Amgen will shut down the former Onyx Therapeutics site in South San Francisco, CA—which the biotech giant acquired with the company a year and a half ago—and cut 300 of 750 jobs now based there, in a consolidation of the company’s oncology operations.

In a memo sent Monday to employees, Amgen chairman and CEO Robert A. Bradway said sales and medical staff inherited from Onyx will be shifted to Amgen’s headquarters in Thousand Oaks, CA, as well as a company research site that is also in South San Francisco.

Bradway said the consolidation would benefit Amgen by combining its scale and immuno-oncology expertise with Onyx's approach to blood malignancies.

“These combined oncology capabilities will create the focus and efficiency Amgen requires to progress our vision in oncology, and to remain a world leader for the long term,” Bradway told employees.

“We anticipate reducing our Onyx workforce by approximately 300 home office and remote worker positions. To ensure our ability to continue delivering for patients, all Onyx home office staff and remote workers will be retained through December 31, 2015, and will be informed of their longer-term employment status by late-April,” Bradway added.

Amgen disclosed the consolidation about a week after trumpeting results from the Phase III ENDEAVOR trial showing that Onyx-developed Kyprolis (carfilzomib) for injection, combined with low-dose dexamethasone, outperformed Takeda’s Velcade® (bortezomib) and low-dose dexamethasone.

Kyprolis met the pivotal trial’s primary endpoint of progression-free survival (PFS), Amgen said on March 1, while patients with relapsed multiple myeloma treated who were treated with Kyprolis lived twice as long without their disease worsening, demonstrating statistically and clinically significant superiority over Velcade (median PFS 18.7 months versus 9.4 months).

The Kyprolis combination demonstrated superiority over the Velcade combination for secondary objectives of higher overall response rate and lower neuropathy events, Amgen reported, adding that overall survival data continue to be monitored.

Amgen acquired Onyx for $10.4 billion, in a deal completed October 1, 2013.

“While I recognize this will be difficult news for our colleagues in Onyx, I want to extend my gratitude and appreciation for everything Onyx has achieved over the years in support of cancer patients,” Bradway added.

Amgen’s shedding of Onyx jobs is the latest wave of layoffs for the company. Last July, Amgen said it would eliminate up to 2,900 jobs companywide, while shutting down its facilities in the states of Washington and Colorado—then increased the number of planned layoffs in October to between about 3,500 and 4,000 positions by the end of 2015—some 20% of the company’s total workforce.