Organization and Description of Business	9 Months Ended
Jun. 30, 2024
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 bifunctional 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 designed the construct to improve drug accumulation in solid tumors, as well as to extend the duration of activity in the body. F_HAB development candidates can be produced in mammalian cell culture, which enables glycosylation of the interleukins, thereby reducing the risk of immunogenicity, as well as E. coli. Sonnet believes its F_HAB technology, for which it received a U.S. patent in June 2021, is a distinguishing feature of its biopharmaceutical platform. The approach is well suited for future drug development across a range of human disease areas, including in oncology, autoimmune, pathogenic, inflammatory, and hematological conditions. 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 is pursuing 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 proof-of-concept study (SB221). Part 1 of this 2-part study was approved in June 2023 by the local Human Research Ethics Committee in Australia under CT-2023-CTN-01399-1 and the Therapeutic Goods Administration has been notified. In August 2023, the FDA accepted the IND for SB221. The trial consists of a modified 3+3 dose-escalation design in Part 1 to establish the maximum tolerated dose (“MTD”) of SON-1010 with a fixed dose of atezolizumab. Clinical benefit in PROC will be confirmed in an expansion group to establish the recommended Phase 2 dose (“RP2D”). Part 2 of the study will then investigate SON-1010 in combination with atezolizumab, or the standard of care (“SOC”) for PROC in a randomized comparison to show proof-of-concept (“POC”). As part of the ongoing cost-cutting efforts, 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 met during the first calendar quarter of 2024 and cleared the trial to proceed to Part 2. Following the completion of the DSMB review, Sonnet announced initial safety data from the CIPN study. Pursuant to a license agreement the Company entered into 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, pending the outcome of any partnering activity. SON-1210 (IL12-F_HAB-IL15), Sonnet’s lead bifunctional construct, combines F_HAB with single-chain human IL-12 and human Interleukin 15 (“IL-15”). This compound is being developed for solid tumor indications, including colorectal cancer. In February 2023, Sonnet 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, pending the outcome of any partnering activity. SON-1411 (IL18-F_HAB-IL12) is a bifunctional combination of human Interleukin 18 (“IL-18”), which was modified to resist interaction with the IL-18 inhibitor binding protein, and single-chain human IL-12 for solid tumor cancers. Cell line development and process development are ongoing, with early experimental drug supply suitable for formulation and analytical method development activities. After some delays in 2023, activities will continue through 2024 with the potential to generate a drug suitable for preclinical studies and subsequent human studies. Sonnet has completed sequence confirmation for SON-3015 (anti-IL6-F_HAB-anti-TGFβ). Early-stage bifunctional drug has been generated and is being stored for future use in in vivo mice studies. The Company 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 incur 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 $3.6 million at June 30, 2024 will fund the Company’s projected operations into November 2024. 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. However, substantial doubt about the Company’s ability to continue as a going concern exists. 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 and/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 or cease 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 technologies through research and development and conducting preclinical and clinical 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, 2024

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 bifunctional 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 designed the construct to improve drug accumulation in solid tumors, as well as to extend the duration of activity in the body. F_HAB development candidates can be produced in mammalian cell culture, which enables glycosylation of the interleukins, thereby reducing the risk of immunogenicity, as well as E. coli. Sonnet believes its F_HAB technology, for which it received a U.S. patent in June 2021, is a distinguishing feature of its biopharmaceutical platform. The approach is well suited for future drug development across a range of human disease areas, including in oncology, autoimmune, pathogenic, inflammatory, and hematological conditions.

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 is pursuing 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 proof-of-concept study (SB221). Part 1 of this 2-part study was approved in June 2023 by the local Human Research Ethics Committee in Australia under CT-2023-CTN-01399-1 and the Therapeutic Goods Administration has been notified. In August 2023, the FDA accepted the IND for SB221. The trial consists of a modified 3+3 dose-escalation design in Part 1 to establish the maximum tolerated dose (“MTD”) of SON-1010 with a fixed dose of atezolizumab. Clinical benefit in PROC will be confirmed in an expansion group to establish the recommended Phase 2 dose (“RP2D”). Part 2 of the study will then investigate SON-1010 in combination with atezolizumab, or the standard of care (“SOC”) for PROC in a randomized comparison to show proof-of-concept (“POC”).

As part of the ongoing cost-cutting efforts, 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 met during the first calendar quarter of 2024 and cleared the trial to proceed to Part 2. Following the completion of the DSMB review, Sonnet announced initial safety data from the CIPN study. Pursuant to a license agreement the Company entered into 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, pending the outcome of any partnering activity.

SON-1210 (IL12-F_HAB-IL15), Sonnet’s lead bifunctional construct, combines F_HAB with single-chain human IL-12 and human Interleukin 15 (“IL-15”). This compound is being developed for solid tumor indications, including colorectal cancer. In February 2023, Sonnet 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, pending the outcome of any partnering activity.

SON-1411 (IL18-F_HAB-IL12) is a bifunctional combination of human Interleukin 18 (“IL-18”), which was modified to resist interaction with the IL-18 inhibitor binding protein, and single-chain human IL-12 for solid tumor cancers. Cell line development and process development are ongoing, with early experimental drug supply suitable for formulation and analytical method development activities. After some delays in 2023, activities will continue through 2024 with the potential to generate a drug suitable for preclinical studies and subsequent human studies.

Sonnet has completed sequence confirmation for SON-3015 (anti-IL6-F_HAB-anti-TGFβ). Early-stage bifunctional drug has been generated and is being stored for future use in in vivo mice studies. The Company 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 incur 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 $3.6 million at June 30, 2024 will fund the Company’s projected operations into November 2024. 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. However, substantial doubt about the Company’s ability to continue as a going concern exists. 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 and/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 or cease 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 technologies through research and development and conducting preclinical and clinical 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.