Murdo Gordon
Executive Vice President of Global Commercial Operations at Amgen
Thank you, Bob. Second quarter product sales increased 3% year-over-year. Volumes increased 8% driven by double-digit growth across a number of our products, including Prolia, Repatha and our biosimilar products MVASI and KANJINTI. Our ex-U.S. business grew 18%, with volume growth of 22% year-over-year. We continue to see gradual recovery from the impacts of the COVID-19 pandemic in Q2 when compared to Q1 2021. Patient visits and lab test procedure trends continue to improve but remain below pre-COVID-19 levels. We remain focused on customer execution.
Overall, U.S. field activity improved quarter-over-quarter, reaching 80% of pre-COVID levels. Face-to-face customer interactions are increasing and accounted for 60% of activity during the second quarter. Over the course of the pandemic, the cumulative decline in diagnoses has suppressed the volume of new patients starting treatment, which we expect will continue to impact our business during the second half of the year. Now let me review some product details, beginning with our innovative portfolio. In bone health, Prolia increased 24% year-over-year, driven primarily by volume growth. In the second quarter, osteoporosis diagnosis rates remained at approximately 90% of prepandemic levels. We remain focused on driving patient growth and are optimistic about Prolia's strength in the second half of the year. EVENITY sales increased 30% year-over-year driven by 32% volume growth.
In the U.S., sales nearly doubled year-over-year as we saw an acceleration in demand trends driven by new and continuing patients. We believe EVENITY's unique bone-building attributes will continue to drive revenue growth. Moving to Repatha, which has reached more than one million patients since launch. Repatha sales increased 43% year-over-year driven by 49% volume growth, and we maintained U.S. and global share leadership in the PCSK9 class.
In the U.S., total volumes grew 37% year-over-year. And outside the U.S., volumes grew 66% year-over-year. The volume growth in the quarter was partially offset by lower net selling price resulting from an increase in Medicare Part D patients receiving Repatha and entering the coverage gap. Looking forward, we expect some ongoing reduction in global net selling price on a sequential basis.
Overall, we're confident in our ability to grow Repatha to help more patients at risk of developing a heart attack or stroke. Now on to Aimovig, which grew 24% quarter-over-quarter. On a year-over-year basis, net sales declined 16%. Volumes grew 11% but were more than offset by lower net selling price and unfavorable changes to estimated sales deductions. In the U.S., Aimovig TRx volume grew 7% year-on-year, and the brand maintained total prescription share leadership among subcutaneous CGRPs. Looking ahead, we see continued rebate pressure as oral CGRPs compete for share in the market. To date, more than 0.5 million patients worldwide have been prescribed Aimovig, and we believe Aimovig has significant potential to help many more patients suffering from chronic migraine given the clinical data that will be published soon showing Aimovig superiority versus topiramate.
Moving to our inflammation portfolio. Otezla sales were $534 million in the quarter, with 5% volume growth, more than offset by unfavorable changes to estimated sales deductions and lower net selling price. In the U.S., Otezla maintained first-line share leadership in psoriasis. New-to-brand prescription volumes grew 10% year-over-year even as patient visits to dermatologists remained 15% below prepandemic levels. The number of new patients who started treatment with Otezla in Q2 was near prepandemic levels, but those gains were largely offset by a lower percentage of 90-day prescription fills and lower prescription refill rates for Otezla.
We expect that pandemic recovery in the dermatology segment will progress over the coming quarters. Looking forward, we're preparing for the anticipated approval of the mild-to-moderate psoriasis indication in the U.S. later this year and for the launch of Otezla in China. Enbrel sales decreased 8% year-over-year, primarily driven by lower net selling prices and unfavorable changes to estimated sales deductions. On a year-over-year basis, volumes declined 1%, supported by Enbrel's long track record of efficacy and safety.
Turning to biosimilars. Q2 sales were $567 million driven by strong volume growth, which was partially offset by declines in net selling price. We continue to hold leading biosimilar shares in Europe for AMGEVITA and in the U.S. for MVASI and KANJINTI. For the remainder of the year, we expect worldwide biosimilar volume growth to be offset by declines in net selling price due to increased competition. Longer term, growth for biosimilars will come from expansion of existing products in new markets and launches of additional biosimilar molecules, such as AMGEVITA in the U.S. and biosimilars for SOLIRIS, STELARA and EYLEA.
In oncology, Neulasta Onpro remains the preferred long-acting G-CSF, with 52% volume share in the quarter. Sales declined 18% year-over-year driven by lower net selling price and lower volume. This was partially offset by a $75 million year-over-year benefit from favorable changes in reimbursement mix. Neulasta's U.S. average selling price declined 35% year-over-year and 12% quarter-over-quarter. We expect this trend will continue throughout 2021 driven by intensifying competition. KYPROLIS sales increased 11% year-over-year, primarily driven by volume growth and net selling price. Moving forward, we expect growth from KYPROLIS use in combination with CD38 antibodies, including DARZALEX and SARCLISA. I'd like to take this opportunity to comment on our recent launch of LUMAKRAS, which is off to a strong start with unaided brand awareness increasing 20 points since launch.
KRAS testing in patients with metastatic non-small cell lung cancer now stands at 70%, and 46 of the top 50 testing labs now identify KRAS G12C as actionable in their laboratories. We're very pleased with the positive reaction from the oncology community, and we'll be working closely with them to ensure access for patients who can benefit from this breakthrough medicine. Overall, I'm pleased with our Q2 execution given the sustained impact of COVID-19 on our business. We closely monitor the course of the pandemic and its impact on patients and physician behavior during the second half of the year. We'll maintain our focus on execution to ensure our medicines continue to reach the patients they can benefit. And with that, I will turn it over to Dave.