LONDON – Barring the dotting of a few i’s and crossing of a few t’s, the $250 million acquisition of Ceptaris Therapeutics Inc. by the Swiss biotech Actelion Ltd. is ready to go ahead, after Ceptaris announced FDA approval of its only product, Valchlor.

“We are now talking mostly formalities; the deal is expected to close at any time, within days or weeks, not months,” Roland Haefeli, senior vice president and head of investor relations at Actelion, told BioWorld International.

Actelion U.S. Holding Co. announced the acquisition of Ceptaris at the end of July, paying $25 million on signing and agreeing to pay a further $225 million on closing, plus milestones based on sales volumes of Valchlor, a gel formulation of the chemotherapeutic mechlorethamine. (See BioWorld Today, Aug. 1, 2013.)

Valchlor is for treating the early stages of mycosis fungoides, the most common type of cutaneous T-cell lymphoma. This rare form of non-Hodgkin’s lymphoma is sparked when malignant T cells migrate to the skin, initially manifesting as a skin rash and subsequently forming lesions and tumors.

Mechlorethamine is approved for the intravenous treatment of mycosis fungoides, but until Valchlor there has been no FDA-approved topical formulation. The product, which is commonly known as nitrogen mustard, has been available in nonstandardized pharmacy preparations in petroleum ointment or aqueous bases.

“With this approval we look forward to working with Actelion to close the merger and make Valchlor available to patients,” said Stephen Tullman, president and CEO of privately-held Ceptaris, of Malvern, Pa. The company previously received a complete response letter on Valchlor from the FDA in May 2012, resubmitting the file in February of this year.

While Ceptaris said the product will be available before the end of 2013, it looks as though an existing commercialization agreement with Accredo Specialty Pharmacy will be axed as a result of the acquisition Haefeli said it is a “reasonable assumption” that Actelion will itself take on that task.

The deal with Allschwil, Switzerland-based Actelion represents a handsome return for Ceptaris investors, who put in $39 million in three financings in the 18 months leading up to the resubmission of Valchlor. That includes a $10 million round in June 2012 to allow Ceptaris to address the requirements set out in the FDA’s complete response letter.

That $10 million show of faith in Valchlor was backed by existing investors Vivo Ventures, Palo Alto Investors, Burrill & Co., Aperture Venture Partners, Osage and Bioadvance, with Third Point LLC joining as a new investor.

Valchlor has not as yet been submitted for European Medicines Agency (EMA) approval. However, it has both EMA and FDA orphan drug status, providing Actelion with the opportunity not only to diversify from its stronghold in pulmonary arterial hypertension (PAH), but also to build on the know-how and infrastructure it has developed in rare diseases through ownership of Zavesca (miglustat), a treatment for Gaucher disease.

“Our overall experience in rare disorders is absolutely [relevant]. However, it will require a dedicated unit of sales representatives to best promote the product,” Haefeli said. The acquisition of Ceptaris also will allow Actelion to better utilize its 300-strong U.S. business unit.

Actelion said when the acquisition of Ceptaris was announced in July that it expected the transaction to become cash-accretive before the end of 2014.

The approval of Valchlor is good news for patients, said Youn Kim, professor of dermatology at Stanford University School of Medicine. “We now have the confidence of an FDA-approved product backed by evidence from a well-controlled clinical trial.”

In addition to consistent and precise formulation, Valchlor comes with data and instructions for use to ensure optimum efficacy.

In the 250-patient pivotal study, 60 percent of patients treated with Valchlor had a confirmed response, defined as at least a 50 percent reduction in lesion severity, while 48 percent of those treated with pharmacy-compounded mechlorethamine achieved a similar response.

Haefeli said that apart from the consistency and assurance that comes from having an FDA approval, Valchlor is easier to apply that compounded formulations. It is expected that this will improve compliance.

Taking control of Valchlor feeds into Actelion’s stated intent to build specialty franchises beyond PAH.

The company has another dermatology product, ponesimod, a sphingosine-1-phosphate receptor modulator in Phase III development for the treatment of psoriasis. n