Study CMEK162B2301, Part 1

In part 1, patients in the study were randomised to receive binimetinib 45 mg orally twice daily plus encorafenib 450 mg orally daily (Combo 450, n = 192), encorafenib 300 mg orally daily (hereafter referred to as Enco 300, n = 194), or vemurafenib 960 mg orally twice daily (hereafter referred to as Vem, n = 191). Treatment continued until disease progression or unacceptable toxicity. Randomisation was stratified by American Joint Committee on Cancer (AJCC) Stage (IIIB, IIIC, IVM1a or IVM1b, vs IVM1c) and Eastern Cooperative Oncology Group (ECOG) performance status (0 vs 1) and prior immunotherapy for unresectable or metastatic disease (yes vs no).

The primary efficacy outcome measure was progression-free survival (PFS) of Combo 450 compared with vemurafenib as assessed by a blinded independent review committee (BIRC). PFS as assessed by investigators (investigator assessment) was a supportive analysis. An additional secondary endpoint included PFS of Combo 450 compared with Enco 300. Other secondary efficacy comparisons between Combo 450 and either vemurafenib or Enco 300 included overall survival (OS), objective response rate (ORR), duration of response (DoR) and disease control rate (DCR) as assessed by BIRC and by investigator assessment.

The median age of patients was 56 years (range 20-89), 58 % were male, 90 % were Caucasian, and 72 % of patients had baseline ECOG performance status of 0. Most patients had metastatic disease (95 %) and were Stage IVM1c (64 %); 27 % of patients had elevated baseline serum lactate dehydrogenase (LDH), and 45% of patients had at least 3 organs with tumour involvement at baseline and 3.5 % had brain metastases. 27 patients (5 %) had received prior checkpoint inhibitors (anti- PD1/PDL1 or ipilimumab) (8 patients in Combo 450 arm (4 %); 7 patients in vemurafenib arm (4 %); 12 patients in Enco 300 arm (6 %) including 22 patients in the metastatic setting (6 patients in Combo 450 arm; 5 patients in vemurafenib arm; 11 patients in Enco 300 arm) and 5 patients in the adjuvant setting (2 patients in Combo 450 arm; 2 patients in vemurafenib arm; 1 patient in Enco 300 arm.

The median duration of exposure was 11.7 months in patients treated with Combo 450, 7.1 months in patients treated with encorafenib 300 mg and 6.2 months in patients treated with vemurafenib. The median relative dose intensity (RDI) for Combo 450 was 99.6 % for binimetinib and 100 % for encorafenib the median RDI was 86.2 % for Enco 300 and 94.5 % for vemurafenib.

Part 1 of study CMEK162B2301 demonstrated a statistically significant improvement in PFS in the patients treated with Combo 450 compared with patients treated with vemurafenib. Table 4 and Figure 1 summarise the PFS and other efficacy results based on central review of the data by a blinded independent radiology committee.

The efficacy results based on investigator assessment were consistent with the independent central assessment. Unstratified subgroup analyses demonstrated point estimates in favour of Combo 450, including LDH at baseline, ECOG performance status and AJCC stage.

Table 4: Study CMEK162B2301, Part 1: Progression-free survival and confirmed overall response results (independent central review)

Encorafenib + binimetinib

n = 192

(Combo 450)

Encorafenib

n = 194

(Enco 300)

Vemurafenib

n = 191

(Vem)