Pilot study using molecular profiling of patients' tumors to find potential targets and select treatments for their refractory cancers

Abstract

Purpose: To compare the progression-free survival (PFS) using a treatment regimen selected by molecular profiling (MP) of a patient's tumor with the PFS for the most recent regimen on which the patient had experienced progression (ie, patient as his own control).

Patients and methods: Patients with refractory metastatic cancer had tissue samples submitted for MP in two formats including formalin-fixed tissue for immunohistochemistry and fluorescent in situ hybridization assays and immediately frozen tissue for oligonucleotide microarray (MA) gene expression assays (all performed in a Clinical Laboratory Improvement Amendments [CLIA]-certified laboratory). The MP approach was deemed of clinical benefit for the individual patient who had a PFS ratio (PFS on MP-selected therapy/PFS on prior therapy) of ≥ 1.3.

Results: In 86 patients who had MP attempted, there was a molecular target detected in 84 (98%). Sixty-six of the 84 patients were treated according to MP results. Eighteen (27%) of 66 patients had a PFS ratio of ≥ 1.3 (95% CI, 17% to 38%; one-sided, one-sample P = .007). Therefore, the null hypothesis (that ≤ 15% of this patient population would have a PFS ratio of ≥ 1.3) was rejected.

Conclusion: It is possible to identify molecular targets in patients' tumors from nine different centers across the United States. In 27% of patients, the MP approach resulted in a longer PFS on an MP-suggested regimen than on the regimen on which the patient had just experienced progression. Issues to be considered in interpretation of this study include limited prior experience with patients as their own controls as a study end point and overall patient attrition.