Tarlatamab

Introduction Overview

Generic Name

tarlatamab

Brand Name

Imdelltra

Dosage Form

injection for intravenous (IV) administration

Drug Class

Bispecific T-cell engagers (BiTE)

Pharmacokinetics

Absorption:
As Imdelltra (tarlatamab) is administered intravenously, it bypasses the gastrointestinal tract, providing complete bioavailability. The drug is directly infused into the bloodstream, allowing rapid systemic exposure. Peak plasma concentrations are typically achieved at the end of the infusion period, which lasts about 1 hour. The intravenous route eliminates variability seen in oral absorption due to factors such as food effect, pH, and first-pass metabolism.

Distribution:
Post IV administration, tarlatamab is distributed through the systemic circulation. As a biologic agent and bispecific antibody, its volume of distribution is expected to be limited mainly to the plasma and extracellular fluid compartments. Distribution is influenced by binding to target antigens, notably CD3 on T-cells and DLL3 expressed on tumor cells, which may lead to target-mediated drug disposition (TMDD). The extent of tissue penetration may be limited due to its large molecular size typical of biotherapeutics. Protein binding is expected to be specific due to antibody characteristics.

Metabolism:
Tarlatamab is metabolized via proteolytic degradation pathways typical to monoclonal antibodies and bispecific antibodies. Catabolic processes include intracellular lysosomal degradation following receptor-mediated endocytosis and nonspecific proteolysis into small peptides and amino acids. It is not metabolized by cytochrome P450 enzymes, thereby minimizing drug-drug interactions related to hepatic enzyme modulation.

Elimination:
Clearance of Imdelltra primarily occurs through proteolytic catabolism and target-mediated internalization and degradation. The elimination half-life is influenced by target binding and the immunogenicity profile. Renal excretion is minimal due to the molecule's size. The drug is eliminated via reticuloendothelial system pathways. Dosage adjustments in renal or hepatic impairment have not been established, but due to the nature of monoclonal antibodies, these organ impairments are less likely to impact elimination significantly. Clinical studies have characterized pharmacokinetic parameters in patients with extensive-stage small cell lung cancer (ES-SCLC), confirming manageable clearance with repeat dosing every two weeks after initial step-up dosing.

Dosage Forms

Available Dosage Forms:
Imdelltra is available as a sterile injection for intravenous administration in single-dose vials. The product comes in two vial strengths requiring reconstitution and further dilution prior to infusion:
- 1 mg single-dose vial
- 10 mg single-dose vial

Dosages for Adults and Adolescents:
Imdelltra dosing is individualized and administered by healthcare providers in clinical settings. The recommended dosing regimen initiates with a step-up dosing schedule to mitigate cytokine release syndrome (CRS):
- Cycle 1, Day 1: Reduced dose (step-up start dose)
- Cycle 1, Day 8 and Day 15: Full therapeutic dose of 10 mg
- Subsequent cycles (every 2 weeks): Full dose administered every 14 days
Each treatment cycle typically lasts 28 days. Therapy continuation depends on clinical benefit and tolerability.

Specific Patient Populations:
Given the limited data in pediatric populations, safety and efficacy of Imdelltra in children have not been established, and use is not recommended. No specific dosage adjustments have been defined for geriatric patients; however, clinical monitoring is advised. Patients with hepatic or renal impairment have not been studied extensively; due to the monoclonal antibody nature, significant dose modifications are generally not expected, but careful clinical evaluation is warranted. Close monitoring is required during pregnancy due to potential teratogenicity and effects on the unborn baby. Effective contraception is necessary for women of childbearing potential during treatment and for two months post-therapy.

Mechanism Of Action

Imdelltra (tarlatamab) is a bispecific T-cell engager (BiTE) designed to harness the body's immune system to selectively target and destroy tumor cells expressing Delta-like ligand 3 (DLL3), a protein prominently overexpressed on small cell lung cancer (SCLC) cells. The molecule possesses two distinct antigen-binding sites: one arm binds to DLL3 expressed on tumor cells, while the other binds to CD3, a component of the T-cell receptor complex on cytotoxic T-cells.

By physically linking CD3-positive T-cells with DLL3-expressing tumor cells, Imdelltra facilitates the formation of an immune synapse, triggering T-cell activation and cytotoxic response specifically at the tumor site. This interaction promotes localized T-cell proliferation, cytokine release, and the release of cytolytic granules that induce tumor cell apoptosis, bypassing major histocompatibility complex (MHC) restrictions.

This dual targeting mechanism allows Imdelltra to directly redirect and amplify the patient’s own immune system against cancer cells, representing an innovative immunotherapeutic approach. Compared to conventional therapies, which broadly suppress tumor growth, Imdelltra provides a more targeted cytotoxic immune response with potential for improved efficacy against extensive-stage small cell lung cancer.

Clinical trials have demonstrated robust anti-tumor activity, supporting its mechanism of engendering potent T-cell mediated tumor cell killing. Furthermore, this mode of action also explains observed side effects like cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, as immune activation can lead to systemic inflammatory responses and neurologic effects.

Pharmacological Actions

Bispecific antibody-mediated engagement of cytotoxic T-cells to DLL3-expressing tumor cells.
Activation of T-cells via CD3 binding, leading to immune synapse formation and targeted cell lysis.
Induction of apoptosis in tumor cells through T-cell cytolytic mechanisms.
Augmentation of antitumor immune response bypassing MHC class I restrictions.
Facilitation of immune cell proliferation and cytokine release in the tumor microenvironment.
Selective targeting of DLL3, minimizing off-target effects on non-tumor tissues.
Immune modulation with potential to overcome chemotherapy resistance in small cell lung cancer.
Enhancement of tumor-infiltrating lymphocyte activity to promote durable tumor regression.
Induction of systemic immune surveillance to possibly prevent disease recurrence.
Potential for combination with other immunotherapies to amplify antitumor effects.

Therapeutic Or Clinical Uses

Treatment of adults with extensive-stage small cell lung cancer (ES-SCLC) that has progressed following platinum-based chemotherapy.
Immunotherapy option for patients with DLL3-positive SCLC tumors.
Therapy to improve overall survival in a disease with limited treatment alternatives.
Use as a second-line or subsequent therapy in relapsed or refractory SCLC.
Potential to reduce tumor burden and improve quality of life in advanced lung cancer patients.
Option for patients ineligible for or who have failed conventional chemotherapy or radiotherapy.
Treatment targeting immunogenic tumor subtypes refractory to existing modalities.
Potential component of combination treatment regimens being evaluated in clinical trials.
Use in patients under careful clinical monitoring due to risk of immune-related adverse events.
Addressing aggressive, rapidly progressing lung cancer cases with poor prognosis.

Side Or Adverse Effects

Cytokine release syndrome (CRS), ranging from mild fever and fatigue to life-threatening systemic inflammatory responses.
Fatigue and general tiredness affecting patient quality of life.
Fever as a manifestation of immune activation.
Metallic or bad taste in the mouth—a common sensory disturbance.
Decreased appetite leading to potential nutritional challenges.
Muscle and bone pain potentially related to inflammatory responses.
Constipation frequently reported during treatment.
Nausea as a gastrointestinal side effect.
Severe hematologic toxicities including neutropenia, anemia, and thrombocytopenia.
Elevations in liver enzymes indicating hepatocellular injury or inflammation.
Hyponatremia and hypokalemia affecting electrolyte balance.
Increased uric acid levels potentially predisposing to gout or renal complications.
Neurologic toxicities including immune effector cell-associated neurotoxicity syndrome (ICANS), seizures, confusion, and motor coordination disturbances.
Serious infections due to immunosuppression associated with cytopenias.
Allergic reactions that may be severe and require emergency intervention.

Precautions

Monitor closely for signs and symptoms of cytokine release syndrome, with readiness to manage promptly.
Assess baseline and periodic blood counts to detect and manage cytopenias early.
Evaluate for infections prior to starting therapy and monitor continuously during treatment.
Careful monitoring of liver function tests to detect drug-induced hepatic injury.
Pregnancy testing prior to initiation; advise effective contraception during and for 2 months post-treatment.
Avoid breastfeeding during treatment due to unknown excretion in human milk.
Use caution in patients with pre-existing neurologic disorders due to risk of neurotoxicity.
Maintain patient hydration and provide supportive care to mitigate gastrointestinal side effects.
Implement step-up dosing schedule to reduce severity of CRS.
Ensure patients have caregiver support and proximity to healthcare facilities during initial dosing phases for monitoring.
Do not administer concomitant medications known to exacerbate immune-mediated toxicities without thorough risk assessment.
Delay or withhold doses as clinically indicated for severe adverse reactions.
Educate patients about early symptoms of adverse effects to ensure timely reporting.
Regularly assess patient cognitive and motor functions during treatment.
Avoid use in pediatric patients due to lack of established safety and efficacy.

Warnings

Boxed Warning for cytokine release syndrome and neurologic toxicity including immune effector cell-associated neurotoxicity syndrome (ICANS).
Risk of life-threatening CRS requiring immediate medical intervention.
Potential for severe cytopenias leading to increased susceptibility to infections and bleeding.
Serious and possibly fatal infections can occur; monitor patients vigilantly.
Possibility of severe allergic reactions necessitating prompt emergency care.
Neurologic adverse events may be delayed and require neurologic specialist evaluation.
May cause fetal harm; contraindicated in pregnancy due to teratogenic risk.
Monitor liver function closely for hepatotoxicity which may manifest independently or concomitantly with CRS.
Careful post-infusion monitoring is required due to variable onset and duration of adverse effects.
Dose interruptions or discontinuations may be necessary based on severity of toxicities.
Patients should remain close to a healthcare facility for 48 hours after initial doses for monitoring.
Caution when administering in patients with compromised organ function due to risk of exacerbated toxicity.
Neurologic symptoms such as seizures, confusion, or tremors require immediate assessment.
Avoid driving or operating machinery if neurologic symptoms manifest during therapy.
Delayed immune-related adverse events may occur; ongoing vigilance post-treatment is essential.

Contraindication

Known hypersensitivity to tarlatamab or any component of the formulation.
Pregnancy due to risk of fetal harm as demonstrated in preclinical studies.
Active uncontrolled infections, particularly systemic infections or sepsis, prior to initiation of therapy.
Concurrent use of immunosuppressive therapies that may increase risk of infection or compromise immune response.
Patients unable to comply with monitoring requirements during the high-risk initial dosing periods.
History of severe allergic reactions to biologic immunotherapies with similar mechanisms.
Severe neurological disorders that may be aggravated by treatment-related neurotoxicity.
Pre-existing hematologic abnormalities that contraindicate further risk of cytopenias.
Severe hepatic impairment, given lack of dosing data and elevated risk profile.
Use in pediatric populations due to absence of safety and efficacy data.
Concurrent administration with other agents known to cause CRS without adequate monitoring protocols.
Situations where required supportive care for CRS or neurotoxicity cannot be provided reliably.
Patients with active autoimmune diseases that may be exacerbated by immunomodulation.
Known hypersensitivity to excipients including polysorbate 80 and sucrose.
Any other condition judged by the physician to increase risk unacceptably.

Drug Interactions

Potential for additive immune-related adverse effects with other immunomodulatory or immunosuppressive agents.
Concomitant use with other drugs causing cytokine release syndrome may exacerbate severity of CRS.
Medications affecting blood cell counts may potentiate hematologic toxicities when combined with Imdelltra.
Drugs causing hepatotoxicity could increase the risk of liver injury in patients treated with Imdelltra.
Coadministration with agents influencing neurologic functions may worsen neurotoxicity symptoms.
No direct cytochrome P450 interactions expected due to monoclonal antibody metabolism.
Live vaccines should be avoided during and after treatment due to immunosuppression risk.
Potential pharmacodynamic interactions with corticosteroids used to manage CRS or neurologic events.
Monitoring advised when used alongside anticoagulants or antiplatelet drugs owing to risk of thrombocytopenia.
Avoid concomitant administration of strong immunosuppressants unless necessary and under strict monitoring.
Drugs that alter electrolyte balance should be used cautiously due to Imdelltra-associated hypokalemia and hyponatremia.
Concomitant treatments causing fatigue may worsen patient tolerability.
Interactions with herbal supplements that modulate immune function have not been well studied and should be disclosed to the healthcare provider.
Due to cytokine release potential, overlapping adverse events with other biologics require careful clinical evaluation.
Medications that affect renal or hepatic function may necessitate additional monitoring during therapy.

Preparations Of The Drug

Available as lyophilized powder in single-dose vials for intravenous infusion.
Dosage strengths include 1 mg and 10 mg vials requiring reconstitution and dilution prior to administration.
Requires aseptic technique for preparation to maintain sterility and product integrity.
Reconstituted solution must be handled carefully to avoid protein denaturation.
Storage conditions include refrigeration at 2°C to 8°C (36°F to 46°F) in original carton to protect from light; do not freeze.
Can be kept at room temperature (20°C to 25°C) for up to 24 hours before use if necessary.
IV Solution Stabilizer (IVSS) vials containing citric acid monohydrate, lysine hydrochloride, polysorbate 80, sodium hydroxide, and water for injection are used in preparation of infusion solution.
Administered by a trained healthcare provider through intravenous infusion over approximately one hour.
Step-up dosing schedule for initial administration requires specific preparatory dosing dilutions.
Prepared infusions must be administered promptly to preserve activity and prevent degradation.
Requires appropriate infusion sets and filters as recommended in prescribing information.
Discard any unused portion remaining in the vial after single use to avoid contamination.
Preparation requires equipment and facilities suitable for handling biologic agents with immunogenic potential.
Patient monitoring during and after infusion necessitates availability of supportive medications and emergency interventions.
Preparation procedures must comply with institutional and regulatory guidelines for biological therapeutics.