Outcomes of patients with metastatic melanoma treated with immunotherapy prior to or after BRAF inhibitors.

BACKGROUND: The immunotherapy (IT) agents ipilimumab and interleukin-2 as well as BRAF inhibitors (BRAFi) vemurafenib and dabrafenib, with or without trametinib (MEK inhibitors), are all FDA-approved treatments for BRAF metastatic melanoma, but there are few studies to guide optimal sequencing. This retrospective analysis describes the outcomes of patients treated with either BRAFi before IT or IT before BRAFi. METHODS: A cohort of patients treated with BRAFi alone or with MEK inhibitor was retrospectively identified. Response rate (RR), overall survival (OS), and progression-free survival (PFS) were evaluated for the entire cohort, subdivided by BRAFi prior to or after IT. RESULTS: RR and median PFS and OS calculated from commencement of BRAFi following IT (N = 32) were 57%, 6.7 months (95% confidence interval [CI] = 4.3-9.1 months), and 19.6 months (95% CI = 10.0-undefined months), respectively; whereas for BRAFi initially (N = 242) were 66%, 5.6 months (95% CI = 4.7-6.8 months), and 13.4 months (95% CI = 10.1-17.0 months). Results were similar when controlled for prognostic variables. A total of 193 patients discontinued BRAFi, with OS of 2.9 months (range of 1.8-4.4 months) from day of BRAFi discontinuation. Forty patients subsequently received IT with ipilimumab. Only half could complete 4 doses of ipilimumab; PFS with ipilimumab was 2.7 months (95% CI = 1.8-3.1 months) and OS was 5.0 months (95% CI = 3.0-8.8 months). CONCLUSIONS: In this retrospective analysis, prior treatment with IT does not appear to negatively influence response to BRAFi. Outcomes for IT with ipilimumab following BRAFi discontinuation are poor. Randomized controlled trials are needed to define if sequencing IT prior to BRAFi therapy is superior to sequencing BRAFi prior to IT.

Potential of new therapies like anti-PD1 in kidney cancer.

OPINION STATEMENT: Various targeted immunotherapies have shown efficacy in metastatic renal cell carcinoma (RCC) recently. Specifically, molecules targeting the PD-1/PD-L1 pathway have shown promising results. These agents appear to provide several advantages over previous standard therapies. First, higher objective responses are attained with these agents, many of which are complete and durable. Second, these drugs are associated with less overall treatment-related toxicity. This allows for the testing of various combination therapies that may provide better clinical outcomes. Finally, these novel therapeutics are unique in that they appear to have benefit in a variety of neoplasms, including those with dismal prognosis such as metastatic non-small cell lung cancer (NSCLC). Further investigations are needed to confirm these findings and explore additional applications. The importance of PD-L1 expression on tumor cells on the efficacy of PD-1 and PD-L1 inhibitors is also under investigation. Patient selection based on this expression may optimize the observed clinical benefit. Thus, we believe that new therapeutics such as Anti-PD1 and Anti-PD-L1 antibodies will make a significant impact on cancer treatment in general as well as in the field of kidney cancer.

A retrospective analysis of High-Dose Interleukin-2 (HD IL-2) following Ipilimumab in metastatic melanoma.

BACKGROUND: High dose interleukin-2 (HD IL-2) can induce durable responses in a subset of patients leading to long-term survival. Immune checkpoint blockade (ICB) has demonstrated similarly durable responses in a larger proportion of patients. However, not all patients respond to immune checkpoint blockade and subsequent therapeutic options need to be explored. METHODS: The PROCLAIM database was queried for patients with metastatic melanoma who had received HD IL-2 after treatment with ipilimumab or without prior ICB. Patient characteristics, toxicity and efficacy were analyzed. RESULTS: A total of 52 metastatic melanoma patients were treated with high dose IL-2 after ipilimumab and 276 patients were treated with high dose IL-2 without prior ICB. The overall response rate in the prior ipilimumab group was 21 % as compared to 12 % in the group that had not received prior ipilimumab. The median overall survival, measured from the initiation of HD IL-2 therapy, was 19.3 months in the prior ipilimumab group and 19.4 months in the no prior ICB group. Toxicities observed on HD IL-2 were relatively equivalent between the groups although there were cases of CTLA4 antibody-induced colitis reported after HD IL-2 treatment and a CTLA4 antibody-induced colitis related death. CONCLUSION: In this retrospective analysis HD IL-2 therapy displayed antitumor activity in melanoma patients who progressed following treatment with ipilimumab. Most HD IL-2 toxicity was not worsened by prior ipilimumab therapy except for one treatment related death from colitis. Care should be taken to avoid reactivation of CTLA4 antibody-induced colitis.

Nivolumab for the treatment of cancer.

INTRODUCTION: One mechanism by which tumor cells are thought to evade the host's immune system is by inducing negative signals that cause T-cell suppression. An important interaction that results in this phenomenon is the one between programmed death-1 (PD-1) on the T cell and its ligand PD ligand-1 (PD-L1) on the tumor cell. PD-1 pathway blocking agents, such as nivolumab , are therefore capable of reversing T-cell suppression and ultimately induce antitumor responses. AREAS COVERED: In this review, the authors summarize investigations related to the safety and efficacy of nivolumab in a variety of malignancies thus far, including advanced melanoma, renal cell carcinoma (RCC) and NSCLC. EXPERT OPINION: The results have been promising with a large number of objective responses and favorable safety profiles inspiring several Phase III trials in these settings. More recent studies are exploring the role of this drug in the treatment of various other cancers. Combination therapies involving nivolumab are also being studied and are yielding interesting results. Finally, the role of tumor PD-L1 expression as a predictive biomarker remains to be ascertained. Thus, with rational refinement through biomarker and combination clinical trials, nivolumab and other PD-1 blocking agents will likely lead to significant improvements in cancer therapeutics.

The role of CD94/NKG2 in innate and adaptive immunity.

CD94/NKG2 is a heterodimer expressed on natural killer (NK) and a small subset of T cells. This receptor varies in function as an inhibitor or activator depending on which isoform of NKG2 is expressed. The ligand for CD94/NKG2 is HLA-E in human and its homolog, Qa1 in mouse, which are both nonclassical class I molecules that bind leader peptides from other class I molecules. Although <5% of CD8 T cells express the receptor in a naïve mouse, its expression is upregulated upon specific recognition of antigen. Similar to NK cells, most CD8 T cells that express high levels of CD94 co-express NKG2A, the inhibitory isoform. The engagement of this receptor can lead to a blocking of cytotoxicity. However, these receptors have also been implicated in the cell survival of both NK and CD8 T cells. The level of CD94 expression is inversely correlated with the level of apoptosis in culture. Thus, CD94/NKG2 receptors may regulate effector functions and cell survival of NK cells and CD8 T cells, thereby playing a crucial role in the innate and adaptive immune response to a pathogen.

Clinical utility of a blood-based BRAF(V600E) mutation assay in melanoma.

BRAF inhibitors (BRAFi) have led to clinical benefit in patients with melanoma. The development of a blood-based assay to detect and quantify BRAF levels in these patients has diagnostic, prognostic, and predictive capabilities that could guide treatment decisions. Blood BRAF(V600E) detection and quantification were performed on samples from 128 patients with stage II (19), III (67), and IV (42) melanoma. Tissue BRAF analysis was performed in all patients with stage IV disease and in selected patients with stage II and III disease. Clinical outcomes were correlated to initial BRAF levels as well as BRAF level dynamics. Serial analysis was performed on 17 stage IV melanoma patients treated with BRAFi and compared with tumor measurements by RECIST. The assay was highly sensitive (96%) and specific (95%) in the stage IV setting, using a blood level of 4.8 pg as "positive." BRAF levels typically decreased following BRAFi. A subset of these patients (5) had an increase in BRAF(V600E) values 42 to 112 days before clinical or radiographic disease progression (PD). From 86 patients with resected, stage II or III melanoma, 39 had evidence of disease relapse (45.3%). Furthermore, BRAF mutation in the blood after surgical resection in these patients was not associated with a difference in relapse risk, although tissue BRAF status was only available for a subset of patients. In summary, we have developed a highly sensitive and specific, blood-based assay to detect BRAF(V600) mutation in patients with melanoma.

The role of TCR stimulation and TGF-beta in controlling the expression of CD94/NKG2A receptors on CD8 T cells.

Following antigen recognition, murine CD8 T cells express CD94/NKG2A receptors. Our results show that this up-regulation occurs rapidly in vitro and is accompanied by an approximately 8-fold increase in CD94 and approximately 125-fold increase in NKG2A mRNA. In contrast, only a twofold increase in NKG2C mRNA is noted. The addition of TGF-beta, but not IL-10, IL-12 or IL-15, leads to a further increase in cell membrane expression of these receptors, as well as a approximately 6-fold increase in mRNA for both chains. TGF-beta also increases CD94/NKG2A expression on memory CD8 T cells that are re-exposed to antigen. The effect of TGF-beta on increasing CD94/NKG2A expression on both naive and memory CD8 T cells occurs only when there is a concurrent stimulation through the TCR. In contrast, TGF-beta does not increase expression of CD94/NKG2A on resting or activated NK cells. We also show by using purified CD8 T cells, that TGF-beta acts directly on these cells. These results implicate a role for both antigen and TGF-beta in increasing expression of inhibitory CD94/NKG2A receptors on CD8 T cells.

Preferential survival of CD8 T and NK cells expressing high levels of CD94.

The Qa-1(b)/Qdm tetramer binds to CD94/NKG2 receptors expressed at high levels on approximately 50% of murine NK cells. Although very few CD8 T cells from naive mice express CD94/NKG2 receptors, approximately 50% of CD8 T cells taken from mice undergoing a secondary response against Listeria monocytogenes (LM) are CD94(high) and bind the tetramer. Although CD94(int) NK cells do not bind the tetramer, CD94(int) CD8 T cells do, and this binding is dependent on the CD8 coreceptor. We found that the extent of apoptosis in CD8 T and NK cells was inversely related to the expression of CD94, with lower levels of apoptosis seen in CD94(high) cells after 1-3 days of culture. The difference in CD8 T cell survival was evident as early as 6 h after culture and persisted until nearly all the CD94(neg/int) cells were apoptotic by 48 h. In contrast, expression of inhibitory Ly-49A,G2,C/I molecules was associated with higher levels of apoptosis. Cross-linking CD94/NKG2 receptors on CD8 T cells from a mouse undergoing an LM infection further reduced the percentage of apoptotic cells on the CD94-expressing populations, while cross-linking Ly-49I had no effect on CD8 T cells expressing Ly-49I. Cross-linking CD3 on CD8 T cells from a mouse undergoing a secondary LM infection increases the extent of apoptosis, but this is prevented by cross-linking CD94/NKG2 receptors at the same time. Similar results were observed with NK cells in that the CD94(high) population displayed less apoptosis than CD94(int) cells after 1-3 days in culture. Therefore, the expression of CD94/NKG2 is correlated with a lower level of apoptosis and may play an important role in the maintenance of CD8 T and NK cells.