TYVERB Film-coated tablet Ref.[9043] Active ingredients: Lapatinib

Pharmacotherapeutic group: Antineoplastic agents, other antineoplastic agents, protein kinase inhibitors
ATC code: L01XE07

Mechanism of action

Lapatinib, a 4-anilinoquinazoline, is an inhibitor of the intracellular tyrosine kinase domains of both EGFR (ErbB1) and of HER2 (ErbB2) receptors (estimated Ki^app values of 3nM and 13nM, respectively) with a slow off-rate from these receptors (half-life greater than or equal to 300 minutes). Lapatinib inhibits ErbB-driven tumour cell growth in vitro and in various animal models.

The combination of lapatinib and trastuzumab may offer complementary mechanisms of action as well as possible non-overlapping mechanisms of resistance. The growth inhibitory effects of lapatinib were evaluated in trastuzumab-conditioned cell lines. Lapatinib retained significant activity against HER2-amplified breast cancer cell lines selected for long-term growth in trastuzumab-containing medium in vitro and was synergistic in combination with trastuzumab in these cell lines.

Clinical efficacy and safety

Combination treatment with Tyverb and capecitabine

The efficacy and safety of Tyverb in combination with capecitabine in breast cancer patients with good performance status was evaluated in a randomised, phase III study. Patients eligible for enrolment had HER2-overexpressing, locally advanced or metastatic breast cancer, progressing after prior treatment that included taxanes, anthracyclines and trastuzumab. LVEF was evaluated in all patients (using echocardiogram [Echo] or multi gated acquisition scan [MUGA]) prior to initiation of treatment with Tyverb to ensure baseline LVEF was within the institutions normal limits. In the clinical study LVEF was monitored at approximately eight week intervals during treatment with Tyverb to ensure it did not decline to below the institutions lower limit of normal. The majority of LVEF decreases (greater than 60% of events) were observed during the first nine weeks of treatment, however limited data was available for long term exposure.

Patients were randomised to receive either Tyverb 1250 mg once daily (continuously) plus capecitabine (2000 mg/m²/day on days 1-14 every 21 days), or to receive capecitabine alone (2500 mg/m²/day on days 1-14 every 21 days). The primary endpoint was time to progression (TTP). Assessments were undertaken by the study investigators and by an independent review panel, blinded to treatment. The study was halted based on the results of a pre-specified interim analysis that showed an improvement in TTP for patients receiving Tyverb plus capecitabine. An additional 75 patients were enrolled in the study between the time of the interim analysis and the end of the enrolment. Investigator analysis on data at the end of enrolment is presented in Table 1.

Table 1. Time to progression data from Study EGF100151 (Tyverb/capecitabine):

The independent assessment of the data also demonstrated that Tyverb when given in combination with capecitabine significantly increased time to progression (Hazard Ratio 0.57 [95% CI 0.43, 0.77] p=0.0001) compared to capecitabine alone.

Results of an updated analysis of the overall survival data to 28 September 2007 are presented in Table 2.

Table 2. Overall survival data from Study EGF100151 (Tyverb/capecitabine):

On the combination arm, there were 4 (2%) progressions in the central nervous system as compared with the 13 (6%) progressions on the capecitabine alone arm.

Data are available on the efficacy and safety of Tyverb in combination with capecitabine relative to trastuzumab in combination with capecitabine. A randomised Phase III study (EGF111438) (N=540) compared the effect of the two regimens on the incidence of CNS as site of first relapse in women with HER2 overexpressing metastatic breast cancer. Patients were randomised to either Tyverb 1250 mg once daily (continuously) plus capecitabine (2000 mg/m²/day on days 1-14 every 21 days), or trastuzumab (loading dose of 8mg/kg followed by 6mg/kg q3 weekly infusions) plus capecitabine (2500mg/m²/day, days 1-14, every 21 days). Randomisation was stratified by prior trastuzumab treatment and number of prior treatments for metastatic disease. The study was halted as the interim analysis (N=475) showed a low incidence of CNS events and, superior efficacy of the trastuzumab plus capecitabine arm in terms of progression-free survival and overall survival (see results of final analysis in Table 3).

In the Tyverb plus capecitabine arm 8 patients (3.2%) experienced CNS as site of first progression, compared with 12 patients (4.8%) in the trastuzumab plus capecitabine arm.

Lapatinib effect on CNS metastasis

Lapatinib has in terms of objective responses demonstrated modest activity in the treatment of established CNS metastases. In the prevention of CNS metastases in the metastatic and early breast cancer settings the observed activity was limited.

Table 3. Analyses of investigator-assessed progression-free survival and overall survival:

CI = confidence interval
^a PFS was defined as the time from randomisation to the earliest date of disease progression or death from any cause, or to the date of censor.
^b Pike estimate of the treatment hazard ratio, <1 indicates a lower risk for Tyverb plus capecitabine compared with Trastuzumab plus capecitabine.
¹ PFS event is Progressed or Died and OS event is Died due to any cause.
² NE=median was not reached.
* Post hoc analysis

Combination treatment with Tyverb and trastuzumab

The efficacy and safety of lapatinib in combination with trastuzumab in metastatic breast cancer were evaluated in a randomised trial. Eligible patients were women with Stage IV ErbB2 gene amplified (or protein overexpressing) metastatic breast cancer who had been exposed to treatment with anthracyclines and taxanes. In addition, per the protocol, patients were to be reported by the investigators as having progressed on their most recent trastuzumab containing regimen in the metastatic setting. The median number of prior trastuzumab-containing regimens was three. Patients were randomised to receive either oral lapatinib 1000 mg once daily plus trastuzumab 4 mg/kg administered as an intravenousloading dose, followed by 2 mg/kg intravenous weekly (N=148), or oral lapatinib 1500 mg once daily (N=148). Patients who had objective disease progression after receiving at least 4 weeks of treatment with lapatinib monotherapy were eligible to crossover to combination therapy. Of the 148 patients who received monotherapy treatment, 77 (52%) patients elected at the time of disease progression to receive combination treatment.

Progression-free survival (PFS) was the primary endpoint of the study with response rate and overall survival (OS) as secondary endpoints. The median age was 51 years and 13% were 65 years or older. Ninety-four percent (94%) were Caucasian. Most patients in both treatment arms had visceral disease (215 [73%] patients overall). In addition, 150 [50%] of patients were hormone receptor negative. A summary of efficacy endpoints and overall survival data is provided in Table 4. Subgroup analysis results based on predefined stratification factor (hormone receptor status) is also shown in Table 5.

Table 4. Progression-free survival and overall survival data (Tyverb/trastuzumab):

PFS = progression-free survival; CI = confidence interval.
¹ Kaplan-Meier estimates

Table 5. Summary of PFS and OS in studies with hormone receptor negative:

Combination treatment with Tyverb and letrozole

Tyverb has been studied in combination with letrozole for the treatment of postmenopausal women with hormone receptor-positive (oestrogen receptor [ER] positive and/or progesterone receptor [PgR] positive) advanced or metastatic breast cancer.

The Phase III study (EGF30008) was randomised, double-blind, and placebo controlled. The study enrolled patients who had not received prior therapy for their metastatic disease.

In the HER2-overexpressing population, only 2 patients were enrolled who had received prior trastuzumab, 2 patients had received prior aromatase inhibitor therapy, and approximately half had received tamoxifen.

Patients were randomised to letrozole 2.5 mg once daily plus Tyverb 1500 mg once daily or letrozole with placebo. Randomisation was stratified by sites of disease and by time from discontinuation of prior adjuvant anti-oestrogen therapy. HER2 receptor status was retrospectively determined by central laboratory testing. Of all patients randomised to treatment, 219 patients had tumours overexpressing the HER2 receptor, and this was the pre-specified primary population for the analysis of efficacy. There were 952 patients with HER2-negative tumours, and a total of 115 patients whose tumour HER2 status was unconfirmed (no tumour sample, no assay result, or other reason).

In patients with HER2-overexpressing MBC, investigator-determined progression-free survival (PFS) was significantly greater with letrozole plus Tyverb compared with letrozole plus placebo. In the HER2-negative population, there was no benefit in PFS when letrozole plus Tyverb was compared with letrozole plus placebo (see Table 6).

Table 6. Progression free survival data from Study EGF30008 (Tyverb/letrozole):

CI= confidence interval
HER2 overexpression = IHC 3+ and/or FISH positive; HER2 negative = IHC 0, 1+ or 2+ and/or FISH negative
Clinical benefit rate was defined as complete plus partial response plus stable disease for ≥6 months.

At the time of the final PFS analysis (with median follow-up of 2.64 years), the overall survival data were not mature and there was no significant difference between treatment groups in the HER2-positive population; this had not changed with additional follow-up (>7.5 years median follow- up time; Table 7).

Table 7. Overall survival (OS) results from study EGF30008 (in the HER2-positive population only):

Median values from Kaplan-Meier analysis; HR and p-values from Cox regression models adjusting for important prognostic factors.
^a Estimate of the treatment hazard ratio, where <1 indicates a lower risk with letrozole 2.5 mg + lapatinib 1500 mg compared with letrozole 2.5 mg + placebo.
^b P-value from Cox regression model, stratifying for site of disease and prior anti-adjuvant therapy at screening.

Cardiac electrophysiology

The effect of lapatinib on the QT-interval was evaluated in a single-blind, placebo-controlled, single sequence (placebo and active treatment) crossover study in patients with advanced solid tumours (EGF114271) (n=58). During the 4-day treatment period, three doses of matching placebo were administered 12 hours apart in the morning and evening on Day 1 and in the morning on Day 2. This was followed by three doses of lapatinib 2000 mg administered in the same way. Measurements, including electrocardiograms (ECGs) and pharmacokinetic samples, were taken at baseline and at the same time points on Day 2 and Day 4.

In the evaluable population (n=37), the maximum mean ΔΔQTcF (90% CI) of 8.75 ms (4.08, 13.42) was observed 10 hours after ingestion of the third dose of lapatinib 2000 mg. The ΔΔQTcF exceeded the 5 ms threshold and the upper bound 90% CIs exceeded the 10 ms threshold at multiple time points. The results for the pharmacodynamics population (n=52) were consistent with those from the evaluable population (maximum ΔΔQTcF (90% CI) of 7.91 ms (4.13, 11.68) observed 10 hours after ingestion of the third dose of lapatinib 2000 mg).

There is a positive relationship between lapatinib plasma concentrations and ΔΔQTcF. Lapatinib produced a maximum mean concentration of 3920 (3450-4460) ng/ml (geometric mean/95% CI), exceeding the geometric mean C_max.ss and 95% CI values observed following the approved dosing regimens. An additional increase in peak exposure of lapatinib can be expected when lapatinib is taken repeatedly with food (see sections 4.2 and 5.2) or concomitantly with strong CYP3A4 inhibitors. When lapatinib is taken in combination with strong CYP3A4 inhibitors the QTc interval can be expected to be prolonged by 16.1 ms (12.6-20.3 ms) as demonstrated in a model-based prediction (see section 4.4).

Food effects on lapatinib exposure

The bioavailability and thereby the plasma concentrations of lapatinib are increased by food, in relation to the content and timing of the meal. Dosing of lapatinib one hour after a meal results in approximately 2-3 times higher systemic exposure, compared to dosing one hour before a meal (see sections 4.5 and 5.2).

The European Medicines Agency has waived the obligation to submit the results of studies with Tyverb in all subsets of the paediatric population in the treatment of breast carcinoma (see section 4.2 for information on paediatric use).