Claud N. Grigg, MD, highlights different frontline combination regimens that are improving outcomes for patients with metastatic renal cell carcinoma.
The frontline treatment of patients with metastatic renal cell carcinoma (RCC) has shifted away from the use of a single-agent TKI toward novel combination regimens in recent years, according to Claud N. Grigg, MD, who added that although choosing among available options have proven particularly challenging, one thing is clear: combinations are the future.
“All patients with clear cell RCC, unless they have a true contraindication to an immune checkpoint inhibitor, really should be receiving some kind of combination therapy in the frontline setting, with the exception of the very rare, favorable-risk patients,” said Grigg. “[We should be] ensuring that these patients aren't receiving TKI monotherapy anymore. The choice between combination therapies is still a difficult one to make and I don't believe that there is necessarily a correct answer for all patients, but all be receiving some kind of combination.”
In an interview with OncLive® during the Institutional Perspectives in Cancer webinar on Genitourinary Malignancies, Grigg, a medical oncologist at Levine Cancer Institute, of Atrium Health, highlighted different frontline combination regimens that are improving outcomes for patients with metastatic RCC.
Grigg: CheckMate-214 was really the first major trial to examine a combination therapy in the frontline setting. Here, the combination of 2 immune checkpoint inhibitors, nivolumab [Opdivo] and ipilimumab [Yervoy] were compared with sunitinib [Sutent] in its standard 4-weeks-on, 2-weeks-off schedule. The [doublet] was associated with an improvement in overall survival [OS]. We have the longest follow-up for this study of over 40 months and many of the responses reported are still durable to this day. The OS benefit continues to be evident as time goes on and follow-up continues.
We now have 2 approved VEGF inhibitor and immunotherapy combinations and we're anticipating a third and potentially a fourth combination in the [near future]. That being said, it’s becoming a very confusing space for many clinicians to differentiate between all these different regimens. Certainly, the idea of combining a VEGF receptor inhibitor with an immune checkpoint inhibitor has had a tremendous impact on our patients. The objective response rates [ORRs] and radiographic response rates are really tremendous with these combinations. We've seen response rates ranging from 50% to 60% [with these approaches]. The rate of tumor [reduction] is around 90% to 95% with these regimens. The majority of our patients achieve at least some benefit from these combinations. In terms of understanding the differences between these options, we don't have a lot of answers; hopefully, we will in the coming years.
In the KEYNOTE-426 trial, investigators compared a combination [comprised] of the PD-1 checkpoint inhibitor pembrolizumab [Keytruda] and axitinib [Inlyta], given at its standard dose of 5 mg twice daily, versus sunitinib, given on a 4-weeks-on, 2-weeks-off schedule. Although [axitinib] can be titrated up and down, it generally is started at that dose. That combination was associated with an improvement in OS, progression-free survival [PFS], and ORR. With longer-term follow-up of a median of 30 months, the improvements in OS and PFS persist.
The toxicity with this regimen seems to be fairly manageable and predictable. We tend to see the same safety profile that we observe with either drug alone. Namely, [we see] autoimmune toxicities with pembrolizumab and standard TKI toxicities with axitinib. Compared with sunitinib, the toxicity profile [of the combination] appears to be comparable or better in some ways. This is certainly a very effective and promising regimen for the frontline setting.
Interim results from the JAVELIN Renal 101 trial were released at a similar time, although they have a shorter follow-up compared with KEYNOTE-426. This was a similar study comparing the PD-L1 checkpoint inhibitor avelumab with the same dose of axitinib versus the same standard dosing of sunitinib. This study was also positive, at least in terms of PFS. The OS data did seem to show a trend toward improvement, although the results are not mature yet. We also saw a very high ORR around 52%. Improvement in PFS and toxicity profiles were comparable [to what has been seen] with the other TKI/immunotherapy combinations.
We are looking forward to seeing the publication of the results from this trial but the findings [reported thus far have been] very impressive. At an early follow-up time, we saw improvements in OS and PFS. The PFS was essentially doubled with the most impressive PFS hazard ratio of all the TKI/immunotherapy combinations. We can't directly compare this study against others because the study populations aren't necessarily comparable. Nonetheless, I believe the improvements in PFS and OS that we saw was good news.
Also, no unexpected toxicities have been reported with the combination compared with nivolumab or cabozantinib alone. As such, [this doublet] should be a welcome addition to the first-line treatment [arsenal].
We saw a press release on the combination of lenvatinib [Lenvima] with immune checkpoint inhibition, [which appears to have been] a positive trial. We look forward to seeing the [full] results. Certainly, newer agents [are also emerging] in the pipeline; specifically, agents targeting HIF-2α have generated a lot of excitement. Several combination studies are being planned at this stage, but many of them are still quite a bit away from [revealing] any results.
The favorable risk population is a challenge because these patients have a really good prognosis by definition and are expected to live a long time. Detecting any improvements in OS can [require] a really long follow-up time. Thus far, at least in some of our subgroup analyses from studies that have longer follow-up like KEYNOTE-426, we haven't seen a true differentiation in terms of OS between TKI/immunotherapy combinations versus TKI monotherapy.
Additionally, the CheckMate-214, the subgroup analysis for the favorable-risk population showed that PFS and ORR favored the TKI versus the immunotherapy/immunotherapy combination. Some of the extended follow-up has suggested no improvement in terms of OS [with the combination] and perhaps even a slight favoring of OS for the TKI monotherapy. At this point, favorable-risk patients should receive TKI monotherapy or in combination with an immune checkpoint inhibitor. [As for which,] I don't believe that we've fully answered that question yet.
The frontline space is becoming crowded. We're learning that all our drugs that work well in the later settings also work well in the frontline setting. Unfortunately, once resistance develops to any individual TKI, although responses can subsequently occur, they are often less robust. With each line of TKI, we see diminishing response and benefit.
What we really need are new drugs that have a new mechanism of action. We're all looking forward to hearing the results of some of the metabolically-targeted drugs. We know that the glucose metabolism pathway is very important in clear cell RCC. [We’re also excited about] the drugs that are targeting HIF-2α, which is a key component of the von Hippel-Lindau inactivation in clear cell disease. Having new drugs with new mechanisms of action will be key to the future.
Editor’s Note: This interview was conducted prior to the 2021 Genitourinary Cancers Symposium.