In the News: Immune checkpoint inhibitors in the renal transplant patient

 

Use of immunotherapy in the renal transplant patient is challenging. Initial case reports had shown over and over acute rejections. In 2017, we had tried a novel way to prevent rejection in a single case report published in NEJM( using mini steroid pulse and mTOR over CNI use). Since then, we have used this approach successfully in several patients to allow for good tumor response and prevent rejection. But one case, two cases, three cases cannot tell the whole story.  More data is needed. A recent meta-analysis done on use of immunotherapy and transplant patients showed of 44 patients,  18 were reported to have acute rejection. Median time from immune checkpoint inhibitors to acute rejection diagnosis was 24 (interquartile range, 10–60) days. Reported types of acute allograft rejection were cellular rejection (33%), mixed cellular and antibody-mediated rejection (17%), and unspecified type (50%). Fifteen (83%) had allograft failure and 8 (44%) died. Three patients had a partial remission (17%), 1 patient achieved cancer response (6%), and 5 patients had stable disease (28%).

Other studies similar to this have showed similar rejection rates of 40%. No studies have tested the clinical efficacy of the use of these agents in renal transplant patients.

In a recent study published in Kidney International, we collected 69 cases from 23 institutions from US, Canada and Europe. This is the largest study to look at both transplant outcomes and efficacy of these agents in renal transplants patients.

Acute rejection rate 42% (29 out of 69), median ICI to rejection=24 days. Rejection is severe: cellular rejection and mixed cellular and antibody-mediated rejection are both common. Once rejection happened, 65% lost allograft.

What are the risk factors of rejection? Being on 3-agents immunosuppression and mTOR inhibitor use were associated with LOWER risk of rejection. This is an interesting finding. This is to tell us the obvious- the less the immunosuppression- the risk for rejection increases but the mTOR finding is interesting( caution- still low Ns). Take a look at this paper as well.
We looked at rejection rate and cancer objective response rate in skin squamous cell carcinoma (cSCC) and melanoma, two most common cancer types in our cohort. In cSCC, rejection rate 37.5%, ORR 36.4% and ICI may be associated with longer overall survival. In melanoma: rejection rate 54.5% (# of immunosuppression agent-dependent), ORR 40%. OS did not differ but limited by small # of patients and short follow-up.

An important figure that is hidden in the supplemental content is below: This tell us the majority of the changes done by centers when immunotherapy was initiated, see the % who increased steroids, converted CNI to mTOR inhibitors, dc CNI , dc MMF. etc.  Interesting changes which were made are not at all standardized. 

Although our study is to our knowledge the largest multicenter cohort of patients with advanced solid malignancies with kidney transplant who received ICI to date, there are several limitations Firstly it is retrospective and small-sample nature of our cohort limited our ability to adjust for a number of confounders in multivariable analysis for the risk of graft rejection. Also less than half of acute rejection were biopsy proven, which limits the accuracy of the diagnosis of rejection. The comparison of outcomes using these historical cohorts suffers from the lack of power due to the small number of cases, but provides a pragmatic approach to address the risk of rejection and objective response rate. Lastly, immunosuppression modification was the providers’ choice at each institution and not standardized.

So what now? This tells us that immunotherapy is a feasible option for kidney transplant pts but with very high risk of rejection.

mTOR inhibitor plus steroid mini-pulse may be effective in preventing rejection?
Or should we continue the immunosuppressive meds “as is” or at least 2 of them and then give the immunotherapy as efficacy was amazing in cSCC and prevent the rejection as well.
What this study also told us is that- stopping the immunosuppression when planning to give immunotherapy doesn’t really help in cancer outcomes or renal transplant outcomes? So should we be even stopping them??

A collaborative effort led by Naoka Murakami from around the world.