PIK3CA Pathway Mutations Predictive of Poor Response Following Standard Radiochemotherapy ± Cetuximab in Cervical Cancer Patients.

Purpose: EGFR is frequently overexpressed in cervical cancer, suggesting EGFR blockade as a promising treatment approach. Cetuximab, an anti EGFR antibody, used conjointly with radiochemotherapy, was feasible in first-line treatment of cervix carcinoma limited to the pelvis.

Experimental Design: This randomized phase II trial enrolled 78 FIGO stage IB2-IIIB cervical cancer patients to either cisplatin-based radiochemotherapy alone (arm B, n = 38) or conjointly with a 6-week course of weekly cetuximab (arm A, n = 40). Brachytherapy was given to the pelvic mass. Primary endpoint was disease-free survival (DFS) at 2 years. EGFR expression and targeted sequencing were performed in 54 of 78 patients.

Results: Cetuximab over a 6-week period did not improve DFS at 24 months. At 31 months median follow-up, DFS was not significantly different (P = 0.18). Complete response at 4 to 6 months was strongly predictive for excellent DFS (log-rank test; P < 0.001). PIK3CA, KRAS, and STK11 mutations were observed in 22%, 4%, and 2% of patients, respectively. No tumor with a PI3K pathway mutation showed complete response (0/8 in arm A and 0/6 in arm B), whereas 14 of 52 (27%) tumors without mutations did (P = 0.021). PI3K pathway-mutated tumors showed a trend toward poorer DFS (P = 0.06) following cetuximab (8/22) as compared with those following standard treatment only (6/18).

Conclusions: Similar to patients with head and neck cancer, patients with cervical cancer showed no gain in DFS at 2 years following a combined treatment of cetuximab with radiochemotherapy. Although treatment tolerance and compliance were satisfactory, it remains to be demonstrated whether maintenance therapy with cetuximab could be beneficial in selected patient groups.