Precision oncotherapy based on liquid biopsies in multidisciplinary treatment of unresectable recurrent rectal cancer: a retrospective cohort study.

Background: Third line innovative systemic treatments and loco-regional chemotherapy by hypoxic pelvic perfusion (HPP) have both been proposed for the treatment of unresectable not responsive recurrent rectal cancer (URRC). In the present study, we have compared the safety and efficacy of HPP/target therapy, using drug regimens selected by liquid biopsy precision oncotherapy, to third-line systemic therapy based on tissue specimens precision oncotherapy.

Methods: HPP/target therapy regimens were selected based on precision oncotherapy, including assays for chemosensitivity and viability, and qRT-PCR for tumor-related gene expression. In the control group, systemic third-line and further lines of therapy were defined according to clinical and biological parameters.

Results: From 2007 to 2019, 62 URRC patients were enrolled, comprised of 43 patients in the HPP/target-therapy group and 19 patients in the systemic therapy control group. No HPP related complications were reported and the most common adverse events were skin and bone marrow toxicity. In the HPP/target-therapy group, the ORR was 41.8% whereas in the systemic therapy control group was 15.8%. DCR of the HPP/target-therapy group was significantly improved over the systemic therapy group (P = 0.001), associated with a PFS of 8 vs 4 months (P = 0.009), and OS of 20 vs 8 months (P = 0.046).

Conclusions: The present data indicate that in URCC patients, the integration of HPP/target-therapy and precision oncotherapy based upon liquid biopsy is as effective and efficacious as third-line treatment in local disease control and, therefore, deserves to be further assessed and compared to conventional systemic treatments in future prospective randomized trials.