Trodelvy® Demonstrates Superior Outcomes to Standard of Care in Second-Line Treatment of Metastatic Triple-Negative Breast Cancer in Phase 3 ASCENT Study

Trodelvy More than Doubled Overall Survival as Second-Line Treatment in New ASCENT Subgroup Analysis –

Gilead Sciences, Inc. (Nasdaq: GILD) today announced new data from the Phase 3 ASCENT study evaluating Trodelvy ^® (sacituzumab govitecan-hziy) in relapsed or refractory metastatic triple-negative breast cancer (TNBC). In this subgroup analysis of brain metastases-negative patients who received only one line of prior systemic therapy in the metastatic setting in addition to having disease recurrence or progression within 12 months of (neo)adjuvant chemotherapy, Trodelvy improved progression-free survival (PFS), with a 59% reduction in the risk of disease worsening or death (HR: 0.41; 95% CI: 0.22-0.76) and a median PFS of 5.7 months (n=33) versus 1.5 months with chemotherapy (n=32). Trodelvy also extended median overall survival to 10.9 months versus 4.9 months with chemotherapy (HR: 0.51; 95% CI: 0.28-0.91). The results were presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract #1080).

"In patients with relapsed or refractory metastatic triple-negative breast cancer, outcomes are typically poor – especially among patients who progress within 12 months of (neo)adjuvant chemotherapy," said Lisa Carey, MD, Medical Director of the UNC Breast Center, the Physician-in-Chief of the North Carolina Cancer Hospital and Associate Director of Clinical Research at UNC Lineberger Comprehensive Cancer Center. "In the Phase 3 ASCENT study, Trodelvy was the first treatment to demonstrate a proven survival advantage in pre-treated patients with locally advanced or metastatic TNBC, and the analysis presented at ASCO reaffirms this benefit over standard of care with important new data in the second-line setting."

Additional results showed Trodelvy demonstrated a higher overall response rate compared with chemotherapy (30% versus 3%). Efficacy results from this subgroup were consistent with those observed in the overall ASCENT study population.

The safety profile of Trodelvy in this subgroup was consistent with prior reports. The most frequent Grade ≥3 treatment-related adverse reactions for Trodelvy compared to chemotherapy were neutropenia (61% versus 21%), leukopenia (9% versus 0%), diarrhea (6% versus 0%), anemia (3% versus 6%), and fatigue (3% versus 0%). One patient in this subgroup who received Trodelvy experienced febrile neutropenia. Adverse reactions leading to treatment discontinuation were low across both groups (6% in each). There were no treatment-related deaths with Trodelvy in this subgroup. The Trodelvy U.S. Prescribing Information has a BOXED WARNING for severe or life-threatening neutropenia and severe diarrhea; see below for Important Safety Information.

"With Trodelvy, we continue to challenge the standard of care in locally advanced and metastatic TNBC. The efficacy observed in the second-line metastatic setting with Trodelvy is highly meaningful, since many patients will progress quickly following chemotherapy. Among these patients, we see median overall survival more than doubled where need is particularly great," said Daejin Abidoye, MD, Senior Vice President, Head of Oncology Clinical Development, Gilead Sciences. "We are committed to improving the prognosis for people with this aggressive cancer, and as we continue to study Trodelvy, we are encouraged by this proven efficacy in TNBC."

Two additional ASCENT subgroup analyses that support the efficacy benefit of Trodelvy were also presented at the meeting – one evaluating Trodelvy efficacy by patients' age (Abstract #1011) and the other comparing Trodelvy with specific single-agent chemotherapy chosen by the patients' treating physicians (Abstract #1077).

About Triple-Negative Breast Cancer (TNBC)

TNBC is an aggressive type of breast cancer, accounting for approximately 15% of all breast cancers. The disease is diagnosed more frequently in younger and premenopausal women and is more prevalent in African American and Hispanic women. TNBC cells do not have estrogen and progesterone receptors and have limited HER2. Medicines targeting these receptors therefore are not typically effective in treating TNBC.

About the ASCENT Study

The Phase 3 ASCENT study, an open-label, active-controlled, randomized confirmatory trial, enrolled more than 500 patients with relapsed/refractory metastatic triple-negative breast cancer who had received two or more prior systemic therapies, including a taxane, at least one of them for metastatic disease. Patients were randomized to receive either Trodelvy or a chemotherapy chosen by the patients' treating physicians. The primary efficacy outcome was PFS in patients without brain metastases at baseline, as measured by a blinded, independent, centralized review using RECIST v1.1 criteria. Additional efficacy measures included PFS for the full population, including all patients with and without brain metastases, and overall survival. More information about ASCENT is available at https://clinicaltrials.gov/show/NCT02574455 .

About Trodelvy

Trodelvy (sacituzumab govitecan-hziy) is a first-in-class antibody and topoisomerase inhibitor conjugate directed to the Trop-2 receptor, a protein frequently expressed in multiple types of epithelial tumors, including metastatic triple-negative breast cancer and metastatic urothelial cancer, where high expression is associated with poor survival and relapse.

In the U.S., Trodelvy is indicated for the treatment of:

• Adult patients with unresectable locally advanced or metastatic triple-negative breast cancer who have received two or more prior systemic therapies, at least one of them for metastatic disease.
• Adult patients with locally advanced or metastatic urothelial cancer who have previously received a platinum-containing chemotherapy and either programmed death receptor-1 (PD-1) or programmed death-ligand 1 (PD-L1) inhibitor.

Beyond the regulatory approvals of Trodelvy in the U.S., regulatory reviews for Trodelvy in metastatic triple-negative breast cancer are currently underway in the EU, U.K., Canada, Switzerland and Australia, as well as in Singapore through our partner Everest Medicines. Trodelvy is also being investigated as potential treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer and metastatic non-small cell lung cancer. Additional evaluation across multiple solid tumors is also underway.

U.S. Important Safety Information for Trodelvy

BOXED WARNING: NEUTROPENIA AND DIARRHEA

• Severe or life-threatening neutropenia may occur. Withhold Trodelvy for absolute neutrophil count below 1500/mm ³ or neutropenic fever. Monitor blood cell counts periodically during treatment. Consider G-CSF for secondary prophylaxis. Initiate anti-infective treatment in patients with febrile neutropenia without delay.

• Severe diarrhea may occur. Monitor patients with diarrhea and give fluid and electrolytes as needed. Administer atropine, if not contraindicated, for early diarrhea of any severity. At the onset of late diarrhea, evaluate for infectious causes and, if negative, promptly initiate loperamide. If severe diarrhea occurs, withhold Trodelvy until resolved to ≤Grade 1 and reduce subsequent doses.

CONTRAINDICATIONS

• Severe hypersensitivity reaction to Trodelvy.

WARNINGS AND PRECAUTIONS

Neutropenia: Severe, life-threatening, or fatal neutropenia can occur and may require dose modification. Neutropenia occurred in 61% of patients treated with Trodelvy. Grade 3-4 neutropenia occurred in 47% of patients. Febrile neutropenia occurred in 7%. Withhold Trodelvy for absolute neutrophil count below 1500/mm ³ on Day 1 of any cycle or neutrophil count below 1000/mm ³ on Day 8 of any cycle. Withhold Trodelvy for neutropenic fever.

Diarrhea: Diarrhea occurred in 65% of all patients treated with Trodelvy. Grade 3-4 diarrhea occurred in 12% of patients. One patient had intestinal perforation following diarrhea. Neutropenic colitis occurred in 0.5% of patients. Withhold Trodelvy for Grade 3-4 diarrhea and resume when resolved to ≤Grade 1. At onset, evaluate for infectious causes and if negative, promptly initiate loperamide, 4 mg initially followed by 2 mg with every episode of diarrhea for a maximum of 16 mg daily. Discontinue loperamide 12 hours after diarrhea resolves. Additional supportive measures (e.g., fluid and electrolyte substitution) may also be employed as clinically indicated. Patients who exhibit an excessive cholinergic response to treatment can receive appropriate premedication (e.g., atropine) for subsequent treatments.

Hypersensitivity and Infusion-Related Reactions: Serious hypersensitivity reactions including life-threatening anaphylactic reactions have occurred with Trodelvy. Severe signs and symptoms included cardiac arrest, hypotension, wheezing, angioedema, swelling, pneumonitis, and skin reactions. Hypersensitivity reactions within 24 hours of dosing occurred in 37% of patients. Grade 3-4 hypersensitivity occurred in 2% of patients. The incidence of hypersensitivity reactions leading to permanent discontinuation of Trodelvy was 0.3%. The incidence of anaphylactic reactions was 0.3%. Pre-infusion medication is recommended . Observe patients closely for hypersensitivity and infusion-related reactions during each infusion and for at least 30 minutes after completion of each infusion. Medication to treat such reactions, as well as emergency equipment, should be available for immediate use. Permanently discontinue Trodelvy for Grade 4 infusion-related reactions.

Nausea and Vomiting: Nausea occurred in 66% of all patients treated with Trodelvy and Grade 3 nausea occurred in 4% of these patients. Vomiting occurred in 39% of patients and Grade 3-4 vomiting occurred in 3% of these patients. Premedicate with a two or three drug combination regimen (e.g., dexamethasone with either a 5-HT3 receptor antagonist or an NK1 receptor antagonist as well as other drugs as indicated) for prevention of chemotherapy-induced nausea and vomiting (CINV). Withhold Trodelvy doses for Grade 3 nausea or Grade 3-4 vomiting and resume with additional supportive measures when resolved to Grade ≤1. Additional antiemetics and other supportive measures may also be employed as clinically indicated. All patients should be given take-home medications with clear instructions for prevention and treatment of nausea and vomiting.

Increased Risk of Adverse Reactions in Patients with Reduced UGT1A1 Activity: Patients homozygous for the uridine diphosphate-glucuronosyl transferase 1A1 (UGT1A1)*28 allele are at increased risk for neutropenia, febrile neutropenia, and anemia and may be at increased risk for other adverse reactions with Trodelvy. The incidence of Grade 3-4 neutropenia was 67% in patients homozygous for the UGT1A1*28, 46% in patients heterozygous for the UGT1A1*28 allele and 46% in patients homozygous for the wild-type allele. The incidence of Grade 3-4 anemia was 25% in patients homozygous for the UGT1A1*28 allele, 10% in patients heterozygous for the UGT1A1*28 allele, and 11% in patients homozygous for the wild-type allele. Closely monitor patients with known reduced UGT1A1 activity for adverse reactions. Withhold or permanently discontinue Trodelvy based on clinical assessment of the onset, duration and severity of the observed adverse reactions in patients with evidence of acute early-onset or unusually severe adverse reactions, which may indicate reduced UGT1A1 function.

Embryo-Fetal Toxicity: Based on its mechanism of action, Trodelvy can cause teratogenicity and/or embryo-fetal lethality when administered to a pregnant woman. Trodelvy contains a genotoxic component, SN-38, and targets rapidly dividing cells. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with Trodelvy and for 6 months after the last dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with Trodelvy and for 3 months after the last dose.

ADVERSE REACTIONS

In the ASCENT study (IMMU-132-05) , the most common adverse reactions (incidence ≥25%) were fatigue, neutropenia, diarrhea, nausea, alopecia, anemia, constipation, vomiting, abdominal pain, and decreased appetite. The most frequent serious adverse reactions (SAR) (>1%) were neutropenia (7%), diarrhea (4%), and pneumonia (3%). SAR were reported in 27% of patients, and 5% discontinued therapy due to adverse reactions. The most common Grade 3-4 lab abnormalities (incidence ≥25%) in the ASCENT study were reduced neutrophils, leukocytes, and lymphocytes.

In the TROPHY study (IMMU-132-06) , the most common adverse reactions (incidence ≥25%) were diarrhea, fatigue, neutropenia, nausea, any infection, alopecia, anemia, decreased appetite, constipation, vomiting, abdominal pain, and rash. The most frequent serious adverse reactions (SAR) (≥5%) were infection (18%), neutropenia (12%, including febrile neutropenia in 10%), acute kidney injury (6%), urinary tract infection (6%), and sepsis or bacteremia (5%). SAR were reported in 44% of patients, and 10% discontinued due to adverse reactions. The most common Grade 3-4 lab abnormalities (incidence ≥25%) in the TROPHY study were reduced neutrophils, leukocytes, and lymphocytes.

DRUG INTERACTIONS

UGT1A1 Inhibitors: Concomitant administration of Trodelvy with inhibitors of UGT1A1 may increase the incidence of adverse reactions due to potential increase in systemic exposure to SN-38. Avoid administering UGT1A1 inhibitors with Trodelvy.

UGT1A1   Inducers : Exposure to SN-38 may be substantially reduced in patients concomitantly receiving UGT1A1 enzyme inducers. Avoid administering UGT1A1 inducers with Trodelvy.

Please see full Prescribing Information , including BOXED WARNING.

About Gilead Sciences

Gilead Sciences, Inc. is a biopharmaceutical company that has pursued and achieved breakthroughs in medicine for more than three decades, with the goal of creating a healthier world for all people. The company is committed to advancing innovative medicines to prevent and treat life-threatening diseases, including HIV, viral hepatitis and cancer. Gilead operates in more than 35 countries worldwide, with headquarters in Foster City, California.

Forward-Looking Statements

This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including Gilead's ability to initiate, progress or complete clinical trials within currently anticipated timelines or at all, including those involving Trodelvy; the possibility of unfavorable results from ongoing or additional trials, including those involving Trodelvy; Gilead's ability to receive regulatory approvals in a timely manner or at all, including additional regulatory approvals of Trodelvy for the treatment of metastatic TNBC, metastatic breast cancer, metastatic UC, metastatic non-small cell lung cancer and other solid tumors, and the risk that any such approvals may be subject to significant limitations on use; and any assumptions underlying any of the foregoing. These and other risks, uncertainties and other factors are described in detail in Gilead's Quarterly Report on Form 10-Q for the quarter ended March 31, 2021, as filed with the U.S. Securities and Exchange Commission. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and are cautioned not to place undue reliance on these forward-looking statements. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation and disclaims any intent to update any such forward-looking statements.

U.S. Prescribing Information for Trodelvy including BOXED WARNING , is available at www.gilead.com .

Trodelvy, Gilead and the Gilead logo are trademarks of   Gilead Sciences, Inc., or its related companies.

For more information about Gilead, please visit the company's website at www.gilead.com , follow Gilead on Twitter (@GileadSciences) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

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