HENDERSON, Nev. (AP) — Spectrum Pharmaceuticals said today it signed an agreement to acquire Allos Therapeutics Inc. in a deal valued at up to $206 million.

Spectrum, based in Henderson, Nev., will pay $1.82 per share for each outstanding share of Allos, a 28 percent premium over its closing price in Wednesday.

Allos shareholders will also a contingent value right to an additional payment of 11 cents per share if it achieves some European regulatory and commercialization milestones for the cancer drug Folotyn.

Shares of Allos, which is based in Westminster, Colo. closed at $1.43 Wednesday and have fallen steadily since closing above $3 about a year ago.

The boards of directors for both companies have unanimously approved the deal.

Folotyn is approved in the U.S. as a treatment for peripheral T-cell lymphoma in patients who have suffered a relapse or who have not responded to previous treatment.

Spectrum sells two oncology drugs, Zevalin, which is approved to treat a form of non-Hodgkin’s lymphoma, and Fusilev, which treats the side effects of methotrexate, a drug used in chemotherapy.

Spectrum Chairman and CEO Dr. Rajesh C. Shrotriya said in a statement the deal accelerates its hematology franchise development and “affirms our commitment to becoming a leader in the treatment of lymphoma.”