Company: NCEL
Filing Date: 2025-08-29
Form Type: 425
Source: 0001213900-25-082554
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Company: NewcelX Ltd.
Filing Date: 2025-08-29
Form: 425
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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 August 2025 (Report No. 3)

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>

Seventh Amendment to the Merger Agreement

On
August 29, 2025, NLS Pharmaceutics Ltd. (the “Company”) entered into a seventh amendment (the “Seventh 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, July 1, 2025, and on July 18, 2025 (the “Merger Agreement”) among the Company, Kadimastem Ltd. (“Kadimastem”)
and NLS Pharmaceutics (Israel) Ltd. (collectively, the “Parties”).

Pursuant
to the Seventh Amendment, the Parties agreed to extend the Merger Agreement’s termination date from August 31, 2025 to October 31,
2025 in order to complete the merger.

This extension is intended to allow additional time for the Company to receive and evaluate further comments from the U.S. Securities
and Exchange Commission on the Company’s pending registration statement on Form F-4 relating to the proposed merger transaction
with Kadimastem. The
Parties remain focused on and fully committed to aligning their efforts to completing the merger as soon as possible and with the utmost
diligence. The Parties are actively working to fulfill