Hydrogen sulfide activatable metal-organic frameworks for Fluorescence Imaging-Guided Photodynamic Therapy of colorectal cancer

Summary Background Surgical resection alone is regarded as the standard of care for patients with liver metastases from colorectal cancer, but relapse is common. We assessed the combination of perioperative chemotherapy and surgery compared with surgery alone for patients with initially resectable liver metastases from colorectal cancer. Methods This parallel-group study reports the trial's final data for progression-free survival for a protocol unspecified interim time-point, while overall survival is still being monitored. 364 patients with histologically proven colorectal cancer and up to four liver metastases were randomly assigned to either six cycles of FOLFOX4 before and six cycles after surgery or to surgery alone (182 in perioperative chemotherapy group vs 182 in surgery group). Patients were centrally randomised by minimisation, adjusting for centre and risk score. The primary objective was to detect a hazard ratio (HR) of 0·71 or less for progression-free survival. Primary analysis was by intention to treat. Analyses were repeated for all eligible (171 vs 171) and resected patients (151 vs 152). This trial is registered with ClinicalTrials.gov, number NCT00006479. Findings In the perioperative chemotherapy group, 151 (83%) patients were resected after a median of six (range 1–6) preoperative cycles and 115 (63%) patients received a median six (1–8) postoperative cycles. 152 (84%) patients were resected in the surgery group. The absolute increase in rate of progression-free survival at 3 years was 7·3% (from 28·1% [95·66% CI 21·3–35·5] to 35·4% [28·1–42·7]; HR 0·79 [0·62–1·02]; p=0·058) in randomised patients; 8·1% (from 28·1% [21·2–36·6] to 36·2% [28·7–43·8]; HR 0·77 [0·60–1·00]; p=0·041) in eligible patients; and 9·2% (from 33·2% [25·3–41·2] to 42·4% [34·0–50·5]; HR 0·73 [0·55–0·97]; p=0·025) in patients undergoing resection. 139 patients died (64 in perioperative chemotherapy group vs 75 in surgery group). Reversible postoperative complications occurred more often after chemotherapy than after surgery (40/159 [25%] vs 27/170 [16%]; p=0·04). After surgery we recorded two deaths in the surgery alone group and one in the perioperative chemotherapy group. Interpretation Perioperative chemotherapy with FOLFOX4 is compatible with major liver surgery and reduces the risk of events of progression-free survival in eligible and resected patients. Funding Swedish Cancer Society, Cancer Research UK, Ligue Nationale Contre le Cancer, US National Cancer Institute, Sanofi-Aventis.

The physiological functions of hydrogen sulfide (H2S) include vasorelaxation, stimulation of cellular bioenergetics, and promotion of angiogenesis. Analysis of human colon cancer biopsies and patient-matched normal margin mucosa revealed the selective up-regulation of the H2S-producing enzyme cystathionine-β-synthase (CBS) in colon cancer, resulting in an increased rate of H2S production. Similarly, colon cancer-derived epithelial cell lines (HCT116, HT-29, LoVo) exhibited selective CBS up-regulation and increased H2S production, compared with the nonmalignant colonic mucosa cells, NCM356. CBS localized to the cytosol, as well as the mitochondrial outer membrane. ShRNA-mediated silencing of CBS or its pharmacological inhibition with aminooxyacetic acid reduced HCT116 cell proliferation, migration, and invasion; reduced endothelial cell migration in tumor/endothelial cell cocultures; and suppressed mitochondrial function (oxygen consumption, ATP turnover, and respiratory reserve capacity), as well as glycolysis. Treatment of nude mice with aminooxyacetic acid attenuated the growth of patient-derived colon cancer xenografts and reduced tumor blood flow. Similarly, CBS silencing of the tumor cells decreased xenograft growth and suppressed neovessel density, suggesting a role for endogenous H2S in tumor angiogenesis. In contrast to CBS, silencing of cystathionine-γ-lyase (the expression of which was unchanged in colon cancer) did not affect tumor growth or bioenergetics. In conclusion, H2S produced from CBS serves to (i) maintain colon cancer cellular bioenergetics, thereby supporting tumor growth and proliferation, and (ii) promote angiogenesis and vasorelaxation, consequently providing the tumor with blood and nutritients. The current findings identify CBS-derived H2S as a tumor growth factor and anticancer drug target.