X0202 4 2006-04-03 0 0000879993 DUSA PHARMACEUTICALS INC DUSA 0001079151 COOPER HILL PARTNERS LLC 767 THIRD AVENUE NEW YORK NY 10017 0 0 1 0 Common Stock, par value $.01 per share 2006-04-03 4 J 0 637008 7.0005 D 2783400 I See footnote Common Stock, par value $.01 per share 2006-04-03 4 J 0 637008 7.0005 A 2783400 I See footnote This filing reflects a transfer between and among the reporting persons and does not reflect a change in the overall beneficial ownership of the reporting persons as previously filed. CLSP, L.P. ("CLSP"), CLSP II, L.P. ("CLSP II"), CLSP/SBS I, L.P. ("CLSP/SBS I"), and CLSP/SBS II, L.P. ("CLSP/SBS II") are each private investment partnerships, the sole general partner of which is Cooper Hill Partners, LLC. As the sole general partner of CLSP, CLSP II, CLSP/SBS I, and CLSP/SBS II, Cooper Hill Partners, LLC has the power to vote and dispose of the Securities owned by each of CLSP, CLSP II, CLSP/SBS I, and CLSP/SBS II and, accordingly, may be deemed the "beneficial owner" of such Securities. The managing member of Cooper Hill Partners, LLC is Casdin Capital, LLC. Purusant to an investment advisory contract, Cooper Hill Partners, L.P. currently has the power to vote and dispose of the Securities held for the account of CLSP Overseas, Ltd. and, accordingly, may be deemed the "beneficial owner" of such Securities. /s/ Peter Freer 2006-04-05