Organization and Description of Business	9 Months Ended
Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business *Description of business* Sonnet BioTherapeutics, Inc. (“Prior Sonnet”) was incorporated as a New Jersey corporation on April 6, 2015. Prior Sonnet completed a merger with publicly-held Chanticleer Holdings, Inc. (“Chanticleer”) on April 1, 2020. After the merger, Chanticleer changed its name to Sonnet BioTherapeutics Holdings, Inc. (“Sonnet” or the “Company”). Sonnet is a clinical stage, oncology-focused biotechnology company with a proprietary platform for innovating biologic medicines of single- or bi-specific action. Known as F_HAB™ (Fully Human Albumin Binding), the technology utilizes a fully human single chain antibody fragment (scFv) that binds to and “hitch-hikes” on human serum albumin (“HSA”) for transport to target tissues. Sonnet’s lead proprietary asset, SON-1010, is a fully human version of Interleukin 12 (“IL-12”), covalently linked to the F_HAB construct, for which Sonnet intends to pursue clinical development in solid tumor indications, including ovarian cancer, non-small cell lung cancer and head and neck cancer. In March 2022, the FDA cleared Sonnet’s Investigational New Drug (“IND”) application for SON-1010. This allowed the Company to initiate a U.S. clinical trial (SB101) in oncology patients with solid tumors during the second calendar quarter of 2022. In September 2021, the Company created a wholly-owned Australian subsidiary, SonnetBio Pty Ltd (“Subsidiary”), for the purpose of conducting certain clinical trials. Sonnet received approval and initiated an Australian clinical study (SB102) of SON-1010 in healthy volunteers during the third calendar quarter of 2022. Interim safety and tolerability data from the SB101 and SB102 studies were reported in April 2023. In January 2023, Sonnet announced a collaboration agreement with Roche for the clinical evaluation of SON-1010 with atezolizumab (Tecentriq®). The companies have entered into a Master Clinical Trial and Supply Agreement (“MCSA”), along with ancillary Quality and Safety Agreements, to study the safety and efficacy of the combination of SON-1010 and atezolizumab in a platinum-resistant ovarian cancer (“PROC”) patient setting. Further, the companies will provide SON-1010 and atezolizumab, respectively, for use in the Phase 1b/Phase 2a combination safety, dose-escalation, and efficacy study (SB221). Part 1 of this 2-part study was recently approved by the local Human Research Ethics Committee in Australia under CT-2023-CTN-01399-1 and the Therapeutic Goods Administration has been notified. Recruitment is expected to begin imminently. As part of the ongoing cost-cutting evaluations, all antiviral development with SON-1010 has been suspended. The Company acquired the global development rights to its most advanced compound, SON-080, a fully human version of Interleukin 6 (“IL-6”), in April 2020 through its acquisition of the outstanding shares of Relief Therapeutics SA. Sonnet is advancing SON-080 in target indications of Chemotherapy-Induced Peripheral Neuropathy (“CIPN”) and Diabetic Peripheral Neuropathy (“DPN”). Sonnet received approval to initiate an ex-U.S. Phase 1b/2a study with SON-080 in CIPN during the third quarter of 2022. The Data Safety Monitoring Board (DSMB) overseeing the study is expected to meet during the third quarter of 2023. Following the completion of the DSMB review, we anticipate announcing initial safety data from the CIPN study. Pursuant to a license agreement the Company entered with New Life Therapeutics Pte, Ltd. (“New Life”) of Singapore in May 2021, Sonnet and New Life will be jointly responsible for developing SON-080 in DPN. The objective will be to analyze the data and to consider initiating a Phase 2 study once the CIPN safety data has been evaluated. SON-1210 (IL12-F_HAB-IL15), Sonnet’s lead bi-specific construct, combines F_HAB with fully human IL-12 and fully human Interleukin 15 (“IL-15”). This compound is being developed for solid tumor indications, including colorectal cancer. In February 2023, the Company announced the successful completion of two IND-enabling toxicology studies with SON-1210 in non-human primates. Sonnet is prepared to initiate the regulatory authorization process for SON-1210 in 2023, subject to having a partnering opportunity in place. Sonnet BioTherapeutics Holdings, Inc. Notes to Unaudited Interim Consolidated Financial Statements SON-1410 (IL18-F_HAB-IL12) is a bi-specific combination of Interleukins 18 (“IL-18”) and 12 (IL-12) for solid tumor cancers. Cell line development for GMP application is underway. After some delays in 2023, process development activities will continue into 2024, with the potential to generate a drug suitable for initial in vivo mice studies during the second half of calendar year 2024. The Company has completed sequence confirmation for SON-3015 (anti-IL6-F_HAB-anti-TGFβ). Early stage bi-specific drug has been generated and is being stored for future use in in vivo mice studies. Sonnet has elected to place the SON-3015 development program on hold for expense reduction purposes. *Liquidity* The Company has incurred recurring losses and negative cash flows from operations since inception and it expects to generate losses from operations for the foreseeable future primarily due to research and development costs for its potential product candidates. The Company believes its cash of $7.0 million at June 30, 2023 will fund the Company’s projected operations into 2024. Substantial additional financing will be needed by the Company to fund its operations. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The accompanying unaudited interim consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The unaudited interim consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. The Company plans to secure additional capital in the future through equity or debt financings, partnerships, collaborations, or other sources to carry out the Company’s planned development activities. If additional capital is not available when required, the Company may need to delay or curtail its operations until such funding is received. Various internal and external factors will affect whether and when the Company’s product candidates become approved for marketing and successful commercialization. The regulatory approval and market acceptance of the Company’s product candidates, length of time and cost of developing and commercializing these product candidates and/or failure of them at any stage of the approval process will materially affect the Company’s financial condition and future operations. Operations since inception have consisted primarily of organizing the Company, securing financing, developing its technologies through performing research and development and conducting preclinical studies. The Company faces risks associated with companies whose products are in development. These risks include the need for additional financing to complete its research and development, achieving its research and development objectives, defending its intellectual property rights, recruiting and retaining skilled personnel, and dependence on key members of management.

Organization and Description of Business

9 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Description of Business

1. Organization and Description of Business

Description of business

Sonnet BioTherapeutics, Inc. (“Prior Sonnet”) was incorporated as a New Jersey corporation on April 6, 2015. Prior Sonnet completed a merger with publicly-held Chanticleer Holdings, Inc. (“Chanticleer”) on April 1, 2020. After the merger, Chanticleer changed its name to Sonnet BioTherapeutics Holdings, Inc. (“Sonnet” or the “Company”). Sonnet is a clinical stage, oncology-focused biotechnology company with a proprietary platform for innovating biologic medicines of single- or bi-specific action. Known as F_HAB™ (Fully Human Albumin Binding), the technology utilizes a fully human single chain antibody fragment (scFv) that binds to and “hitch-hikes” on human serum albumin (“HSA”) for transport to target tissues.

Sonnet’s lead proprietary asset, SON-1010, is a fully human version of Interleukin 12 (“IL-12”), covalently linked to the F_HAB construct, for which Sonnet intends to pursue clinical development in solid tumor indications, including ovarian cancer, non-small cell lung cancer and head and neck cancer. In March 2022, the FDA cleared Sonnet’s Investigational New Drug (“IND”) application for SON-1010. This allowed the Company to initiate a U.S. clinical trial (SB101) in oncology patients with solid tumors during the second calendar quarter of 2022. In September 2021, the Company created a wholly-owned Australian subsidiary, SonnetBio Pty Ltd (“Subsidiary”), for the purpose of conducting certain clinical trials. Sonnet received approval and initiated an Australian clinical study (SB102) of SON-1010 in healthy volunteers during the third calendar quarter of 2022. Interim safety and tolerability data from the SB101 and SB102 studies were reported in April 2023.

In January 2023, Sonnet announced a collaboration agreement with Roche for the clinical evaluation of SON-1010 with atezolizumab (Tecentriq®). The companies have entered into a Master Clinical Trial and Supply Agreement (“MCSA”), along with ancillary Quality and Safety Agreements, to study the safety and efficacy of the combination of SON-1010 and atezolizumab in a platinum-resistant ovarian cancer (“PROC”) patient setting. Further, the companies will provide SON-1010 and atezolizumab, respectively, for use in the Phase 1b/Phase 2a combination safety, dose-escalation, and efficacy study (SB221). Part 1 of this 2-part study was recently approved by the local Human Research Ethics Committee in Australia under CT-2023-CTN-01399-1 and the Therapeutic Goods Administration has been notified. Recruitment is expected to begin imminently. As part of the ongoing cost-cutting evaluations, all antiviral development with SON-1010 has been suspended.

The Company acquired the global development rights to its most advanced compound, SON-080, a fully human version of Interleukin 6 (“IL-6”), in April 2020 through its acquisition of the outstanding shares of Relief Therapeutics SA. Sonnet is advancing SON-080 in target indications of Chemotherapy-Induced Peripheral Neuropathy (“CIPN”) and Diabetic Peripheral Neuropathy (“DPN”). Sonnet received approval to initiate an ex-U.S. Phase 1b/2a study with SON-080 in CIPN during the third quarter of 2022. The Data Safety Monitoring Board (DSMB) overseeing the study is expected to meet during the third quarter of 2023. Following the completion of the DSMB review, we anticipate announcing initial safety data from the CIPN study. Pursuant to a license agreement the Company entered with New Life Therapeutics Pte, Ltd. (“New Life”) of Singapore in May 2021, Sonnet and New Life will be jointly responsible for developing SON-080 in DPN. The objective will be to analyze the data and to consider initiating a Phase 2 study once the CIPN safety data has been evaluated.

SON-1210 (IL12-F_HAB-IL15), Sonnet’s lead bi-specific construct, combines F_HAB with fully human IL-12 and fully human Interleukin 15 (“IL-15”). This compound is being developed for solid tumor indications, including colorectal cancer. In February 2023, the Company announced the successful completion of two IND-enabling toxicology studies with SON-1210 in non-human primates. Sonnet is prepared to initiate the regulatory authorization process for SON-1210 in 2023, subject to having a partnering opportunity in place.

Sonnet BioTherapeutics Holdings, Inc.

Notes to Unaudited Interim Consolidated Financial Statements

SON-1410 (IL18-F_HAB-IL12) is a bi-specific combination of Interleukins 18 (“IL-18”) and 12 (IL-12) for solid tumor cancers. Cell line development for GMP application is underway. After some delays in 2023, process development activities will continue into 2024, with the potential to generate a drug suitable for initial in vivo mice studies during the second half of calendar year 2024.

The Company has completed sequence confirmation for SON-3015 (anti-IL6-F_HAB-anti-TGFβ). Early stage bi-specific drug has been generated and is being stored for future use in in vivo mice studies. Sonnet has elected to place the SON-3015 development program on hold for expense reduction purposes.

Liquidity

The Company has incurred recurring losses and negative cash flows from operations since inception and it expects to generate losses from operations for the foreseeable future primarily due to research and development costs for its potential product candidates. The Company believes its cash of $7.0 million at June 30, 2023 will fund the Company’s projected operations into 2024. Substantial additional financing will be needed by the Company to fund its operations. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The accompanying unaudited interim consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The unaudited interim consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

The Company plans to secure additional capital in the future through equity or debt financings, partnerships, collaborations, or other sources to carry out the Company’s planned development activities. If additional capital is not available when required, the Company may need to delay or curtail its operations until such funding is received. Various internal and external factors will affect whether and when the Company’s product candidates become approved for marketing and successful commercialization. The regulatory approval and market acceptance of the Company’s product candidates, length of time and cost of developing and commercializing these product candidates and/or failure of them at any stage of the approval process will materially affect the Company’s financial condition and future operations.

Operations since inception have consisted primarily of organizing the Company, securing financing, developing its technologies through performing research and development and conducting preclinical studies. The Company faces risks associated with companies whose products are in development. These risks include the need for additional financing to complete its research and development, achieving its research and development objectives, defending its intellectual property rights, recruiting and retaining skilled personnel, and dependence on key members of management.