JCO PO author Dr. Hatim Husain at University of California San Diego, shares insights into his JCO PO article, "Adagrasib Treatment After Sotorasib-Related Hepatotoxicity in Patients With KRASG12C-Mutated Non–Small Cell Lung Cancer: A Case Series and Literature Review", one of the top downloaded articles of 2024. Host Dr. Rafeh Naqash and Dr. Husain discuss how to utilize real-world and clinical trial data to discern the safety of adagrasib (another KRASG12C inhibitor), following sotorasib discontinuation due to hepatotoxicity.

TRANSCRIPT

Dr. Rafeh Naqash: Hello and welcome to JCO Precision Oncology Conversations where we bring you engaging conversations with authors of clinically relevant and highly significant JCOPO articles. I'm your host, Dr. Rafeh Naqash, Podcast Editor for JCO Precision Oncology and Assistant Professor at the OU Stephenson Cancer Center. 

Today, I'm very excited to be joined by Dr. Hatim Hussain, Professor of Medicine at the University of California, San Diego, and author of the JCO Precision Oncology article, "Adagrasib Treatment After Sotorasib-Related Hepatotoxicity in Patients With KRAS-G12C-Mutated Non-Small Cell Lung Cancer: A Case Series and Literature Review." This was one of the top downloaded articles of 2024. And the other interesting thing is we generally don't do podcasts for case reports or case series, so this is one of the very few that we have selected for the podcast. 

And at the time of the recording, our guest disclosures will be linked in the transcript. 

Dr. Hussain, welcome to our podcast and thank you for joining us today.

Dr. Hatim Husain: Thank you Dr. Naqash. Such a pleasure to be here and to speak with you all.

Dr. Rafeh Naqash: And for the sake of this podcast, we'll refer to each other using our first names. So again, as I mentioned earlier that this is one of the very few case reports that we have selected for podcasts in JCOPO and the intention was very deliberate because it caters to something that is emerging where we are trying to treat more KRAS mutant patients with different KRAS inhibitors. And you tried to address one very unique aspect of it in this article which pertains to toxicity, especially hepatotoxicity. So for the sake of our listeners who tend to be community oncologists, trainees, academic faculty, can you tell us what are KRAS inhibitors? What is KRAS-G12C? And how do some of these approved KRAS inhibitors try to inhibit KRAS-G12C?

Dr. Hatim Husain: Sure. For a long time actually we've not had a selective way to inhibit mutant KRAS. And over the last several years actually now, we've seen some dramatic advances here, particularly with the FDA approval of some of the selective inhibitors against the G12C variant. So KRAS-G12C is an isoform of KRAS that is most common in lung cancer and in fact actually is a transversion mutation in the KRAS gene that is a product of the carcinogen of tobacco. And in fact, the incidence of KRAS-G12C in lung cancer, it's quite astounding where as many KRAS-G12C patients there are, there can be, as you know, more than EGFR patients in certain populations and cohorts. The medicines sotorasib and adagrasib were rationally designed to be selective KRAS-G12C inhibitors. And the way that they do this is that they lock the KRAS protein in the OFF state. KRAS is a protein that oscillates between an ON and an OFF state and by virtue of locking the protein in an OFF state, it has shown inhibition of downstream signaling and mitigation of tumor growth and, in fact, tumor cell death.

Dr. Rafeh Naqash: I absolutely love the way you describe the ON and OFF state, the oscillation where the ON is bound to the GTP and the OFF is bound to the GDP. The two KRAS inhibitors as currently FDA approved, as you mentioned, are RAS OFF inhibitors and they're emerging KRAS inhibitors that are RAS ON. So now, as we have known from previous data related to immunotherapy and EGFR TKIs such as osimirtinib where toxicity tends to be a compounded effect when you have osimertinib given within a certain timeline of previous checkpoint therapy, we've seen that in the clinic as the data for these KRAS inhibitors is emerging, you talk about some very interesting aspects and data about what has been published so far with regards to prior use of immunotherapy or chemo immunotherapy and the subsequent use of KRAS inhibitors. Could you elaborate upon that?

Dr. Hatim Husain: Sure. So for this population of patients, the first line approved strategy is a strategy that most cases will incorporate immune therapy and chemotherapy. Immune therapy can have some important responses for patients with KRAS-G12C. This may be due to the fact that KRAS-G12C patients may have a higher incidence of prior smoking, perhaps higher mutation burdens in some patients, and perhaps immunogenicity is defined in that context. So the standard of care in the first line currently includes immune therapy or immune therapy and chemotherapy. Where the current FDA approvals for selective G12C inhibitors are are after the first line of therapy. There are a number of trials exploring these medicines in the first line to see if they may be incorporated into a future treatment paradigm.

Dr. Rafeh Naqash: Thank you for that explanation. Now, going to what you published in this manuscript, can you help us understand the context of why you looked at this? Even though the data just comprises a case series of a handful of patients, but the observations are very interesting and these are real world scenarios where we often tend to be in situations where an individual has had toxicity on a certain drug and may have some response to that drug, but at the same time, the toxicity is challenging. And then you try to debate whether another drug in the same class might be beneficial without those toxicities. So you've tried to address that to some extent using this data set. So can you elaborate upon the question, the methodology, what you tried to look at, and important observations that you have?

Dr. Hatim Husain: Yes, our paper was actually inspired by one of my patients. My patient was a patient who had received chemotherapy and immune therapy and actually in the past, even, you know, additional lines of immune therapies, it was really coming to the edge of where standard treatments would exist. It was right at the same time that these selective inhibitors had been approved and the patient had received sotorasib. And what was remarkable was, when given sotorasib, patient had a very high peak and spike in the transaminases. And we would do different trials of strategies around dose, around interruptions. And it was becoming quite difficult, actually, for the patient to proceed with additional therapy. It was around similar times, actually, and I do want to make a note that the patient was progressing, driven in large fact by the fact that we've had to interrupt the medicine. So we feel and believe that the patient had had inadequate dosing because of the level of toxicity that the patient was having with transaminase increase. So it was around the same time that adagrasib was first commercially available that we were at that point, and we did a trial of adagrasib post-sotorasib, largely driven by necessity, without having additional options to provide this patient in our environment. What was remarkable was when the patient received the adagrasib, there were no spikes in transaminases similar to what we had seen before. And that really led us thinking and to say, "Is this adverse event of transaminase increase or hepatotoxicity, is this a class effect with KRAS-G12C inhibitors, or is it more nuanced than that? Are there different, perhaps, mechanisms by which the medicines may work that may more or less differentially contribute to this adverse event?" And so that inspired us to kind of do a larger analysis, kind of really reach out to a larger network of physicians to gather insights and to gather responses in patients who had had a serial approach of sotorasib and then adagrasib. 

What we found in this process was, in fact, actually there were many more cases of patients who resembled my patient, where the sequence of sotorasib going to adagrasib may have demonstrated differential contribution of hepatotoxicity in that context. And that really motivated us to put the publication together to due diligence, and in the publication spend a lot of time to kind of outline each patient case in detail around metrics surrounding time from last immune therapy, the number of days on sotorasib, the best response to sotorasib, the interval between sotorasib and adagrasib, the duration of adagrasib and then the grade of hepatotoxicity seen in each of the contexts, and particularly kind of the adagrasib and patient disease status as well. We were quite inspired by the effort to try to, if we do not have randomized data in comparison of one medicine to another, which we do not at this juncture, we do not have a randomized analysis to really diligently and rigorously compare the rates of AEs across each medicine, and even in sequence, we do not have that with immune therapy. But what we felt was trying to get more analysis of this sequential approach of, if patients had received a medicine, had to be t