EXECUTION VERSION

THIS SECURITIES PURCHASE

AGREEMENT (this "Agreement"), dated as of March 11, 2019, is by and among BioBlast Pharma Ltd., a company

formed under the laws of the State of Israel (the "Company"), and each investor identified on the signature

pages hereto (each, an "Investor" and collectively, the "Investors").

Company is a party to that certain Agreement and Plan of Merger, dated as of November 19, 2018 (the "Merger Agreement"),

together with Enlivex Therapeutics Ltd., a company formed under the laws of the State of Israel ("Enlivex"),

and Treblast Ltd., a company formed under the laws of the State of Israel and a wholly owned subsidiary of the Company ("Merger

Sub"); and, pursuant to the transactions contemplated by the Merger Agreement, Merger Sub will merge with and into Enlivex

(the "Merger") with Enlivex surviving the Merger as a wholly owned subsidiary of the Company, and the Company's

name will change to "Enlivex Therapeutics Ltd", and Enlivex's name will change to "Enlivex Therapeutics

connection with the transactions contemplated by the Merger Agreement, upon the terms and subject to the conditions stated in

this Agreement, the Company desires to issue and sell, and each Investor, severally and not jointly with any other Investor, desires

to purchase, that number of the Company's ordinary shares, NIS 0.40 per share (the "Ordinary Shares"),

set forth on such Investor's signature page to this Agreement.

Closing shall take place substantially concurrently with the consummation of the Merger.

NOW, THEREFORE, IN CONSIDERATION

of the mutual covenants contained in this Agreement, and for other good and valuable consideration the receipt and adequacy of

which are hereby acknowledged, the Company and the Investors, intending to be legally bound hereby, agree as follows:

In addition to the terms defined elsewhere in this Agreement, the following terms have the meanings indicated:

means any Person that, directly or indirectly through one or more intermediaries, controls or is controlled by or is under common

control with a Person, as such terms are used in and construed under Rule 144 under the Securities Act.

has the meaning set forth in the Preamble.

means any day other than a Friday, Saturday, Sunday, or any day which shall be a federal legal holiday in the United States or

a legal holiday in Israel.

means the closing of the purchase and sale of the Ordinary Shares pursuant to Section 2.1.

means the "Closing Date" as defined in the Merger Agreement, subject to the making of the deliverables required by

Section 2.2 and satisfaction of the deliverables conditions set forth in Sections 5.1 and 5.2 (other than

those to be satisfied at the Closing and those conditions waived by the Person entitled to the benefit of such conditions).

has the meaning set forth in the Preamble.

has the meaning set forth in the Recitals.

means the Securities Exchange Act of 1934, as amended.

has the meaning set forth in Section 3.2(c).

"Indemnified Person"

has the meaning set forth in Section 6.2.

has the meaning set forth in the Preamble.

has the meaning set forth in Section 6.1.

means any and all losses, claims, damages, liabilities, settlement costs and expenses, including, without limitation, reasonable

has the meaning set forth in the Recitals.

has the meaning set forth in the Recitals.

has the meaning set forth in the Recitals.

means New Israeli Shekels.

has the meaning set forth in the Recitals.

Price" hast the meaning set forth in Section 2.1.

means an individual, a limited liability company, a partnership, a joint venture, a corporation, a trust, an unincorporated organization,

a government or any department or agency thereof and any other legal entity.

means an action, claim, suit, investigation or proceeding (including, without limitation, a partial proceeding, such as a deposition),

whether commenced or threatened in writing.

"Prohibited Transaction"

has the meaning set forth in Section 3.2(i).

"Registrable Securities"

means the Ordinary Shares acquired hereunder any shares of capital stock issued or issuable with respect to such Ordinary Shares

as a result of any stock split, dividend, distribution, recapitalization or similar transaction; provided, that the Registrable

Securities shall cease to be Registrable Securities when (a) a registration statement covering such Registrable Securities has

been declared effective by the SEC and such Registrable Securities have been disposed of pursuant to such effective registration

statement, or (b) such Registrable Securities may be sold without restrictions or other limitations pursuant to Rule 144 (or any

successor provision) under the Securities Act (including, without limitation, volume restrictions) and without the need for current

public information required by Rule 144(c)(1).

Statement" has the meaning set forth in Section 4.2.

means Regulation S promulgated under the Securities Act.

has the meaning set forth in Section 7.14.

means Rule 144 promulgated by the SEC under the Securities Act.

means the U.S. Securities and Exchange Commission.

means the Securities Act of 1933, as amended, including the rules and regulations promulgated thereunder.

means and includes, without limitation, all "short sales" as defined in Rule 200 promulgated under Regulation SHO under

the Exchange Act and all types of direct and indirect stock pledges, forward sale contracts, options, puts, calls, short sales,

swaps, derivatives and similar arrangements (including on a total return basis), and sales and other transactions through non-U.S.

broker-dealers or foreign regulated brokers.

"Transaction Documents"

means this Agreement and each of the other agreements or instruments entered into or executed by the parties hereto in connection

with the transactions contemplated by this Agreement and the other Transaction Documents.

Subject to the terms and conditions set forth in this Agreement, at the Closing, the Company shall issue and sell to each Investor,

and each Investor shall, severally and not jointly, purchase from the Company, such number of Ordinary Shares set forth on such

Investor's signature page to this Agreement, at a purchase price per Ordinary Share equal to $12.25 (the "Per

Share Purchase Price"). The date and time of the Closing shall be 10:00 a.m., Eastern Time, on the Closing Date. The

Closing shall take place at the offices of Greenberg Traurig, P.A., 333 S.E. 2nd Avenue, Suite 4400, Miami, Florida

33131, (or pursuant to the electronic or other remote exchange of all executed documents and other deliverables required by this

Agreement to be delivered at Closing) or at such other location as the parties determine.

the Closing, the Company shall deliver to each Investor a certificate, duly executed by the Company and registered in the name

of such Investor, or, if so indicated on such Investor's signature page, in such other name(s) as designated by such Investor,

inclusive of such restrictive and other legends as set forth in Section 4.1(b), evidencing such number of Ordinary

Shares as is set forth on such Investor's name on the Schedule of Investors. In lieu of such certificate, the Company may

deliver a copy of issuance instructions in respect of such Investor's Ordinary Shares delivered to the Company's transfer

the Closing, each Investor shall deliver or cause to be delivered to the Company the following:

aggregate amount equal to the Per Share Purchase Price multiplied by the number of Ordinary Shares to be purchased by such Investor

hereunder, as set forth on such Investor's signature page to this Agreement, in immediately available funds, by wire transfer

to an account designated in writing to such Investor by the Company for such purpose; and

completed and executed Investor Signature Page to this Agreement.

REPRESENTATIONS AND WARRANTIES

of Certain Representations and Warranties from Merger Agreement. The Company hereby represents and warrants to the Investors

as follows: The representations and warranties made by the Company and Merger Sub to Enlivex as set forth in Article III, Sections

3.01 through 3.27 of the Merger Agreement, and the representations and warranties made by Enlivex to the Company and Merger Sub

as set forth in Article IV Sections 4.01 through 4.28 of the Merger Agreement, with such representations and warranties as qualified

by the exceptions disclosed in the Bioblast Disclosure Letter (as defined in the Merger Agreement) and the Enlivex Disclosure

Letter (as defined in the Merger Agreement), are incorporated herein by reference and deemed made by the Company to the Investors

as of the Closing (except to the extent that any such representations and warranties are made as of a specific date, in which

case such representations and warranties are made as of such date).

and Warranties of the Investors. Each Investor hereby, as to itself only and for no other Investor, represents and warrants

to the Company as follows:

Authority. Such Investor, if such Investor is not a natural person, is an entity duly organized, validly existing and, to the