SECURITIESAND EXCHANGE COMMISSION

Washington,D.C. 20549

FORM6-K

REPORTOF FOREIGN PRIVATE ISSUER

PURSUANTTO RULE 13a-16 OR 15d-163

UNDERTHE SECURITIES EXCHANGE ACT OF 1934

Forthe month of July 2025

AlterityTherapeutics Limited

(Nameof Registrant)

Level 14, 350 Collins Street,Melbourne, Victoria 3000 Australia

(Addressof Principal Executive Office)

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

Form20-F ☒       Form 40-F ☐

ThisForm 6-K is being incorporated by reference into our Registration Statement on Form S-8 (Files No. 333-251073, 333-248980and 333-228671) and ourRegistration Statements on Form F-3 (Files No. 333-274816, 333-251647, 333-231417and 333-250076)

ALTERITYTHERAPEUTICS LIMITED

(adevelopment stage enterprise)

Thefollowing exhibits are submitted:

SIGNATURE

Pursuantto the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf bythe undersigned, thereunto duly authorized.

Date:July 28, 2025

Exhibit 99.1 

Alterity Therapeutics Reports Positive ToplineData from Open-Label Phase 2 Clinical Trial of ATH434 in Multiple System Atrophy

– ATH434 Demonstrated Clinical Benefiton the Unified MSA Rating Scale and Global Measures of Neurological Symptoms –

– NeuroimagingBiomarkers Showed Target Engagement and Slowed Brain Atrophy –

– ATH434 wasWell-Tolerated with Favorable Safety Profile –

– Data are Consistentwith Phase 2 Double-Blind Trial and Support Advancement of ATH434 in MSA –

MELBOURNE, AUSTRALIA AND SAN FRANCISCO, USA– 28 July 2024: Alterity Therapeutics (ASX: ATH, NASDAQ: ATHE) (“Alterity” or “the Company”), a biotechnologycompany dedicated to developing disease modifying treatments for neurodegenerative diseases, today announced positive topline data fromthe ATH434-202 open-label Phase 2 clinical trial in individuals with multiple system atrophy (MSA). The ATH434-202 trial evaluated a patientpopulation with more advanced disease than was studied in Alterity’s double-blind Phase 2 trial ATH434-201. ATH434 has been shownpreclinically to reduce α-synuclein pathology and preserve neuronal function by redistributing iron in the central nervous system.

The topline data showed that ATH434 conferreda clinical benefit on areas of impairment in MSA and stabilized key biomarkers that underpin the pathology of the disease.

The results from the ATH434-202 trial indicatethat ATH434 demonstrated a clinical benefit on the Modified Unified MSA Rating Scale Part I (UMSARS I)¹, as well as stabilizationof overall neurological symptoms. Over the 12-month treatment period, disease progression as assessed with UMSARS I was reduced by approximatelyhalf as compared to historical controls². In addition, 30% of participants reported stable neurological symptoms over the courseof the study. These outcomes are potentially promising as stabilization of MSA symptoms is unexpected in this patient population. On theimportant symptom of orthostatic hypotension³, ATH434 on average stabilized low blood pressure symptoms in study participants.Importantly, the aggregate data indicate that ATH434 has similar clinical efficacy in this advanced MSA population as was observed inthe earlier stage patients in Study ATH434-201.

Biomarker endpoints were used to evaluate potentialdrug effect and target engagement. Neuroimaging outcomes indicate that ATH434 slowed brain atrophy in MSA affected areas, as measuredby the MSA Atrophy Index (MSA-AI)⁴, when compared to placebo-treated participants in Study 201. Moreover, the effects on brainvolume were comparable to those observed in participants in the 75 mg dose group in Study 201. In addition, ATH434 led to lower iron accumulationin the putamen and globus pallidus as compared to placebo treated patients in Study 201, providing further evidence of target engagement.

“I am very encouraged by the positive resultsfrom the ATH434-202 trial, as they reinforce the robust efficacy we observed in our double-blind study,” said David Stamler, M.D.,Chief Executive Officer of Alterity. “The data from our Phase 2 studies are consistent and strongly support advancing our ATH434program in MSA. With the favorable clinical and biomarker outcomes we have seen, we continue to believe that ATH434 has the potentialto slow the progression of this devastating disease. We are committed to bringing this new therapy to patients as soon as possible.”

Daniel Claassen, M.D., M.S., Professor of Neurologyat Vanderbilt University Medical Center and principal investigator for the ATH434-202 Phase 2 study, commented, “These results arevery helpful in establishing the clinical response to therapy. The consistent changes in UMSARS, along with quantitative measures in imaging,support the findings we noted in Study 201. Currently, there are no disease modifying medications for the treatment of MSA, and thesedata encourage the continued development of ATH434 to treat this disease. We are indebted to the study participants and their familieswho contributed to this study.”

ATH434-202 Topline Data Summary

The ATH434-202 Phase 2 clinical trial was an openlabel study in advanced MSA. Ten (10) participants were enrolled in the trial and were diagnosed with MSA using a multimodal approach(clinical, neuroimaging, fluid biomarkers). Participants were treated with oral ATH434 75 mg twice daily for 12 months. The study assessedthe safety and efficacy of ATH434 treatment on clinical and biomarker endpoints. The pre-specified key clinical endpoints included themodified UMSARS I, the clinical global impression of change, and the patient global impression of change. Enrolled participants were moreadvanced than those in the double blind ATH434-201 Phase 2 trial based on baseline variables including duration of motor symptoms, UMSARSI score, frequency of severe orthostatic hypotension, and plasma NFL levels.

Based on the observed clinical and neuroimagingdata, ATH434 improved overall neurological symptoms and slowed disease progression compared to historical data.

Clinical Endpoints at 12 months

Modified Unified MSA Rating Scale Part I (UMSARSI)

Global Impression of Change

Orthostatic Hypotension Symptom Assessment(OHSA)

Biomarker Endpoints at 12 months

Brain volume

The key biomarker endpoint was defined as thechange in brain volume from baseline to 12-months, as measured by the MSA Atrophy Index (MSA-AI), which compares brain volume change inMSA affected regions to age matched controls using a composite z-score:

Brain iron

A secondary biomarker endpoint was change in ironcontent in MSA affected areas (substantia nigra, putamen, globus pallidus) from baseline to 12-months, as measured by MRI (quantitativesusceptibility mapping):

Neurofilament Light Chain (NfL) is a markerof axonal injury in neurons and is elevated in individuals with MSA. On average, plasma and CSF NFL levels were stable over the 12-monthtreatment period.

Safety Results

The safety population (n=10) includes all enrolledparticipants who received at least one dose of study drug.

Additional information on the open label Phase2 trial can be found at clinicaltrials.gov NCT05864365.

About ATH434

Alterity’s lead candidate, ATH434, is anoral agent designed to inhibit the aggregation of pathological proteins implicated in neurodegeneration. ATH434 has been shown preclinicallyto reduce α-synuclein pathology and preserve neuronal function by restoring normal iron balance in the brain in preclinical models.As an iron chaperone, it has excellent potential to treat Parkinson’s disease as well as various Parkinsonian disorders such asMultiple System Atrophy (MSA). Phase 1 studies have demonstrated the agent is well tolerated and achieved brain levels comparable to efficaciouslevels in animal models of MSA. Positive results from the randomized, double-blind, placebo-controlled Phase 2 clinical trial in patientswith MSA demonstrated robust clinical efficacy, target engagement on key biomarkers, and a favorable safety profile. A second Phase 2open-label biomarker trial in patients with more advanced MSA is ongoing. ATH434 has been granted Fast Track Designation by the U.S. FDA,and Orphan Drug Designation by the U.S. FDA and the European Commission for the treatment of MSA.

About Multiple System Atrophy

Multiple System Atrophy (MSA) is a rare, neurodegenerativedisease characterized by failure of the autonomic nervous system and impaired movement. The symptoms reflect the progressive loss of functionand death of different types of nerve cells in the brain and spinal cord. It is a rapidly progressive disease and causes profound disability.MSA is a Parkinsonian disorder characterized by a variable combination of slowed movement and/or rigidity, autonomic instability thataffects involuntary functions such as blood pressure maintenance and bladder control, and impaired balance and/or coordination that predisposesto falls. A pathological hallmark of MSA is the accumulation of the protein α-synuclein within glia, the support cells of the centralnervous system, and neuron loss in multiple brain regions. MSA affects at least 15,000 individuals in the U.S., and while some of thesymptoms of MSA can be treated with medications, currently there are no drugs that are able to slow disease progression and there is nocure.⁷

Definitions and References

About Alterity Therapeutics Limited

Alterity Therapeutics is a clinical stage biotechnologycompany dedicated to creating an alternate future for people living with neurodegenerative diseases. The Company is initially focusedon developing disease modifying therapies in Parkinson’s disease and related disorders. Alterity recently reported positive datafor its lead asset, ATH434, in a Phase 2 clinical trial in participants with Multiple System Atrophy (MSA), a rare and rapidly progressiveParkinsonian disorder. ATH434 is also being evaluated in a Phase 2 clinical trial in advanced MSA. In addition, Alterity has a broaddrug discovery platform generating patentable chemical compounds to treat the underlying pathology of neurological diseases. The Companyis based in Melbourne, Australia, and San Francisco, California, USA. For further information please visit the Company’s websiteat www.alteritytherapeutics.com.

Authorisation & Additional information

This announcement was authorized by David Stamler, CEO of AlterityTherapeutics Limited.

Investor and Media Contacts:

Australia

Millie Macdonald
Head of Investor Relations and Business Development

mmacdonald@alteritytherapeutics.com

+61 468 304 742

Ana Luiza Harrop

we-aualteritytherapeutics@we-worldwide.com

+61 452 510 255

U.S.

Remy Bernarda

remy.bernarda@iradvisory.com

+1 (415) 203-6386

Forward Looking Statements

This press release contains “forward-lookingstatements” within the meaning of section 27A of the Securities Act of 1933 and section 21E of the Securities Exchange Act of 1934.The Company has tried to identify such forward-looking statements by use of such words as “expects,” “intends,” “hopes,”“anticipates,” “believes,” “could,” “may,” “evidences” and “estimates,” andother similar expressions, but these words are not the exclusive means of identifying such statements.

Important factors that could cause actual resultsto differ materially from those indicated by such forward-looking statements are described in the sections titled “Risk Factors”in the Company’s filings with the SEC, including its most recent Annual Report on Form 20-F as well as reports on Form 6-K, including,but not limited to the following: statements relating to the Company’s drug development program, including, but not limited to the initiation,progress and outcomes of clinical trials of the Company’s drug development program, including, but not limited to, ATH434, and any otherstatements that are not historical facts. Such statements involve risks and uncertainties, including, but not limited to, those risksand uncertainties relating to the difficulties or delays in financing, development, testing, regulatory approval, production and marketingof the Company’s drug components, including, but not limited to, ATH434, the ability of the Company to procure additional futuresources of financing, unexpected adverse side effects or inadequate therapeutic efficacy of the Company’s drug compounds, including, butnot limited to, ATH434, that could slow or prevent products coming to market, the uncertainty of obtaining patent protection for the Company’sintellectual property or trade secrets, the uncertainty of successfully enforcing the Company’s patent rights and the uncertaintyof the Company freedom to operate.

Any forward-looking statement made by us inthis press release is based only on information currently available to us and speaks only as of the date on which it is made. We undertakeno obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether asa result of new information, future developments or otherwise.