Barry Greene
Analyst · Barclays
Thanks, John. Good morning, everybody. I hope everybody is healthy and staying safe. I'll begin by reviewing our commercial performance in the first quarter. For ONPATTRO, we achieved $66.7 million in global net product revenues, representing nearly 20% quarter-on-quarter growth. As of March 31, we're delighted that over 950 patients are on commercial ONPATTRO treatments worldwide. In the United States, we continue to see progress with both repeat and new prescribers. And in the first quarter, we had 22 new prescribers. As for the mix of these U.S. prescribers, 57% of start forms submitted in the first quarter came from neurologists, 26% from cardiologists and 17% from other physician specialties. Fortunately for patients, we're seeing a treatment that's increasingly handled by multidisciplinary teams that include neurology, cardiology and other physician specialties, and we expect this mix to continue to evolve.
In the United States, we also continued to see increased concomitant use for ONPATTRO with TTR stabilizers. And recent market research suggests we've got about 15% to 30% of patients with hATTR amyloidosis polyneuropathy are receiving the common treatment as we expect this pattern in the U.S. to grow. Overall adherence to therapy remains very strong at over 90% in the first quarter, which we believe is an encouraging sign and consistent with the APOLLO Phase III data. Regarding U.S. market access, we continue to avoid any of the payer headwinds often reported with other orphan drug launches. Our VBA strategy continues to be very well received.
Now turning to the rest of the world. We're again very pleased with ONPATTRO performance. Japan delivered another very strong quarter of growth, and we continue to anticipate it will be our second-largest country after the U.S. for ONPATTRO revenue and patients on therapy exiting 2020. In the CEMEA region, we observed strength in France, Germany and the U.K. in the first quarter and continue to expand our footprint with recent launches in Italy, Sweden, Israel, Turkey and Spain.
Our team also remains committed to addressing the challenge of raising disease awareness and improving diagnosis of hATTR amyloidosis, including with Alnylam Act, our third-party genetic screening initiative in the United States and Canada and now recently in Brazil. As of April, almost 25,000 samples have been submitted, out of which over 1,500 have tested positive for a pathogenic TTR mutation. As with most diagnostics and tests across therapeutic areas, we've seen some slowdown in testing as the pandemic phase set in, but we expect sample numbers to return to near pandemic numbers as recovery phase in Q3 begins and beyond into the new normal.
Moving to GIVLAARI, for acute hepatic porphyria, or AHP, we achieved $5.3 million in U.S. net product revenues, with strong performance in our first full quarter of launch. We've received over 60 start forms in the United States with over 50 patients on commercial treatment from launch through March 31. We're pleased to see that patients are getting on drug within 1 to 2 weeks after the physician has submitted a start form. We're also seeing patients initiate therapy outside of start forms, a strong sign that providers appreciate the strong access environment Alnylam is establishing for their patients. To that point, similar to our experience with ONPATTRO, we've not experienced any major payer headwinds with GIVLAARI in the United States to date. Again, our VBA-based approach is looking successful here. And we're pleased to report that we've already had 1 signed VBA for GIVLAARI and our discussions with multiple payers interested in the VBA approach are progressing well.
Another highlight of patient access is that payers are adopting medical policies that are generally consistent with the approved GIVLAARI label, without restrictions to a number of baseline attacks. Now outside the United States, we're pleased to announce the approval in the EU of GIVLAARI in the first quarter and expect to open up key commercial geographies this year, with our initial European launch underway in Germany in Q2 and named patient sales occurring elsewhere in the region. Again, our team is focused on improving awareness and diagnosis of AHP in the patient and physician communities. Through Alnylam Act, we can report 809 tests submitted and 84 patients with positive AHP mutations as of April, representing about a 10% hit rate in samples tested.
Let me finish with more color around our supply chain and commercial activities in the face of COVID-19. As John mentioned, we expect 2020 to be comprised of the pandemic period through most of Q2, a recovery phase in Q3 and a new normal starting in Q4. Our supply chain remains intact, and we're confident we have sufficient inventory of commercial products, drug product, drug substance as well as raw materials for ONPATTRO and GIVLAARI and for lumasiran as we begin to prepare for that launch. We have comprehensive mitigation measures in place to reduce any potential supply chain exposure, if needed.
Our global field operations have largely shifted to virtual interactions with HCPs, payers and patients, with the exception of Japan, where our field employees are still able to conduct in-person meetings subject to local restrictions. I want to note that for some time, Alnylam has been developing digital and virtual tools. So we were well prepared for virtual interactions. We expect these virtual interactions and engagements to continue through the pandemic phase and into recovery phase. And while live face-to-face interactions are preferable in many cases, these new virtual tools will be part of the new normal. We believe some of the changes are actually very positive, and we think they can improve the efficiency and effectiveness of HCP interactions for our field force going forward.
Our teams also have been successful helping patients receive their ONPATTRO infusions or GIVLAARI injections at appropriate sites of care as determined with their physicians, including home setting, which is particularly important during this pandemic period. For ONPATTRO, home infusion has become broadly available in most countries, thanks in part to the recognition of value by physicians, payers and regulators. In the -- in U.S., a recent rule change by CMS created options for our Medicare patients to have coverage for home-based administration. Looking at the proportion of treatments received across academic centers, local centers and in the home, we've seen a significant shift toward home care from Q4 2019 into Q1 2020 as the pandemic response expands globally.
We believe, particularly in the United States, we'll continue to see patients shift to home care for local infusion centers in Q2 and beyond. For ONPATTRO, we believe adherence will likely decrease during the pandemic phase in Q2 due in part to some skipped doses or dose delays caused by patients moving to new care sites, including home care. We will continue with site-of-care optimization through the recovery phase as patients regain comfort returning to hospitals and clinics for treatment or decide to continue with in-home administration if that's an option for them.
Finally, we also anticipate that the pace of new patients [ instituting ] therapy will slow during Q2, given reduced genetic testing and diagnosis and patient flow through the health care systems. Thus, we expect some negative impact in Q2 with ONPATTRO revenues, potentially decreasing by about 10% versus Q1. And then we expect improvement and growth in the second half of the year as health care systems return in recovery and into a new normal.
Let me highlight here that the midpoint of our ONPATTRO revenue guidance represents expected year-on-year growth of greater than 70%, and we remain highly confident in our growth trajectory in all regions. We're playing the long game here, and our goal is to continue to build an industry-leading TTR franchise.
Now let me turn to GIVLAARI. AHP patients who experience debilitating porphyria attacks often require urgent care or hospitalization. So in this sense, new patient starts and continuity of GIVLAARI treatment are particularly important, given the impact of COVID-19 on urgent care and hospital sites. Given the ENVISION results, which show reduction in AHP attacks requiring urgent care visits or hospitalizations, we expect less of an impact on GIVLAARI adherence and new patient starts during the pandemic phase relative to ONPATTRO.
In summary, I'll reiterate that we're not simply waiting for the pandemic to pass, we're taking numerous steps to do what's right for patients and to mitigate impact on our business during the pandemic phase. We're very confident about our growth in the recovery phase and beyond, and also continue to see a very bright long-term prospects for our broader ATTR franchise and other marketed products like GIVLAARI.
As we've heard from -- as you heard from us many times, we're up for the ever-changing environment and will be stronger for it; as John said, challenge accepted.
With that, I'll now turn over to Akshay to review our recent R&D and pipeline progress. Akshay?