Company: NCEL
Filing Date: 2025-07-18
Form Type: 425
Source: 0001213900-25-065658
Chunk: 0

Company: NewcelX Ltd.
Filing Date: 2025-07-18
Form: 425
Chunk 0
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Filed by NLS Pharmaceutics Ltd. pursuant to

Rule 425 under the Securities Act of 1933, as amended

Subject Company: Kadimastem Ltd.

<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

under the Securities Exchange Act of 1934

For the month of July 2025 (Report No. 4)

Commission file number: 001-39957

NLS PHARMACEUTICS LTD.

(Translation of registrant’s name into English)

The Circle 6

8058 Zurich, Switzerland

(Address of principal executive offices)</div>

Indicate by check mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.

<div align='center'>Form 20-F ☒
Form 40-F ☐

CONTENTS</div>

Sixth Amendment to the Merger Agreement

On
July 18, 2025, NLS Pharmaceutics Ltd. (the “Company”) entered into a sixth amendment (the “Sixth Amendment”) to
the Agreement and Plan of Merger, dated November 4, 2024, and as previously amended on January 30, 2025, February 17, 2025, May 5, 2025,
June 5, 2025 and July 1, 2025 (the “Merger Agreement”) among the Company, Kadimastem Ltd. (“Kadimastem”) and NLS
Pharmaceutics (Israel) Ltd. (collectively, the “Parties”).

Pursuant
to the Sixth Amendment, the Parties have amended the Merger Agreement to provide that the components used to calculate the Exchange Ratio
will be determined based on information available as of the close of business on the day immediately prior to the extraordinary general
meeting of the shareholders of the Company. The Sixth Amendment clarifies the timing references used in calculating the relative valuation
of the Company and Kadimastem and the number of shares of the Company that will be issued in connection with the Merger. Except as stated
above, the Sixth Amendment does not make any other substantive changes to the Merger Agreement.

The
foregoing description of the Sixth Amendment does not purport to be complete and