Exhibit 99.1

Radiopharm Theranostics Limited Appendix 4E Preliminary final report

1. Company details

2. Results for announcement to the market

No dividends have been paid or declared by the group for the current financial year. No dividends were paid for the previous financial year.

3. Explanation of results

The group reported a loss for the year ended 30 June 2026 of $56,950,494 (30 June 2025: $38,342,457). The increase in loss in the current year compared to prior year is mainly attributable to higher research and development expenditures incurred during the year to advance and broaden the developmental phases of ongoing clinical studies.

The group's net assets for the year ended 30 June 2026 decreased to $22,323,683 (30 June 2025: $42,871,904). Net assets decreased primarily due to a decrease in cash balances attributable to higher investment in research and development activities during the financial year. As at 30 June 2026, the group had cash reserves of $4,138,074 (30 June 2025: $29,116,835).

The Appendix 4E financial report follows, with the further details to be included in the audited financial statements is expected to be released by 30 September 2026.

4. Net tangible assets per security

5. Changes in controlled entities

During the year ended 30 June 2026, Radiopharm Theranostics increased its ownership in Radiopharm Ventures, LLC, a joint venture created with The University of Texas M.D. Anderson Cancer Center (MDACC) from 75% to 87.5%.

There have been no other changes in controlled entities during the year ended 30 June 2026.

Radiopharm Theranostics Limited Appendix 4E Preliminary final report

6. Other information required by Listing Rule 4.3A

On 9 July 2022, Radiopharm Theranostics (USA) Inc. and The University of Texas MD Anderson Cancer Center formed Radiopharm Ventures, LLC, a joint venture to develop novel radiopharmaceutical therapeutic products for cancer. The joint venture continues to focus on developing products based on MD Anderson intellectual property. On 26 August 2024, Radiopharm announced they had increased their ownership in Radiopharm Ventures from 51% to 75%. During the year ended 30 June 2026, Radiopharm Theranostics increased its ownership in Radiopharm Ventures, LLC, from 75% to 87.5%.

d. Other information: N/A

7. Audit

The financial statements are currently in the process of being audited. Audited financial statements along with the independent auditor report for the year ended 30 June 2026 is expected to be released by the end of September 2026 with a material uncertainty in relation to going concern.

Radiopharm Theranostics Limited

ABN 57 647 877 889

Preliminary Final Report - 30 June 2026

Radiopharm Theranostics Limited Contents 30 June 2026

General information

The financial statements cover Radiopharm Theranostics Limited as a consolidated entity consisting of Radiopharm Theranostics Limited and the entities it controlled at the end of, or during, the year. The financial statements are presented in Australian dollars, which is Radiopharm Theranostics Limited's functional and presentation currency.

Radiopharm Theranostics Limited is a listed public company limited by shares, incorporated and domiciled in Australia. Its registered office and principal place of business is:

Level 3, 62 Lygon Street, Carlton VIC 3053

Radiopharm Theranostics Limited Statement of profit or loss and other comprehensive income For the year ended 30 June 2026

The above statement of profit or loss and other comprehensive income should be read in conjunction with the accompanying notes

Radiopharm Theranostics Limited Statement of financial position As at 30 June 2026

The above statement of financial position should be read in conjunction with the accompanying notes

Radiopharm Theranostics Limited Statement of changes in equity For the year ended 30 June 2026

The above statement of changes in equity should be read in conjunction with the accompanying notes

Radiopharm Theranostics Limited Statement of changes in equity For the year ended 30 June 2026

The above statement of changes in equity should be read in conjunction with the accompanying notes

Radiopharm Theranostics Limited Statement of cash flows For the year ended 30 June 2026

The above statement of cash flows should be read in conjunction with the accompanying notes

Radiopharm Theranostics Limited Notes to the financial statements 30 June 2026

Note 1. Segment information

Management has determined based on the reports reviewed by the Chief Operating Decision Maker (CODM) that are used to make strategic decisions, that the group has one reportable segment being the research, development and commercialisation of health technologies. As such, the financial information presented in the body of the financial report represents the results of the Group's sole operating segment. The CODM continues to monitor and review the appropriateness of this segment determination on a regular basis.

Note 2. Revenue from contract with customers

During the period ended 30 June 2025, the group entered into a strategic development services contract with Lantheus to advance clinical development of innovative radiopharmaceuticals in Australia.

Note 3. General and administrative expenses

Radiopharm Theranostics Limited Notes to the financial statements 30 June 2026

Note 4. Research and development expenses

The categories shown here align with the intellectual property held by the group and represents the amount of R&D expended on developing the respective intellectual property.

Note 5. Cash and cash equivalents

(i) Reconciliation to cash flow statement

The above figures reconcile to the amount of cash shown in the consolidated statement of cash flows at the end of the financial year and period, respectively, as follows:

(ii) Classification as cash equivalents

Term deposits are presented as cash equivalents if they have a maturity of three months or less from the date of acquisition and are repayable with 24 hours notice with no loss of interest.

(iii) Risk exposure

The maximum exposure to credit risk at the end of the reporting year is the carrying amount of each class of cash and cash equivalents mentioned above.

Radiopharm Theranostics Limited Notes to the financial statements 30 June 2026

Note 6. Trade and other receivables

(i) Accrued receivables

Accrued receivables comprise $15,877,895 from the Australian Taxation Office in relation to the R&D tax incentive (30 June 2025: $10,171,532). Subsequent to year-end, Radiopharm received $5,780,657 relating to the accrued income recognised at 30 June 2025. This receipt represents the settlement of the outstanding balance and has been recorded as cash in the following financial year.

Note 7. Trade and other payables

Note 8. Other financial liabilities

Radiopharm Theranostics Limited Notes to the financial statements 30 June 2026

Note 9. Share capital

(i) Movements in ordinary shares: 

Note 10. Events after the reporting period

On July 24, 2026, the Company announced an A$12.5 million institutional offer and launched A$6 million Share Purchase Plan. The institutional offer comprises of two-tranche placement of approximately 448,839,531 new fully paid ordinary shares at A$0.015 per New Share to an Australian international institutional and sophisticated investors; and 384,493,800 underlying ordinary shares at US$3.16 per ADS to a US Direct Registration Offering. The Share Purchase Plan offer closes on 10 September 2026.

No other matter or circumstance has arisen since 30 June 2026 that has significantly affected, or may significantly affect the consolidated entity's operations, the results of those operations, or the consolidated entity's state of affairs in future financial years.