shall take place.”

3.        Addition of New Section 2.6 of the Purchase Agreement.    A new Section 2.6 shall be added to the Purchase Agreement and shall read in its entirety as follows:

“2.6    Sixth Closing.    On June 30, 2011, the sixth closing of the purchase and sale of the Notes in the principal amounts set forth opposite each Investor’s name under the heading “Sixth Closing Principal Amount of Note” on the Schedule of Investors attached hereto (the “Sixth Closing” and each of the Sixth Closing,

Fifth Closing, Fourth Closing, Third Closing, Second Closing and Initial Closing, a “Closing”) shall take place.

(a)        Deliveries by the Company. At the Sixth Closing, the Company shall deliver to each Investor participating in the Sixth Closing (a) a duly executed Note (in the principal amount set forth on the Schedule of Investors attached hereto under the heading “Sixth Closing Principal Amount of Note”) and (b) a duly executed Warrant to purchase the Warrant Shares.

(b)        Deliveries by Investors.    At the Sixth Closing, the Investors shall, in the aggregate, deliver to the Company funds, by check or wire transfer, in the amount set forth on the Schedule of Investors attached hereto under the heading “Sixth Closing Principal Amount of Note.”

4.        Section 6.6 of the Purchase Agreement.    The last sentence of Section 6.6 of the Purchase Agreement shall be amended and restated to read in its entirety as follows:

“All communications shall be sent (i) to the Company at 5810 Nancy Ridge Drive, San Diego, California 92121, Attn: Chuck Covington, Facsimile No: (858)  ###-###-#### or (ii) to the Investors at the address shown on the Schedule of Investors, or at such other address as such party may designate by written notice to the other party.”

5.        Schedule of Investors attached to the Purchase Agreement.    The Schedule of Investors attached to the Purchase Agreement is hereby amended and restated to read in its entirety as set forth on Exhibit A hereto.

6.        Effect of Amendment.    Except as expressly modified by this Amendment, the Purchase Agreement shall remain unmodified and in full force and effect.

7.        Governing Law.    This Amendment shall be governed by and construed under the laws of the State of California as applied to agreements among California residents, made and to be performed entirely within the State of California without giving effect to its conflicts of laws principles.

8.        Counterparts.    This Amendment may be executed in any number of counterparts and signatures delivered by facsimile, each of which shall be deemed an original, but all of which together shall constitute one instrument.

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IN WITNESS WHEREOF, the parties have executed this FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT as of the date first written above.

EXHIBIT A

SCHEDULE OF INVESTORS

¹ $1,000,000 in the aggregate to be lent by The Reiss Family GST Exempt Marital Deduction Trust and/or The Reiss Family Survivor’s Trust UDT dated December 19, 1988.