Consensus molecular subtype 4 (CMS4)-targeted therapy in primary colon cancer: A proof-of-concept study

Background

Mesenchymal Consensus Molecular Subtype 4 (CMS4) colon cancer is associated with poor prognosis and therapy resistance. In this proof-of-concept study, we assessed whether a rationally chosen drug could mitigate the distinguishing molecular features of primary CMS4 colon cancer.

Methods

In the ImPACCT trial, informed consent was obtained for molecular subtyping at initial diagnosis of colon cancer using a validated RT-qPCR CMS4-test on three biopsies per tumor (Phase-1, n=69 patients), and for neoadjuvant CMS4-targeting therapy with imatinib (Phase-2, n=5). Pre- and post-treatment tumor biopsies were analyzed by RNA-sequencing and immunohistochemistry. Imatinib-induced gene expression changes were associated with molecular subtypes and survival in an independent cohort of 3232 primary colon cancer.

Results

The CMS4-test classified 52/172 biopsies as CMS4 (30%). Five patients consented to imatinib treatment prior to surgery, yielding 15 pre- and 15 post-treatment samples for molecular analysis. Imatinib treatment caused significant suppression of mesenchymal genes and upregulation of genes encoding epithelial junctions. The gene expression changes induced by imatinib were associated with improved survival and a shift from CMS4 to CMS2.

Conclusion

Imatinib may have value as a CMS-switching drug in primary colon cancer and induces a gene expression program that is associated with improved survival.

Adjuvant HIPEC in patients with colon cancer at high risk of peritoneal metastases: Primary outcome of the COLOPEC multicenter randomized trial

482

Background: Patients with T4 or perforated colon cancer are at high risk (~25%) of peritoneal metastases (PM). Sensitivity of imaging modalities for PM is limited and the majority of patients is diagnosed in a palliative setting. This provides a rationale for adjuvant hyperthermic intraperitoneal chemotherapy (HIPEC). In this study, the effectiveness of adjuvant HIPEC in reducing the risk of PM was determined. Methods: In this multicenter trial, patients with T4 (either cT4 or pT4, N0-2, M0) or perforated colon cancer, who underwent curative resection were randomized to adjuvant HIPEC followed by routine adjuvant systemic chemotherapy or to adjuvant systemic chemotherapy alone (1:1). Adjuvant HIPEC with oxaliplatin was performed simultaneously (9%) or within five-eight weeks (91%) after the primary tumor resection. Patients without evidence of recurrent disease at 18 months based on CT imaging underwent diagnostic laparoscopy in both arms. The primary endpoint was PM free survival (PMFS) at 18 months using Kaplan Meier analysis. Results: Between April 2015 and January 2017, 204 patients were randomized: 102 in the control arm (0 drop-outs), 102 in the experimental arm (two drop-outs). Surgical exploration at the start of the HIPEC procedure at five-eight weeks postoperatively revealed metastases in 11 patients (PM in 9/11) in the experimental arm, and adjuvant HIPEC was not applied. Adjuvant systemic chemotherapy was administered in 89/100 eligible patients after median 6 weeks (IQR 5-7) in the control arm and in 84/89 after 10 weeks (IQR 9-12) in the experimental arm. PM rate after completion of 18 months follow-up was 22/102 and 18/100, respectively. In the ITT analysis no difference in 18 months PMFS was observed: 77% (control) versus 81% (experimental), HR 0.836 (0.489-1.428)). Also, no differences were observed in 18 months DFS (HR 1.016 (0.646-1.598)) and OS (HR 1.139 (0.532-2.439)). One patient developed encapsulating peritoneal sclerosis after HIPEC. Conclusions: Adjuvant HIPEC with oxaliplatin for patients with T4 or perforated colon cancer does not result in improved 18 months PMFS. Long-term results have to be awaited to assess the role of HIPEC in the adjuvant setting. Clinical trial information: NCT02231086.