compare two treatment regimens to find out whether one of them FOLFIRI is better than the other Irinotecan alone when combined with Arsenic trioxide

Intervention1: modified FOLFIRI plus Arsenic trioxide: Irinotecan 180mg per m2 IV over 90 mins on Day 1
Leucovorin 300mg per m2 IV over 2 hours on Day 1
5 FU - 2400mg per m2 IV over 46 hours continuous infusion starting on Day 1
Arsenic Trioxide 0.15mg per kg IV in 250 ml NS over two hours 1st dose on Days 1 and 2
1 cycle, administered every 2 weeks
Start of next IV cycle on D 15
If ATO is well tolerated during the first infusion, then it can be infused over 1 hour from the second dose onwards.
Control Intervention1: Irinotecan monotherapy: Irinotecan 180 mg per m2 IV over 90 mins on Day 1
1 cycle, administered every 2 weeks
Start of next IV cycle on D 15
The patient will be on supportive care and reviewed with imaging and serologically on a periodic basis, every 3 months + or -15 days as per study or on an SOS basis in case of symptomatic disease worsening
Primary outcome(s): Progression free survivalTimepoint: 5 years
Study Design: Other Method of generating randomization sequence:Other Method of allocation concealment:Other Blinding and masking:Open Label