Apr 19, 2023
Dr. Nigel Key and Dr. Anna Falanga join us for a conversation on
the updated ASCO VTE prophylaxis and treatment in patients with
cancer guideline. They discuss recent evidence assessing apixaban
for VTE treatment in patients with cancer and evaluating direct
factor Xa inhibitors for extended postoperative prophylaxis. Based
on this new evidence, they present updated evidence-based
recommendations from the guideline expert panel. Dr. Key and Dr.
Falanga also discuss outstanding questions regarding VTE
prophylaxis and treatment in patients with cancer.
Read the full guideline update, “Venous Thromboembolism Prophylaxis and Treatment in Patients with Cancer: ASCO Guideline Update” at www.asco.org/supportive-care-guidelines.
This guideline, clinical tools, and resources are available at www.asco.org/supportive-care-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.23.00294.
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. Nigel Key from University of North Carolina, and Dr. Anna Falanga from University of Milan Bicocca, co-chairs on ‘Venous Thromboembolism Prophylaxis and Treatment in Patients with Cancer: ASCO Guideline Update’.
Thank you for being here, Dr. Key, and Dr. Falanga.
Dr. Nigel Key: Thank you.
Dr. Falanga: Thank you.
Brittany Harvey: Then, before we discuss this guideline, I'd just 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 our guests on this episode, are available online with the publication of the guideline in the Journal of Clinical Oncology, linked in the show notes.
So then, jumping into this guideline update, Dr. Key, what prompted an update to the ‘ASCO VTE Guideline’, which was last updated in 2019?
Dr. Nigel Key: Okay, well, thank you, Brittany, for that question. Well, first of all, ASCO has been providing this guideline since 2007 with iterations and full reviews of the data, the last complete one being in 2019. This update was really triggered by ASCO's signals approach, which relies on experts in the field suggesting an update to the guidelines based on recent publications that may be practice-changing. So, in this case, the signals were really a randomized control trial assessing apixaban for VTE treatment, venous thromboembolism treatment, in patients with cancer called the CARAVAGGIO trial, and we'll discuss that a little bit later. There were also a couple of randomized control trials which evaluated direct factor Xa inhibitors for extended postoperative prophylaxis, and these were new areas subsequent to the 2019 guidelines. So, a systematic review was carried out in the relevant topics for randomized control trials published between November 1, 2018, and June 6, 2022. And what you'll hear today is the result of that process.
Brittany Harvey: Great. And then you just described that guideline recommendations were updated both for prophylaxis and for treatment. So then, Dr. Falanga, what is the updated recommendation for perioperative VTE prophylaxis?
Dr. Falanga: Thank you for this question. For this update, actually, there were two randomized trials addressing the extended thromboprophylaxis in cancer patients. This is an important question, and direct oral anticoagulants had never been included in the previous guidelines. So this new data indicating safety and in some way efficacy of these drugs were important to be in some way included. Actually, the two trials, one tested laparoscopic surgery in patients with colorectal cancer, so major surgery in colorectal cancer and tested the drug rivaroxaban against the placebo after one week of low molecular weight heparin. And the other trial tested in a different type of cancer, gynecological cancer surgery, apixaban versus a placebo after a short course with low molecular weight heparin.
So the two trials are very different, and the recommendation, after all, is weak. But the panel felt it was important to split the previous recommendation 3.5 into three recommendations. The 3.6 specifies which are the cancer patients that really need extended prophylaxis, or the recommendation addresses this population in particular at high risk, which means patients with laparoscopic or laparotomic abdominal pelvic surgery for cancer who have high risk characteristics, including restricted mobility, obesity, previous history of thrombosis, and other additional risk factors. So the recommendation is limited to this population. As I said, there is a weak recommendation because the two trials differ in the type of surgery, the type of the number of patients, the timing of prophylaxis, and one tested rivaroxaban and one tested apixaban.
But in any case, the recommendation now reads that prophylaxis with these two direct oral anticoagulants may be offered in addition to the previous recommendation with the low molecular weight heparin for this indication, although the low molecular weight heparin indication remains a strong recommendation where these other two drugs are added. But still other research is needed to strengthen this recommendation.
Brittany Harvey: Understood. Thank you for describing where there is evidence and where future research is needed to strengthen those recommendations and the qualifying statements for who is appropriate to receive this VTE prophylaxis.
So then, Dr. Key, what did the expert panel update regarding treatment of patients with cancer with established VTE to prevent recurrence?
Dr. Nigel Key: Yes. First of all, I want to make it very clear that this particular recommendation deals, as you say, with patients with established venous thromboembolism. This is quite distinct from recommendations regarding primary prophylaxis in ambulatory patients, which is dealt with in a separate recommendation. That's number two in the 2019 guideline, and those have not been updated. But in terms of treatment of established venous thrombosis, there were three randomized control trials considered. They essentially all addressed the possible role of apixaban, which had not been included in the 2019 guideline. In this revised recommendation, the data looked at both the initial treatment of patients presenting with venous thrombosis as well as extended treatment, which what we know at present, really extends out to six months in terms of using non-vitamin K antagonists, preferably for extended prophylaxis.
So, in 4.1, the CARAVAGGIO trial that I mentioned earlier was a very large trial involving almost 1200 patients with cancer who had symptomatic or incidental acute proximal DVT or pulmonary embolism. And these patients were randomized to six months of treatment with either apixaban or dalteparin. And, in a nutshell, apixaban was non-inferior to dalteparin for the primary outcome of a recurrent VTE during the six month trial period. There was also a similar rate of major bleeding, 3.8 versus 4% in the two arms. So this was strong evidence that initial treatment could include apixaban in addition to what was already in the recommendations. And for those choosing to treat with heparin for initial five to ten days, as before, the recommendation is for low molecular heparin over unfractionated heparin.
So, the second part of this took into account the CARAVAGGIO trial, which I've already mentioned the result of, as well as two smaller trials. They had a VTE trial which had almost 300 patients, and again compared apixaban to dalteparin. And then there was a third smaller study comparing apixaban to lovenox in about 100 patients. But, essentially, the net outcome of the systematic review was that the recommendations 4.1 and 4.2 for, respectively, initial and extended treatment of established VTE, gave high quality evidence with a strong recommendation to include apixaban both for initial treatment and for extended treatment.
Brittany Harvey: Understood. So then you've both discussed this a bit by describing the randomized trials supporting these recommendations. But Dr. Falanga, what should clinicians know as they implement these updated recommendations?
Dr. Anna Falanga: Well, clinicians should know that there are more options to offer to their patients for long-term treatment of VTE, as Dr. Key said, up to six months. This is an important expansion of the spectrum of choices for a more personalized treatment on the basis of the patient's characteristics and the drug characteristics. So this is very important to know. Also, for the postoperative prophylaxis, this update is relevant because of the recommendation. Although we are open to the perspective of using new drugs based on oral intake as an alternative to low molecular weight heparin, and knowing this drug appears to be safe in the specific setting where they were tested in the trial is important.
Brittany Harvey: Definitely, it's great to have more options for patients.
So then in your view, Dr. Key, how will these guideline recommendations impact patients with cancer?
Dr. Nigel Key: Well, I think that with more information that Dr. Falanga just presented, essentially we're looking at two different situations here, both the extended thrombosis prophylaxis after surgery and the choice of agent does need to be individualized with a discussion with a physician. There are still remaining concerns about increased bleeding with direct Xa inhibitors in patients with GI and GU malignancy, for example. So this needs to be taken into account, patients' creatinine values and so on, and what other drugs there are in terms of interactions with direct Xa inhibitors. So I think what you're looking at though is the ability to be confident for that patient that oral agents are, for the most part, as safe and effective as low molecular weight heparins. And hopefully, this will be something that is seen as a positive and maybe somewhat liberating effect for patients.
Brittany Harvey: That's great to hear.
So then finally, Dr. Falanga, you've already mentioned a few areas in which more research would be helpful to strengthen the recommendations. But are there other outstanding questions regarding VTE prophylaxis and treatment in patients with cancer?
Dr. Anna Falanga: Yes, there is a lot of work to be done ahead for prophylaxis. As we already mentioned, it's important to improve the evidence for direct oral anticoagulant safety and efficacy for extended, postoperative prophylaxis. In the medical setting, we have open questions about how to improve the management of patients with VTE beyond six months; we don't know for the treatment of VTE beyond six months, and identify better what are the best drugs and the best strategies to be utilized in this interval.
Then I think that we need to understand, in collaboration with cardiologists and neurologists, whether arterial thrombosis associated with the cancer may need a different treatment compared to subjects without cancer, and understand how to manage anticoagulant together with antiplatelet drugs in these patients who are often thrombocytopenic.
Finally, it is, of course, important to test new drugs for VTE treatment with potentially reduced bleeding risk, such as the new inhibitors of factor XI and factor XII. I think these are the major points that we need to address in the near future possibly.
Brittany Harvey: Absolutely. Well, we'll look forward to future updates of this ASCO guideline to discuss that research as it comes along.
So I want to thank you both so much for your work to update this guideline and thank you for your time today, Dr. Falanga and Dr. Key.
Dr. Anna Falanga: Thanks a lot. Bye bye.
Dr. Nigel Key: Thank you. You’re very welcome. Bye bye.
Brittany Harvey: And 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/supportive-care-guidelines. You can also find many of our guidelines and interactive resources in the newly redesigned ASCO Guidelines app, available for free 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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