elet counts prior to initiation of KADCYLA and prior to each KADCYLA dose [see Dosage and Administration (2.2)]. KADCYLA has not been studied in patients with platelet counts <100,000/mm3 prior to initiation of treatment. In the event of decreased platelet count to Grade 3 or greater (< 50,000/mm3) do not administer KADCYLA until platelet counts recover to Grade 1 (≥ 75,000/mm3) [see Dosage and Administration (2.2)]. Patients with thrombocytopenia (< 100,000/mm3) and patients on anti-coagulant treatment should be closely monitored during treatment with KADCYLA.
5.7 Neurotoxicity
Peripheral neuropathy, mainly as Grade 1 and predominantly sensory, was reported in clinical trials of KADCYLA (14 of 884 treated patients with ≥ Grade 3; 196 of 884 treated patients with any Grade). In the randomized trial (Study 1), the overall frequency of peripheral neuropathy was 21.2% in the KADCYLA-treated group and 13.5% in the lapatinib plus capecitabine-treated group [see Adverse Reactions (6.1)]. The incidence of ≥ Grade 3 peripheral neuropathy was 2.2% in the KADCYLA-treated group and 0.2% in the lapatinib plus capecitabine-treated group.
KADCYLA should be temporarily discontinued in patients experiencing Grade 3 or 4 peripheral neuropathy until resolution to ≤ Grade 2. Patients should be clinically monitored on an ongoing basis for signs or symptoms of neurotoxicity [see Nonclinical Toxicology (13.2)].
5.8 HER2 Testing
Detection of HER2 protein overexpression or gene amplification is necessary for selection of patients appropriate for KADCYLA therapy because these are the only patients studied for whom benefit has been shown [see Indications and Usage (1), Clinical Studies (14.1)]. In the randomized study (Study 1), patients with breast cancer were required to have evidence of HER2 overexpression defined as 3+ IHC by Dako Herceptest™ or evidence of overexpression defined as FISH amplification ratio ≥ 2.0 by Dako HER2 FISH PharmDx™ test kit. Only limited data were available for patients whose breast cancer was positive by FISH and 0 or 1+ by IHC.
Assessment of HER2 status should be performed by laboratories with demonstrated proficiency in the specific technology being utilized. Improper assay performance, including use of sub- optimally fixed tissue, failure to utilize specified reagents, deviation from specific assay instructions, and failure to include appropriate controls for assay validation, can lead to unreliable results.
5.9 Extravasation
In KADCYLA clinical studies, reactions secondary to extravasation have been observed. These reactions, observed more frequently within 24 hours of infusion, were usually mild and comprised erythema, tenderness, skin irritation, pain, or swelling at the infusion site. Specific treatment for KADCYLA extravasation is unknown. The infusion site should be closely monitored for possible subcutaneous infiltration during drug administration.
6 ADVERSE REACTIONS
The following adverse reactions are discussed in greater detail in other sections of the label:
•Hepatotoxicity [See Warnings and Precautions (5.1)]
•Left Ventricular Dysfunction [See Warnings and Precautions (5.2)]
•Embryo-Fetal Toxicity [See Warnings and Precautions (5.3)]
•Pulmonary Toxicity [See Warnings and Precautions (5.4)]
•Infusion-Related Reactions, Hype
