Increasing utilization of comprehensive genomic profiling (CGP) and a growing number of targeted agents (TAs) has led to substantial improvements in outcomes among patients with cancer with actionable mutations. We sought to evaluate real-world use and outcomes of off-label TA among patients who underwent CGP.
The National Precision Oncology Program database and VA Corporate Data Warehouse were queried to identify patients who underwent CGP between Feb 2019 and Dec 2021 and were prescribed 1 of 73 TAs for malignancy. OncoKB (accessed March 2022) annotations were used to select patients who received offlabel TAs based upon CGP results. Chart abstraction was performed in April 2022 to review response to offlabel TAs, toxicities, and treatment duration.
Of 18,686 patients who underwent CGP, 2,107 (11%) were prescribed a TA and 170 (0.9%) were prescribed a total of 185 off-label TA regimens. Median age was 68 years, 88% were male, and 82% had prior systemic therapy, with 28% receiving 3 or more prior lines. Frequency of off-label TA prescriptions was highest for patients with unknown primary (CUP) (9%), thyroid (8%), and breast (6%) cancers. Most frequently targeted alterations involved ERBB2 (22%), BRAF (22%), and BRCA1/BRCA2/ATM (20%). Among the 161 regimens prescribed > 4 weeks, 44 (27%) led to complete or partial response, and 63 (39%) were administered for 6 months or longer or are continuing. Median progression free (PFS) and overall survival (OS) were 5.3 (95% CI, 4.3–6.5) and 9.9 (95% CI, 8.3–12.4) months, respectively. Patients with OncoKb level 2/3A/3B annotations had improved PFS (HR 0.45; 95% CI, 0.24-0.82; P = .01) and OS (HR 0.27; 95% CI, 0.15-0.48; P < .005) compared to level 4 treatments. Across all 185 regimens prescribed, 30 (16.2%) were discontinued due to toxicity, and further systemic treatment was prescribed subsequently in 58 (31.3%).
While the overall use of off-label TAs is low, nearly 10% of CUP and thyroid cancer patients who undergo CGP are prescribed TAs for off-label indications. More than one-quarter of off-label TA regimens lead to treatment response. Treatments associated with level 4 annotations lead to worse outcomes than TAs bearing superior levels of evidence.