Daratumumab

Introduction Overview

Generic Name

daratumumab

Brand Name

Darzalex

Dosage Form

infusion solution (100 mg/5 mL, 400 mg/20 mL)

Drug Class

CD38 monoclonal antibodies

Pharmacokinetics

Absorption:
Daratumumab is administered intravenously as an infusion solution or subcutaneously in the form of Darzalex Faspro. Following intravenous administration, daratumumab exhibits a concentration-dependent pharmacokinetic profile mediated by target-mediated drug disposition, characteristic of monoclonal antibodies directed against cell surface antigens. The subcutaneous formulation allows for more rapid absorption, achieving peak serum concentrations typically within several days. The bioavailability of the subcutaneous formulation is not directly comparable to intravenous dosing; however, it maintains therapeutic serum levels adequate for clinical efficacy. Absorption can be influenced by patient factors such as body weight and tumor burden, which may affect pharmacokinetic variability.

Distribution:
Daratumumab exhibits a typical monoclonal antibody distribution pattern, with a volume of distribution approximating the plasma volume, reflecting limited distribution beyond the vascular and interstitial compartments. It binds selectively and with high affinity to CD38 antigens expressed on multiple myeloma cells and other hematopoietic and immune cells. Due to its molecular size (~148 kDa), daratumumab does not cross the blood-brain barrier. Distribution can be altered in patients with high tumor burden due to antigen sink effects, reducing circulating drug levels initially.

Metabolism:
As a monoclonal antibody, daratumumab is metabolized via catabolic pathways into small peptides and amino acids by proteolytic enzymes throughout the reticuloendothelial system. This catabolism occurs primarily in lysosomes following receptor-mediated endocytosis and nonspecific clearance mechanisms. Daratumumab does not undergo cytochrome P450-mediated metabolism and is not subject to hepatic metabolic interactions typical of small-molecule drugs.

Elimination:
Elimination of daratumumab is biphasic, with an initial distribution phase followed by a prolonged terminal half-life averaging approximately 18 days, varying depending on dose and patient-specific factors. Clearance decreases with increasing dose and repeated dosing due to target saturation. Elimination occurs primarily via proteolytic degradation by the reticuloendothelial system rather than renal or hepatic excretion. The prolonged half-life supports dosing intervals ranging from weekly to monthly in maintenance therapy. Immunogenicity is low, with minimal formation of anti-drug antibodies affecting elimination or efficacy.

Dosage Forms

Available Dosage Forms:
- Intravenous infusion solution: single-dose vial of 100 mg/5 mL
- Intravenous infusion solution: single-dose vial of 400 mg/20 mL

Dosages for Adults and Adolescents:
- Dosing is weight-based at 16 mg/kg actual body weight.
- In combination regimens with lenalidomide or pomalidomide and dexamethasone, dosing follows a 4-week cycle:
* Weeks 1-8: weekly infusions (16 mg/kg)
* Weeks 9-24: every 2 weeks
* Week 25 and onward: every 4 weeks until disease progression
- In combination with bortezomib, melphalan, and prednisone (6-week cycle):
* Weeks 1-6: weekly infusions
* Weeks 7-54: every 3 weeks
* Week 55 onward: every 4 weeks
- In combination with bortezomib, thalidomide, and dexamethasone (4-week cycle):
* Induction phase: weekly then biweekly dosing
* Consolidation phase after autologous stem cell transplant: biweekly dosing
- In combination with bortezomib and dexamethasone (3-week cycle):
* Weeks 1-9: weekly
* Weeks 10-24: every 3 weeks
* Week 25 onward: every 4 weeks
- In combination with carfilzomib and dexamethasone (4-week cycle):
* Week 1: 8 mg/kg on days 1 and 2
* Weeks 2-8: weekly 16 mg/kg
* Weeks 9-24: every 2 weeks
* Week 25 onward: every 4 weeks
- Monotherapy dosing follows similar cycles as above depending on clinical scenario.

Specific Patient Populations:
- Dosing adjustments are primarily weight-based; no dose reductions are recommended based on renal or hepatic impairment due to catabolic metabolism.
- Elderly patients have been treated following the same dosing regimens.
- Patients with high tumor burden may experience altered pharmacokinetics requiring close monitoring.
- Use in pregnant or breastfeeding women is contraindicated or requires strict precautions due to potential fetal harm.

Additional Notes:
- The initial dose at Week 1 can be split over 2 consecutive days if necessary (8 mg/kg each day).
- Pre- and post-infusion medications (e.g., corticosteroids, antihistamines) are recommended to mitigate infusion-related reactions.
- Darzalex Faspro is a separate subcutaneous preparation with a distinct dosing and administration schedule.

Mechanism Of Action

Daratumumab is a fully human IgG1 kappa monoclonal antibody that specifically targets the CD38 antigen, a transmembrane glycoprotein highly expressed on multiple myeloma cells and various hematopoietic cells. By binding to CD38, daratumumab induces malignant plasma cell death through multiple immune-mediated mechanisms. First, it triggers complement-dependent cytotoxicity (CDC), where the antibody-antigen complex activates the complement cascade leading to the formation of membrane attack complexes that lyse the target cells.

Second, daratumumab mediates antibody-dependent cellular cytotoxicity (ADCC), whereby natural killer (NK) cells recognize the Fc region of the antibody bound to myeloma cells and release cytolytic granules resulting in cell death. Third, it facilitates antibody-dependent cellular phagocytosis (ADCP) by macrophages that engulf and destroy daratumumab-opsonized tumor cells. Additionally, daratumumab can induce apoptosis directly via cross-linking of CD38, leading to programmed cell death in tumor cells.

Beyond direct cytotoxicity, daratumumab modulates the tumor microenvironment by depleting CD38-expressing immunosuppressive regulatory cells, such as regulatory T cells and myeloid-derived suppressor cells, thereby enhancing endogenous immune response against cancer cells. This immunomodulatory effect contributes to long-term anti-tumor immunity and improved clinical responses.

Comparatively, unlike traditional chemotherapeutic agents, daratumumab is a targeted therapy focusing specifically on CD38, minimizing off-target effects. Clinical studies have demonstrated that daratumumab monotherapy or in combination regimens improves progression-free survival and overall response rates in multiple myeloma patients, including those refractory to prior therapies. The unique multi-faceted mechanism of action and favorable safety profile position daratumumab as an effective targeted immunotherapy in multiple myeloma management.

Pharmacological Actions

Monoclonal antibody targeting CD38 antigen expressed on multiple myeloma cells.
Induces complement-dependent cytotoxicity leading to tumor cell lysis.
Mediates antibody-dependent cellular cytotoxicity via natural killer cells.
Promotes antibody-dependent cellular phagocytosis by macrophages.
Directly induces apoptosis through CD38 cross-linking.
Modulates tumor microenvironment by depleting immunosuppressive regulatory cells.
Enhances anti-tumor immune response and promotes long-term immunity.
Acts as a targeted cancer immunotherapy distinct from cytotoxic chemotherapy.
Used as monotherapy or in combination with other anti-myeloma agents.
Exhibits prolonged half-life allowing for flexible dosing intervals.
Low immunogenicity with minimal anti-drug antibody formation reported.

Therapeutic Or Clinical Uses

Treatment of newly diagnosed multiple myeloma patients ineligible for autologous stem cell transplant in combination with lenalidomide and dexamethasone.
Treatment of newly diagnosed multiple myeloma patients ineligible for transplant in combination with bortezomib, melphalan, and prednisone.
Use in newly diagnosed transplant-eligible patients in combination with bortezomib, thalidomide, and dexamethasone.
Management of patients with relapsed or refractory multiple myeloma after at least one prior therapy, combined with bortezomib and dexamethasone.
Treatment in combination with carfilzomib and dexamethasone for relapsed/refractory multiple myeloma with one to three prior therapies.
Used with pomalidomide and dexamethasone for patients with at least two prior therapies including lenalidomide and a proteasome inhibitor.
Monotherapy option for patients with multiple prior treatments including a proteasome inhibitor and immunomodulatory agent.
Improves progression-free survival and overall response rates in multiple myeloma.
Used to delay progression of multiple myeloma disease.
Administered within combination regimens to enhance anti-myeloma efficacy.
Option for patients refractory to other multiple myeloma treatments.
Improves quality and length of life in multiple myeloma patients.
Utilized as a CD38-targeting immunotherapeutic agent in oncology.

Side Or Adverse Effects

Common side effects: nausea, constipation, diarrhea, fever, and fatigue.
Respiratory symptoms including shortness of breath and cough.
Peripheral neuropathy manifesting as tingling, numbness, or pain.
Edema with swelling of hands, ankles, or feet.
Upper respiratory tract infection symptoms such as sore throat, sneezing, and nasal congestion.
Infusion-related reactions including chills, wheezing, and rash during administration.
Serious allergic reactions: anaphylaxis, facial or throat swelling, hives, difficulty breathing.
Hematologic toxicities: neutropenia, thrombocytopenia, anemia leading to increased infection risk and bleeding.
Chest pain and respiratory distress symptoms suggesting pulmonary complications.
Neurologic adverse effects including burning pain and neuropathy symptoms.
Hepatitis B reactivation in patients with prior infection.
Risk of delayed wound healing and increased susceptibility to infections.
Fatigue and weakness impacting quality of life during therapy.
Potential interference with blood typing assays up to six months post-treatment.

Precautions

Monitor carefully for infusion-related reactions during administration; premedication is recommended.
Screen for hepatitis B virus infection prior to initiation and monitor liver function throughout treatment.
Instruct patients regarding the importance of reporting respiratory symptoms promptly due to risk of serious infections.
Avoid use in patients with known hypersensitivity to daratumumab or its excipients.
Caution in patients with breathing disorders or history of herpes zoster; antiviral prophylaxis may be necessary.
Use effective contraception during treatment and for 3 months after last dose due to potential fetal harm.
Be aware of potential interference with blood compatibility testing; inform transfusion services accordingly.
Consider patient body weight for accurate dosing; under- or overdosing may affect efficacy or toxicity.
Monitor blood counts regularly due to risk of cytopenias; adjust supportive care accordingly.
Avoid concurrent live vaccines during therapy.
For patients receiving combination with lenalidomide, pomalidomide, or thalidomide, follow REMS program guidelines.
Avoid breastfeeding during treatment and for a period thereafter due to unknown breastmilk excretion.
Evaluate renal and hepatic function, although no formal dose adjustment is recommended.
In patients with hereditary fructose intolerance, avoid due to presence of sorbitol excipient.

Warnings

Risk of severe infusion-related reactions; immediate medical intervention required if symptoms develop.
Potential for hepatitis B reactivation leading to serious hepatic injury or failure.
May cause prolonged interference with blood compatibility testing, complicating transfusion management.
Possible severe hematologic toxicities, including life-threatening neutropenia and thrombocytopenia.
Can exacerbate respiratory disorders; monitor closely patients with pre-existing lung disease.
Pregnancy may result in fetal harm or death; contraindicated unless benefits outweigh risks.
Risk of serious infections including pneumonia; implement appropriate prophylaxis and surveillance.
Delayed wound healing and increased susceptibility to opportunistic infections.
Discontinue therapy or delay dosing if severe adverse effects or intolerability occur.
Risk of increased tumor lysis syndrome in patients with high tumor burden.
May increase risk of secondary malignancies when used in combination therapies.
Hypersensitivity and anaphylactic reactions can occur; emergency preparedness essential during infusions.
Concomitant use with other immunosuppressants may exacerbate immunodeficiency.

Contraindication

Known hypersensitivity to daratumumab or any excipients in the formulation.
Active severe infections without adequate control prior to initiation.
Pregnancy, unless potential benefits justify potential fetal risks.
History of severe infusion-related hypersensitivity to monoclonal antibodies.
Patients with hereditary fructose intolerance due to sorbitol excipient content.
Use with caution or contraindicated in uncontrolled respiratory disorders.
Severe immune compromise where additional immunosuppression is contraindicated.
Hypersensitivity reactions to prior administration of daratumumab formulations.

Drug Interactions

May interfere with blood compatibility testing, leading to false-positive Coombs tests.
Potential interactions with immunosuppressive agents increasing infection risk.
Concomitant use with lenalidomide, pomalidomide, or thalidomide requires compliance with REMS program due to teratogenicity.
No known cytochrome P450 mediated interactions due to monoclonal antibody metabolism.
Use with other monoclonal antibodies may increase immune-related adverse effects.
Concurrent use of live vaccines not recommended during daratumumab therapy.
Potential additive hematologic toxicity when combined with chemotherapeutic agents.
May impact laboratory assays leading to confounding diagnostic results.
Drugs requiring active immune response may have reduced efficacy when combined.
Interaction with blood products necessitates communication with transfusion services.
Inhibitors or inducers of immune function may alter pharmacodynamic response.
No reported significant interactions with over-the-counter vitamins or herbal products, but caution advised.

Preparations Of The Drug

Darzalex injection solution, single-dose vial containing 100 mg/5 mL daratumumab.
Darzalex injection solution, single-dose vial containing 400 mg/20 mL daratumumab.
Formulated as a sterile, preservative-free intravenous infusion solution.
Storage conditions require refrigeration at 2°C to 8°C (36°F to 46°F), protected from light.
Do not freeze or shake the product to maintain stability.
Contains inactive ingredients such as glacial acetic acid, L-histidine, mannitol, polysorbate 20, sodium acetate, sodium chloride, sorbitol, and water for injection.
Administered intravenously over several hours with pre- and post-infusion medications to reduce infusion reactions.
Separate product: Darzalex Faspro, a subcutaneous combination of daratumumab and hyaluronidase-fihj, administered over 3-5 minutes (not included in Darzalex formulation).
Supplied by Janssen Biotech, Inc., Horsham, PA, USA.
No preservatives included; single-use vial discard after use.
Packaging includes information for dosing and handling to maintain sterility and efficacy.