2.1 Recommended Doses and Schedules

The recommended dose of MARGENZA is 15 mg/kg, administered as an intravenous infusion every 3 weeks (21-day cycle) until disease progression or unacceptable toxicity.

Administer MARGENZA as an intravenous infusion at 15 mg/kg over 120 minutes for the initial dose, then over a minimum of 30 minutes every 3 weeks for all subsequent doses.

On days when both MARGENZA and chemotherapy are to be administered, MARGENZA may be administered immediately after chemotherapy completion.

Refer to the respective Prescribing Information for each therapeutic agent administered in combination with MARGENZA for the recommended dosage information, as appropriate.

2.2 Dose Modification or Important Dosing Considerations

If a patient misses a dose of MARGENZA, administer the scheduled dose as soon as possible. Adjust the administration schedule to maintain a 3-week interval between doses.

2.3 Preparation for Administration

Administer as an intravenous infusion after dilution.

5.1 Left Ventricular Dysfunction

Left ventricular cardiac dysfunction can occur with MARGENZA. In SOPHIA, left ventricular dysfunction occurred in 1.9% of patients treated with MARGENZA. MARGENZA has not been studied in patients with a pretreatment LVEF value of < 50%, a prior history of myocardial infarction or unstable angina within 6 months, or congestive heart failure NYHA class II-IV.

Withhold MARGENZA for ≥ 16% absolute decrease in LVEF from pretreatment values or LVEF value below institutional limits of normal (or 50% if no limits are available) and ≥ 10% absolute decrease in LVEF from pretreatment values. Permanently discontinue MARGENZA if LVEF decline persists for greater than 8 weeks, or if dosing is interrupted on greater than 3 occasions due to LVEF decline [see Dosage and Administration (2.2)].

5.2 Embryo-Fetal Toxicity

Based on findings in animals and mechanism of action, MARGENZA can cause fetal harm when administered to a pregnant woman. There are no available data on the use of MARGENZA in pregnant women to inform the drug-associated risk. In postmarketing reports, use of a HER2-directed antibody during pregnancy resulted in cases of oligohydramnios and oligohydramnios sequence manifesting as pulmonary hypoplasia, skeletal abnormalities and neonatal death. In an animal reproduction study, intravenous administration of margetuximab-cmkb to pregnant cynomolgus monkeys once every 3 weeks starting at gestational day (GD) 20 until delivery resulted in oligohydramnios and delayed infant kidney development. Animal exposures were ≥ 3 times the human exposures at the recommended dose, based on Cmax.

Verify pregnancy status of females of reproductive potential prior to initiation of MARGENZA. Advise pregnant women and females of reproductive potential that exposure to MARGENZA during pregnancy or within 4 months prior to conception can result in fetal harm. Advise females of reproductive potential to use effective contraception during treatment and for 4 months following the last dose of MARGENZA [see Use in Specific Populations (8.1, 8.3)].

5.3 Infusion-Related Reactions

MARGENZA can cause infusion-related reactions (IRRs) [see Adverse Reactions (6.1)]. Symptoms may include fever, chills, arthralgia, cough, dizziness, fatigue, nausea, vomiting, headache, diaphoresis, tachycardia, hypotension, pruritus, rash, urticaria, and dyspnea.

In SOPHIA, IRRs were reported by 13% of patients on MARGENZA plus chemotherapy. Most of the IRRs occur during Cycle 1. Grade 3 IRRs were reported in 1.5% of MARGENZA-treated patients. All IRRs resolved within 24 hours, irrespective of severity. In SOPHIA, IRRs leading to interruption of treatment occurred in 9% of patients treated with MARGENZA and chemotherapy. One patient (0.4%) on MARGENZA discontinued treatment due to IRR.

An infusion substudy in 88 patients in SOPHIA evaluated MARGENZA administered over 120 minutes for the initial dose, then 30 minutes from Cycle 2 forward. IRRs were ≤ Grade 2 and most occurred during the first (120 minutes) administration of MARGENZA. From Cycle 2 onward, one patient (1.1%) had an IRR (Grade 1).

Monitor patients for IRRs during MARGENZA administration and as clinically indicated after completion of infusion. Have medications and emergency equipment to treat IRRs available for immediate use. Monitor patients carefully until resolution of signs and symptoms.

In patients who experience mild or moderate IRRs, consider premedications, including antihistamines, corticosteroids, and antipyretics. Decrease the rate of infusion for mild or moderate IRRs. Interrupt MARGENZA infusion in patients experiencing dyspnea or clinically significant hypotension and intervene with medical therapy which may include epinephrine, corticosteroids, diphenhydramine, bronchodilators and oxygen. Patients should be evaluated and carefully monitored until complete resolution of signs and symptoms. Permanently discontinue MARGENZA in all patients with severe or life-threatening IRRs.

6.1 Clinical Trials 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 rates observed in practice.

The safety of MARGENZA was evaluated in HER2-positive breast cancer patients who received two or more prior anti-HER2 regimens in SOPHIA [see Clinical Studies (14.1)].

Patients were randomized (1:1) to receive either MARGENZA 15 mg/kg every 3 weeks plus chemotherapy or trastuzumab plus chemotherapy. Among patients who received MARGENZA, 40% were exposed for 6 months or longer and 11% were exposed for greater than one year.

Serious adverse reactions occurred in 16% of patients who received MARGENZA. Serious adverse reactions in > 1% of patients included febrile neutropenia (1.5%), neutropenia/neutrophil count decrease (1.5%) and infusion related reactions (1.1%). Fatal adverse reactions occurred in 1.1% of patients who received MARGENZA, including viral pneumonia (0.8%) and aspiration pneumonia (0.4%).

Permanent discontinuation due to an adverse reaction occurred in 3% of patients who received MARGENZA. Adverse reactions which resulted in permanent discontinuation in > 1% of patients who received MARGENZA included left ventricular dysfunction and infusion-related reactions.

Dosage interruptions due to an adverse reaction occurred in 11% of patients who received MARGENZA. Adverse reactions which required dosage interruption in > 5% of patients who received MARGENZA included infusion-related reactions.

Table 1 summarizes the adverse reactions in SOPHIA.

Clinically relevant adverse reactions in ≤10% of patients who received MARGENZA in combination with chemotherapy included: dizziness and stomatitis (10%) each, decreased weight, dysgeusia, rash, and insomnia (6%) each, hypertension (5%), and syncope (1.5%).

Table 2 summarizes the laboratory abnormalities in SOPHIA.

6.2 Immunogenicity

As with all therapeutic proteins, there is potential for immunogenicity with MARGENZA. The detection of antibody formation is highly dependent on assay sensitivity and specificity. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to MARGENZA in the studies described below with the incidence of antibodies in other studies or to other products may be misleading.

In SOPHIA, samples were obtained from patients on MARGENZA for immunogenicity testing at baseline, every 2 cycles, and at end of study therapy. All patients enrolled in SOPHIA received trastuzumab previously, and treatment-emergent anti-margetuximab antibodies were observed in 4 patients (1.7%). Of these 4 patients, anti-margetuximab antibodies were detected prior to Cycle 7 of MARGENZA dosing in 1 patient, and more than 2 months after the last MARGENZA dose in 3 patients. In the infusion substudy, treatment-emergent anti-margetuximab antibodies were observed in 2 patients (3.8%). Of these 2 patients, anti-margetuximab antibodies were detected prior to Cycle 3 of MARGENZA dosing in 1 patient, and more than 6 months after the last MARGENZA dose in 1 patient. Due to the limited number of patients who developed anti-margetuximab antibodies during treatment with MARGENZA, the impact of anti-margetuximab antibodies on the PK, safety and efficacy of MARGENZA is unknown.

Anthracyclines

Patients who receive anthracyclines less than 4 months after stopping MARGENZA [see Clinical Pharmacology (12.3)] may be at increased risk of cardiac dysfunction. While this interaction has not been studied with MARGENZA, clinical data from other HER2-directed antibodies warrants consideration. Avoid anthracycline-based therapy for up to 4 months after stopping MARGENZA. If concomitant use is unavoidable, closely monitor patient's cardiac function.

8.1 Pregnancy

8.2 Lactation

8.3 Females and Males of Reproductive Potential

MARGENZA can cause fetal harm when administered to a pregnant woman.

8.4 Pediatric Use

Safety and effectiveness of MARGENZA have not been established in pediatric patients.

8.5 Geriatric Use

Of the 266 patients treated with MARGENZA 20% were 65 years of age or older and 4% were 75 years or older. No overall differences in efficacy were observed between patients ≥ 65 years of age compared to younger patients. There was a higher incidence of Grade ≥ 3 adverse reactions observed in patients age 65 years or older (56%) compared to younger patients (47%), as well as adverse reactions associated with potential cardiotoxicity (35% vs 18%).

12.1 Mechanism of Action

Margetuximab-cmkb binds to the extracellular domain of the human epidermal growth factor receptor 2 protein (HER2). Upon binding to HER2-expressing tumor cells, margetuximab-cmkb inhibits tumor cell proliferation, reduces shedding of the HER2 extracellular domain and mediates antibody-dependent cellular cytotoxicity (ADCC).

In vitro, the modified Fc region of margetuximab-cmkb increases binding to activating Fc receptor FCGR3A (CD16A) and decreases binding to inhibitory Fc receptor FCGR2B (CD32B). These changes lead to greater in vitro ADCC and NK cell activation.

12.2 Pharmacodynamics

The exposure-response relationship and time course of pharmacodynamic response for the safety and effectiveness of margetuximab-cmkb have not been fully characterized.

12.3 Pharmacokinetics

Following the approved recommended dosage, the steady-state geometric mean (%CV) Cmax of margetuximab-cmkb is 466 (20%) µg/mL and AUC0-21d is 4120 (21%) µg.day/mL in patients with HER2-positive relapsed or refractory advanced breast cancer. Margetuximab-cmkb undergoes both linear and nonlinear elimination. After a single dose, margetuximab-cmkb Cmax and AUC0-21d increase in an approximately dose proportional manner from 10 to 18 mg/kg (0.67 to 1.2 times the approved recommended dose). At the approved recommended dosage, time to steady-state was 2 months, and accumulation ratio was 1.65 based on AUC0-21d. No clinically significant differences in margetuximab-cmkb exposure were observed when infusion time was reduced from 120 minutes to 30 minutes.

13.1 Carcinogenesis, Mutagenesis, and Impairment of Fertility

Studies have not been performed to evaluate carcinogenic or mutagenic potential of margetuximab-cmkb.

Animal fertility studies have not been conducted with margetuximab-cmkb. In repeat-dose toxicity studies of up to 13-week duration, margetuximab-cmkb had no effect on male and female reproductive organs in sexually mature cynomolgus monkeys.

14.1 Metastatic Breast Cancer

The efficacy of MARGENZA plus chemotherapy was evaluated in SOPHIA (NCT02492711), a randomized, multicenter, open-label trial of 536 patients with IHC 3+ or ISH-amplified HER2+ metastatic breast cancer who had received prior treatment with other anti-HER2 therapies. Patients were randomized (1:1) to MARGENZA plus chemotherapy or trastuzumab plus chemotherapy. Randomization was stratified by chemotherapy choice (capecitabine, eribulin, gemcitabine, or vinorelbine), number of lines of therapy in the metastatic setting (≤ 2, > 2), and number of metastatic sites (≤ 2, > 2). Patients were required to have progressed on or after the most recent line of therapy. Prior radiotherapy and hormonal therapy were allowed. Patients received MARGENZA intravenously at a dose of 15 mg/kg every 3 weeks administered over 120 minutes for the initial administration and then over 30 to 120 minutes thereafter. Trastuzumab was given intravenously at an initial dose of 8 mg/kg over 90 minutes, followed by 6 mg/kg over 30 minutes every 3 weeks thereafter. Patients were treated with MARGENZA or trastuzumab in combination with chemotherapy until disease progression or unacceptable toxicity.

Major efficacy outcome measures were progression-free survival (PFS) by blinded independent central (BICR) review and overall survival (OS) of MARGENZA plus chemotherapy, compared with trastuzumab plus chemotherapy. Additional efficacy outcome measures were objective response rate (ORR) and duration of response (DOR) assessed by BICR.

The median age was 56 years (range: 27-86); 78% of patients were < 65 years. The majority of patients were female (99.4%), and the majority were White (80%). Patients had an ECOG performance status of 0 (58%) or 1 (42%) at baseline. Forty seven percent had visceral disease, 57% had bone metastases, and 13% had brain metastases. Sixty percent were hormone receptor positive. The median number of prior lines of therapy in the locally advanced/metastatic setting was 2 (range: 1-4). All study patients had previously received trastuzumab, all but 1 patient had previously received pertuzumab, and 91% had previously received ado-trastuzumab emtansine.

Efficacy results are summarized in Table 3 and Figure 1.

Results for investigator-assessed PFS were similar to the independent blinded PFS results.

Consistent PFS results were observed across patient subgroups defined by study stratification factors (chemotherapy choice, number of lines of therapy in the metastatic setting, and number of metastatic sites).

16.1 How Supplied

MARGENZA (margetuximab-cmkb) injection is a clear to slightly opalescent, colorless to pale yellow or pale brown solution in a single-dose vial supplied as:

16.2 Storage

Store vials refrigerated at 2°C to 8°C (36°F to 46°F) in original carton to protect from light until time of use.

Do not freeze. Do not shake.

Left Ventricular Dysfunction

Advise patients to contact a health care professional immediately for any of the following: new onset or worsening shortness of breath, cough, swelling of the ankles/legs, swelling of the face, palpitations, weight gain of more than 5 pounds in 24 hours, dizziness or loss of consciousness [see Warnings and Precautions (5.1)].

Embryo-Fetal Toxicity

Advise pregnant women and females of reproductive potential that exposure to MARGENZA during pregnancy or within 4 months prior to conception can result in fetal harm. Advise female patients to contact their healthcare provider with a known or suspected pregnancy [see Warnings and Precautions (5.2), Use in Specific Populations (8.1)].

Advise females of reproductive potential to use effective contraception during treatment with MARGENZA and for 4 months following the last dose [see Warnings and Precautions (5.2), Use in Specific Populations (8.3)].