Sacituzumab Govitecan-Hziy

Introduction Overview

Generic Name

sacituzumab govitecan-hziy

Brand Name

Trodelvy

Dosage Form

injection for intravenous infusion

Drug Class

Miscellaneous antineoplastics

Pharmacokinetics

Absorption:
Trodelvy is administered intravenously, resulting in complete bioavailability directly into systemic circulation. The drug is delivered via intravenous infusion, circumventing gastrointestinal absorption variability that oral agents face. Following infusion, the antibody-drug conjugate (ADC) circulates in the bloodstream, reaching target tumor sites to exert its action. The infusion duration for the first dose is approximately 3 hours, with subsequent doses administered over 1 to 2 hours, optimizing drug delivery kinetics and reducing infusion-related reactions.

Distribution:
Sacituzumab govitecan-hziy, as an ADC, exhibits distribution characteristics influenced by the monoclonal antibody's pharmacodynamics and the payload's physicochemical properties. The antibody component targets Trop-2-expressing tumor cells, facilitating selective delivery. The drug demonstrates a volume of distribution consistent with large molecules, predominantly restricted to plasma and extracellular fluids. Preclinical and clinical studies indicate preferential accumulation in tumors expressing Trop-2, minimizing systemic exposure to SN-38. The distribution is also influenced by the binding affinity to Trop-2 and internalization rates within cancer cells.

Metabolism:
The metabolism of Trodelvy involves intracellular processing post-target binding. After sacituzumab govitecan binds Trop-2 on cancer cells, the ADC is internalized, and the linker is cleaved intracellularly, releasing SN-38, the active topoisomerase I inhibitor. Systemically, SN-38 undergoes hepatic metabolism primarily through glucuronidation by UGT1A1 enzymes into inactive SN-38 glucuronide. Variability in UGT1A1 activity can influence exposure levels and toxicity risk. Co-administration of UGT1A1 inhibitors or inducers can alter SN-38 metabolism and pharmacokinetics. The antibody portion is metabolized via proteolytic pathways into small peptides and amino acids.

Elimination:
The primary route of elimination for the small molecule payload SN-38 is via hepatic conjugation and biliary excretion of its glucuronide metabolites into feces. A smaller proportion is renally excreted. The elimination half-life of the ADC and its payload is modulated by the release rate of SN-38 and systemic clearance of the antibody. Renal and hepatic function can impact clearance rates, with caution advised in moderate to severe hepatic impairment. The antibody component is eliminated through reticuloendothelial system uptake and proteolysis. The balance between ADC stability in circulation and effective payload release is critical to therapeutic efficacy and safety.

Dosage Forms

Available Dosage Forms:
Trodelvy is supplied as an injection for intravenous infusion. The commercial preparation consists of single-dose vials containing 180 mg of sacituzumab govitecan-hziy. The formulation includes inactive ingredients such as 2-(N-morpholino) ethane sulfonic acid (MES), polysorbate 80, and trehalose dihydrate. The vials should be refrigerated at 2°C to 8°C and protected from light until reconstitution.

Dosages for Adults and Adolescents:
The recommended dosing regimen for adults with locally advanced or metastatic breast cancer is 10 mg/kg of body weight, administered intravenously on Days 1 and 8 of every 21-day treatment cycle. The initial infusion is administered over approximately 3 hours; if tolerated, subsequent infusions may be shortened to 1 to 2 hours. Dose modifications are indicated in the case of adverse effects such as neutropenia or diarrhea, with dose adjustments and treatment delays guided by clinical judgment and standardized protocols. Therapy continues until disease progression or unacceptable toxicity.

Specific Patient Populations:
There is limited data on Trodelvy use in patients with moderate or severe hepatic impairment, and its safety has not been established in pediatric populations. Patients with reduced UGT1A1 activity are at increased risk of hematologic toxicities and may require closer monitoring and dose adjustments. Special precautions should be taken when administering to patients with pre-existing liver disease. Women who are pregnant or breastfeeding should avoid treatment due to potential fetal harm. No specific formulations or dosing guidelines exist for pediatric or elderly populations beyond general dose adjustment recommendations based on tolerability and organ function.

Mechanism Of Action

Trodelvy is a pioneering Trop-2-directed antibody-drug conjugate (ADC) composed of a humanized monoclonal antibody linked to SN-38, the active metabolite of irinotecan and a potent topoisomerase I inhibitor. Trop-2 is a transmembrane glycoprotein highly expressed on the surface of many epithelial cancers, including triple-negative and hormone receptor-positive breast cancers. By targeting Trop-2, Trodelvy enables selective delivery of SN-38 directly into tumor cells, sparing normal tissues.

The monoclonal antibody component binds with high affinity to the Trop-2 antigen expressed on cancer cells. Upon binding, the ADC is internalized by receptor-mediated endocytosis. Inside the cancer cell, the hydrolysable linker between the antibody and SN-38 is cleaved by intracellular enzymes or acidic conditions within lysosomes, releasing the cytotoxic payload.

SN-38 acts by inhibiting topoisomerase I, an enzyme essential for DNA replication and transcription by inducing reversible single-strand breaks. Inhibition prevents relegation of DNA strands, leading to DNA damage accumulation, replication fork collapse, and ultimately apoptosis of malignant cells. The targeted delivery of SN-38 optimizes its therapeutic index by enhancing tumor-specific cytotoxicity while reducing systemic exposure, which is a limitation of conventional irinotecan chemotherapy.

Clinical studies have demonstrated that Trodelvy's selective mechanism results in significant tumor shrinkage and progression-free survival benefits in patients with heavily pre-treated metastatic breast cancer. Compared with systemic chemotherapy, Trodelvy provides a refined approach by combining targeted immunotherapy principles with traditional cytotoxic chemotherapy, resulting in improved efficacy and tolerability profiles. This ADC represents a significant advancement in precision oncology with a mechanism that integrates antibody-mediated targeting and topoisomerase I inhibition.

Pharmacological Actions

Targets Trop-2 antigen expressed on cancer cells, enabling selective tumor targeting.
Delivers cytotoxic agent SN-38 directly into tumor cells via an antibody-drug conjugate mechanism.
Inhibits topoisomerase I, causing DNA damage and apoptosis in malignant cells.
Reduces tumor growth by promoting cancer cell death with minimal impact on healthy tissues.
Exerts cytotoxic effects primarily via DNA replication interference leading to cell cycle arrest.
Facilitates internalization and intracellular release of the active chemotherapeutic agent.
Improves therapeutic index over conventional chemotherapy through targeted delivery.
Modulates immune recognition indirectly through monoclonal antibody binding.
Demonstrates antineoplastic activity particularly in triple-negative and HR+/HER2- breast cancers.
Potential reduction in off-target toxicities compared to systemic irinotecan treatment.

Therapeutic Or Clinical Uses

Treatment of unresectable locally advanced or metastatic triple-negative breast cancer in patients who have received at least two prior systemic therapies including at least one for metastatic disease.
Treatment of unresectable locally advanced or metastatic hormone receptor-positive, HER2-negative breast cancer in patients previously treated with endocrine therapy and at least two additional systemic therapies in the metastatic setting.
Used as a targeted therapy to improve progression-free survival in heavily pretreated metastatic breast cancer.
Provides an option for patients with limited treatment alternatives in metastatic breast cancer.
Off-label and investigational uses include other Trop-2 expressing solid tumors though more evidence is needed.
Potential alternative to conventional chemotherapy with improved tolerability in specific breast cancer subsets.
Applicable for patients intolerant or refractory to other cytotoxic chemotherapies.
Administered in combination with supportive care measures for management of metastatic disease.
Shows efficacy in patients with prior multiple lines of systemic therapy including chemotherapy and endocrine agents.
Not approved for metastatic urothelial cancer following withdrawal based on recent confirmatory study outcomes.

Side Or Adverse Effects

Fatigue or weakness occurring in approximately 65% of patients.
Diarrhea, frequent and can be severe, reported in 59% of treated individuals.
Nausea affecting 57% of patients, sometimes severe requiring antiemetic treatment.
Alopecia (hair loss) observed in up to 47% of patients receiving Trodelvy.
Constipation occurring in about 37% of cases.
Vomiting reported in 33% of patients; may require symptomatic management.
Stomach or abdominal pain in approximately 30% of patients.
Loss of appetite noted in 28% of individuals undergoing therapy.
Cough seen in 24% of patients, requiring clinical evaluation.
Neutropenia, including severe and life-threatening cases, necessitating treatment interruption or dose modification.
Serious infusion-related hypersensitivity reactions including anaphylaxis.
Risk of serious infections due to immunosuppression and neutropenia.
Potential liver and kidney function abnormalities as evidenced by laboratory test derangements.
Severe diarrhea possibly leading to dehydration, electrolyte imbalance, and hospitalization.
Nausea and vomiting severe enough to require prophylactic antiemetics and possible dose withholding.

Precautions

Monitor closely for infusion-related reactions; premedicate to reduce risk.
Assess hepatic function before and during treatment due to potential metabolism concerns.
Regular complete blood counts to detect neutropenia; consider granulocyte colony-stimulating factor support.
Advise patients regarding symptoms of infection and promptly evaluate febrile episodes.
Implement anti-diarrheal therapy at first sign of diarrhea; maintain hydration and electrolyte balance.
Avoid use in patients with history of severe allergic reactions to sacituzumab govitecan-hziy or formulation components.
Evaluate UGT1A1 genotype where feasible to identify patients at increased risk for hematological toxicity.
Reproductive precautions: Women of childbearing potential must use effective contraception during treatment and for at least six months after therapy completion.
Male patients should use contraception during treatment and for three months following final dose due to potential fetal harm.
Breastfeeding is contraindicated during treatment and for at least one month after discontinuation.
Dose adjustment or discontinuation should be considered in patients experiencing severe or life-threatening toxicities.
Clinical monitoring for nausea and vomiting; antiemetic regimens should be employed proactively.
Use in moderate or severe hepatic impairment is not established; caution advised.
Not established for use in pediatric patients; restricted to adults.
Patient education on symptom recognition and adherence to follow-up monitoring is essential.

Warnings

Serious hypersensitivity and infusion-related reactions including anaphylaxis can occur; immediate medical intervention is required.
Severe diarrhea can result in dehydration and electrolyte disturbances; prompt treatment is essential.
Neutropenia can be severe or life-threatening, potentially leading to febrile neutropenia and infections.
Treatment must be withheld for absolute neutrophil counts below 1500/mm3 or presence of neutropenic fever.
Nausea and vomiting may be severe; use preventive antiemetic therapy and withhold Trodelvy for grade 3 or 4 symptoms.
Patients with reduced UGT1A1 activity are at increased risk of hematologic toxicities including neutropenia and anemia.
Fetal harm can occur; effective contraception is mandatory for women of childbearing potential and male partners.
Do not administer if previous severe allergic reaction to Trodelvy or its components occurred.
Not recommended in patients with moderate or severe liver dysfunction due to unknown safety.
Infusion should be slowed or stopped if infusion-related symptoms develop during administration.
Treatment delay or discontinuation may be necessary for severe adverse reactions.
Patient exposure to drugs interfering with UGT1A1 metabolism can increase toxicity risk.
Trodelvy is a hazardous drug; adhere to special handling and disposal guidelines to minimize exposure risks.
Close monitoring during and post-infusion for at least 30 minutes is required to detect hypersensitivity.
Metastatic urothelial cancer indication was withdrawn due to failure to demonstrate survival benefit.

Contraindication

Known hypersensitivity or severe allergic reaction to sacituzumab govitecan-hziy or any inactive ingredients.
Patients who have experienced life-threatening infusion-related reactions to Trodelvy.
Concurrent use with other irinotecan or SN-38 containing drugs due to additive toxicity.
Use is contraindicated during pregnancy due to potential for fetal harm.
Contraindicated in breastfeeding women during treatment and for one month after last dose.
Patients with unresolved severe neutropenia or active serious infections.
Inability to accommodate premedication regimen for infusion reactions or antiemetic prophylaxis.
No established safety for use in pediatric patients contraindicates use under 18 years of age.
Known severe hepatic impairment where metabolism and clearance of payload would be impaired.
Any condition or history that prediposes to severe infusion reactions without ability to monitor.
Use is contraindicated if unable to comply with treatment schedule or monitoring requirements.

Drug Interactions

Co-administration with UGT1A1 inhibitors, such as flunitrazepam or propofol, may increase systemic exposure to SN-38, increasing the risk of toxicity.
Use with UGT1A1 inducers like phenytoin and phenobarbital may reduce SN-38 exposure, potentially decreasing efficacy.
Avoid concomitant use of other medications containing irinotecan or its active metabolite SN-38 to prevent additive toxicity.
Potential interactions with medications altering hepatic enzyme activity impacting SN-38 metabolism.
Drugs causing myelosuppression may exacerbate hematologic toxicities when used with Trodelvy.
Concurrent use with strong inhibitors or inducers of cytochrome P450 enzymes may influence ADC pharmacodynamics indirectly.
Immunosuppressive agents may increase risk of infections during Trodelvy treatment.
Use caution with other drugs known to prolong QT interval due to potential additive cardiac risks.
Antiemetic agents are often co-administered to manage nausea and vomiting; no significant interaction reported.
Herbal supplements with enzyme-modulating properties should be disclosed as they may alter metabolism.
Patients should inform their healthcare providers of all prescription, over-the-counter, and herbal products to minimize interaction risks.
No significant interaction data with common cardiovascular and metabolic agents; however, clinical monitoring remains prudent.
No dose adjustment guidance currently exists for drug-drug interactions; clinical evaluation recommended.
Monitoring is advised when Trodelvy is administered alongside medications affecting immune function.
Data is limited on interactions with other targeted cancer therapies; combination use should be managed cautiously.

Preparations Of The Drug

Trodelvy is prepared as a sterile, single-dose vial containing 180 mg of sacituzumab govitecan-hziy.
Vials should be stored refrigerated at 2°C to 8°C (36°F to 46°F) and protected from light until use.
Do not freeze the vials to preserve stability and efficacy.
Reconstitution and dilution must be performed according to prescribing information to prepare for intravenous infusion.
Prepared solutions should be handled using precautions for hazardous drugs to avoid occupational exposure.
Administered intravenously over 3 hours for the initial dose, with subsequent infusions over 1 to 2 hours if tolerated.
Premedication with antihistamines, corticosteroids, and antiemetics is recommended prior to infusion to reduce adverse reactions.
Prepared infusion solutions have stability data supporting use within specified time frames post-dilution.
Detailed handling, preparation, and administration guidelines are provided in the official prescribing information.
Quality control measures and aseptic techniques are critical during preparation to maintain safety and effectiveness.
Disposal of unused portions must conform to institutional hazardous waste protocols.
Healthcare providers receive specific training for preparation and administration to ensure patient safety.
Preparation facilities should be equipped to manage admixture and infusion in controlled environments.
The drug formulation includes excipients such as MES, polysorbate 80, and trehalose dihydrate to maintain stability.