Filed Pursuant to Rule 424(b)(3)
Registration No. 333-290598
PROSPECTUS SUPPLEMENT
(to Prospectus dated December 23, 2025)
232,956 American Depositary Shares representing
116,478,000 Ordinary Shares
Kazia Therapeutics Limited
This prospectus supplement is being filed to update and supplement
the information contained in the prospectus dated December 23, 2025 (the “Prospectus”), which forms a part of our Registration
Statement on Form F-1 (Registration No. 333-290598), as amended, with the information contained in our current report on Form 6-K, furnished
to the Securities and Exchange Commission on September 22, 2026 (the “September 22, 2026 Form 6-K”). Accordingly, we have
attached the September 22, 2026 Form 6-K to this prospectus supplement.
This prospectus supplement updates and supplements the information
in the Prospectus and is not complete without, and may not be delivered or utilized except in combination with, the Prospectus, including
any amendments or supplements thereto. This prospectus supplement should be read in conjunction with the Prospectus and if there is any
inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus
supplement.
The ADSs are listed on The Nasdaq Capital Market (“Nasdaq”)
under the symbol “KZIA.” On September 21, 2026, the last reported sale price of the ADSs on Nasdaq was $10.65 per ADS.
Investing in our securities involves a high degree of risk. See
“Risk Factors” beginning on page 9 of the Prospectus and the “Risk Factors” in “Item 3. Key Information-D.
Risk Factors” of our most recent Annual Report on Form 20-F, which is incorporated by reference in the Prospectus, as well as in
any other recently filed reports and, if any, in any applicable prospectus supplement.
Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of the Prospectus or this prospectus
supplement. Any representation to the contrary is a criminal offense.
The date of this prospectus supplement is September
22, 2026
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 September 2026
Commission File Number: 000-29962
Kazia Therapeutics Limited.
(Exact Name of Registrant as Specified in Its Charter)
Three International Towers Level 24 300 Barangaroo
Avenue Sydney NSW 2000
(Address of principal executive offices)
Indicate by check mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.
Form 20-F ☒ Form
40-F ☐
INFORMATION CONTAINED IN THIS FORM 6-K REPORT
Press Release
On September 22, 2026, Kazia Therapeutics Limited (the “Company”)
issued a press release titled “Kazia Therapeutics Announces Sovargen Co. Doses First Patient in Phase 1b/2a Trial of Paxalisib for
Rare Seizure Disorders”. A copy of this press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.
Incorporation by Reference
The Company hereby incorporates by reference the information contained
herein, including Exhibit 99.1, except for the quotes of Dr. John Friend, Chief Executive Officer of the Company, contained in Exhibit
99.1, into the Company’s registration statements on Form F-3 (File Nos. 333-276091, 333-281937 and 333-294392).
EXHIBIT INDEX
The following exhibits are furnished as part of this Form 6-K:
| Exhibit |
|
Description |
| 99.1 |
|
Press Release dated September 22, 2026 |
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.
| |
Kazia Therapeutics Limited. |
| |
|
|
| |
By: |
/s/ John Friend |
| |
Name: |
John Friend |
| |
Title: |
Chief Executive Officer |
| |
|
|
| Date: September 22, 2026 |
|
|
Exhibit
99.1
Kazia
Therapeutics Announces Sovargen Co. Doses First Patient in Phase 1b/2a Trial of Paxalisib for Rare Seizure Disorders
Clinical
Milestone Expands Development of Paxalisib Beyond Oncology and Triggers $2 Million Payment to Kazia
SYDNEY,
Australia, September 22, 2026 – Kazia Therapeutics Limited (NASDAQ: KZIA), an oncology-focused biotechnology company developing
therapies that selectively reprogram cancer biology, restore anti-tumor immunity and overcome treatment resistance, today announced that
Sovargen Co., Ltd., a biotechnology company specializing in central nervous system (CNS) diseases that has exclusively licensed paxalisib
from Kazia for the development and commercialization of paxalisib as a potential treatment for mTORopathy-related epilepsies, has dosed
the first patient in a Phase 1b/2a clinical trial evaluating paxalisib for the treatment of intractable epilepsy associated with focal
cortical dysplasia type 2 (FCD T2) and tuberous sclerosis complex (TSC). The dosing triggers a $2 million development milestone payment
to Kazia under the companies’ exclusive licensing agreement.
Kazia
and Sovargen entered into the agreement in March 2024, under which Sovargen is responsible for developing, manufacturing and commercializing
paxalisib as a potential treatment for the mTORopathy-related epilepsies in all countries worldwide, excluding mainland China, Hong Kong,
Macao and Taiwan. Under the agreement, Kazia is eligible to receive additional milestone payments of up to $17 million upon the achievement
of further development and regulatory milestones, plus a percentage of sub-licensing revenues and royalties on net sales of any products
incorporating paxalisib.
FCD
T2 and TSC are rare, genetically driven neurological disorders in which somatic mutations in the PI3K/Akt/mTOR pathway, or mutations
in the TSC1 or TSC2 genes, drive overactivation of the mTOR pathway and contribute to treatment-resistant seizures. There are currently
no approved therapies for FCD T2. Paxalisib is an oral, brain-penetrant dual inhibitor of PI3K and mTOR.
“This
milestone reflects the steady progress Sovargen is making in advancing paxalisib for patients with FCD T2 and TSC, two rare disorders
with significant unmet need,” said Dr. John Friend II, CEO of Kazia Therapeutics. “While our own clinical focus for paxalisib
remains in oncology, we’re pleased to see its potential being explored in additional indications where its mechanism of action
may address significant unmet medical needs. We look forward to the data generated through this study as the program advances.”
“Families
living with FCD T2 and TSC have long faced limited treatment options, making the advancement of new therapies crucial,” said Cheolwon
Park, CEO of Sovargen. “Dosing the first patient is a significant step for our program and reflects the dedication of our team
and investigators in bringing this study to life. As enrollment continues, we remain focused on executing a rigorous clinical trial and
generating the data needed to better understand paxalisib’s potential as a treatment for these rare neurological disorders.”
About
Kazia Therapeutics
Kazia
Therapeutics (NASDAQ: KZIA) is an oncology-focused drug development company, based in Sydney, Australia. The Company’s lead asset,
paxalisib, is an investigational brain-penetrant inhibitor of the PI3K/Akt/mTOR pathway, which is being developed to treat multiple forms
of cancer. Licensed from Genentech in late 2016, paxalisib is or has been the subject of over 15 clinical trials. A completed Phase 2/3
study in glioblastoma (GBM AGILE) was reported in 2024, and discussions are ongoing for designing and executing a pivotal registrational
study in pursuit of a standard approval. Other clinical trials involving paxalisib are ongoing in advanced breast cancer, brain metastases,
diffuse midline gliomas, and primary central nervous system lymphoma, with several of these trials having reported encouraging interim
data. Paxalisib was granted Orphan Drug Designation for glioblastoma by the U.S. Food and Drug Administration (FDA) in February 2018,
and Fast Track Designation (FTD) for glioblastoma in August 2020. Paxalisib was also granted FTD in July 2023 for the treatment of solid
tumor brain metastases harboring PI3K pathway mutations in combination with radiation therapy. Additionally, paxalisib was granted Rare
Pediatric Disease Designation and Orphan Drug Designation by the FDA for diffuse intrinsic pontine glioma in August 2020 and for atypical
teratoid/rhabdoid tumors in June 2022 and July 2022, respectively. Kazia is also developing EVT801, a small molecule inhibitor of VEGFR3,
which was licensed from Evotec SE in April 2021. In addition to its clinical-stage programs, Kazia is advancing NDL2, a potentially first-in-class
intracellular PD-L1 protein degrader program targeting a newly identified mechanism of immunotherapy resistance and metastatic progression,
as well as MSETC, a potentially first-in-class SETDB1 inhibitor program intended to restore immune signaling in tumors that have become
resistant to immunotherapy, including checkpoint inhibitors. Both programs are currently in preclinical development. For more information,
please visit www.kaziatx.com or follow us on X @KaziaTx.
About
Sovargen
Sovargen
Co., Ltd. is a clinical-stage biotechnology company based in Korea, founded in 2018 as a spin-out from the Korea Advanced Institute of
Science and Technology (KAIST). The Company is focused on the discovery and development of medicines for rare and intractable neurological
disorders caused by brain somatic mosaicism. The Company’s lead clinical asset, SVG103 (paxalisib), is a brain penetrant dual PI3K/mTOR
inhibitor in-licensed from Kazia Therapeutics for the treatment of mTORopathy-related epilepsies, including focal cortical dysplasia
type II (FCD T2), tuberous sclerosis complex (TSC), and hemimegalencephaly (HME) — conditions in which mTOR pathway hyperactivation
is the underlying cause of drug-resistant seizures. SVG103 is currently being evaluated in a Phase 1b/2a study in adult patients with
FCD T2, TSC, and HME. SVG105 is an antisense oligonucleotide targeting intractable epilepsies that has been out-licensed to a European
global pharmaceutical company for worldwide development and commercialization. Sovargen’s pipeline is underpinned by its proprietary,
integrated platform designed to discover and develop therapeutics for intractable CNS diseases. The platform features SovarIN™
for identifying disease-causing somatic mutations and therapeutic targets. SovarON™ for ASO design, screening, and optimization,
and SovarUP™ for target validation and preclinical efficacy evaluation using disease-relevant animal models and human organoid
systems. For more information, please visit www.sovargen.com.
Forward-Looking
Statements
This
press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section
21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements are generally identified by words such as “anticipates,”
“believes,” “expects,” “intends,” “plans,” “may,” “will,” “could,”
“should,” “estimates,” “projects,” “potential,” and similar expressions. These forward-looking
statements include, but are not limited to, statements regarding: the $2 million development milestone payment to Kazia; additional milestone
payments of up to $17 million upon the achievement of further development and regulatory milestones, plus sub-licensing revenues and
royalties; the progress and enrollment of Sovargen’s Phase 1b/2a clinical trial of paxalisib for FCD T2, TSC, and HME; the potential
of paxalisib as a treatment for mTORopathy-related epilepsies and other non-oncology indications; and data generation from the clinical
study.
These
forward-looking statements are based on management’s current expectations and assumptions as of the date of this press release
and are subject to significant risks, uncertainties, and other factors that could cause actual results to differ materially from those
expressed or implied. Such risks and uncertainties include, but are not limited to: risks associated with the development of early-stage
therapeutic programs; the conduct and enrollment of clinical trials; regulatory review and approval processes; reliance on third-party
licensees, collaborators and trial sites; the Company’s ability to obtain, maintain and protect its intellectual property; general
economic and market conditions; and the Company’s ability to maintain compliance with NASDAQ listing requirements.
For
a more complete discussion of risks and uncertainties, please refer to the Company’s filings with the SEC, including the “Risk
Factors” section of the Company’s most recent Annual Report on Form 20-F. The Company undertakes no obligation to update
or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by
law.
All
forward-looking statements are qualified in their entirety by this cautionary statement.
Media
Contact
Michaela
Fawcett
KCSA
Strategic Communications
mfawcett@kcsa.com