FDA Approves Companion Diagnostic for Inavolisib in HR+/HER2–, PIK3CA-Mutated Breast Cancer
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The FDA has approved FoundationOne CDx as a companion diagnostic for inavolisib (Itovebi) in combination with palbociclib and fulvestrant for endocrine-resistant, PIK3CA-mutated, HR-positive, HER2-negative advanced breast cancer. This approval expands the targeted therapy landscape and underscores the importance of genomic testing in patient selection.
Inavolisib FDA approval now has a fuller diagnostic gate: after the October 2024 Itovebi triplet nod, FDA cleared tissue-based FoundationOne CDx in June 2026 to find PIK3CA-mutated HR-positive, HER2-negative patients eligible for inavolisib plus palbociclib and fulvestrant.
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Key Takeaways
- October 10, 2024: FDA approved inavolisib (Itovebi) with palbociclib and fulvestrant for endocrine-resistant, PIK3CA-mutated HR+/HER2− advanced breast cancer.
- Same day, FDA approved FoundationOne Liquid CDx as a companion diagnostic for that regimen.
- June 2026: Foundation Medicine announced FDA approval of tissue-based FoundationOne CDx for the same Itovebi use.
- Tissue CDx matters when circulating tumor DNA shed is too low for a reliable liquid result.
What did the original Inavolisib FDA approval cover?
FDA’s October 10, 2024 decision authorized inavolisib with palbociclib and fulvestrant for adults with endocrine-resistant, PIK3CA-mutated, HR-positive, HER2-negative locally advanced or metastatic breast cancer after recurrence on or after adjuvant endocrine therapy, as detected by an FDA-approved test.
See the agency’s FDA inavolisib approval announcement. Genentech’s contemporaneous Itovebi approval press release ties the label to INAVO120 and early biomarker testing.
Why does a June 2026 tissue CDx still matter?
Liquid biopsy is convenient, but some tumors shed little DNA into blood. A tissue CDx gives oncologists a second FDA-labeled path to document a PIK3CA mutation before starting the Itovebi triplet.
Foundation Medicine’s June 2, 2026 Business Wire announcement states FoundationOne CDx is now approved as a companion diagnostic for Itovebi with palbociclib and fulvestrant, following the October 2024 Liquid CDx approval.
How does this change testing workflows?
- Prefer liquid CDx when blood-based genomic profiling is already planned and ctDNA yield is adequate.
- Reflex to tissue FoundationOne CDx when liquid is negative or quantity-not-sufficient and biopsy tissue is available.
- Document the FDA-approved test name in the chart—the label requires detection by an FDA-approved assay.
Neither CDx replaces clinical judgment on endocrine resistance, HER2 status, or comorbidity screening for PI3K-pathway toxicity.
What efficacy package underpins the drug label?
INAVO120 was the registrational Phase 3 backbone cited at approval. Secondary coverage and PubMed safety analyses discuss progression-free survival and response gains versus placebo plus palbociclib and fulvestrant; treat any specific PFS months as label- or primary-paper figures only.
For labeled indication language, stay with FDA and Genentech sources above rather than conference abstracts.
What should BD and diagnostics teams watch next?
Watch payer policies on dual liquid/tissue CDx reimbursement and Roche/Genentech contracting that bundles drug and test. Competitive diligence should map other PI3K/AKT inhibitors’ companion diagnostics against the same HR+/HER2− PIK3CA niche.
Also track whether additional assays seek CDx claims for Itovebi—Foundation Medicine’s franchise is not the only possible future platform.
What remains unproven?
Tissue CDx approval does not expand Itovebi into new lines of therapy or new genotypes beyond the labeled PIK3CA-mutated HR+/HER2− population. It also does not prove that every local lab NGS panel is equivalent to an FDA-approved CDx.
Overall survival benefit was described as a supportive trend at the 2024 approval; do not market OS superiority unless a later FDA label update says so.
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Frequently Asked Questions
When did FDA approve inavolisib (Itovebi)?
On October 10, 2024, FDA approved inavolisib with palbociclib and fulvestrant for adults with endocrine-resistant, PIK3CA-mutated, HR-positive, HER2-negative advanced breast cancer after adjuvant endocrine therapy, as detected by an FDA-approved test.
What companion diagnostics are approved for Itovebi?
FoundationOne Liquid CDx was approved with the October 2024 drug approval. Foundation Medicine announced FDA approval of tissue-based FoundationOne CDx for the same Itovebi regimen in June 2026.
Which patients does the indication cover?
Adults with endocrine-resistant, PIK3CA-mutated, HR-positive, HER2-negative locally advanced or metastatic breast cancer whose disease recurred on or after completing adjuvant endocrine therapy.
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