Objective Two conjunctival cell lines (CRMM-1 and CRMM-2) have been established from recurrent conjunctival melanoma. The authors examined the chemosensitivity of these cell lines to cytotoxic substances and combinations to identify substances that inhibit cell growth efficiently in vitro.

Material and methods CRMM-1 and CRMM-2 were exposed to cisplatin, mitomycin C (MMC), all-trans-retinoic-acid (ATRA), fotemustine or imatinib for 24 h. Sulforhodamine-B assays were used to assess the IC₅₀. Isobolograms were performed to test possible synergism and antagonism with ATRA or imatinib.

Results Cisplatin and MMC were efficient to inhibit the growth of CRMM-1 and CRMM-2. Combination of imatinib with MMC showed additive antitumoral effect on both cell lines. Combined treatment of imatinib with fotemustine or cisplatin resulted in antagonism. Strong antagonisms were also obtained with ATRA and fotemustine or cisplatin in both cell lines. A synergism was found for ATRA and mitomycin or imatinib in CRMM-2, in contrast to CRMM-1, where antagonism was obtained.

Conclusions Cisplatin and MMC inhibit cell growth in conjunctival melanoma cell lines. The potential of ATRA was evident only in combination with MMC or imatinib in CRMM-2 cells. Imatinib and mitomycin increased their efficiency under combination therapy.