TUKYSA SAFETY PROFILE

Of the most common adverse events in the TUKYSA arm, a majority were Grade 1 or 21,2

Adverse reactions in ≥10% of patients and at ≥5% higher incidence in the TUKYSA arm3

Adverse events table—please see Prescribing Information for details
Adverse events table—please see Prescribing Information for details
  • The increase in serum creatinine observed in the TUKYSA arm can be attributed to the inhibition of renal tubular transport of creatinine, as opposed to impaired glomerular function, based on findings from in vitro studies1

Serious adverse events occurring in ≥2% of patients1-3

  • TUKYSA arm: any event, 25.7% (diarrhea, 4.0%; vomiting, 2.5%; nausea, 2.0%; abdominal pain, 1.7%; seizure, 1.7%)
  • Control arm: any event, 26.9% (diarrhea, 3.6%; vomiting, 2.5%; nausea, 1.5%; abdominal pain, 0%; seizure, 1.0%)
  • Fatal reactions: 2.5% in the control arm and 1.5% in the TUKYSA arm

*Stomatitis includes stomatitis, oropharyngeal pain, oropharyngeal discomfort, mouth ulceration, oral pain, lip ulceration, glossodynia, tongue blistering, lip blister, oral dysesthesia, tongue ulceration, and aphthous ulcer.

†Rash includes rash maculo-papular, rash, dermatitis acneiform, erythema, rash macular, rash papular, rash pustular, rash pruritic, rash erythematous, skin exfoliation, urticaria, dermatitis allergic, palmar erythema, plantar erythema, skin toxicity, and dermatitis.

‡Hepatotoxicity includes hyperbilirubinemia, blood bilirubin increased, bilirubin conjugated increased, alanine aminotransferase increased, transaminases increased, hepatotoxicity, aspartate aminotransferase increased, liver function test increased, liver injury, and hepatocellular injury.

§Anemia includes anemia, hemoglobin decreased, and normocytic anemia.

¶Peripheral neuropathy includes peripheral sensory neuropathy, neuropathy peripheral, peripheral motor neuropathy, and peripheral sensorimotor neuropathy.

PPE = palmar-plantar erythrodysesthesia.

Adverse events of clinical interest

Diarrhea1,3

  • Prophylactic support to manage diarrhea was not required per HER2CLIMB protocol
  • 81% of patients who received TUKYSA experienced diarrhea, including 12% with Grade 3 and 0.5% with Grade 4
    • Median time to onset (any grade) was 12 days
    • Median time to resolution was 8 days
    • Median duration of antidiarrheal use was 3 days for each 21-day repeating regimen
  • If diarrhea occurs, administer antidiarrheal treatment and perform diagnostic tests to exclude other causes, as clinically indicated; based on the severity, interrupt dose, then dose reduce or permanently discontinue TUKYSA

Alopecia4

  • Alopecia was infrequent and mostly Grade 1 (all grades: 4.7% in the TUKYSA arm, 3.6% in the control arm; there was one case of Grade 2 alopecia in each arm)

Interstitial lung disease (ILD)4

  • There was only one case of ILD in HER2CLIMB (Grade 1 pneumonitis in the TUKYSA arm), which was not considered by the investigator to be caused by the study’s agents*

For information on how to manage selected adverse reactions associated with TUKYSA, trastuzumab, and capecitabine, please refer to the respective Prescribing Information for each agent.

*Events of pneumonitis are searched from preferred terms of ILD, organizing pneumonia, pneumonitis, and acute interstitial pneumonitis. For the one case of ILD, no dose modifications or discontinuations of the study’s agents were required.

Discontinuation of TUKYSA due to adverse events was infrequent (6%)3

In both treatment arms of HER2CLIMB, capecitabine was most frequently reduced, held, or discontinued due to adverse events4

Discontinuation of agents in the control arm due to adverse events
Discontinuation of agents in the TUKYSA arm due to adverse events
  • Frequencies of modifications and discontinuations are descriptive data that are not intended to provide conclusions about safety and should be interpreted with caution
  • Adverse reactions leading to treatment discontinuation of TUKYSA in ≥1% of patients were hepatotoxicity (1.5%) and diarrhea (1%)3
  • Adverse reactions leading to dose reduction of TUKYSA in ≥2% of patients were hepatotoxicity (8%) and diarrhea (6%)3

†Reduction of the trastuzumab dose was not allowed per HER2CLIMB protocol.
‡Dose hold frequency for trastuzumab includes interruptions during infusion of trastuzumab.

Important Safety Information

Warnings and Precautions

  • Diarrhea: TUKYSA can cause severe diarrhea including dehydration, hypotension, acute kidney injury, and death. In HER2CLIMB, 81% of patients who received TUKYSA experienced diarrhea, including 12% with Grade 3 and 0.5% with Grade 4. Both patients who developed Grade 4 diarrhea subsequently died, with diarrhea as a contributor to death. Median time to onset of the first episode of diarrhea was 12 days and the median time to resolution was 8 days. Diarrhea led to TUKYSA dose reductions in 6% of patients and TUKYSA discontinuation in 1% of patients. Prophylactic use of antidiarrheal treatment was not required on HER2CLIMB.

    If diarrhea occurs, administer antidiarrheal treatment as clinically indicated. Perform diagnostic tests as clinically indicated to exclude other causes of diarrhea. Based on the severity of the diarrhea, interrupt dose, then dose reduce or permanently discontinue TUKYSA.
  • Hepatotoxicity: TUKYSA can cause severe hepatotoxicity. In HER2CLIMB, 8% of patients who received TUKYSA had an ALT increase >5 × ULN, 6% had an AST increase >5 × ULN, and 1.5% had a bilirubin increase >3 × ULN (Grade ≥3). Hepatotoxicity led to TUKYSA dose reductions in 8% of patients and TUKYSA discontinuation in 1.5% of patients.

    Monitor ALT, AST, and bilirubin prior to starting TUKYSA, every 3 weeks during treatment, and as clinically indicated. Based on the severity of hepatotoxicity, interrupt dose, then dose reduce or permanently discontinue TUKYSA.
  • Embryo-Fetal Toxicity: TUKYSA can cause fetal harm. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential, and male patients with female partners of reproductive potential, to use effective contraception during TUKYSA treatment and for at least 1 week after the last dose.

Adverse Reactions

Serious adverse reactions occurred in 26% of patients who received TUKYSA; those occurring in ≥2% of patients were diarrhea (4%), vomiting (2.5%), nausea (2%), abdominal pain (2%), and seizure (2%). Fatal adverse reactions occurred in 2% of patients who received TUKYSA including sudden death, sepsis, dehydration, and cardiogenic shock.

Adverse reactions led to treatment discontinuation in 6% of patients who received TUKYSA; those occurring in ≥1% of patients were hepatotoxicity (1.5%) and diarrhea (1%). Adverse reactions led to dose reduction in 21% of patients who received TUKYSA; those occurring in ≥2% of patients were hepatotoxicity (8%) and diarrhea (6%).

The most common adverse reactions in patients who received TUKYSA (≥20%) were diarrhea, palmar-plantar erythrodysesthesia, nausea, fatigue, hepatotoxicity, vomiting, stomatitis, decreased appetite, abdominal pain, headache, anemia, and rash.

Lab Abnormalities

In HER2CLIMB, Grade ≥3 laboratory abnormalities reported in ≥5% of patients who received TUKYSA were decreased phosphate, increased ALT, decreased potassium, and increased AST.

The mean increase in serum creatinine was 32% within the first 21 days of treatment with TUKYSA. The serum creatinine increases persisted throughout treatment and were reversible upon treatment completion. Consider alternative markers of renal function if persistent elevations in serum creatinine are observed.

Drug Interactions

  • Strong CYP3A/Moderate CYP2C8 Inducers: Concomitant use may decrease TUKYSA activity. Avoid concomitant use of TUKYSA.
  • Strong or Moderate CYP2C8 Inhibitors: Concomitant use of TUKYSA with a strong CYP2C8 inhibitor may increase the risk of TUKYSA toxicity; avoid concomitant use. Increase monitoring for TUKYSA toxicity with moderate CYP2C8 inhibitors.
  • CYP3A Substrates: Concomitant use may increase the toxicity associated with a CYP3A substrate. Avoid concomitant use of TUKYSA where minimal concentration changes may lead to serious or life-threatening toxicities. If concomitant use is unavoidable, decrease the CYP3A substrate dosage.
  • P-gp Substrates: Concomitant use may increase the toxicity associated with a P-gp substrate. Consider reducing the dosage of P-gp substrates where minimal concentration changes may lead to serious or life-threatening toxicity.

Use in Specific Populations

  • Lactation: Advise women not to breastfeed while taking TUKYSA and for at least 1 week after the last dose.
  • Renal Impairment: Use of TUKYSA in combination with capecitabine and trastuzumab is not recommended in patients with severe renal impairment (CLcr < 30 mL/min), because capecitabine is contraindicated in patients with severe renal impairment.
  • Hepatic Impairment: Reduce the dose of TUKYSA for patients with severe (Child-Pugh C) hepatic impairment.

Indication

TUKYSA is indicated in combination with trastuzumab and capecitabine for treatment of adult patients with advanced unresectable or metastatic HER2-positive breast cancer, including patients with brain metastases, who have received one or more prior anti-HER2-based regimens in the metastatic setting.

Please see full Prescribing Information.

References

  • 1. Murthy RK, Loi S, Okines A, et al. Tucatinib, trastuzumab, and capecitabine for HER2-positive metastatic breast cancer. N Engl J Med. 2020;382:597-609.
  • 2. Data on file. Seattle Genetics, Inc.
  • 3. TUKYSA [Prescribing Information]. Bothell, WA: Seattle Genetics, Inc. April 2020.
  • 4 Okines A, Paplomata E, Wahl T, et al. Management of adverse events in patients with HER2+ metastatic breast cancer treated with tucatinib, trastuzumab, and capecitabine (HER2CLIMB). Poster presented at: American Society of Clinical Oncology Annual Meeting; May 29-31, Chicago, IL.