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A multicenter, multinational retrospective analysis of mitomycin C (MMC) in refractory metastatic colorectal cancer (mCRC).

3577 Background: A considerable number of mCRC patients (pts) who progress on standard treatment with 5-fluorouracil (5FU), oxaliplatin, irinotecan and monoclonal antibodies still have good performance and desire further treatment. MMC has been widely used in this situation, and despite good tolerability, there is no agreement on its role.


METHODS
In order to assess the activity of MMC in the refractory mCRC setting, we retrospectively evaluated 109 heavily pre-treated pts who received MMC as single agent or in combination for mCRC at three different institutions.


RESULTS
Of the 109 pts, 30 (27.5%) were treated at M. D. Anderson Cancer Center (USA); 55 (50.5%) at Hospital Sírio Libanês (Brazil) and 24 (22%) at Instituto do Câncer de São Paulo (Brazil). Median age was 54 years old, 57% were male and 94% were performance status ECOG 0 or 1 at diagnosis. MMC was used in second-line in 11%, third-line in 37.6% and fourth-line or beyond in 51.4% of pts. Median TTF on the regimen prior to MMC therapy was 3.7 months. 42% received MMC as single agent while 58% received MMC combinations, mainly with fluoropyrimidines (49%). Severe toxicity was rare (1.8%), with dose reductions in 6.4% of pts. Clinical benefit with MMC, defined as improved symptoms by clinician assessment, was 12%. By response criteria, no radigraphic responses were seen. Median survival was only 4.6 months (95% CI of 4.1 to 5.5).


CONCLUSIONS
This retrospective data represents the largest reported series of refractory mCRC patients treated with MMC. There were no patients with radiographic response and the low clinical benefit rate is not consistent with an active regimen. The median survival of 4.6 months is similar to the median survival expected for best supportive care in the refractory setting (4.5 months). This lack of activity strongly suggests that mitomycin should not be used in refractory mCRC.