Filed
pursuant to Rule 424(b)(5)
Registration
No. 333-271901
PROSPECTUS
SUPPLEMENT AMENDMENT NO. 3 DATED JANUARY 27, 2026
(To
Prospectus Supplement dated April 26, 2024, as amended by Prospectus Supplement Amendment No. 1, dated December 20, 2024 and by Prospectus
Supplement Amendment No. 2, dated March 28, 2025, and Prospectus dated May 24, 2023)

Up
to $26,441,569
American
Depositary Shares
Representing
Ordinary Shares
This
prospectus supplement amendment no. 3 (this “amendment”) amends the prospectus supplement, dated April 26, 2024 (the “original
prospectus supplement”), as amended by the prospectus supplement amendment no. 1, dated December 20, 2024 (the “first amendment”)
and by the prospectus supplement amendment no. 2, dated March 28, 2025 (the “second amendment” and, the original prospectus
supplement, as amended by the first amendment and the second amendment, the “amended prospectus supplement”), relating to
the offer and sale of American depositary shares (“ADSs”), each representing one of our ordinary shares, pursuant to the
ATM Sales Agreement (the “Original Sales Agreement”), dated April 26, 2024, as amended on December 20, 2024 (the Original
Sales Agreement, as so amended, the “Sales Agreement”), with Virtu Americas LLC (“Virtu”) and Rodman & Renshaw
LLC (“Rodman & Renshaw” and, together with Virtu, each a “Sales Agent” and, collectively, the “Sales
Agents”). This amendment should be read in conjunction with the amended prospectus supplement and the accompanying prospectus,
dated May 24, 2023 (the “prospectus”), each of which are to be delivered with this amendment, and is qualified by reference
thereto, except to the extent that the information herein amends or supersedes the information contained in the amended prospectus supplement
or the prospectus.
We
are filing this amendment to amend the amended prospectus supplement to (i) update the maximum dollar amount of ADSs that we may sell
pursuant to the Sales Agreement, as we are no longer subject to the offering limits in General Instruction I.B.5 of Form F-3 and (ii)
update the use of our net proceeds, if any, from the sale of the ADSs pursuant to the Sales Agreement. The prospectus supplement as amended
by the first amendment originally authorized us to offer and sell ADSs having a maximum aggregate offering price of up to $29,696,999.
As of the date of this amendment, we have sold ADSs pursuant to the Sales Agreement for gross proceeds of $3,255,430. This amendment
is increasing the dollar amount of ADSs available to be sold from time to time under the prospectus supplement to $26,441,569, which
consists of the remaining amount available to be sold under the prospectus supplement.
The
ADSs are listed on the Nasdaq Capital Market (“Nasdaq”) under the symbol “GNTA.” The last reported sale price
of the ADSs on the Nasdaq on January 26, 2026 was $1.30 per ADS. The trading price of the ADSs has fluctuated and is likely
to continue to fluctuate due to a variety of factors.
We
are an “emerging growth company” as defined in Section 2(a) of the Securities Act of 1933, as amended, and, as such, have
elected to comply with certain reduced disclosure and regulatory requirements. Investing in our securities involves a high degree of
risk. Before buying any of our securities, you should carefully read the discussion of material risks of investing in our securities.
Please read the section entitled “Risk Factors” beginning on page A-3 of the first amendment and the section entitled “Risk
Factors” beginning on page S-4 of the original prospectus supplement, as well as the section entitled “Item 3. Key Information—D.
Risk Factors” beginning on page 3 of our Annual Report on Form 20-F for the year ended December 31, 2024, which report is incorporated
by reference in this amendment and the amended prospectus supplement, before investing in our securities.
Neither
the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined
if this amendment, the amended prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the
contrary is a criminal offense.
| RODMAN
& RENSHAW LLC |
 |
The
date of this prospectus supplement amendment no. 3 is January 27, 2026.
TABLE
OF CONTENTS
Prospectus
Supplement Amendment No. 3
We
are responsible for the information contained and incorporated by reference in this amendment, the amended prospectus supplement,
the accompanying prospectus, and in any related free writing prospectus we prepare or authorize. We have not authorized anyone to give
you any other information, and we take no responsibility for any other information that others may give you. If you are in a jurisdiction
where offers to sell, or solicitations of offers to purchase, the securities offered by this documentation are unlawful, or if you are
a person to whom it is unlawful to direct these types of activities, then the offer presented in this document does not extend to you.
The information contained in this document speaks only as of the date of this document, unless the information specifically indicates
that another date applies. Our business, financial condition, results of operations and prospects may have changed since those dates.
USE
OF PROCEEDS
We
may issue and sell ADSs having aggregate sales proceeds of up to $26,441,569 from time to time. Because there is no minimum offering
amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any,
are not determinable at this time. There can be no assurance that we will sell any ADSs under or fully utilize the Sales Agreement as
a source of financing.
We
currently intend to use the net proceeds from this offering, if any, for general corporate purposes and working capital. We may also
use a portion of the net proceeds to acquire or make investments in businesses, products, offerings and technologies. We have not determined
the amount of net proceeds to be used specifically for the foregoing purposes. As a result, our management will have broad discretion
in the allocation of the net proceeds from this offering. Pending use of the net proceeds, we currently intend to invest any proceeds
in a variety of capital preservation instruments, including short-term, investment-grade, and interest-bearing instruments and
government securities.

Up
to $26,441,569
American
Depositary Shares
Representing
Ordinary Shares
PROSPECTUS
SUPPLEMENT AMENDMENT NO. 3
TO
PROSPECTUS SUPPLEMENT
| Rodman
& Renshaw LLC |
 |
January
27, 2026