Dose EScalation Induction of EvERolimus

The BOLERO-2 study demonstrated an enormous benefit for patients who received everolimus in addition to exemestane in patients who progressed during/after a non steroidal (NSAI), which led to approval of everolimus in this indication. However, experience from routine use report a high rate of intolerability of this innovative treatment approach especially during the first 12 weeks of treatment. Most common side effect is mucositis/Mucositis which is considered the leading cause for treatment discontinuation not related to tumor progression.

This outside clinical trial experience is contrary to findings from BOLERO-2, where the number of patients still taking full-dose (10mg) of everolimus at 4, 8, and 12 weeks is 77.8%, 75.6%, and 75.6%, respectively. These findings are in concordance with non-interventional studies. However, findings might be biased by positive pre-selection.

In the non-responder part (setting III) of the neoadjuvant GeparQuinto study, everolimus was given as salvage treatment in combination with paclitaxel for patients without response to 4 cycles epirubicin/cyclophosphamide +/- bevacizumab. A dose-escalation schema was successfully used to improve tolerability of everolimus together with the cytotoxic agent. In fact the addition of everolimus to paclitaxel led only to increases of grades 1-4 leukopenia, grades 1-2 thrombocytopenia, leukopenia, skin changes and hyperlipidemia. Grades 3-4 hematological and nonhematological toxic effects were infrequent with no differences between treatment arms.

Moreover, Ravaud et al performed a metaanalysis of clinical trials in order to evaluate the potential relationship between everolimus exposure, safety and efficacy. Previous studies have shown that maximum everolimus concentrations are reached 1-2 hours after administering 5-70 mg oral doses, maximum everolimus concentrations increase in a dose-proportional manner between 5 mg and 10 mg and that continuous 5-10 mg once-daily dosing enables steady state to be achieved within 1 week.

The metaanalysis shows that a two-fold increase in the minimum concentration of everolimus increased the probability of tumor size reduction (odds ratio 1.4), which was associated with a trend for reduced risk of PFS events (risk ratio [RR] 0.9), but with an increased risk of grade 3 pulmonary toxicity (RR1.93), Mucositis (RR 1.49), and metabolic toxicity (RR 1.3).

Taking together these results suggest a dose-dependent antitumor effect of everolimus that have to be balanced against the correlated increased toxicities. For this reason the optimal dose and schedule need to be explored within randomized prospective clinical trial, in order to increase compliance and tolerability, maximizing efficacy.

Eligibiltiy according to Everolimus label (ie. postmenopausal women)

Inclusion criteria

(most important)

• Locally advanced or metastatic stage of disease not amenable to curative treatment by surgery or radiotherapy alone.
• No indication for chemotherapy (e.g. symptomatic visceral metastasis) -Histological confirmed hormone receptor-positive (HR+), HER2- negative carcinoma of the breast.
• Postmenopausal women
• Disease progression following prior therapy with non steroidal aromatase inhibitors (NSAI), defined as:

• Recurrence while on, or following completion of an adjuvant treatment with Letrozole or Anastrozole, or
• Progression while on or following completion of Letrozole or Anastrozole treatment for ABC/MBC. Note: Non-steroidal aromatase inhibitors (i.e. Letrozole or Anastrozole) do not have to be the last treatment prior to enrollment. Other prior anticancer therapy, e.g. Tamoxifen, Fulvestrant, Exemestane, is also allowed. Patients must have recovered to grade 1 or better from any adverse events (except alopecia) related to previous therapy prior to enrollment.
• At least 4 weeks since radiotherapy, with full recovery. The measurable disease must be completely outside the radiation field or there must be pathologic proof of newly progressive disease.

Exclusion criteria

(most important):

• Concurrent immunotherapy or hormonal therapy (contraceptive and/or replacement therapy). Bisphosphonates or denosumab may be continued or started before randomization.
• Life expectancy of less than 3 months.
• Parenchymal brain metastases, unless adequately controlled by surgery and/or radiotherapy.
• Any ongoing toxicity from prior anti-cancer therapy that is grade 3-4 and/or that is progressing in severity, except alopecia or anemia controlled by growth factors.
• Known or suspected congestive heart failure (>NYHA I) and/or coronary heart disease, angina pectoris requiring anti-anginal medication, previous history of myocardial infarction ≤ 6months, evidence of transmural infarction on ECG, un- or poorly controlled arterial hypertension (i.e. BP >150/100 mmHg under treatment with two antihypertensive drugs), rhythm abnormalities requiring permanent treatment, clinically significant valvular heart disease.
• Currently active infection.
• History of other malignancies within the last 5 years which significantly affect the diagnosis, assessment or prognosis of metastatic breast cancer.
• Malabsorption syndrome or insufficient gastrointestinal function, preexisting diagnosis of ulcerative colitis.
• Concurrent treatment with other experimental drugs; participation in another clinical trial with any investigational not marketed drug within 30 days prior to study entry.
• Insufficiently controlled diabetes, known HIV infection or chronic hepatitis B or C and seriously impaired liver function (Child-Pugh, class A, B or C).