Inavolisib

12.1 Mechanism of Action Inavolisib is an inhibitor of phosphatidylinositol 3-kinase (PI3K) with inhibitory activity predominantly against PI3Kα. In vitro, inavolisib induced the degradation of mutated PI3K catalytic alpha subunit p110α (encoded by the PIK3CA gene), inhibited phosphorylation of the downstream target AKT, reduced cellular proliferation, and induced apoptosis in PIK3CA -mutated breast cancer cell lines. In vivo, inavolisib reduced tumor growth in PIK3CA -mutated, estrogen receptor-positive, breast cancer xenograft models. The combination of inavolisib with palbociclib and fulvestrant increased tumor growth inhibition compared to each treatment alone or the doublet combinations.

1 INDICATIONS AND USAGE ITOVEBI, in combination with palbociclib and fulvestrant, is indicated for the treatment of adults with endocrine-resistant, PIK3CA -mutated, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer, as detected by an FDA-approved test, following recurrence on or after completing adjuvant endocrine therapy [see Clinical Studies (14.1) ] . ITOVEBI is a kinase inhibitor indicated in combination with palbociclib and fulvestrant for the treatment of adults with endocrine-resistant, PIK3CA -mutated, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer, as detected by an FDA-approved test, following recurrence on or after completing adjuvant endocrine therapy. ( 1 , 14.1 )

2 DOSAGE AND ADMINISTRATION Select patients for the treatment of HR-positive, HER2-negative, locally advanced or metastatic breast cancer with ITOVEBI based on the presence of one or more PIK3CA mutations in plasma specimen. ( 2.1 ) Recommended dosage: 9 mg orally once daily with or without food. ( 2.3 ) See Full Prescribing Information for dosage modifications of ITOVEBI due to adverse reactions. ( 2.4 ) Reduce the starting dose in patients with moderate renal impairment. ( 2.5 ) 2.1 Patient Selection Select patients for the treatment of HR-positive, HER2-negative, locally advanced or metastatic breast cancer with ITOVEBI based on the presence of one or more PIK3CA mutations in plasma specimens [see Clinical Studies (14.1) ] . Information on FDA-approved tests for the detection of PIK3CA mutations in breast cancer is available at: http://www.fda.gov/companiondiagnostics. 2.2 Recommended Evaluation Before Initiating ITOVEBI Evaluate fasting plasma glucose (FPG)/blood glucose (FBG) and hemoglobin A 1C (HbA 1C ) and optimize blood glucose prior to starting ITOVEBI and at regular intervals during treatment [see Warnings and Precautions (5.1) ]. 2.3 Recommended Dosage The recommended dosage of ITOVEBI is 9 mg taken orally once daily, with or without food, until disease progression or unacceptable toxicity. Advise patients to take ITOVEBI at approximately the same time each day. Swallow ITOVEBI tablet(s) whole. Do not chew, crush, or split prior to swallowing. If a patient misses a dose, instruct the patient to take the missed dose as soon as possible within 9 hours. After more than 9 hours, instruct the patient to skip the dose and take the next dose at the scheduled time. If a patient vomits a dose, instruct patients not to take an additional dose on that day and resume the usual dosing schedule the next day. Administer ITOVEBI in combination with palbociclib and fulvestrant. The recommended dosage of palbociclib is 125 mg taken orally once daily for 21 consecutive days followed by 7 days off treatment to comprise a cycle of 28 days. Refer to the Full Prescribing Information for palbociclib and fulvestrant for dosing information. For premenopausal and perimenopausal women, administer a luteinizing hormone-releasing hormone (LHRH) agonist in accordance with local clinical practice. For men, consider administering an LHRH agonist in accordance with local clinical practice. 2.4 Dosage Modifications for Adverse Reactions The recommended dose reduction levels of ITOVEBI for adverse reactions are listed in Table 1 . Permanently discontinue ITOVEBI if patients are unable to tolerate the second dose reduction. Table 1: Dose Reduction for Adverse Reactions Dose Level Dose and Schedule Recommended starting dose 9 mg daily First dose reduction 6 mg daily Second dose reduction 3 mg daily The recommended dosage modifications of ITOVEBI for adverse reactions are summarized in Table 2 . Table 2: Recommended Dosage Modifications for Adverse Reactions Adverse Reaction Severity Dosage Modification Hyperglycemia Before initiating treatment with ITOVEBI, test FPG or FBG, and HbA 1C levels, and optimize plasma/blood glucose levels in all patients. After initiating treatment with ITOVEBI, monitor FPG or FBG levels based on the recommended schedule, and as clinically indicated [see Warnings and Precautions (5.1) ]. [see Warnings and Precautions (5.1) ] Fasting glucose levels (FPG or FBG) > ULN to 160 mg/dL (> ULN – 8.9 mmol/L) No adjustment of ITOVEBI required. Consider dietary modifications and ensure adequate hydration. Initiate or intensify oral anti-hyperglycemic medications for patients with risk factors for hyperglycemia. Fasting glucose levels > 160 to 250 mg/dL (> 8.9 – 13.9 mmol/L) Withhold ITOVEBI until FPG or FBG ≤ 160 mg/dL (≤ 8.9 mmol/L). Initiate or intensify anti-hyperglycemic medications. Resume ITOVEBI at the same dose level. If FPG or FBG persists > 200 – 250 mg/dL (> 11.1 – 13.9 mmol/L) for 7 days under appropriate anti-hyperglycemic treatment, consider consultation with a healthcare professional experienced in the treatment of hyperglycemia. Fasting glucose levels > 250 to 500 mg/dL (> 13.9 – 27.8 mmol/L) Withhold ITOVEBI. Initiate or intensify anti-hyperglycemic medications. Administer appropriate hydration if required. If FPG or FBG decreases to ≤ 160 mg/dL (≤ 8.9 mmol/L) within 7 days, resume ITOVEBI at the same dose level. If FPG or FBG decreases to ≤ 160 mg/dL (≤ 8.9 mmol/L) in ≥ 8 days, resume ITOVEBI at one lower dose level. If FPG or FBG > 250 to 500 mg/dL (> 13.9 – 27.8 mmol/L) recurs within 30 days, withhold ITOVEBI until FPG or FBG decreases to ≤ 160 mg/dL (≤ 8.9 mmol/L). Resume ITOVEBI at one lower dose level. Fasting glucose levels > 500 mg/dL (> 27.8 mmol/L) Withhold ITOVEBI. Initiate or intensify anti-hyperglycemic medications. Assess for volume depletion and ketosis and administer appropriate hydration. If FPG or FBG decreases to ≤ 160 mg/dL (≤ 8.9 mmol/L), resume ITOVEBI at one lower dose level.

6 ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the label: Hyperglycemia [see Warnings and Precautions (5.1) ] Stomatitis [see Warnings and Precautions (5.2) ] Diarrhea [see Warnings and Precautions (5.3) ] The most common (≥ 20%) adverse reactions, including laboratory abnormalities, were decreased neutrophils, decreased hemoglobin, increased fasting glucose, decreased platelets, decreased lymphocytes, stomatitis, diarrhea, decreased calcium, fatigue, decreased potassium, increased creatinine, increased ALT, nausea, decreased sodium, decreased magnesium, rash, decreased appetite, COVID-19 infection, and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Genentech at 1-888-835-2555 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Locally Advanced or Metastatic Breast Cancer INAVO120 The safety of ITOVEBI was evaluated in a randomized, double-blind, placebo-controlled study (INAVO120) in 324 patients with PIK3CA -mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer [see Clinical Studies (14.1) ] . Patients received either ITOVEBI 9 mg (n=162) or placebo (n=162) with palbociclib and fulvestrant. The median duration of treatment with ITOVEBI was 9 months (range: 0 to 39 months) in the ITOVEBI with palbociclib and fulvestrant arm. Serious adverse reactions occurred in 24% of patients who received ITOVEBI with palbociclib and fulvestrant. Serious adverse reactions in ≥ 1% of patients included anemia (1.9%), diarrhea (1.2%), and urinary tract infection (1.2%). Fatal adverse reactions occurred in 3.7% of patients who received ITOVEBI with palbociclib and fulvestrant, including (0.6% each) acute coronary syndrome, cerebral hemorrhage, cerebrovascular accident, COVID-19 infection, and gastrointestinal hemorrhage. Permanent discontinuation of ITOVEBI due to an adverse reaction occurred in 6% of patients. Adverse reactions which resulted in permanent discontinuation of ITOVEBI included hyperglycemia (1.2%), and (0.6% each) stomatitis, gastric ulcer, intestinal perforation, anal abscess, increased ALT, decreased weight, bone pain, musculoskeletal pain, transitional cell carcinoma, and acute kidney injury. Dosage interruptions of ITOVEBI due to an adverse reaction occurred in 69% of patients. Adverse reactions which required dosage interruption in ≥ 2% of patients included hyperglycemia (28%), neutropenia (23%), COVID-19 infection (16%), stomatitis (10%), diarrhea (7%), thrombocytopenia (4.9%), anemia (4.3%), upper respiratory tract infection (4.3%), decreased white blood cell count (3.7%), pyrexia (3.1%), nausea (2.5%), and fatigue (2.5%). Dose reductions of ITOVEBI due to adverse reactions occurred in 14% of patients. Adverse reactions which required dose reduction of ITOVEBI in ≥ 2% of patients were stomatitis (3.7%) and hyperglycemia (2.5%). The most common (≥ 20%) adverse reactions, including laboratory abnormalities, were decreased neutrophils, decreased hemoglobin, increased fasting glucose, decreased platelets, decreased lymphocytes, stomatitis, diarrhea, decreased calcium, fatigue, decreased potassium, increased creatinine, increased ALT, nausea, decreased sodium, decreased magnesium, rash, decreased appetite, COVID-19 infection, and headache. Adverse reactions and laboratory abnormalities in INAVO120 are summarized in Table 3 and Table 4 , respectively. Patient-reported symptoms are summarized in Table 5 . Table 3: Adverse Reactions (≥ 10% with ≥ 5% [All Grades] or ≥ 2% [Grade 3-4] Higher Incidence in the ITOVEBI Arm) in INAVO120 Adverse Reaction ITOVEBI + Palbociclib + Fulvestrant N=162 Placebo + Palbociclib + Fulvestrant N=162 All Grades (%) Grade 3-4 (%) All Grades (%) Grade 3-4 (%) Gastrointestinal Disorders Stomatitis Includes aphthous ulcer, glossitis, glossodynia, lip ulceration, mouth ulceration, mucosal inflammation, and stomatitis. 51 6 No Grade 4 adverse reactions were observed. 27 0 Diarrhea 48 3.7 16 0 Nausea 28 0.6 17 0 Vomiting 15 0.6 5 1.2 General Disorders and Administration Site Conditions Fatigue 38 1.9 25 1.2 Skin and Subcutaneous Tissue Disorders Rash Includes other related terms. 26 0 19 0 Alopecia 19 0 6 0 Dry skin Includes dry skin, skin fissures, xerosis, and xeroderma. 13 0 4.3 0 Metabolism and Nutrition Disorders Decreased appetite 24 0 9 0 Infections and Infestations COVID-19 infection 23 1.9 11 0.6 Urinary tract infection 15 1.2 9 0 Nervous System Disorders Headache 22 0 14 0 Investigations Decreased weight 17 3.7 0.6 0 Clinically relevant adverse reactions occurring in < 10% of patients who received ITOVEBI in combination with palbociclib and fulvestrant included abdominal pain, dry eye, dysge