Celator Pharmaceuticals Inc., which advanced lead compound CPX-351 into a pivotal phase III study in acute myeloid leukemia (AML), hit its target enrollment of 300 patients ahead of schedule and said it would allow others who started the referral and evaluation process to complete enrollment.

Last week, the Ewing, N.J.-based company priced an underwritten public offering of approximately 6.6 million shares to raise $12.9 million. With fresh capital in the bank, the company looked to the next milestone of reporting phase III induction response rate findings for CPX-351 in the second quarter of 2015, with overall survival (OS) data – the primary endpoint – expected in the first quarter of 2016.

The randomized, multicenter, open-label phase III study is comparing CPX-351, a liposomal formulation of cytarabine and daunorubicin, to conventional cytarabine and daunorubicin therapy. The study enrolled patients between the ages of 60 and 75 with newly diagnosed, previously untreated AML arising from prior myelodysplasia or chronic myelomonocytic leukemia, prior history of chemotherapy or radiotherapy treatment, or with cytogenetic evidence of abnormalities associated with myelodysplasia. Patients were randomized to CPX-351 or conventional chemotherapy.

In addition to the OS, the phase III is evaluating secondary endpoints of complete response rate, duration of remission, 30- and 60-day mortality, event-free survival, aplasia rate and rate of stem cell transplant. The study, which began enrollment in December 2012, is being conducted in the U.S. and Canada, in partnership with the Leukemia & Lymphoma Society.

CPX-351 represents a drug development approach in which drug molar ratios with synergistic anti-tumor activity are encapsulated in a drug delivery vehicle to maintain the desired ratio following administration. The compound was granted orphan drug status by the FDA and European Commission to treat AML.

Celator previously conducted two randomized, controlled, phase II studies of CPX-351, including one in newly diagnosed elderly AML patients and a second in patients with AML in first relapse. In both studies, treatment with CPX-351 resulted in improvements in response rates, 60-day mortality and OS in the highest risk patients. Those findings propelled Celator to a $20 million series D, closed in 2010. (See BioWorld Today, Sept. 2, 2010.)

Last year, with phase III enrollment under way, the company raised $39.3 million in a private placement of common stock and warrants that included $6.8 million from prior closings. (See BioWorld Today, June 25, 2013.)

Celator then was approved for a listing on the OTC Bulletin Board and subsequently jumped to the Nasdaq, where its shares (NASDAQ:CPXX) closed even on Monday, at $2.25.

The company was in a quiet period following last week's financing, and company officials declined additional comment about the timetable for the phase III trial.

Celator also has CPX-1, a liposomal formulation of irinotecan and floxuridine, which completed a phase II study in colorectal cancer; CPX-571, a liposomal formulation of irinotecan and HCl cisplatin designed to treat solid tumors; CPX-8, a hydrophobic docetaxel prodrug nanoparticle formulation under investigation by the National Cancer Institute's Nanotechnology Characterization Laboratory; and other undisclosed programs exploring combinations of existing drugs, including molecularly targeted therapies.

The programs emerged from the company's drug ratio technology platform, Combiplex, which is designed to find synergistic ratios of drugs for cancer therapy and then lock in those ratios using a delivery system based on liposomes, polymers and nanotechnology.

In a supplement to its prospectus filed last week, Celator estimated global peak year sales of approximately $250 million for CPX-351 in the newly diagnosed AML population and said the drug could exceed $750 million in peak year sales with potential label expansion and positive data in other AML patient populations and hematologic malignancies. Celator said exploratory studies are underway in some additional patient groups.

Celator reported $24.9 million in cash as of June 30, 2014. The company has not disclosed timing of its third quarter financial results.

Last month, H.C. Wainwright & Co. analyst Andrew Fein initiated coverage with a buy rating and 12-month price target of $7 per share. He predicted Combiplex "could be a game changer in cancer chemotherapy" and described Celator as "a low risk, high reward scenario, since the platform evaluates chemotherapy drugs that are used in the front-line setting and importantly, whose existing efficacy and safety profiles are well known."