Kiniksa Pharmaceuticals International (KNSA) Q2 2026 earnings call transcript

Thank you, Operator. Good morning, everyone, and welcome to the Kiniksa Pharmaceuticals second quarter 2026 earnings call. A press release highlighting our financial results and recent portfolio execution can be found on our website under the Investors section.

As for the agenda, our Chief Executive Officer, Sanj K. Patel, will start with an introduction that will be followed by Ross Mote, our Chief Operating Officer, who will provide an update on ARCALIST commercial execution. From there, Kiniksa's Chief Medical Officer, Dr. John Paolini, will review our KPL 387 Development Program and the ongoing Phase 2-3 clinical trial in recurrent pericarditis. After that, Mark Ragosa, our Chief Financial Officer, will review our second quarter 2026 financial results. And finally, Sanj will share closing remarks and kick off the Q&A session.

Before getting started, please note that we will be making forward-looking statements today that are subject to risks and uncertainties that may cause actual results to differ materially from such statements. A review of these statements and risk factors can be found on this slide, as well as under the caption, Risk Factors, contained in our SEC filings. These statements speak only at the date of this presentation, and we undertake no obligation to update such statements, except as required by law.

With that, I'll turn it over to Sanj.

Thanks, Jonathan, and good morning or good afternoon, everyone. Again, Kiniksa is in a strong position more than halfway through 2026 as we continue to execute across our portfolio. We continue to make excellent progress with our list and have advanced the KPL 307 program into the pivotal stage with the initiation of the phase three trial, which we have named PASTER-OFF. Additionally, KPL1161, which is our FC-modified IL-1 alpha and beta inhibitor with a target profile of quarterly dosing, is progressing well, and the program remains on track to initiate a Phase I study by the end of this year. Importantly, we continue to maintain a robust financial position, which together with strong commercial momentum and key advancements in our development pipeline, positions the company with multiple value-creating drivers in both the near and long term.

Our ongoing execution of the Onclus commercial strategy resulted in a meaningful increase in the number of patients on therapy. Robust revenue growth of more than $29 million over the previous quarter drove sales of $243.6 million in the second quarter. And we continue to build on our strong commercial momentum, and we've raised our full year 2026 revenue guidance from $930 to $945 million to between $980 and $995 million. On the clinical side, just this morning, we announced data from the dose-focusing portion of the KPL387 Phase II, Phase III study in recurrent pericarditis.

On the basis of the Phase II data, I'm happy to report that we are moving forward with the target profile of a monthly dose into the pivotal Phase III portion of the trial. Today, we also announced that this phase 3 study has already started and is now enrolling and dosing patients. The ongoing phase 3 study, PASOAL, marks a key milestone in bringing additional treatment options to patients suffering from recurrent pericarditis. This trial follows Rhapsody, the successful Phase III program with ArcList, with both trials having the same registrational endpoint of reduction in the risk of pericarditis recurrence.

John will share additional details about the Phase II data in a moment, as well as provide an overview of the design of this Phase III study. We anticipate a potential commercial launch of KPL 307 in the 2028 and 2029 timeframe, extending our leadership in the recurrent pericoditis market so it can help many more patients. And with that, I'll turn it over to Ross to review our commercial execution.

Ross.

Thank you, Saj. In Q2, the Kiniksa commercial team continued to drive strong growth with Arculus. Our net revenue was $243.6 million, which is more than $85 million growth versus Q2 of 2025, and more than $29 million growth compared to Q1 2026. This represents the largest quarterly net revenue increase since our launch more than five years ago, and is a direct result of the execution of the strategy that we laid out at the beginning of this year. Our commercial approach has helped to change the treatment paradigm for recurrent pericarditis, and we are focused on continuing to unlock future growth for ArcList.

Over time, we have made disciplined, value-driven investments across our sales infrastructure, as well as innovative strategies that have enabled us to reach more patients. Firstly, we've been diligently ensuring that prescribers have a positive prescribing experience, which encourages deeper prescribing as well as peer-to-peer education to other healthcare professionals. Additionally, we've been investing in machine learning and the use of AI to provide our sales team with insights on not just who to target, but importantly, when to visit and what messages should be delivered. Secondly, in April of this year, we launched our targeted DTC campaign called Hearts Home. This campaign is aimed at educating and empowering patients who are suffering from recurrent pericarditis to visit their healthcare professional and ask for ARCLIS.

So far, the campaign has reached thousands of patients who are suffering from recurrent pericarditis. While it's still in the early stages, we are starting to see encouraging signs of engagement with our campaign and patients visiting their healthcare professional to discuss ARCLIST. Thirdly, our teams have been highly focused on disseminating the 2025 ACC concise clinical guidance for recurrent peritillitis. The understanding of this guidance and the recommendation of moving ARCLIST earlier in line after NSAIDs and colchizine and ahead of corticosteroids has helped to expand the utilization of ARCLIST. Since our focus on disseminating this publication, we've seen an increase in doctors who have changed their treatment approach and are now using ArcList earlier in the disease course.

Finally, the commercialization is underpinned by ArcList's highly efficacious and well-tolerated profile, along with robust compliance, growing persistence, and an excellent payer approval rate. As of the end of Q2, our penetration into the multiple recurrence population had grown to approximately 21% compared to around 18% at the end of 2025. This demonstrates both strong growth as well as the substantial opportunity ahead. As mentioned on the last slide we seeing continued momentum in the breadth and depth of ARCLEs prescribing which in Q2 led to significantly higher number of new patient enrollments compared to any quarter since our launch Approximately 450 additional healthcare professionals wrote their first ARKLIS prescription in the second quarter, bringing the total prescriber base to more than 5,000 launched to date.

As a reminder, there are more than 25,000 healthcare professionals across the country who manage recurrent pericarditis patients. Therefore, the opportunity for continued growth is evident. Additionally, the number of healthcare professionals who have written multiple prescriptions increased by approximately 150 compared to Q1 of 2026, meaning that around 29% of the prescriber base have written ARCLIS for two or more patients.

The dual acceleration in both new and repeat prescribing led to an increase in patient enrollments, which resulted in a substantial increase to the number of patients on therapy and illustrates the demand for a highly efficacious treatment that protects patients from suffering unnecessary additional flares. As you can hear, we're pleased with the Q2 performance, but we continue to be even more excited by the opportunity that's ahead. And with that, I'll turn the call over to Dr. John Paolini to share more information on our KPL 387 program in recurrent pericarditis. John.

Thank you, Ross. As Sanj mentioned, the pivotal Phase III trial of KPL387 and recurring pericarditis has now been initiated and is already enrolling and dosing patients. Before that, I'll provide a brief overview of the Phase II dose-focusing portion of the trial, data from which affirmed the dose level for Phase III. As a reminder, for the Phase 2-3 study, we have combined both portions into a single integrated protocol in order to maximize operational efficiency, thus allowing the Phase 3 portion to begin even while the Phase 2 trial is still ongoing. Phase 2 is designed to define the PK-PD relationship and provide information on the cadence and magnitude of initial response, as well as the durability of effect of defined subcutaneously administered KPL387 dose levels.

Up to approximately 80 participants presenting at screening with a pericarditis recurrence despite treatment with NSAIDs and colchicine are randomized equally into four arms to receive subcutaneously administered KPL 387 at 100 milligrams or 300 milligrams dosed biweekly or once monthly. Concommonate treatment with conventional oral therapies is weaned and discontinued within two weeks. To attain KPL387 monotherapy. The primary endpoint of the Phase II dose focusing study is time to treatment response through 24 weeks, defined as an NRS score of less than or equal to 2 on the 11-point daily pericarditis NRS pain scale, and normalization of C-reactive protein, a marker of pericardial inflammation. The data we announced today show that the KPL387 300-milligram monthly dose level demonstrated rapid and sustained onset of action with durable efficacy throughout the monthly dosing interval, affirming the 300-milligram monthly dose being evaluated in the Phase III study, Pasteurab.

Specifically, in this analysis, median time to treatment response was four days, with a 95% confidence interval of three to six days. Median time to pain response was four days, with a confidence interval of three to six days. And median time to CRP normalization was eight days, with a confidence interval of seven to nine days. The cadence and magnitude of these reductions in pain and inflammation are consistent with prior studies which supported ARCHELIST approval in recurring pericarditis.

KPL387 was generally well-tolerated, consistent with the well-known safety profile of IL-1 pathway inhibition. Regarding the other dose levels in the study not selected for Phase III, the 100-milligram subcutaneous biweekly and monthly dose levels showed some effect, but not at the level to support further study. The KTL387-300-milligram biweekly dose level was efficacious, without incremental benefit above the monthly dose level. The totality of data available supported the initiation of Pastoral with the 300 mg subcutaneous monthly dose level.

The Pastoral design should look familiar based upon our prior work in Rhapsody. This pivotal phase 3 trial is a placebo-controlled, event-driven, randomized withdrawal study Designed to measure the reduction in risk of pericarditis recurrence as the primary demonstration of KPL 387 efficacy for the label. The primary efficacy endpoint is time to first adjudicated pericarditis recurrence during the randomized withdrawal period.

The trial will enroll up to approximately 85 participants experiencing a pericarditis recurrence despite conventional oral therapies into a single-blind run-in period. During which KPL-387 is initiated and oral therapies are weaned and discontinued. Participants are blinded to the duration of the run-in period. Subsequently, participants who respond to KPL-387 in the run-in period then enter the randomized withdrawal period in which they either continue receiving KPL-387 300 milligrams once monthly or switch to placebo. However, upon closure of the randomized withdrawal period, participants may be eligible to continue into a long-term extension.

As we have mentioned, our goal is to bring this potential new additional treatment option to patients in the 2028 to 2029 timeframe. I will now turn the call over to Mark to cover our second quarter financials. Mark?

Thanks, John. This morning, I'll walk through our second quarter 2026 financial performance and highlight the key drivers behind the results. As always, detailed financial information is available in today's press release. The quarter reflected strong execution with continued momentum across our commercial business, advancement of our development pipeline, and further strengthening of our financial position. Starting on the left-hand side of this slide with the income statement, ARCLIS revenue grew 55% year-over-year to $243.6 million in the second quarter. As you've heard from Ross, this growth was driven by continued expansion in new and repeat prescribers, as well as patient enrollments. Operating expense growth year-over-year was driven by several factors. Higher cost of goods sold due to ARC-less revenue growth, increased collaboration expenses aligned with higher ARC-less revenue and collaboration profit, higher R&D primarily due to the increased KPL 387 clinical trial costs as well as manufacturing costs, and also increased preclinical development investment.

And lastly, additional SG&A, primarily driven by investment associated with the commercialization of ARQIST. Together, these factors contributed to year-over-year increases in operating income and net income, which were $27.2 million and $25.4 million, respectively. The calculation for ARCLIS collaboration profit drives total collaboration expenses is on the right-hand side of the slide. Here, we continue to leverage disciplined commercial investment as ARCLIS collaboration profit grew faster than sales on a year-over-year basis, increasing 68% to $176.1 million. Turning next to cash at the bottom of the slide we ended the second quarter with a million cash balance representing approximately million of net cash generation for the period Looking ahead we believe our operating plan enables us to continue helping patients while creating additional value over both the near and longer term With that I turn the call back to Sanj for closing remarks Thanks Mark As you heard Kiniksa is well to build significant future value as we grow our IO1 Alpha and Beta inhibition franchise We are dedicated to helping as many patients as possible with our clists, and to advancing the development of our clinical portfolio in order to bring additional therapies to patients.

With that, I'll now turn the call back to the operator for questions.

Thanks, Nick. I'll say a few comments, and I'm sure I'll give it to Ross to dive into some detail. But look, as always, it's continuing to execute across the entire commercial strategy, and overall growing the adoption of IL-1 pathway inhibition as the preferred treatment for recurrent pericarditis. And that continues to happen every quarter. Certainly this quarter, Russell died into the number of new unique prescribers we've had this quarter, as well as the number of new repeat prescribers and the new enrollments. But ultimately, it's a matter of just continuing to penetrate into the total population, which we're doing. And obviously, the total duration of therapy is very important. That's about in line, really, with the median duration of the disease, about three years.

But ultimately, penetrating into that, as we just reported, we're now around 21% penetrated into the multiple recurrence population. But that, to me, represents a meaningful opportunity ahead. And so that's what we're focused on. So very excited about it. Ross, why don't you dive into some of the drivers and the actual numbers across those metrics? But there's a special source that just continues to execute.

Thanks, Sanj. And thanks for the question, Nick. And I think that's absolutely right. I mean, this is a culmination of, you know, a lot of work across all our commercial and cross-functional teams at this point, and where we've got to really understand in the recurrent pericolitis market and really just generally executing flawlessly across the board. So really kudos to all of the team that have been able to help so many patients throughout Q2. Ultimately, we've seen a substantial uplift in the number of both new prescribers and new repeat prescribers, as San said. We have more than 450 new prescribers coming to the total prescribing base in Q2, more than 150 new repeat prescribers, meaning they prescribe for two or more patients in the quarter.

And ultimately, that's kind of grown the number of patients that are on therapy, which led to both the results in Q2 being the highest number of new revenue, incremental revenue that we've had in any quarter since launch, as well as the highest number of new prescribers. Ultimately, some of the driving factors underneath that as well are some of the actions that we've put into place around investing in AI and machine learning, trying to make our field team even more effective than they historically have been, knowing just not only kind of who to call upon in a very traditional targeting approach, but more importantly now seeing when to call upon doctors. And some of that through claims analysis alerts, but importantly predictive alerts as well of when patients may be coming into FLARE and visiting particular healthcare professionals.

As you know, we've also invested in the DTC campaign, and that's starting to show some early signs of success driving patients into the clinic to ask specifically for ARCLIST. And I think the third point that's worth mentioning is around the dissemination of the ACC concise clinical guidance, which actually was published in August of last year. But generally speaking, because these recurrent pericarditis patients are very widely dispersed around the country, many of the general cardiologists are not familiar with the ACC concise clinical guidance for recurrent pericarditis. So our dissemination efforts in really explaining what that guidance document means and how, you know, IO1 inhibition is now placed after NSAIDs and colchizine use and prior to corticosteroids has been a key part in the transformation of really changing the treatment paradigm and being able to help many more patients.

So I think all said, it's really rolled up to just ongoing, solid execution across the team and acknowledging that even now, five years plus into the launch, there remains very significant opportunity for Arcus moving forward.

Thank you very much. It's all very helpful. Thank you.

Ross, why don't you start with a big important mark, if you can comment on the GTN. Yeah, absolutely. Let's do that.

Thank you, Ava, for the question. We haven't really seen any changes in the actual patient profiles as such, whether that's through, you know, kind of demographics of the patients for what, you know, to what level we know about that, or the type of institutions that healthcare professionals that are prescribing is still really across the board, kind of academic centers, more rural centers. The opportunity, I think, is still, you know, very, very broad across the country. So we haven't really seen a change in patient profile or phenotype to what we've seen. I think this is really more through just a greater understanding of recurrent pericarditis, greater efforts from the cardiology community to really differentiate between, you know, the first index pericarditis episode and actually when this becomes recurrent pericarditis.

As you know, historically, the misdiagnosis and underdiagnosis rate is pretty substantial, and patients go through seeing many healthcare professionals before getting the recurrent pericarditis diagnosis. So we've seen that, I think, improve over time, and I think that's really everything. There's no major changes, and I'm just happy to see more patients getting the help that they really need and deserve.

I guess, David, your second question regarding gross to net in the quarter. Historically, gross to net does move lower sequentially in the second quarter. That was the case again this year. Year-to-date, gross to net is 7.2 percent, down from 8.6 percent in the first quarter, with the main driver being lower copay due to changes that we made to our support program at the beginning of the year. And I think as you look throughout the rest of the year here, you know, we don't provide specific growth to net guidance, but we do anticipate support to continue to be favorable to growth to net on an annual basis, with the majority of the impact having taken place in the first quarter.

And additionally, we do expect sort of the normal pattern to hold here. So absent any prior period reserve adjustments, you know, our gross net historically has been highest in the first quarter, a lower in Q2 and Q3, and then, you know, works a little bit higher in the fourth quarter as industry dynamics begin to play a factor. So I'll leave it there.

Very helpful. Thanks. Thank you.

John, I'm not sure if you want to come up on the Phase 3 study, but essentially, obviously, we're pretty excited about the Phase 2 results we've seen. We're obviously now moving into Phase 3. As we've said, we're excited about the target profile of KPL 387, So, we're just focusing on really getting through the rest of the enrollment on the Phase 3 study and hopefully seeing the results and being on the market in the 2829 timeframe. But John, any comments from the Phase 3 study?

No I mean I would say that the profile as Sanch mentioned of KTL 387 that we taking into the Phase III study is one that we very excited about Rapid onset of action durable efficacy you know throughout the monthly dose interval that being studied you know in Phase III and pastoral So that sets us up in an excellent position you know for the pivotal Phase III trial The design of the Phase III trial is one that you know we understand well and that is well you know understood you know in the scientific community as a randomized withdrawal study design And so, you know, we are prepared to execute on that and to bring the trial forward.

Thanks, Jeff. I appreciate your question. So if I just answer your question on ARC-List, thinking about the demand in the first recurrence population, we've seen that physicians are continuing to utilize ARC-List broadly across the very broad label that we have, which, as you know, is agnostic to the number of recurrences that a patient has suffered from. There's around 40,000 patients in any given year that fit within the recurrent pericarditis label. When you break that down, we have about 80% of all new patient prescribing happening in the 2-plus recurrence, so that's about 80% of new prescriptions that are coming in in a quarter for patients that are on their second or more recurrence, And that's a 14,000 patient population.

And based upon that population, that's where we mentioned that we're now penetrated around 21% into that opportunity. And that's not accounting for the patients, to your question directly, that are on their first recurrence. And again, fitting within the label, that's a larger patient group. It's around 26,000 of the 40,000 patients. And we see about 20% of the ARKLIST prescriptions in Q2 that are within that patient group. And that's been growing over time, and I think some of that reflects the acknowledgement of the broad label, the increasing confidence of using ARKLIST, and ultimately the ongoing opportunity that there is ahead.

Thank you. Thank you. Thank you.

John, why don't you start and jump in. Sounds great.

Thank you, Adepam, for the question. Yes, we would concur that the data that we have shown from the Phase II trial in terms of time to treatment response, time to pain response, and time to CO3 normalization, You know, are very robust and are consistent with what has been seen previously in trials that supported, you know, relatoceptic approval and recurring pericarditis, especially when one takes a confidence interval approach, you know, to looking at the numbers with your point estimates.

Ross? Yeah, thank you, Anya Pam. Yes, we did previously share some market research around thoughts from patients and healthcare professionals on the target product profile of KPL387 versus kind of current commercial and other investigational therapies. And really, that showed that, you know, both to a high degree for both the patients and the healthcare professionals, they were pretty excited about the KPL 387 target product profile with around 75% of patients saying that they would prefer the KPL 387 target product profile over current commercial or available or investigational therapies. And around 92% of healthcare professionals indicating a high likelihood to prescribe for new patients in the context of the target product profile.

Additionally, you know, the potential availability of another, you know, IL-1 therapy could also expand the pool of patients for IL-1 inhibition overall with the monthly target product profile. Thank you.

Maybe I'll come and Jonathan, if you can take the rest. Thanks, Paul. So, look, we're always looking at our Salesforce analytics and working out the best way to reach these physicians and healthcare professionals. That's an ongoing basis for us. So I don't know if there's anything to report really on that side. As Ross mentioned, we continue to leverage the AI and machine learning and digital marketing, which has been really helpful. But, again, it's just really one part. There are a multitude of ways that we've got to continue to keep working to continue to penetrate into the total population, which we're doing. So it's really a matter of no one-size-fits-all. You've got to continue to execute across all those functions.

So we'll continue to crack on. Clearly, the 21% penetration so far tells you there's an awful lot more work to do, and that's what we're geared up to do. So we'll do it with the best where we can across all those different areas and hopefully continue to report information to you going forward.

Thank you, Paul, for your question. So, yes, the KTL-387 transition to monotherapy, the dosing and administration study, it was a phase two study designed to provide supplemental information for the label and to assist, provide basically the information to assist clinicians as they move, you know, across different therapies, if you will, for recurring pericarditis. And so that trial is designed to, with different dosing regimens, to test that efficacy and safety as patients move from regimens of NSAIDs and colchicine or corticosteroids or IL-1 pathway inhibitors, including anakinra and rolanoset. And so at the end of that study, you know, with these different dosing paradigms having been tested, that enables the writing, if you will, of the dosing and administration section of the label in order to, you know, allow patients to move smoothly, you know, across therapeutic lines.

Okay, great. Thank you. Thank you.

Yeah, thank you, David, for the question. So, the data that were obtained for this analysis is an interval analysis of the ongoing study, and as such, you know, the disclosure is limited. And so what we can say is that we have harvested this information to affirm the 300-milligram monthly dose, certainly beyond the monthly dose interval in order to show that at the trough, if you will, of the monthly dose interval, the treatment effect is robust. And other than that, that is the limit of what we have said. What we have also said, though, is that the 300-milligram biweekly dose level, which, of course, delivers more drugs, did not provide incremental benefit above the 300-milligram monthly dose.

Okay. Okay, thanks. Thank you.

Thank you, Operator. Well, we better crack on. Thank you for all the questions today. Joining the call, we look forward to the remainder of the year and to providing additional updates in the future. Thank you.