* Denosumab promising in breast, mixed tumours vs Zometa
* Adverse events and survival rates similar for both drugs
* Amgen R&D head says denosumab has clear advantages
* Amgen shares up 1.5 percent
(Recasts with abstract on breast cancer study, executive comments, latest shares)
By Ben Hirschler
BERLIN, Sept 21 (Reuters) - Amgen's (AMGN.O: Quote, Profile, Research, Stock Buzz) closely watched experimental bone-strengthening drug denosumab helped patients with advanced cancer, researchers said on Monday, reinforcing its potential as an alternative to standard therapy.
Breast cancer patients on the drug survived without their disease progressing for longer than those using Novartis' (NOVN.VX: Quote, Profile, Research, Stock Buzz) Zometa, according to a late-stage Phase III study to be presented this week at the ECCO-ESMO cancer congress in Berlin.
Shares of Amgen rose 1.5 percent in early trade as another study data also showed denosumab helped patients with a mix of advanced cancer types.
Amgen research and development chief Roger Perlmutter told Reuters in an interview in New York that denosumab had clear advantages over Zometa in effectiveness, in convenience and in not causing the kidney toxicity seen with the Novartis drug.
Amgen shares had soared in July when it announced denosumab reduced and delayed serious bone complications among patients with advanced breast cancer. But analysts said investors were subsequently concerned the detailed data would show worrisome trends about time-to-tumour progression.
In fact, an abstract released at the cancer meeting in Berlin showed a hazard ratio of 0.99, where anything over 1 would have indicated a negative trend for denosumab.
"With an ever-so-slight trend favoring (denosumab)..., we think concerns as to the potential for increased risk of tumour progression are now effectively alleviated," Chris Raymond, an analyst with Robert W. Baird, said in a research note.
The second study in mixed tumour types showed denosumab was similarly effective as Novartis's Zometa in delaying time to fracture or other skeletal-related events (SREs).
The delay to first SRE was actually numerically greater with Amgen's drug at 20.6 months, against 16.3 months for Zometa, but this difference was not statistically significant.
The study's goal had been to show non-inferiority and Amgen had announced last month that it met this endpoint.
The trial looked at 1,776 advanced cancer patients with solid tumours, not including breast and prostate cancer, or multiple myeloma. Bone destruction is a major cause of pain in approximately 70 percent of patients with metastatic disease.
Adverse events, including jaw damage, were similar between the two groups, as was survival and the time to cancer progression. The study investigators added the drug's profile on kidney function was reassuring.
"It is encouraging to see denosumab's efficacy in this broad cancer population. There is no need for renal monitoring or dose adjustments due to renal impairment," said David Henry of Pennsylvania Hospital, Philadelphia.
Full results of the study in breast cancer patients will be detailed at the meeting on Tuesday.
Amgen believes denosumab will be a popular choice with doctors and patients, since it is given as a monthly injection under the skin rather than intravenously. It also avoids the flu-like symptoms associated with Zometa.
Henry said this made it "an exciting potential treatment option for advanced cancer patients".
"I'm a practising oncologist and what is so important to our patients is convenience and safety," he said.
"In our clinics we see patients every day (and what is important is) helping patients get in and out quickly with the least impact on quality of life."
Denosumab is the first in a new class of drugs that inhibit proteins that activate bone-destroying cells. It is expected to be used first for osteoporosis, or brittle bone disease.
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