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Jun 21, 2021

Dr. Stephen Liu, associate professor of medicine and director of Thoracic Oncology and Developmental Therapeutics at the Georgetown Lombardi Comprehensive Cancer Center, highlights key abstracts in lung cancer featured at the 2021 ASCO Annual Meeting.



ASCO Daily News: Welcome to the ASCO Daily News Podcast. I'm Geraldine Carroll, a reporter for the ASCO Daily News. My guest today is Dr. Stephen Liu. He is an associate professor of medicine and the director of thoracic oncology and developmental therapeutics at the Georgetown Lombardi Comprehensive Cancer Center.

Dr. Liu joins me to highlight advances in lung cancer featured at the 2021 ASCO Annual Meeting. Dr. Liu has served in a consulting or advisory role for Genentech, Pfizer, and AstraZeneca, among other organizations. His full disclosures and those relating to all episodes of the podcast are available on our transcripts at Dr. Liu, it's great to have you on the podcast today.

Dr. Stephen Liu: Thanks for having me.

ASCO Daily News: Dr. Liu, a lot of people were talking about the IMpower010 study during the annual meeting. That's abstract 8500, an interim analysis that showed really promising results for patients with resected non-small cell lung cancer. Can you tell us about this practice-changing study?

Dr. Stephen Liu: Well, IMpower010 was a global randomized phase III trial, and I think this really was one of the highlights of the ASCO Annual Meeting from a lung cancer standpoint. As a reminder, our current standard of care is cisplatin-based chemotherapy for patients with resected stage II to III non-small cell lung cancer and for select patients with stage IB. We know from decades of experienced multiple phase III trials, large meta-analyses, that the risk of recurrence is quite high for resected stage II/III lung cancer. And the use of up to four cycles of cisplatin-based chemotherapy does lead to an improvement in survival, and that's our standard of care. That survival improvement, however, is modest, with an absolute improvement and 5-year survival of about 5%. And so we've been trying to improve outcomes in this setting for quite some time.

We know from last year's ASCO that the subset of patients whose tumor harbors an EGFR mutation received some benefit from disease-free survival with the use of adjuvant osimertinib. IMpower010 presented at this year's ASCO by Dr. Heather Wakelee looks at the use of immunotherapy as a complementary adjuvant therapy. And we knew from press release that this study had met its primary endpoint. This was our first chance to look at the data first-hand and really see how it would impact practice. And I think the data were quite impressive.

It's a fairly simple design. This study included patients with completely resected stage IB to IIIA non-small cell lung cancer, either histology. Note that this used AJCC version 7, and so the stage IB that were included had a size of at least four centimeters, and that's the subset that seems to derive the most benefit from chemotherapy.

Now patients received cisplatin-based chemotherapy one to four cycles first. And those who received at least one cycle of chemotherapy were then randomly assigned 1 to 1 to receive 1 year of atezolizumab, PD-L1 inhibitor, or best supportive care. This was a large study, over 1,000 patients randomly assigned.

It began enrollment in 2014. So it did include some EGFR and some ALK when maybe we didn't know quite as much about including those patients in these studies, but the EGFR was about 12%, the ALK was 3%. Some were unknown EGFR and ALK status, but these were likely the squamous histology, as those numbers line up.

The PD-L1 testing, importantly, was done by the VENTANA SP263 assay, looking at tumor cell expression only, which is a fairly straightforward assay. And what we saw after a median follow up of almost 3 years was that in the primary high-risk population stage II to IIIA resected non-small cell lung cancer with the PD-L1 expression of at least 1%, the use of adjuvant atezolizumab significantly improved disease-free survival. And the hazard ratio there was 0.66.

If we look at the 2-year disease-free survival (DFS) rate, it improved from 61% with best supportive care to 75%, and at 3-year DFS from 48% to 60%. So an improvement in the 3-year DFS rate and a hazard ratio of 0.66. The fourth plot showed that signal was greater in node-positive. As expected, no signal in that ALK subset, though it was small.

But this is a pretty substantial improvement in disease-free survival. When we look at these Kaplan-Meier curves, they split immediately, really right at the first scan. And when we look at a study like this, this phase III trial, it reminds us how poor our current standard is; how many patients do suffer relapse and recurrence and death from this potentially curable cancer. Atezolizumab clearly improving outcomes in this subset.

We then saw analyses of the resected stage II to III across PD-L1 strata, so positive and negative. And there the hazard ratio, as expected, less impressive, 0.79. If we look at the forest plot there, the hazard ratio for PD-L1 high, using that 50% cutoff we're used to, was substantial at 0.43.

So overall, the DFS and PD-L1 positive 0.66 and the PD-L1 high 0.43. So no report on the PD-L1 low, which is what we're waiting for, that one at 49%, presumably not as impressive as 0.66. And we'll wait for those data to come out. But PD-L1 positive, a clear benefit. PD-L1 high, a substantial benefit.

That's really where the formal analyses stopped. The stage IB to IIIA overall population was too immature for analysis, and overall survival was not yet formally tested. This will take a few years to breathe out. They did provide an early look at overall survival. And in that stage II to IIIA PD-L1 positive, there was the right trend, with a hazard ratio of 0.77, though not statistically significant. We did see these curves start to come apart at about 12 to 18 months, which is what you would expect if this study ultimately would lead out to be positive.

We do want to wait for OS results. But one has to wonder, is a DFS benefit this substantial enough to change practice? And atezolizumab not yet approved in this setting, but the trial did meet its primary endpoint. And to me, for PD-L1 positive, and certainly for PD-L1 high, I do think these data aren't practice- changing.

ASCO Daily News: Absolutely. Well, another trial that attracted a lot of attention was the CheckMate-816 trial. That's Abstract 8503. What can you tell us about the surgical outcome data reported in CheckMate-816?

Dr. Stephen Liu: So CheckMate- 816 was a randomized phase III trial that looked at neoadjuvant therapy. So this also focused on resectable lung cancer. This is an area where we hope for cure, but for some of the more advanced stages, we don't necessarily expect it. Much room for improvement.

We saw the IMpower010 data showing adjuvant immunotherapy improved DFS. Here we're looking at the neoadjuvant space. And at AACR in 2021, Dr. Patrick Forde presented some of the early PCR results. And that showed the pathologic complete response rates with neoadjuvant nivolumab plus chemotherapy for three cycles was superior to chemotherapy alone for three cycles.

So the addition of nivolumab to chemotherapy improved the pathological CR rate from 2% to 24%. Really astounding. What Dr. Jonathan Spicer presented at ASCO 2021 were the surgical outcomes from that study. And we see that adding immunotherapy to chemotherapy significantly improves the pathologic CR rate.

Does it come at a cost? Does it lead to more surgical complications? This is always a concern with neoadjuvant therapies. We've got someone in our clinic with a resectable lung cancer. If we mismanage that patient, we may lose the window for resection. So we always worry about delayed surgeries, canceled surgeries, more complicated surgeries.

There have anecdotally been reports of increased perihilar fibrosis after neoadjuvant immunotherapy. Wouldn't that lead to longer, more complicated surgeries? And what we saw, frankly, was a bit surprising, for me. Surgery consistently easier, better in the experimental arm really across the board. The rates of going to surgery, completing surgery, 83% with nivolumab/chemotherapy, versus 75% with chemotherapy. So more patients going to surgery, fewer canceled surgeries.

If we look at the type of surgery, minimally invasive surgery rates 30% with nivolumab/chemotherapy, [and] 22% with chemotherapy alone. Conversion to open thoracotomy was more common in the chemotherapy alone at 16%, the additional nivolumab 11%. And the complete R0 resection was achieved in 83% with nivolumab/chemotherapy, 78% with chemotherapy alone.

Adverse events delayed surgery in six patients getting nivolumab and chemotherapy. It's important to watch that. But it was nine patients in getting chemotherapy alone. And if we look at the duration of surgery, and certainly there are many confounders in a statistic like this, but the surgery was shorter with nivolumab, certainly not lengthening the surgery. 184 minutes for nivolumab/chemotherapy, 217 [minutes] with chemotherapy alone.

So these data are very reassuring to someone with a potentially resectable cancer. And I think that when I take a step back and look, maybe these results do make sense. Maybe this is what I should have expected. If we give a treatment that is more effective, that is a higher response rate, it works better. Those patients are less likely to have progressive disease, and the surgery should be more straightforward if there's less cancer to resect.

So the CheckMate-816 surgical data, we've been waiting for this shoe to drop, and it was very reassuring. Perioperative immunotherapy is going to be an important part in the management of stage II/III non-small cell lung cancer in the years to come. Now going forward, we'll need to compare these adjuvant and neoadjuvant approaches and the relative merits of either strategy, but these results, I thought, were very reassuring.

ASCO Daily News: Excellent. Well, moving on to the PACIFIC trial, Abstract 8511, this study reported improvements in 5-year overall survival and progression-free survival for unresectable stage III non-small cell lung cancer. What are your takeaways from this study?

Dr. Stephen Liu: Sure. The PACIFIC study is a randomized phase III trial that's really set our standard of care for unresectable stage III locally advanced non-small cell lung cancer. This is a group where our standard of care, historically, has been concurrent chemoradiation, with the goal of cure, though, unfortunately, not necessarily the expectation, with recurrence rates quite high. We saw years ago the addition of 1 year of durvalumab improved progression-free survival, then ultimately improved overall survival compared to placebo.

This was a fairly straightforward study. It enrolled unresectable stage III non--small cell lung cancer after chemoradiation, who did not have evidence of progression after completing therapy, to receive 1 year of durvalumab or placebo, a 2 to 1 randomization. The results markedly positive, leading to U.S. Food and Drug Administration (FDA) approval and really our new standard of care.

These are long-term survival data, and it was presented by Dr. David Spigel. These are really important. Immunotherapy, the whole appeal of the strategy is the durability, the induction of memory T cells, meaningful long-term survival. Will this increase the rate of cure really is what we're going for. And when we saw the survival benefit with durvalumab, we knew that we were curing more patients.

Long-term follow up is important to make sure that we don't have late recurrences, that we really are curing and not just delaying a recurrence for some patients. And in this analysis, with a 5-year follow up, we see durvalumab improve the median survival from 29 months with chemoradiation alone to 48 months with the addition of durvalumab. That's a hazard ratio of 0.72, 28% reduction in the risk of death, pretty substantial.

That 5-year survival rate was 43% versus 33%. And importantly, these were very similar to the 4-year data that were presented by Dr. Corinne Faivre-Finn at World Conference in Lung Cancer, really very little drop off between year 4 and 5. And we refer to that as flattening of the tail, where the events are early, and at some point, they kind of stop happening. It's really what we want to see.

While survival is what we hone in on, in an abstract like this, we also need to pay attention to progression-free survival (PFS). And the PFS rate at 5 years was 33% with durvalumab, versus 19% with chemoradiation alone. So 33% with no evidence of progression at 5 years. And if you are cured from lung cancer, then you can't have progression. So one in the three patients with no progression at 5 years, I think, is very reassuring, that PFS hazard ratio of 0.55.

So prior to ASCO21, durvalumab was our standard of care. Now we just have longer term follow up to really solidify that choice. These are important data for patients and families to set expectations right, but our clear standard. Still, though, room for improvement in that 5-year PFS rate of 33%. We would like to see that higher, and ongoing strategies hopefully will help push that up.

ASCO Daily News: Excellent. Some great survival data in the PACIFIC trial. Well, Abstract 9007 sparked a lot of interest as well. This is an expansion study of patritumab/deruxtecan in patients with EGFR-mutant non-small cell lung cancer. That's a difficult drug to pronounce, so I'm sure you'll do a better job. What can you tell us about this?

Dr. Stephen Liu: Well, yeah, all these antibody drug conjugates do have tricky names, and so they are kind of fun to say. So patritumab/deruxtecan is a HER3 antibody drug conjugate. I suspect it will be better known as HER3-DXd, a little easier off the tongue. This was a study that looked at this agent in patients with EGFR-mutant non--small cell lung cancer after TKI therapy.

And when we turn our attention to targeted agents, we have really transformative drugs with very wide therapeutic windows, little toxicity, very high efficacy, [and are] really game changers in patients with driver positive non--small cell lung cancer. But as we know, these treatments aren't cures. And we do expect resistance to osimertinib. The third generation TKI has been pretty heterogeneous.

And once patients progress in osimertinib, the next standard therapy really is chemotherapy. And there's a bit of a drop off, with more toxicity, [and] less efficacy overall. So this remains an unmet need. Many studies are looking at different strategies there. We've seen the addition of MET inhibitors if MET is amplified for certain subtypes, RET, BRAF, for example, the addition of the targeted agents.

This study, Abstract 9007 presented by Dr. Pasi Janne, looked at the HER3-DXd antibody drug conjugate. So patritumab/deruxtecan has a monoclonal antibody targeting HER3, a proprietary linker, and then a topoisomerase 1 warhead. And this was a phase I study that looked at 57 patients with EGFR-mutant lung cancer after TKI therapy mostly, but 90% were coming off of osimertinib. And what we saw, I thought, was very encouraging.

This is a small, early study. These are very selective patients. But the response rate here almost 40%, disease control rate 72%, and the median progression-free survival with monotherapy of patritumab/deruxtecan was 8.2 months. These numbers may change as the studies get larger, but there's a clear signal of efficacy for patients who'd received chemotherapy before and then moved on to patritumab/deruxtecan. The response rate didn't really drop off, 37%. So even those that were more heavily pretreated, we're seeing a clear signal with response rates that really are higher than chemotherapy.

What was, I think, most important, we saw efficacy of patritumab/deruxtecan across multiple different mechanisms of resistance. And so it wasn't one biomarker select. It really was active, very versatile agent. And really, I think that's what we need. While biomarker-driven resistance will be something we always hone in on and try to focus, we do need something that's much more versatile for rapid implementation. And this is having a lot of potential.

[It was] very well tolerated. If we look at treatment-emergent adverse events, only one person stopped from a TEAE. Only 4% stopped due to TEAEs, so very well tolerated treatment. Response was also durable. One response listed was after 4 years of therapy, and so the potential for long-term disease control, long-term responses.

So clearly an active drug. This is an area where we need a lot of drug development. Well tolerated, only 4% stopping due to adverse events and a nice signal of activity. Our next steps will be to make this a larger study to look in more patients to really hone in on the mechanisms and where this really is working. Can we widen that therapeutic index? And can we look at combinations? Is there a role to continue TKI with this, maybe for better CNS coverage or activity? That's what we'll see in the years to come.

ASCO Daily News: Excellent. Well I'd like to ask you about a trial that you were involved in, the ARROW trial, Abstract 9089. Can you tell us about this impactful study?

Dr. Stephen Liu: Yeah, sure. The ARROW trial is a study that I've been a co-investigator on for many years. This was presented by Dr. Giuseppe Curigliano. And this looks at a RET inhibitor called pralsetinib, originally when we first got involved called BLU-667. RET fusions are present in about 1% of non- small cell lung cancer. These are important events, because we know from other studies, such as the immunotarget registry led by Julien Mazieres,  that RET-positive lung cancers don't seem to respond as well to immunotherapy.

However, in the past, the kinase inhibitors, the targeted agents we had the targeted RET, weren't very good. They had response rates around 30%, 40%, a lot of toxicity. These are drugs like vandetanib, cabozantinib. With the introduction of selective RET inhibitors, we've seen striking efficacy and much better tolerability. And we now have two approved RET inhibitors in this space--selpercatinib and pralsetinib--both receiving FDA accelerated approval based on their respective single arm studies.

What we saw at ASCO 2021 from Dr. Curigliano was an update on the RET fusion positive lung cohort of ARROW. Again, this was a phase I/II trial looking at pralsetinib given at a dose of 400 milligrams by mouth once daily. We look at the patients with RET fusion-positive lung cancer. Now we just have longer follow up and more patients. And overall, the cohort exceeded 200 patients, so 216 patients for a pretty rare driver. And the response rate, 69%, very durable. The duration of response, 22 months. So really solidifying the efficacy and confirming the role in patients with RET fusion-positive lung cancer.

If we break those data down a little bit, patients who had prior chemotherapy, which was 125 patients, response rate was 62%. The disease control rate, 91%. These responses are quick. The median time to responses is 1.8 months, so really that first scan. And that's what we see with targeted therapy.

And we look at these waterfall plots, and I encourage you to take a peek at that. It's exactly what we want to see, the vast majority of patients, almost all patients, with some reduction and some with a quite substantial reduction. Again, the disease control rate after chemo was 91%. So really, the waterfall plot has that look that we seek for effective targeted therapy.

The outcomes were even better in the first-line setting. Response rate originally 79% as first-line therapy. But the way the trial was originally written, it only included frontline patients who weren't eligible for chemotherapy for whatever reason. So that's going to be a more selective cohort. That was changed with an amendment. And once that was removed for people that were eligible for whatever frontline therapy you wanted to give, really our real world first line cohort, the response rate was 88%, disease control rate of 96%.

So to think of a response rate in almost 90% of patients really gives us that confidence we want when we have a driver that we detect when we start a new agent. We're very confident that we're going to see efficacy in these drugs, very well tolerated, very few patients stopping due to a adverse event. A disease control rate of 96% in that first-line setting gives me the confidence to really use this in the first-line setting.

ASCO Daily News: Absolutely. Well, as you know, the Annual Meeting this year focused on equity in cancer care. And there were a number of studies presented in the lung cancer space. I just wanted to get your thoughts on how this issue was addressed at the Annual Meeting in the lung cancer setting. I'm thinking of Abstract 9005 that looked at racial disparities. What are your thoughts on this issue?

Dr. Stephen Liu: Yeah, this was an important abstract, I think. And the theme that Dr. Lori Pierce set of equity really was met by several different abstracts and was a recurrent focus for many important and really overdue discussions.

Abstract 9005 was presented by Dr. Debora Bruno, and this really looked at disparities in biomarker testing. And we just talked about advances for EGFR-mutant lung cancer for RET fusion-positive non--mall cell lung cancer. We have many, many more, but we can only offer these agents if we know the target is present.

And if we don't do proper biomarker testing, our care will not be optimal. If we don't know the molecular genotype of the cancer, we can't treat it properly. We are just guessing, and we're much more likely to deliver an ineffective therapy. We are potentially making subsequent therapies more dangerous.

Knowing the right biomarker is critical to the proper management of non-small cell lung cancer. And if we don't have that, the outcomes will not be as good. The testing really is critical for the management of lung cancer. And what we saw from this abstract was there are disparities in how patients with non-small cell lung cancer are being tested, which simply isn't acceptable.

This was a retrospective analysis that looked at Flatiron data, recent data, 2017 to 2020, a large data set, almost 15,000 patients with non-small cell lung cancer. Demographics were 66% white, 9% Black. If we look at biomarker testing specifically, patients who were Black were less likely to be tested, less likely to have proper biomarker testing, 73% versus 76%, less likely to have full next generation sequencing with a 10% difference, and less likely to get tested early.

We know that testing really influences treatment from the jump right away. And if we don't have that information, our outcomes won't be as good. Our Black patients weren't being tested properly, weren't being tested in a timely manner. And more data showed that clinical trial participation was also decreased among Black patients, 4% involvement for white patients, 2% with Black patients.

And these were actually very similar to what we saw in Abstract 9001 that was presented by Dr. Akinboro from the FDA. And that looked at patients who'd received chemoimmunotherapy. This was a pooled analysis looking at different PD-L1 cohorts. And what was noted on the demographics is that in the phase III registrational landmark studies, Black patients only represented about 2% of patients there as well. So strikingly similar numbers and a gross under-representation. It really is inexcusable and something we need to address. And we need to correct, because this is showing that our care is simply not up to par. 

Trial participation is how we move the field, but many cases, especially in lung cancer, a field that moves so quickly, a clinical trial often represents the best possible option. And Black patients simply aren't enrolling in studies. And I think some of the disparities in clinical trial participation likely reflect some of the disparities in clinical trialists. And I think that if we continue to improve diversity in our workforce, in our oncology subspecialty, that'll be an important step into rectifying this. But this is something we need to look at critically. We need to assess all of our processes and think how we can do better today, and not tomorrow.

ASCO Daily News: Absolutely. Thank you so much, Dr. Liu, for highlighting these really critical points and sharing your valuable insight on all of these impactful studies in lung cancer. Thank you so much.

Dr. Stephen Liu: My pleasure. Thanks for having me.

ASCO Daily News: And thank you to our listeners for joining us today. If you enjoyed this episode, please take a moment to rate, review, and subscribe wherever you get your podcasts.


Disclosures: Dr. Stephen Liu

Consulting or Advisory Role: Genentech, Pfizer, Lilly, Bristol-Myers Squibb, AstraZeneca, Takeda, Regeneron, G1 Therapeutics, Guardant Health, Janssen Oncology, MSD Oncology, Jazz Pharmaceuticals, Blueprint Medicines, Inivata, PharmaMar, Daiichi Sankyo/UCB Japan, BeiGene, Amgen, Turning Point Therapeutics, Elevation Oncology, and Novartis

Research Funding (institution): Genentech/Roche, Pfizer, Bayer, Merck, AstraZeneca, Blueprint Medicines, Lilly, Rain Therapeutics, Alkermes, Bristol-Myers Squibb, Turning Point Therapeutics, RAPT, Merus, Elevation Oncology, and Erasca, Inc

Travel, Accommodations, Expenses: AstraZeneca, Roche/Genentech, and MSD Oncology


Disclaimer: The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.