Trastuzumab + Alpelisib +/- Fulvestrant vs Trastuzumab + CT in PIK3CA-mutated HER2+ Advanced BC (ALPHABET)

1. Is the biology right?

• Somatic driver evidence: yes · ERBB2, PIK3CA, ESR1 in breast carcinoma

  Rule: Open Targets has somatic-mutation evidence for the target in this cancer. Source: Open Targets: ERBB2 in breast carcinoma, 2026-11-11

  Published context: 2.3× relative success for targets with somatic (IntOGen) support in oncology (Minikel et al., Nature 2024, drug programs to 2023). A ratio between groups, not a probability for this program; mostly phase 2 to 3.
• Human genetic evidence: yes · ERBB2: somatic; PIK3CA: somatic; ESR1: germline, somatic

  Rule: Any germline or somatic human genetic evidence for the target in this cancer, counted apart from animal-model and literature evidence. Source: Open Targets: ERBB2 in breast carcinoma, 2026-11-11

  Published context: 2.6× relative probability of success, phase 1 to launch, with human genetic support (Minikel et al., Nature 2024, drug programs to 2023). All therapy areas, mostly germline evidence; not a probability for this program.
• Pediatric target: yes · ERBB2, PIK3CA on the FDA list

  Rule: Target is on FDA's Pediatric Molecular Target List (relevant targets); membership alone neither requires nor waives a study. Source: FDA Pediatric Molecular Target List (Listed as February 2026 on the FDA Pediatric Oncology page; the file served is 9.7.22_the_relevant_molecular_target_list.xlsx, whose Summary of Changes sheet is headed 'SEPTEMBER 2022 UPDATE' (footnote date 2022-09-01)), 2026-11-11
• Haematologic cancer: no · Solid tumour

  Rule: From the indication, or the registry conditions when no indication matches. Source: ClinicalTrials.gov NCT05063786, 2026-11-11

  Published context: Likelihood of approval from phase 1: 7.5% haematologic vs 4.6% solid (BIO / Informa / QLS 2021, 2011–2020). Population-level, not a prediction.

• Background therapy: Capecitabine: standard agents, not counted in these flags.
• ERBB2 (via Trastuzumab): Evidence types in breast carcinoma: literature, affected_pathway, somatic_mutation, clinical; literature listed separately from human genetics. Datasources: clinical_precedence, cancer_gene_census, crispr, europepmc. · Open Targets: ERBB2 in breast carcinoma
• PIK3CA (via Alpelisib): Evidence types in breast carcinoma: literature, affected_pathway, somatic_mutation, clinical; literature listed separately from human genetics. Datasources: clinical_precedence, cancer_gene_census, eva_somatic, crispr, europepmc. · Open Targets: PIK3CA in breast carcinoma
• ESR1 (via Fulvestrant): Evidence types in breast carcinoma: rna_expression, clinical, affected_pathway, literature, genetic_association, somatic_mutation; literature listed separately from human genetics. Datasources: clinical_precedence, gwas_credible_sets, cancer_gene_census, crispr, europepmc, expression_atlas. · Open Targets: ESR1 in breast carcinoma
• TUBB4B (via Vinorelbine): Evidence types in breast carcinoma: literature, rna_expression, clinical; literature listed separately from human genetics. Datasources: clinical_precedence, europepmc, expression_atlas. · Open Targets: TUBB4B in breast carcinoma
• TUBB1 (via Vinorelbine): Evidence types in breast carcinoma: literature, clinical; literature listed separately from human genetics. Datasources: clinical_precedence, europepmc. · Open Targets: TUBB1 in breast carcinoma
• TUBA3C (via Vinorelbine): Evidence types in breast carcinoma: literature, clinical; literature listed separately from human genetics. Datasources: clinical_precedence, europepmc. · Open Targets: TUBA3C in breast carcinoma

• Not loaded on this app yet: Normal-tissue expression in vital organs. Source: Human Protein Atlas (ticket 36).
• Not loaded on this app yet: Pan-essential in cell lines. Source: DepMap (ticket 36).
• Not loaded on this app yet: Approved drug on this target. Source: Drugs@FDA (ticket 30).

2. Can the result be trusted?

• Randomised: yes · Randomised allocation

  Rule: Registry allocation field. Source: ClinicalTrials.gov NCT05063786, 2026-11-11
• Small denominator: yes · 27 enrolled; each patient moves a rate by 100 ÷ 27 = 3.7 points

  Rule: Enrolment under 30; the arithmetic is shown, not a benchmark. Source: ClinicalTrials.gov NCT05063786, 2026-11-11
• Primary endpoint is overall survival: no · Progression Free Survival (PFS)

  Rule: A registered primary outcome measure names overall survival. Source: ClinicalTrials.gov NCT05063786, 2026-11-11

  Published context: Non-OS primary endpoint: odds ratio 2.79 for a positive phase 3 (Otsuka 2021, 400 phase 3 oncology trials, to 2020). Shown with the next figure: a surrogate is easier to hit, and often a weak guide to survival.

  Published context: 52% of surrogate-to-OS correlations are low (Prasad 2015, published to 2014). Shown with the figure above.
• Results overdue: no · Primary completion 2025-12-23, 10 months ago; within 12 months

  Rule: Primary completion (actual) more than 12 months ago and no results posted to the registry. Source: ClinicalTrials.gov NCT05063786, 2026-11-11

• Not loaded on this app yet: Treated and evaluable counts, assessor, confirmed response, follow-up and data cutoff. Source: Readout extraction (ticket 32).
• Not loaded on this app yet: Primary endpoint changed between registry versions. Source: Registry versions in the store (ticket 32).

3. What must it beat?

• Not loaded on this app yet: Control-arm result and approved therapies for the same segment, with label links. Source: Drugs@FDA, FDA labels and readouts (tickets 30, 32).

4. Too crowded, or too late?

• Stopped on this target: 192 terminated, withdrawn or suspended trials of drugs against ERBB2; 21 give no reason. Reasons are quoted as the registry gives them on the target page. · ERBB2: what already stopped

• Not loaded on this app yet: Programs on the target by phase and months behind the leader. Source: Programs and Drugs@FDA (ticket 33).

5. Can it be approved, and stay approved?

• Single-country: no · 106 sites in 6 countries; 0 in the United States (0%)

  Rule: All listed sites are in one country; the share of US sites is shown. Source: ClinicalTrials.gov NCT05063786, 2026-11-11
• EU paediatric investigation plan: yes · EMEA-002016-PIP05-23 (alpelisib, Treatment of lymphatic malformations associated with a PIK3CA mutation): P: decision agreeing on a investigation plan, with or without partial waiver(s) and or deferral(s), 12 Apr 2024; EMEA-002016-PIP03-19-M02 (alpelisib, Treatment of PIK3CA related overgrowth spectrum): PM: decision on the application for modification of an agreed PIP, 30 Sept 2022; EMEA-002016-PIP04-20 (alpelisib, Treatment of Fallopian tube carcinoma (excluding rhabdomyosarcoma and germ cell tumours);Treatment of ovarian carcinoma (excluding rhabdomyosarcoma and germ cell tumours);Treatment of peritoneal carcinoma (excluding blastomas and sarcomas)): W: decision granting a waiver in all age groups for all conditions or indications, 17 Mar 2021; compliance positive 20 Sept 2019; EMEA-002016-PIP02-16 (alpelisib, Treatment of breast cancer): W: decision granting a waiver in all age groups for all conditions or indications, 16 Mar 2017

  Rule: An EMA PIP decision (agreement, modification or waiver) lists the drug as its active substance, exact name. Source: EMA data download (dated snapshot), 2026-11-11
• EU orphan designation: yes · EU/3/21/2420 positive 26 Mar 2021: Treatment of PIK3CA related overgrowth spectrum; EU/3/23/2841 positive 13 Oct 2023: Treatment of lymphatic malformations; EU/3/18/2133 positive 11 Jan 2019: Treatment of soft tissue sarcoma

  Rule: An EU orphan designation lists the drug as its active substance (exact name) or belongs to a medicine that does; withdrawn and expired designations are listed with their status. Source: EMA data download (dated snapshot), 2026-11-11
• Authorised in the EU: yes · Herwenda: authorised since 15 Nov 2023; Herceptin: authorised since 28 Aug 2000; Phesgo: authorised since 21 Dec 2020; Kanjinti: authorised since 16 May 2018; +14 more

  Rule: An EMA medicine record lists the drug as its active substance or INN, exact name; national-only authorisations are not in this file. Source: EMA data download (dated snapshot), 2026-11-11
• FDA orphan designation: not published · FDA's orphan designation database turns away automated requests, so this app does not read it; search it by hand at the link

  Rule: Would be: an FDA orphan designation names the drug. Source: FDA orphan designations search
• FDA pediatric oncology approval: no · FDA's table lists no pediatric approval of Trastuzumab, Alpelisib, Fulvestrant, Vinorelbine

  Rule: FDA's Pediatric Oncology Drug Approvals table names the drug. Source: FDA Pediatric Oncology Drug Approvals (content current as of 2026-03-03), 2026-11-11
• Registered studies open to children: yes · 124 interventional studies of Trastuzumab, Alpelisib, Fulvestrant, Vinorelbine include patients under 18; 36 are recruiting, not yet recruiting or active

  Rule: The registry's age group includes Child (birth to 17 years), which also counts studies that set no minimum age. Source: ClinicalTrials.gov search, 2026-11-11

• Caveat: Site counts are not patients per country, and trials registered only outside ClinicalTrials.gov are not covered. Where the sites are is a fact about the record, not a judgement of its quality.
• Rare pediatric disease voucher: FDA, content current as of 29 Apr 2026: “As of February 3, 2026, enactment of the Consolidated Appropriations Act, 2026, the rare pediatric disease PRV program will sunset after September 30, 2029. FDA may not award any PRVs under this program after September 30, 2029.” Voucher sale prices are not shown here; they appear only as company-reported news. · FDA: Rare Pediatric Disease Designation and Priority Review Voucher Programs

• Not loaded on this app yet: Precedent approvals for target, modality and endpoint; accelerated-approval status. Source: Drugs@FDA and FDA accelerated-approval tables (ticket 30).

6. Can the sponsor finish?

• Sponsor: Spanish Breast Cancer Research Group (academic or other) · ClinicalTrials.gov NCT05063786
• study director: Study Director, H. Clínico Universitario Valencia. Valencia, Spain. · Person page
• study director: Study Director, Istituto Europeo di Oncologia. Milan, Italy. · Person page
• study director: Study Director, Princess Margaret Cancer Center. Toronto, Canada · Person page

• Not loaded on this app yet: Filed cash, quarterly spend and the runway arithmetic. Source: SEC XBRL company facts (ticket 37).
• Not loaded on this app yet: Sponsor's completed vs stopped oncology trials and results-reporting record. Source: Registry, by company (ticket 37).

What public data cannot tell you

Public records cannot show: sales forecasts; a probability of success for this asset; full deal terms and net prices; FDA designations and action dates before approval (shown only as company-reported); clinical holds unless the company disclosed them; manufacturing; patents on unapproved drugs; whether preclinical findings have been replicated.