Filip Dubovsky
Analyst · Jefferies. Please, go ahead
Thanks, Stan. Since the last call, we have developed a significant amount of new clinical data. Today, I'm going to review data from Study 307, which is our lot to lot consistency study that includes boosting on top of two and three doses of mRNA. Then, I'll describe preliminary findings from 311, our strain change study that evaluated boosted responses to a prototype vaccine, Omicron BA.1 vaccine and bivalent vaccine when given on top of three doses of mRNA vaccine. But first, I want to review some findings we have recently disclosed. Please advance to slide seven. From our UK study, we recently published that our vaccine had 82% efficacy for preventing all infections over six-month observation period. This was despite the majority of cases being caused by the alpha variant. Protection from infection is important, because if you don't get infected, you can't transmit virus, you can't get sequelae for COVID, and you can't get long COVID and you can't be the source of new variants. In our adult US-Mexico Phase 3 study, we achieved a formal regulatory endpoint supporting boosting in the US population, and we demonstrated a durable immune response, as well as a broad immune response that includes cross-reactive antibody levels directed against Omicron variants that were consistent with levels associated with protection in our Phase 3 studies. In our adolescents Phase 3 study, we made the regulatory endpoint for boosting in 12 to 17-year-olds and show the hemologic responses to Omicron variants were comparable to those associated with protection. Okay. Let's go to slide eight and talk about Study 307, which is our lot to lot consistency study. For this study, I'll discuss data supporting the achievement of our lot-to-lot endpoint and the magnitude and breadth of the heterologous boosting response. This is still preliminary data and additional immunologic assessment is ongoing. So let's move to slide nine, please. Study 307 enrolled 911 adults in the US who had no history of recent COVID infection and who had received two or three doses of an approved COVID vaccine with the last dose being at least six months prior to enrollment. As you can see on this slide, most of our subjects received two or three doses of either Moderna or Pfizer. If you received one or two doses of J&J and a very small number had received two doses of Novavax. After enrollment, all subjects were boosted with one of three different lots of Novavax vaccine and the serum was collected at day 28 for hemologic assessment. Let's move to slide 10. Demographics show the three lot groups were well balanced. The racial makeup was broadly representative of the general US population and the median interval prior to the Novavax boost was approximately nine months. Let's go to slide 11 and look at the primary endpoint. As you can see here, the primary endpoint of non-inferior immunogenicity was achieved, as measured by anti-S IgG titers at day 28. This was the regulatory endpoint confirming consistency of our manufacturing process. You can please note the extremely tight confidence intervals here. But let's look at the immune responses following heterologous and homologous boosting on slide 12, please. Because most of the subjects in this trial received the Novavax vaccine as a heterologous booster, we had the opportunity to evaluate the magnitude and breadth of immunogenicity in different subsets. Shown on the far left are IgG responses in a small group of seven subjects who received two doses of Novavax's priming series followed by a single Novavax boost. We're also showing responses for those who received two prior does of Moderna, two prior doses of Pfizer, and one dose of J& J. A super imposed a closer protection threshold derived by the US government based on our US Phase 3 trial and the actual Phase 3 levels we obtained in our two Phase 3 studies. The post-booster levels we saw in this trial matched or exceeded the levels achieved in the Phase 3 efficacy study. Consistent with what we've seen previously, we observed the highest antibody titers for the homologous Novavax boosting subset. Okay, let's go to slide 13 and look at heterologous boosting on top of three doses of mRNA. This is a similar set up to the previous slide, but for the group's received three prior doses of Moderna or Pfizer or two prior doses of J&J. So, a full primary course plus one prior boost. In each of these subsets, the antibody levels exceeded the Phase III levels. And for the mRNA recipients levels were approximately 20% to 30% higher than we saw in the previous slide with priming was just two doses of mRNA. The group with two doses of J&J had broad conference intervals because of the small sample size. Now, let's look at slide 14 to look at the breadth of immune response. Here, we evaluated IgG responses to prototype and to Omicron sub-variants BA.1 and 5. we are displaying the two doses of Novavax boosted once with Novavax as a solid bar on the far left hand side of each triplet. And as compared to three doses of Moderna or three doses of Pfizer boosted once with Novavax. In all cases, IgG titers achieved levels predicted to be or protection was approximately 88% to 95%. As before, the highest antibody titers against both prototype and variants were in homologous Novavax boosted subjects. In summary, we believe the 307 findings are important both because they confirm consistency of manufacturing, which is critical for vaccine life insured in the US and because they showed robust immune responses to prototype and variants after homologous and heterologous boosting with post-boosting antibody levels approximating those levels associated with protection in our Phase 3 studies. So, let's move to slide 15 and talk about the next study. Now, I'll review the topline data from study 311. The study was designed as a strain change study and evaluated the performance of our prototype vaccine and Omicron BA.1 vaccine and a bivalent format vaccine when given after two and three doses of mRNA. So, let's go to slide 16, the design. The study was conducted in Australia in adults 18 to 64 years of age. The participants received two or three doses of mRNA and were boosted with either our prototype vaccine, the BA.1 vaccine, or the bivalent vaccine. Today, I will only talk about participants who received three prior doses of mRNA and who are boosted at least 90 days after their last dose. So, let's look at demographics on slide 17. The study groups are well balanced with facial group's representative of the overall Australian population, the participants received their boost the median of 180 days after their last mRNA dose. You can see that Australia did a better job of controlling infection is a relatively large proportion of this group did not have evidence of prior COVID infection. So, let's look at the endpoints on slide 18. The primary endpoint for the strain change portion was pre-specified to be in a three-dose group and participants who had no prior COVID infections. We compared the day 14 neutralizing responses against BA.1 in the three treatment groups. In the first column, we compare BA.1 in closed responses after being boosted with BA.1 vaccine to the BA.1 responses after being boosted with prototype. This was a strain change endpoint. And because the BA.1 vaccine responses against BA.1 were higher than those induced by the prototype vaccine, the study achieved a statistical endpoint, allowing for a strain change, if eventually needed. Let's get a click. The second column compares a bivalent vaccine to prototype. The responses were similar, with the conference intervals overlapping one. And the final column compares the bivalent vaccine to the BA.1 vaccine and the responses were lower for the bivalent vaccine. Let's have a click. So as far as the BA.1 responses go, the data does not support a measurable benefit for the bivalent vaccine. Okay. Let's look at some comparative data on slide 19. Here, we're looking at IgG responses against BA.1 and all the participants who received three prior doses of mRNA vaccine. This group most closely resembles the general population. Here, the responses were similar between all three vaccines. Although, when boosted with our prototype, it was numerically higher by about 15%. Please advance to slide 20. Here, we're looking at IgG responses against prototype the Wuhan strain. Once again, the responses were statistically comparable, with up to a 20% numerical benefit for boosting with the prototype vaccine. Of course, neither prototype nor BA.1 are in circulation currently. So let's look at forward different strains. Slide 21, please. Displayed here is a neutralization response against BA.5 measured in functional pseudoneutralization assay. BA.5 is an omicron subvariant that was not in any of the vaccines, but it's related to the BA.1, so we would expect a superior response with BA.1 vaccine. However, there was no benefit observed for either BA.1 vaccine nor the bivalent vaccine compared to the prototype vaccine. In fact, the prototype vaccine get numerically higher responses. This indicates that boosting with our current vaccine is a viable approach and be considered as a future-proof strategy for emerging variants. Okay, let's look at some reactogenicity on slide 22. When given as a second boost dose for all three formulations, they were similarly well tolerated with patterns consistent to what we've seen previously. Here are the most common local reactions are pain in tenderness, the vast majority being none, mild or moderate in severity. Let's go to slide 23 and look at solicited systemic symptoms, and the pattern is also very similar to what we've seen previously, with very low rates of grade three events and a negligible fever signal. Okay. Let's sum this up on slide 24. So to sum up, we believe our data supports the continued and future use of NVX-2373 as a booster. From our US-Mexico Phase 3 study using our prototype vaccine, we have described a durable immune response and the hemologic data indicating that the levels achieved against drifted Omicron variants were consistent with levels associated with protection in our Phase 3 studies. Today, I showed you data that when we are used as a heterologous booster after two or three doses of authorized vaccine, we achieved broad immune responses against drifted Omicron variants. And the magnitude of these responses are considered to be protective when applying the NIH US government calls of protection thresholds. Finally, our study with Omicron BA.1 vaccine and bivalent vaccine indicated no measurable benefit over our prototype vaccine. So when we think about what will be causing illness over the next few months, it will not BA.5, where there's some variant that is yet to emerge. The vaccine that induces high levels of cross-variant responses might be appealing as a way to future-proof the ongoing boosting effort. Importantly, the vaccine is currently stocked and can be deployed immediately. Finally, because this is our original vaccine, we have confidence in the preexisting long-lived safety database. This may be a feature that's attractive to individuals who are hesitant to be boosted. Okay. Let me turn it over to John Trizzino.