Dr. Greg Kalemkerian joins us on the ASCO Guideline Podcast to discuss the newest ASCO – Ontario Health (Cancer Care Ontario) Guideline on systemic therapy for small-cell lung cancer (SCLC). He reviews the evidence-based recommendations from the panel, including guidance on systemic therapy options for resected, limited-stage, extensive-stage, and relapsed SCLC, and NSCLC with an EGFR mutation that has transformed to SCLC, recommendations for older adults with poor performance status, the role of biomarkers, and the use of myeloid supportive agents. Dr. Kalemkerian also highlights future research for systemic therapy options for SCLC, and the impact of guidelines on both clinicians and patients with SCLC.
Read the full guideline, "Systemic Therapy for SCLC: ASCO-OH (CCO) Guideline" at www.asco.org/thoracic-cancer-guidelines."

TRANSCRIPT

This guideline, clinical tools, and resources are available at http://www.asco.org/thoracic-cancer-guidelines. Read the full text of the guideline and review authors' disclosures of potential conflicts of interest disclosures in the Journal of Clinical Oncology, https://ascopubs.org/doi/10.1200/JCO.23.01435

Brittany Harvey: Hello and welcome to the ASCO Guidelines podcast, one of ASCO's podcasts delivering timely information to keep you up to date on the latest changes, challenges, and advances in oncology. You can find all the shows, including this one, at asco.org/podcasts.

My name is Brittany Harvey, and today I'm interviewing Dr. Greg Kalemkerian from the University of Michigan, co-chair on "Systemic Therapy for SCLC: American Society of Clinical Oncology – Ontario Health Guideline." Thank you for being here, Dr. Kalemkerian.

Dr. Greg Kalemkerian: Thank you.

Brittany Harvey: Before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines and ensuring that the ASCO conflict of interest policy is followed for each guideline. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Kalemkerian, who has joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes.

So then, to move into what we're here today to discuss, Dr. Kalemkerian, can you provide an overview of both the scope and the purpose of this guideline?

Dr. Greg Kalemkerian: So, the guideline is meant to update the systemic treatment for small-cell lung cancer. There have been several changes in the last couple of years. For the first time in quite a few decades, we actually have some newer drugs that have demonstrated benefits in this disease. So we're really focusing on the systemic therapy. And ASCO does endorse the ASTRO guidelines for the radiotherapy involved in patients with small-cell lung cancer.

Brittany Harvey: Great. That's great to hear that there's new systemic therapy options for patients with small-cell lung cancer.

So then I'd like to review the key recommendations of this guideline. This guideline reviews eight clinical questions in total, so we can go through the key points of the recommendations for each question. So let's start with what is recommended for adjuvant systemic therapy in patients with resected small-cell lung cancer?

Dr. Greg Kalemkerian: So, to start with, only fewer than 5% of people have what would be considered resectable small-cell lung cancer, and that's stage I small-cell lung cancer. So tumors less than 5 cm in size without any lymph node involvement, either hilar or mediastinal lymph node involvement. So purely the very early stages, which are rare in small-cell. And if patients undergo surgical resection for such tumors, the recommendation afterward is to provide adjuvant chemotherapy with four cycles of either cis-or carboplatin plus etoposide in order to try and improve longer-term survival for those patients.

The other part of the recommendation is we do recommend that treatment be started within eight weeks of surgery. There is little data on timing in small-cell lung cancer, but that's derived from extrapolating from non-small cell lung cancer as well.

Brittany Harvey: Understood. I appreciate you reviewing those recommendations for resectable small-cell lung cancer.

So then, moving along, what does the panel recommend for patients with limited-stage small-cell lung cancer?

Dr. Greg Kalemkerian: So, the treatment with limited-stage small cell lung cancer unfortunately has not changed in quite some time. We recommend that patients receive four cycles of either cisplatinum or carboplatin and etoposide concurrently with radiotherapy. Preferably the radiotherapy should be given early and concurrently with the chemotherapy, though we do not recommend that people wait for the radiation to get started in order to start the chemotherapy. So we do recommend that the chemotherapy get started as soon as possible and then the radiation can be added in on the second cycle of chemotherapy.

Brittany Harvey: Then to follow that up, what is recommended for patients with extensive stage small-cell lung cancer?

Dr. Greg Kalemkerian: So, extensive stage small-cell lung cancer now is probably the most straightforward of the portions of this. Based on the data from two trials thus far, the IMpower 133 trial and the CASPIAN trial, we now recommend chemotherapy with immunotherapy. The chemotherapy should be cisplatinor carboplatin plus etoposide along with concurrently either atezolizumab or durvalumab as the immunotherapy for four cycles of the combined chemo-immunotherapy followed by maintenance with the immunotherapy drug of choice. With regard to the choice of either cisplatin or carboplatin, meta-analysis has demonstrated that there is no significant difference between the two and our belief is that carboplatin is likely the more reasonable drug in the palliative treatment situation based on its better non-hematologic toxicities.

Brittany Harvey: Appreciate you sharing those recommendations and some of the rationale behind those.

So then moving along, what options are available for patients with relapsed small-cell lung cancer?

Dr. Greg Kalemkerian: So relapsed small-cell lung cancer gets a little more potentially complicated. One of the main drivers of outcome in patients with relapsed small cell lung cancer is the time since they completed their initial chemotherapy. Patients who have had a longer time since chemotherapy do better and have better responses to subsequent therapy. For patients who relapse with a short interval within 90 days or three months of completion of prior chemotherapy, our recommendation is that they be treated with single-agent chemotherapy. There are two drugs that are currently FDA approved for use in relapsed small cell lung cancer, topotecan and lurbinectedin, and either one of those is the preferred agent as a single-agent treatment in this scenario.

For people with a longer chemotherapy-free interval, so beyond the 90 days or three months, one could either use combination chemotherapy, so reinitiation or re-induction with the regimen such as carboplatin and etoposide, or one could use single-agent chemotherapy with the preferred agents being topotecan or lurbinectedin again. The use of combination chemotherapy has been shown to improve response rates in this situation over topotecan alone. However, we have not been able to demonstrate that there is a significant improvement in overall survival. So one has to look at the individual patient and make some judgment on whether you think that the added potential toxicity of combination chemotherapy is beneficial for that individual.

For people who have progression of disease while they are on maintenance therapy with immunotherapy for extensive stage small-cell lung cancer, we do not recommend continuation of the immunotherapy. So if people progress while they're on the immunotherapy, even if they're nine months out on that, then treatment with second-line chemotherapy, either with the combination agent or with single agents, would be what we would recommend, and not continuing the immunotherapy. If patients had previously been treated for limited-stage small-cell lung cancer where immunotherapy is not part of the initial treatment at this time, and they relapse, say, six months or nine months out from their initial chemotherapy and radiation therapy treatment, then it would be reasonable to perhaps initiate carboplatin etoposide and one of the immunotherapy agents as appropriate treatment, because that patient is immunotherapy naive.

However, the single-agent immunotherapy does not have a role in the treatment of patients with relapsed small-cell lung cancer.

Brittany Harvey: Understood. It sounds like some of the treatment options are individualized to the specific patient then.

So the next question also addresses specific groups of patients. So what did the panel recommend for older adults with small cell lung cancer or for those with poor performance status?

Dr. Greg Kalemkerian: Approximately half of people who have small-cell lung cancer are over the age of 70 years old, so it is a disease of older smokers. Many of these people have comorbidities that can limit our ability to use standard treatments. Many of these individuals also have poor performance status because the disease is an aggressive disease that causes a lot of problems for people. So the issue of older individuals and people of poor performance status is something that we run into on a regular basis in treating people with small-cell lung cancer.

For patients with limited-stage small-cell lung cancer who are older and have a performance status of 0 to 2, it is very reasonable to utilize standard treatment with standard chemo and radiotherapy with curative intent. For people with limited-stage small-cell lung cancer who have a performance status of 3 or 4, and this would include people who might be in an ICU with an obstructive airway, then it is reasonable to initiate chemotherapy in order to try and shrink the cancer down and improve their situation.

Small-cell lung cancer is a disease that is very sensitive to chemotherapy initial treatment, so many of these people will have shrinkage of tumor and improvement of their symptoms. If the poor performance status is due to the small-cell lung cancer, it has potential to get better. So we do recommend for people at limited-stage small-cell lung cancer and a poor performance status that is felt to be due to the disease, the cancer, then it is reasonable to initiate treatment with chemotherapy. And depending on the person's response and recovery and improvement in their performance status, then one could add radiotherapy later on or do it sequentially with the definitive radiotherapy for the limited-stage small-cell lung cancer.

For older individuals with extensive stage small cell lung cancer who have a performance status of 0-2, it is very reasonable to utilize the standard chemotherapy and immunotherapy as we outlined previously in treating that. For individuals who have a poorer performance status, so performance status 3 or 4, one really needs to individualize the situation. If the poor performance status is due to the cancer, then again, it would be reasonable to attempt chemotherapy in an effort to try and shrink the cancer. There is no data on the use of chemo plus immunotherapy in this patient population. But the use of standard chemotherapy, obviously, in the older individuals preferring carboplatin over cisplatinum with etoposide would be a reasonable option, taking into account abnormalities in organ function that may require dose adjustments or reductions.

Because small-cell lung cancer is a disease that is quite sensitive and responds well to chemotherapy, then one can individualize in those situations for patients with poor performance status to see if they can improve their overall situation and have some period of time of optimized quality of life. Clearly, it is a very individualized decision-making whether or not to treat these patients. That requires clearly the patient's input as well, as a primary driver of what is done.

Brittany Harvey: Absolutely. That nuance is helpful for patient-clinician shared decision-making, depending on the factors that you mentioned.

So then, switching to the next topic that the expert panel addressed, what does the panel recommend for patients with non-small cell lung cancer with an EGFR mutation that has then transformed to small-cell lung cancer?

Dr. Greg Kalemkerian: The EGFR mutant non-small cell lung cancer transformation to small-cell lung cancer is relatively rare. I think in the real world, this probably is occurring in 2%-3% of people with EGFR mutant non-small cell lung cancer, but we do see it. Now, these patients are initially being treated with EGFR inhibitor therapy for their mutant non-small cell lung cancer and then they develop a more aggressive progression of disease. It is important to note that when people progress in that situation, it is important to get a biopsy in order to see whether or not transformation has occurred and whether or not there are any other new driver mutations that might be targetable. If the patient has a small cell lung cancer transformation, then the recommendation is to treat them as we treat patients with small cell lung cancer with chemotherapy consisting of platinum and etoposide for four to six cycles, as we usually do.

It does not appear that there is a role for immunotherapy in this situation, though we clearly have a paucity of data on these patients. So we do not yet have any trials that have looked at the management of this population. We do have several series that have presented these individuals and what their outcomes are with treatment. And their outcomes are very similar to people with de novo small-cell lung cancer. So not a very good situation, but we do recommend that they be treated with standard chemotherapy, platinum plus etoposide.

Another question that arises is do you continue with the targeted therapy with the EGFR inhibitor. And the honest answer is we don't know. We don't have data on that. We do know from case reports, the series, and from personal experiences, that some people, in fact, I think many people, if not most of these individuals, have a mix of both EGFR mutant adenocarcinoma and small-cell lung cancer at the time that they transform. So not every tumor in their body is transforming, so that EGFR mutant tumor is still present in their body. So even though the small-cell lung cancer component, because it's progressing, is clearly not responsive to the EGFR inhibitor any longer, the adenocarcinoma component most likely is still sensitive to the EGFR inhibitor. So it is not unreasonable to continue with the EGFR-targeted therapy along with the small cell lung cancer-directed chemotherapy. Even though we don't have any strong data supporting one way or the other.

Brittany Harvey: I appreciate that guidance, even with the dearth of data in this relatively rare scenario.

So then we've talked a bit about individualized treatment, and often in that conversation, biomarkers come up. So what does the guideline say regarding the role of biomarkers for patients with small-cell lung cancer?

Dr. Greg Kalemkerian: This is pretty straightforward. Thus far, in people with de novo small-cell lung cancer - so we're not talking about the transformed patients from EGFR mutant, we're talking about people who present with small-cell lung cancer - we have no evidence that molecular diagnostic testing would help guide treatment or improve patient outcomes at this time. So we do not support obtaining molecular diagnostic testing for the routine care of patients with de novo small-cell lung cancer. I would love to talk for the next half hour about what's coming down the pipeline in small-cell lung cancer with regard to identifying subsets of patients and trying to identify the vulnerabilities within those subsets of patients that may lead to better-targeted therapy based on molecular diagnostics, but in the current environment, there is no role for molecular diagnostics.

Brittany Harvey: Understood. We'll look for that in future guideline updates instead, then.

So then the last clinical question that the guideline addressed - what myeloid supportive options may be offered for patients with small cell lung cancer?

Dr. Greg Kalemkerian: So this has to be couched initially with whether or not one thinks that myeloid suppressive agents are necessary in the treatment of patients with small-cell lung cancer. So in extensive-stage disease with the use of chemotherapy, say, carboplatin and etoposide, the majority of patients likely don't require myeloid supportive agents. However, if one believes that the patient, because of their own individual characteristics, or in a patient who has already developed myelosuppressive problems, then one could either utilize trilaciclib, which was FDA-approved a couple of years ago and was shown to improve the blood counts in people with small cell lung cancer treatment, or one could utilize G-CSF. So either trilaciclib or G-CSF could be utilized to support the patient's bone marrow.

In patients who have limited-stage disease, for many years, we have recommended against using G-CSF in combination with chemotherapy and radiotherapy due to concerns for increasing toxicities, including thrombocytopenia. Recent data suggests that this may not necessarily be a hard and fast rule and that if one feels that the patient requires or would benefit from some myeloid support, then G-CSF may be offered to patients undergoing chemotherapy and radiotherapy. I do not think that the standard patient that we see who is starting on treatment requires such support, but some subsets of patients or patients who have already proven that they're getting into trouble with their counts, G-CSF could be utilized in this situation.

So with regard to this recommendation, overall, it's that for patients with extensive stage disease, trilaciclib or G-CSF could be used if one feels they're necessary. And for limited-stage small cell lung cancer, G-CSF could be utilized if you feel it's necessary.

Brittany Harvey: Thank you for reviewing those options and all of these recommendations. The panel was certainly hard at work reviewing the evidence and developing these recommendations.

In your view, Dr. Kalemkerian, what is the importance of this guideline for both clinicians and for patients with small-cell lung cancer?

Dr. Greg Kalemkerian: Well, I think it's not just small-cell lung cancer, but when you look at guidelines overall, I think they are very important to have evidence-based guidelines as well as expert consensus-based guidelines because, quite honestly, the field is moving very quickly, the field of oncology. Now, small-cell lung cancer hasn't moved as quickly as we would like compared to other aspects of oncology, but it's very hard for the clinician who is trying to care for patients with lots of different tumor types to keep up with all of the flood of literature, the flood of new FDA approvals that are coming out every week. So I do think that utilizing the guidelines is important in order to see what the standard approach might be.

Now, I also have to couch that with saying that guidelines are never enough. We have to look at the individual sitting across the exam table from us. We have to personalize the treatment to that individual. I will say that in my own practice, there are very few people who walk in the door who are the optimal patient, who are the person who has outstanding physical function. And in lung cancer, that's even more true because patients tend to be older smokers, and they have a lot of comorbidities and other things that you have to personalize therapy towards in them. So the guidelines are a very good starting point in order to know what the optimal treatment might be and then to adjust that accordingly to the person sitting in the room with you.

Brittany Harvey: Definitely, we hope guidelines are a place that clinicians can turn to for evidence-based recommendations and succinct recommendations, but individualized patient and clinician decision-making is paramount to each of our guidelines.

So then, Dr. Kalemkerian, we've already talked about this a little bit when you mentioned molecular testing advances down the road. So maybe I'll ask what are the most pressing, unanswered questions about systemic therapy for small-cell lung cancer?

Dr. Greg Kalemkerian: Yeah, so one of them I'll come back to limited-stage small-cell lung cancer. So, obviously, in the extensive stage, we've now incorporated immunotherapy. And yet I didn't talk about immunotherapy in the limited-stage setting, and neither do the guidelines because thus far we don't have any data on the use of immunotherapy in limited-stage small-cell lung cancer. We are expecting data to be coming down the line within the next year hopefully, definitely, within the next two years, because a number of trials that are either ongoing or have recently been completed looking at incorporating immune checkpoint inhibitors into the treatment of limited-stage small-cell either concurrently with chemoradiation or as consolidation after chemoradiotherapy. So that data is anxiously anticipated. And we're hoping that that might move the needle a little bit further in limited-stage small-cell lung cancer and hopefully improve that long-term survival or cure rate that we see in that disease.

Other avenues coming down the line – many of us have made a career of doing negative trials in small-cell lung cancer, myself included, and a lot of that has had to do with trying to target therapies to specific molecular abnormalities, and none of those have really panned out thus far. But coming down the line, as we start to molecularly subtype lung cancers, and the best molecular subtyping that we have thus far is not based on mutational analysis, but more based on expression, gene expression analysis, expression of particular transcriptional factors within different subsets of small cell lung cancer, we're now starting to see some vulnerabilities. So one of these subsets in the small cell lung cancer array has a high expression of DLL3, which is part of the Notch pathway, and we can target that. We haven't figured out how to target it as far as its activity goes, but we can target it as a homing device in order to get either drugs delivered by use of antibody-drug conjugates, or to use a BiTE—a T-cell engaging type molecule—that targets both DLL3and T cells in order to try and amplify that immune response in small cell lung cancers. So recently a compound called tarlatamab had data presented at ASCO and also published in JCO that shows some response, about 20-25% response, in people with relapse small cell lung cancer. These were heavily pretreated patients. So that's moving the needle a bit in favor of a specific targeted therapy. And we're hoping that will lead to further avenues to look at the vulnerabilities of different subsets and be able to develop newer targeted treatments for these diseases, trying to amplify that immunotherapy response as well.

Small cell lung cancer is a little bit of an outlier in that it does not respond well to immunotherapy compared to other tumors. Not what we expected based on the high tumor mutational burden and the aggressiveness of the disease. But we know that it does not express a lot of PD-L1. We know that it doesn't have MHC class I molecules. So there are a number of reasons why it doesn't respond, and there is work going on to try and amplify that immune response as well. So I think those three things: the use of immunotherapy in limited-stage, the development of targeted therapies based on subsets, and trying to amplify that immune response are the things that I look forward to in the next few years.

Brittany Harvey: That's great to hear. We'll await the data to provide answers to those outstanding questions.

So I want to thank you so much for your work to develop these evidence-based guidelines, and thank you for sharing your perspective with me today, Dr. Kalemkerian.

Dr. Greg Kalemkerian: Thank you, Brittany. And thanks to ASCO for getting these guidelines together and getting the outstanding group of people we had to work on it and getting them out in a timely manner so they can help our patients.

Brittany Harvey: And also, thank you to all of our listeners for tuning in to the ASCO Guidelines podcast. To read the full guideline, go to www.asco.org/thoracic-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app available in the Apple App Store or the Google Play Store. If you have enjoyed what you've heard today, please rate and review the podcast and be sure to subscribe so you never miss an episode.

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