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Good afternoon, and welcome to Castle Biosciences Fourth Quarter and Full Year 2023 Conference Call. As a reminder, today's call is being recorded. We will begin today's call with opening remarks and introductions followed by a question and answer session. I would now like to turn the call over to Camilla

Thank you, operator. Good afternoon, everyone. Welcome to Castle Biosciences fourth-quarter and full year 2023 financial results conference call. Joining me today is Castle's Founder, President, and Chief Executive Officer, Derek Maetzold, and Chief Financial Officer, Frank Stokes. Information recorded on this call speaks only as of today, February 28, 2024. Therefore, if you are listening to the replay or reading the transcript of this call, any time-sensitive information may no longer be accurate. A recording of today's call will be available on the Investor Relations page of the company's website for approximately three weeks following the conclusion of the call. Before we begin, I would like to remind you that some of the statements made today will contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, statements about our financial outlook; ; and similar items referenced in our earnings release issued today, and statements containing projections regarding future events or our future financial or operational performance, including our anticipated 2024 total revenue and our 2025 outlook, our expectations regarding reimbursement for our products, and impact of our investments in growth initiatives and expanded commercial team. Forward-looking statements are based upon current expectations and involve inherent risks and uncertainties. There can be no assurances that the results contemplated in these statements will be realized. A number of factors and risks could cause actual results to differ materially from those contained in these forward-looking statements. These factors and other risks and uncertainties are described in detail in the company's annual report on Form 10-K for the year ended December 31, 2023 under the heading Risk Factors, and in the company's other documents and reports filed or to be filed with the Securities and Exchange Commission. These forward-looking statements speak only as of today, and we assume no obligation to update or revise these forward-looking statements as circumstances change. In addition, some of the information discussed today includes non-GAAP financial measures such as adjusted revenue, adjusted gross margin, and adjusted EBITDA that has not been calculated in accordance with generally accepted accounting principles in the United States or GAAP. These non-GAAP items should be used in addition to, and not as a substitute for, any GAAP results. We believe these metrics provide useful supplemental information in assessing our revenue and operating performance. Reconciliations of these non-GAAP financial measures to the most directly comparable GAAP financial measures are presented in the tables at the end of our earnings release issued earlier today, which has been posted on the Investor Relations page of the company's website. I will now turn the call over to Derek.

Thank you, Camilla, and good afternoon, everyone. I'm happy to report that we closed outstanding fourth quarter, achieving very strong results for 2023, with fourth quarter revenue of $66.1 million. We grew revenue 60% year over year for the full year to $219.8 million, nearly $45 million above the midpoint of our expectations at the beginning of 2023, We've now grown revenue at a 43% CAGR rate over the last five years, continuing our track record of consistent execution. We also achieved impressive test volume results by delivering a total of 70,429 total test reports in 2023, representing 59% growth compared to 2022. Furthermore, the fourth quarter marked the second consecutive quarter in which we achieved positive cash flow from operations and positive adjusted EBITDA. In 2023, we achieved numerous accomplishments, and I would like to take this opportunity to highlight some of them. We opened our new state-of-the-art laboratory in Pittsburgh, Pennsylvania; received advanced diagnostic laboratory test or ADLT status for our DecisionDx-SCC test, bringing our total to five tests that have been designated as ADLTs; expanded our significant body of evidence across our entire test portfolio; made progress across our pipeline initiatives; and won multiple awards for being a top workplace. None of our accomplishments would be possible without the hard work and strong execution of the entire Castle team, and I can't thank them enough. As I just mentioned, we expanded our significant body of evidence across our entire test portfolio in 2023. I want to touch base on specifically on DecisionDx-melanoma. We have demonstrated clinical validity, utility, and patient impact in fifty peer-reviewed publications, and studied the test in more than 10,000 patients, including two 2023 publications, demonstrating an association with clinical use of our tests and improved patient outcomes. The first publication is from our collaboration with the National Cancer Institute's SEER program in an unselected prospectively-tested real-world patient population, which show that testing with DecisionDX-melanoma was associated with lower melanoma-specific and overall mortality relative to untested patients. That is, patients who received DecisionDX-melanoma as part of their clinical care live longer. Specifically, DecisionDx-melanoma testing was associated with a 29% lower melanoma-specific mortality, and a 17% lower overall mortality relative to patients who did not receive DecisionDx-melanoma as part of their clinical care. The second publication is from an independent multicenter study of sentinel lymph node negative patients, showing that patients who received routine imaging after high risk DecisionDx-melanoma test scores, had an earlier recurrence diagnosis, with lower tumor burden leading to better clinical outcomes, including improved overall survival. We believe these studies demonstrate the clear positive impact testing with DecisionDx-melanoma has on patient outcomes. And further, DecisionDx-melanoma is the only melanoma prognostic test shown to be associated with improved patient survival. Now let me take you through execution strategy highlights from the fourth quarter and the fiscal year, and then Frank will provide additional financial highlights before we turn to your questions. Let's start with our core dermatology business, which continues to perform extremely well. For DecisionDx-melanoma and DecisionDx-SCC combined, test volume was 44,772 in 2023, a 33% increase over 2022. We are very pleased with our volume performance and believe these two core dermatology offerings continue to represent a significant growth opportunity. We continue to see overlap between clinicians who order our DecisionDx-melanoma test and those who adopt DecisionDx-SCC. In fact, during the year ended December 31, 2023, approximately 78% of all clinicians ordering DecisionDx-SCC had also ordered our DecisionDx-melanoma tests during the same period. We believe this is evidence of a high unmet clinical need that our tests are designed to address, coupled with the fact that clinicians who diagnose and manage early-stage cutaneous melanoma skin cancer also diagnose other skin cancers, like cutaneous squamous cell carcinoma. For DecisionDx-melanoma, we delivered 33,330 test reports in 2023, a 20% year-over-year increase. Consistent with prior years, our third and fourth quarter test volume reflected normal seasonality. We believe the documented clinical impact our tests have in improving outcomes in patients diagnosed with cutaneous melanoma including improved survival, coupled with our prior commercial expansion investments, have been and continue to be significant drivers of growth. Moving on to our DecisionDx-SCC tests, we continue to see a very strong test report volume momentum with 11,442 test reports delivered in 2023, an increase of 92% compared to 2022. As with our growth in DecisionDx-melanoma, we believe that our strong growth for DecisionDx-SCC is due in large part to the combination of a high clinical need in the high risk patient population, coupled with the value that our test provides. We continue to expand on the body of evidence surrounding the tests. For instance, a study published just last month in the Journal of Clinical and Aesthetic Dermatology found that using DecisionDx-SCC to guide decisions surrounding adjuvant radiation therapy, or ART, could result in significant Medicare healthcare savings of up to approximately $972 million annually. Data show that integrating the objective DecisionDx-SCC tests into the management of patients diagnosed with high-risk SCC who are ART-eligible identify those who may safely avoid ART, eading to an improvement not only in health outcomes, but also a reduction in the cost in the Medicare population. I would now like to turn to our TissueCypher. I'll remind you that as part of our strategic growth plans, we acquired Cernostics and the TissueCypher test in December 2021. The adoption of the TissueCypher Barrett's Esophagus test has exceeded our expectations to date. As you may recall, this test expanded our estimated in-market commercial US time by $1 billion, and we believe that it contributes to long-term value creation, and also positions us to make a meaningful impact on patient care in other areas with unmet clinical needs. We delivered 9,100 TissueCypher test reports in 2023, compared to 2,128 test reports in 2022, which is more than 300% growth. We continue to be extremely pleased with the reception of TissueCypher by the gastroenterology clinician community, and based on current volume growth trends, we plan to expand this commercial team modestly in the second quarter of 2024. As you may recall, we had multiple data announcements during 2023, bringing our total to 14 peer-reviewed publications, demonstrating the ability and performance of our TissueCypher tests, and risk stratifying patients with Barrett's Esophagus disease to guide risk-appropriate treatment plan decisions. Turning to our mental health business, we delivered 10,921 IDgenetix test reports in 2023 compared to 3,249 test reports in 2022, which is more than 200% growth. We believe a significant driver of growth is our differentiated tests for the treatment of mental health conditions, including identifying drug-drug, drug-gene, and lifestyle factors to improve medication response or remission rates in a large, underpenetrated mental health market. In fact, real-world evidence confirms a consistent impact of IDgenetix on medication response and remission rates in patients with major depressive disorder, or MDD. Specifically, the study found that real-world patient outcomes are strongly aligned to the result of a previously-published randomized control trial, which show that patients whose medication management was guided by IDgenetix were 2.65 times more likely to achieve remission of depressive symptoms compared to patients whose medications was not guided by our tests. Moving on to our inflammatory disease pipeline initiative to develop a genomic test, or series of tests, aimed at predicting response systemic therapy in patients with moderate-to-severe atopic dermatitis, psoriasis, and related conditions. Last quarter, we shared some early yet promising discovery data. The data demonstrated that in patients with moderate-to-severe atopic dermatitis, we're able to show that using our noninvasive method of tissue sampling, coupled with gene expression profiling, can separate out responders to nonresponders. Furthermore, our inflammatory skin disease pipeline tests could help distinguish a atopic dermatitis, psoriasis, and mycosis fungoides skin lesions to help ensure proper therapy selection based upon an individual patient's molecular profile. We expect to provide you with additional development updates in the second half of 2024 with a test targeted for launch by the end of 2025, assuming a positive outcome of our discovery, development, and validation efforts. I will now turn the call over to Frank, who will provide details relating to our financial results and outlook.

Thank you, Derek, and good afternoon, everyone. Reiterating Derek's sentiment, we're excited with the strong year we had in 2023 and the momentum we are carrying forward. In the fourth quarter of 2023 we delivered total revenue of $66.1 million, a 72% increase over the fourth quarter of 2022, and we delivered $219.8 million for the full year 2023, a 60% increase over 2022. The increase was driven by higher ASPs and test volume growth. Adjusted revenue, which excludes the effects of revenue adjustments in the current period related to tests delivered in prior periods, was $70.2 million for the quarter, and $224.3 million for the full year 2023. For 2024, we anticipate generating total revenue of $235 million to $240 million, driven by further consistent execution on our growth plans. Our gross margin in the fourth quarter was 77.8% compared to 69.4% in the fourth quarter of 2022, and our gross margin for the full year was 75.4% compared to 70.6% in 2022. Our adjusted gross margin, which excludes the effects of intangible asset amortization related to our acquisitions, and excludes the effects of revenue adjustments in the current period associated with test reports delivered in prior periods was 82.3% for the quarter, and 79.9% for the year, compared to 74.6% and 77% for the same periods in 2022. Turning to expenses, our total operating expenses, including cost of sales for the quarter ended December 31, 2023, were $71.8 million compared to $61.2 million for the prior year, and were $287.8 million for the full year compared to $209.9 million for 2022. Sales and marketing expense increased by $27.1 million or 31.2% for the year ended December 31, 2023, compared to the year ended December 31, 2022, primarily attributable to higher personnel costs. General and administrative expenses increased by $10.1 million or 17.9% for the year ended December 31, 2023 compared to the year ended December 31, 2022, primarily attributable to higher personnel costs and higher information technology and software related costs. R&D expense increased by $1.7 million in the fourth quarter, and by $8.7 million for the full year 2023 compared to 2022, primarily consisting of higher personnel costs and higher clinical studies expense, partially offset by lower expense from advisory boards and consulting services. Total non-cash stock-based compensation expense, which is allocated among cost of sales, R&D expense, and SG&A expense, totaled $51.2 million for the year ended December 31, 2023, compared to $36.3 million for the year ended December 31, 2022. We expect material increases in stock-based compensation expense in future periods attributable to both existing awards outstanding and anticipated additional grants to our current and future employees. We expect to complete an annual grant of equity awards to our employees in March of 2024. Interest income was $10.6 million for the full year 2023 compared to $4 million in 2022, primarily a result of higher interest rates and/or purchases of marketable investment securities beginning in the third quarter of 2022. Our net loss for the fourth quarter of 2023 was $2.6 million, compared to a net loss of $20.6 million for the fourth quarter of 2022, and our net loss for the full year 2023 was $57.5 million compared to a net loss of $67.1 million for 2022. Diluted loss per share for the fourth quarter was $0.10 compared to diluted loss per share of $0.17 in the fourth quarter of 2022. Diluted loss per share for the full year 2023 was $2.14 compared to diluted loss per share of $2.58 for 2022. Adjusted EBITDA for Q4 was $9.4 million compared to negative $10.4 million for the comparable period in 2022, an improvement of $19.8 million. For the full year 2023 adjusted EBITDA was negative $4.4 million compared to negative $42.6 million in 2022, an improvement of $38.2 million. Net cash provided by operating activities was $18.6 million for the fourth quarter, and net cash used in operating activities was $5.6 million for the year ended December 31st, 2023. We expect the first quarter of 2024 to be a net operating cash use quarter due to annual cash bonus payments and certain healthcare benefit payments that are not expected to recur during the remaining three quarters of 2024. Net cash used in investing activities was $15.2 million for the 12 months ended December 31, 2023, and consisted primarily of purchases of marketable investment securities of $189.1 million and purchases of property and equipment of $13.6 million, partially offset by the maturity of marketable investable securities of $186.5 million. We increased our cash position by more than $13 million in the fourth quarter of 2023 compared to the third quarter of 2023, ending the year with cash, cash equivalents and marketable securities of $243.1 million. In the current high interest rate environment, we believe our strong financial position allows us to continue to invest in our business, execute on our strategic growth plans, and maintain our competitive lead. In 2024, we expect our capital allocation priorities to remain consistent. These include the continued assessment and evolution of our commercial team, focused R&D efforts to build evidentiary support and develop tests, and as a lesser priority, exploring strategic opportunities in our current therapeutic areas. In conclusion, our 2023 financial and operational results were outstanding. We delivered strong growth in both revenue and test report volume as we continue to execute on our growth initiatives. I'll now turn the call back over to Derek.

Thank you, Frank. We believe our success in 2023 has allowed us to enter 2024 with momentum, and the potential to further position the company as an industry leader. I would like to conclude today by thanking our Castle team. Our excellent progress in 2023 is due to their accomplishments and dedication to the patients that we serve. This concludes our remarks. I thank you again for your continued interest in Castle Biosciences. Operator, we are now ready for Q&A.

[Operator Instructions]. First person we have online is Kyle Mikson of Canaccord.

Hey, thanks, guys, for the questions. Congrats on the quarter. Wanted to start with the '24 guidance and the underlying growth in the dermatologic test business. If you back out as you see revenue in '23 you might have had like $160 million to $170 million in quarter revenue. If you annualize the sequential growth in the fourth quarter, you've got about maybe 17%, 19% annual growth. if you apply that to the core revenue base there, it gets you maybe like $200 million in revenue next year. Then the guide would imply that the new tests, like, as you said, TissueCypher, IDgenetix, like don't grow next year, or I guess this current year? So maybe just talk about what the core growth of the derm tests, Dx-SCC looks like this year, and if there's anything that's going to be happening in 2024 that causes growth to decelerate a bit to lower levels.

Yes, sure, Kyle. I don't -- I might need to get with you right then. I wasn't track in your math there. Yes, you should you should recall that the 2023 actual results have a full year of SCC revenue included. The 2024 expectation only has this quarter for SCC. We're taking out our SCC test out of that guidance for the rest of the year -- Q3 and 4. So to apples -- if you want to apples to apples the growth -- you need to sort of either back out SCC from 2023, or kind of think about what it would look like for '24, just in order to avoid having to reduce or change guidance negatively, if SCC is no longer reimbursed, we just we take it out the rest of the year. And that would be, as we talked about in the past, Kyle, that would be a just a terrible outcome for patients. I mean, we've already got significant evidence that we've published showing that ART is widely used. It's really bad for patients, and if you properly use ART only where it's appropriate, our test can save the system about $900 million a year or so. And that would be a poor outcome for healthcare costs and for patients, but we are assuming we don't have that coverage for the rest of the year.

Okay. That's helpful.

And then the second part is no, we don't see -- we don't think that TissueCypher or the other tests are not growing. We expect those tests to continue to grow.

Yes. I think that you kind of clarified the what's going on, like the dynamics on the guide or so. That was great. Just follow up on -- simple one on gross margins. I guess going forward, if we are kind of like taking out SCC for a little while, should we model like a lower gross margin than what we've seen in the past? Because you still have the volume, but like you've got such great low-80%s gross margins, what's the right way to think about that going forward? And then maybe just related to cash, I mean, could you guys -- did you kind of say you could generate cash this year based on what you've done the past couple quarters?

Let me take the first part. As you know better than we do, Kyle, when you're not paid appropriately for a service you provided, it has a negative impact on group gross margin. So if we were to not have coverage for one or any of our tests, then that would impact that gross margin. With appropriate coverage in place, we think those margins are stable. If you recall, our long range guidance was gross -- adjusted gross margins, I mean, I should correct that -- adjusted gross margins in the 80% range. So those should be stable. This quarter will be a cash use quarter from operations, I would expect. And then the rest of the year, it'll depend on what the reimbursement picture looks like.

Thanks all. We now have Subbu Nambi of Guggenheim.

Awesome. This is Brandon on for Subbu. We have just got a quick two parter on TissueCypher. Alright. A little bit of a delay. Quick two-parter on TissueCypher. Can you hear me?

Yes, we can hear you.

Hello? Got it. Sorry about that. Just a quick two parter on TissueCypher. You mentioned in your last call that some of the key performance drivers were that newly diagnosed or rescoped patient population of about 400,000 patients. And then secondly, the need for the patients in the non-dysplastic group making up about 95% of the overall patient population. I just wanted to clarify, what impact did that have in the fourth quarter, and what are your expectations for both of those drivers going into 2024? Thank you.

Yes. So, as I think we shared, we think the market there may maybe a little bit bigger than we had anticipated when we first were looking at TissueCypher. The right population for us to think about there is the surveillance endoscopy. So patients that are having a surveillance endoscopy or an upper GI endoscopy for Barrett's Esophagus. And we've got really good data now that says about 417,000 or so of those a year, which is a higher number than we thought. Now the second piece of that -- so that's that's the total pool, but we're not appropriate -- well, it would not be useful to physicians to test on patients who have that procedure, and then come back from pathology with high-grade dysplasia. And that's that's about 5%or 6% of those cases are high-grade dysplasia. And the reason is just that, at that point, that's going to be concerning enough that the physician is going to want to go ahead to ablate that patient. So you can kind of take -- if you want to use round numbers -- take 90% of the 417,000, and that's the that's the group we think we are appropriate for each year. That's more of a -- you'd want to think of that as more of an incidents type measure, because there are certainly more patients than that that have Barrett's, but if they're not having that surveillance endoscopy, then they're not candidates, or we wouldn't be wouldn't be able to test. That's the tissue we test is the is the pinch biopsy tissue from the surveillance endoscopy.

Thank you. Next question comes from Sung Ji Nam of Scotiabank.

Hey, thanks for taking the questions and congrats on the year. Maybe starting out with SCC, just kind of -- DecisionDx-SCC -- you talked about the overlap with the DecisionDx-melanoma, in terms of I think, over 70% of the orders are coming in for both. There's overlap. I'm just kind of curious, given that you've had SCC commercially available now over a year, just curious kind of what you're seeing from the same-store sales, if you will, standpoint, just based on, you know, with the physicians and their experiences with SCC? Kind of if you're seeing any trends in terms of reordering patterns and things like that?

Hi, Sung Ji, Derek here. We haven't disclosed that, following today or on the press release, as far as our call. We do expect, and did expect early on, that clinicians who diagnose skin cancer of cutaneous melanoma will also be the same medically-oriented dermatologists who will diagnose the skin cancer squamous cell carcinoma. So we assume there'd be significant kind of overlap from a perspective of will this dermatology customer be seeing these kinds of patients, and two, it was also our belief that if these clinicians who adopted or are using our DecisionDx-melanoma tests appropriately for medical necessary purposes, that they would be more open to, I guess, seeing how use of our test for squamous cell carcinoma would go ahead and fill what we see as a significant unmet need. Sort of what I think we're seeing is the actual experience of our expectation, which is good by the way. But I think the other aspect here is to say, why? And the why part to me is that in patients with high-risk squamous cell carcinoma, there's there's this pinch point here. And as Frank mentioned earlier, 99% of patients that we test today are eligible under guidelines for adjuvant radiation therapy or ART. And adjuvant radiation therapy has been recognized as an effective treatment for high-risk patients for, I think, at least two or three decades. We've published data recently presented last summer to the Medicare contractors, demonstrating that not only can our tests identify patients who are in this high-risk category, who will have a low risk of progression, or a high risk of progression compared to the population base estimate, but also able to go ahead and demonstrate that we can find people who are eligible for ART, who actually have a very, very low likelihood of getting any kind of response. And the benefit to that, of course, is avoidance of radiation complications. The therapy itself and at least based upon a publication back in January of this year, the use of our tests in these ART-eligible patients to help rule out unnecessary intervention probably saves the Medicare trust fund north of $900 million, which is a great way to improve healthcare outcomes by reducing complications with no benefit. And of course, costs extraction.

Got it. And then just on the follow-up on the TissueCypher, obviously great to see that product know outperforming your expectations. Just kind of curious, looking back, what do you think are the key drivers of the outperformance? Other than you know, that market being actually bigger than you had initially estimated?

Well, you took away one of the drivers, but okay. I think that what we saw during diligence prior to the acquisition was a fairly rapid sort of head nodding, I guess I would call it, from the guest neurologists that we contacted during diligence about market interest, and what's the clinical unmet need really like. And I think to a tee, there is good recognition saying, hey, we have this FDA-approved device, radiofrequency ablation tool or tools, that we use in people with high risk at -- on pathology, high-risk on pathology. And this tool is showing to be very, very effective at really stopping progression to esophageal cancer in its tracks. The problem is that we also recognize that because we don't ARV with people with non-dysplastic Barrett's Esophagus disease, which is that ends up being the larger population of people actually progress to cancer, because we're just surveying them. And so the ability of our tests to say, hey, you can take a non-dysplastic Barrett's disease, which has a lower chance as a population of progressing compared to a high risk on pathology Barrett's patient, we can demonstrate with our test that the risk of progression is actually higher, or the same as depending on what study one looks at, as a high-risk pathology patient, that therefore the use of intervention like RFA ablation would be a fantastic way to basically halt those patients likelihood of progressing. And so that was a fairly easy concept to present to guest neurologists during diligence, and I think on the side sort of under sizing the market opportunity during diligence a couple of years ago, and that obviously having impact in terms of volume. The other areas that the assumptions we made in terms of physician interest and really getting to a better treatment plan for their patients is being realized.

We will go next to Mason Carrico of Stephens.

Hey, guys, this is Jacob on for Mason. Thanks for the questions here. Just one on SCC real quick. So on the potential of updated NCCN guidelines, including DecisionDx-SCC, do you perhaps have any insight into what level inclusion or what the language would have to look like in NCCN guidelines to meet the threshold of the Novitas draft LCD, based on how it's currently written? Or maybe what are the different ways that SCC could be included in the updated guidelines, but for whatever reason, still not be covered?

So we don't have any insight in terms of how that might be considered or discussed. I can tell you we think is probably appropriate, maybe. So within the current squamous cell carcinoma NCCN guidelines, there is a table that sort of defines patients in the categories of risk. Having one or more of these clinical pathologic factors puts you in kind of a high-risk patient population, and having of subset or multiple factors puts you in what they call the very high-risk patient population. Both of those populations are eligible for adjuvant radiation therapy. We would think it's probably appropriate, given how it's structure in the NCCN guidelines to basically add our DecisionDx-SCC test result as a molecular factor in that sort of clinical pathologic and now molecular factor table, putting people in the categories of high-risk and very high-risk disease. That to me makes the most logical sense under the current structure. That might be an expectation we would kind of have because it seems to be the easiest way to have a clinician contemplate on the value of our tests. The second question is, if the Novitas LCD finalizes as is, what does that mean, I guess, was your question, if I got that right, Jacob. I would think that, one, that nobody has any experience with this Novitas LCD to see how different inclusions are approached with different tests, but I assume if it was included somewhere like I just described, then that should be considered a covered tests, at least based upon, I don't want to say just natural common logic there, but that seems to make the most sense.

Yes, that makes. That makes sense. And that's helpful. Thanks for that color there. And then one follow-up here on your pipeline atopic dermatitis test. You mentioned it on the call that you plan on launching it by the end of 2025, and maybe some additional data this year. But just on, in terms of reimbursement for that test, is there a foundational LCD in place that you could obtain Medicare coverage for? Or would it have to go through the whole submission, draft, final LCD process?

That's an excellent question. So there is no foundational LCD or even test specific LCD. covering these kinds of tests that can help guide on which systemic therapy one should use for psoriasis or atopic dermatitis patients. So that with this, that doesn't exist at all today. However, it's also important to understand that we think that the inflammatory skin disease test is likely to be a younger population anyway, so you're looking at different reimbursement opportunities besides Medicare playing an important role relative to say, melanoma or skin cancer.

We now have Catherine Schulte of Baird.

Hi, everyone, this is Bob Peterson on for Catherine. Thanks for taking our question, and congrats on a solid quarter, and a solid 2023. I guess maybe one for Frank to start, how should we be thinking about OpEx growth in 2024? And I heard your comments on sort of the cash flow from operations cadence here in '24, but, you know, given the reimbursement outlook, I guess how confident are you in achieving that net positive cash from operations target in 2025 that you've previously set?

Hey, thanks for the question, as we said before, we still we haven't changed or amended that long-range target guidance that we gave, I guess, a year and a half ago, maybe at this point. So we're still on track for that. I think you'll see OpEx growth will be will be lower than revenue growth. But like other companies, we continue to see pressure on costs, and inflation is real. So it impacts every every aspect of your business at this point. So yes, there's growth to grow the business. There's growth as a result of inflation in the economy, and then there's also we're working hard to be financially disciplined to make sure we manage to that. So still maintaining the guidance we gave and feel good about getting there.

We now have Thomas Flaten of Lake Street.

Hey, thanks. Congrats on the quarter. Just to clarify, Frank, it was implied in an answer you gave earlier, but if Novitas finalizes as it is, you will continue accepting SEC claims, even though you're not going to get paid on them. Is that is that a fair assumption?

We have a -- that's a bigger question, Thomas, as you do you stop making a test available if it's not being appropriately reimbursed? I don't know that we've made that decision. I think that and there's a lot lot that goes into that. It's a valuable test. It's important for patients. We're seeing every day with literally thousands of doctors how it's changing the way they're treating their patients, and you and I talked about it, you know my dad's 85, and if he had a small squamous cancer on his on his head, and just because it was a little bit over a centimeter and the doctor wants to do head above the shoulders radiation therapy, that's awfully tough. I mean that's, -- that would be tough to put a patient through. So, um, we haven't made any decisions about keeping or dropping availability of the test, but we would have to have to wrestle with that at some point if it got there, I guess.

Got it. And you mentioned expanding the TissueCypher sales force. And I think last time you mentioned specific numbers -- 24 reps. Is that as that going up to 33? Can you give us some quantify -- can you quantify that? And then as a follow on to that, any changes you're making to the IDgenetix sales team?

So I don't think we discussed the numbers, we're targeting growth. The plan we're working towards is a early second quarter expansion plan. I don't think we've disclosed numbers--

And then on IDgenetix, Thomas, we'll keep an eye on that one. As you saw from the report, we're getting -- we're very pleased with the traction we're getting there. Again, that test makes such a difference to the physicians who are their patients. And we really would like to increase the size of the for that. It's a great test and it gets good traction. But we're also reiterating an earlier answer., we're also being very careful on on some operating expenses and trying to balance that. So we're likely not seeing the volume growth that we could possibly see there, but we're making sure that we also don't have a a big increase in cash usage.

We now have Mark Massaro of BTIG.

Hey guys, this is on for Mark. Thanks for taking the question, I'll maybe just keep it to one. So on your recent publication on , also recognizing that you did publish a study on SCC fairly recently earlier this year, what additional evidence and readouts should we be expecting on the SEC front?

So we have discussed, um, I guess back in the summertime, that we have presented data that have been published in abstract form to both Medicare contractors that were reviewing our SCC test. One piece of data was a sort of request, I guess you would say, from the MolDX program to really have a more clear understanding of the independent value that our SCC test adds on top of NCCN or or late staging systems. And so, a publication on that focuses on that has been accepted, and that should come out shortly. That one significant piece of data that we think answers on a significant portion, if not all -- I think all is too aggressive there -- of the MolDX questions, I guess, you could call it, in the draft LCD. The other article, which has also been accepted, and we presented this data last summer and last fall, certainly to both Medicare and also clinicians, focuses on the on the newer data of our test to take patients who are eligible for adjuvant radiation therapy, identify the proportion of patients who get a really strong benefit from that intervention, and more importantly, perhaps, from a healthcare system and patient care perspective, identify the majority of patients who appear to get no benefit from adjuvant radiation therapy. And as such, that allows a clinician and a patient in a shared decision-making process to say, hey, you are eligible on ART. Based upon the DecisionDx-SCC test result, however, say it was a low risk class one test result, you have a low likelihood of progressing. So it's not zero, but it's a lower likelihood than I thought you would you would be at risk for relative to your clinical and pathological factors. And by the way, a class one test result in this test from Castle also demonstrates that you have a very low likelihood of actually receiving any benefit from adjuvant radiation therapy. So that study has also been accepted and again, should be out shortly. So I think those are some noteworthy near-term publication milestones that are not only important for the clinical use of our tests, with clinicians thinking through where do I use this test? How do we use -- how do we get value out of it, but also hopefully for both of the Medicare contractors.

Thank you. We have no further questions. So I would like to hand it back to CEO Derek for any final remarks.

This concludes our fourth quarter and full year 2023 earnings call. We thank you again for joining us today, and for your continued interest in Castle Biosciences.