ALBERT

Description: Vemurafenib and dabrafenib selectively inhibit the v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) kinase, resulting in high response rates and increased survival in melanoma. Approximately 22% of individuals treated with vemurafenib develop cutaneous squamous cell carcinoma (cSCC) during therapy. The prevailing explanation for this is drug-induced paradoxical ERK activation, resulting in hyperproliferation. Here we show an unexpected and novel effect of vemurafenib/PLX4720 in suppressing apoptosis through the inhibition of multiple off-target kinases upstream of c-Jun N-terminal kinase (JNK), principally ZAK. JNK signaling is suppressed in multiple contexts, including in cSCC of vemurafenib-treated patients, as well as in mice. Expression of a mutant ZAK that cannot be inhibited reverses the suppression of JNK activation and apoptosis. Our results implicate suppression of JNK-dependent apoptosis as a significant, independent mechanism that cooperates with paradoxical ERK activation to induce cSCC, suggesting broad implications for understanding toxicities associated with BRAF inhibitors and for their use in combination therapies.

Description: Extracorporeal photopheresis (ECP) is an effective frontline therapy for patients with leukemic cutaneous T-cell lymphoma (L-CTCL), but the mechanisms of action are not fully understood. To elucidate molecular mechanisms underlying the efficacy of ECP, we used Agilent Whole Human Genome Microarrays to examine blood transcriptional profiles in L-CTCL patients after ECP therapy. Ten L-CTCL patients including 5 clinical responders and 5 non-responders were studied. Their peripheral blood was collected before ECP (baseline), at Day 2, and one month post-ECP. Total RNA extracted from peripheral blood mononuclear cells was assayed with Whole Human Genome Oligo Microarrays (4 × 44 K) (Agilent, Santa Clara, CA). The differentially expressed gene analysis (DGA) was done using the paired t-test with Benjamini- Hochberg correction (P value 〈 0.05) between post-ECP and baseline. The fold change of gene expression between post-ECP and baseline were calculated from the normalized values. Hierarchical clustering of differentially expressed genes was performed with the Pearson correlation. The DGA between responders and non-responders were cross-compared. Canonical biological pathways were identified using Ingenuity Pathway Analysis (IPA, Ingenuity Systems, Redwood City, CA). Differentially expressed gene profiles were different in responders from non-responders. As indicated in Figure 1, there were more genes differentially regulated in responders than in non-responders post-ECP at both Day 2 (549 genes in responders versus 66 genes in non-responders) and at one month (472 genes in responders versus 95 genes in non-responders). Among 472 differentially expressed genes in responders at one month post-ECP, almost twice as many genes (313) were down-regulated compared to up-regulated genes (159). The top down-regulated genes were IL-1β, EGR1, CCL3, CCL3L3, and CXCL2. The down-regulated genes were mainly related to functions of platelets, immune and/or stress responses, and chromatin remodeling. The upregulated genes were mainly related to functions of the nucleolus and included USP34, POLR3F, ZNF529, C22orf35, and BAT2D1. The ingenuity pathway analysis revealed that the top 5 pathways affected by ECP at one-month in responders were 1) integrin signaling; 2) granulocyte adhesion and diapedesis; 3) signaling by Rho Family GPTases; 4) agranulocytes (lymphocyte, monocyte and macrophage) adhesion and diapedesis; and 5) triggering receptor expressed on myeloid cells 1 (TREM1) signaling (Table 1). In contrast, these pathways and genes were less affected in non-responders. Of note, a comparison of all DGA results indicated that the responder group overlapped in the differentially expressed genes between Day 2 group (RD2) and one month group (RM1), but had few genes in common to the non-responder group (NM1). There were 94 genes consistently downregulated among RD2 and RM1 while only 6 genes were found in common between the RM1 and NM1 group. Similarly, 61 genes were consistently upregulated in group RD2 and RM1 while only 3 genes were found in common between the RM1 and NM1 group. In summary, the blood transcriptional profiling by this study identifies a signature of genes and pathways relevant to clinical response to ECP in L-CTCL patients. These findings expand our understanding of molecular mechanisms of ECP. Further validation of these genes and pathways is warranted in the future studies. Table 1. Top canonical pathways affected by ECP in L-CTCL patients responded to ECP at one-month Canonical Pathways Downregulated genes Upregulated genes Integrin Signaling 15/201 (7%) ITGA2B, MAP3K11, ITGA5, MYLK, ITGB3, MYL9, PARVB, AKT1, RHOB, CAPN1, ACTN4, CTTN, ARPC4, ACTN1, ITGB5 2/201 (1%) ITGB1, PPP1R12A Granulocyte Adhesion and Diapedesis 14/179 (8%) CSF3R, ICAM1, PPBP,ITGA5, CXCL5, SDC4, CCL3, ITGB3, GNAI2, CLDN5, CCL3L3, IL1B, CXCL1, CXCL2 1/179 (1%) ITGB1 Signaling by Rho Family GTPases 13/236 (6%) SEPT5, MAP3K11, ITGA5, MYLK, GNAZ, CDC42EP2, GNAI2, MYL9, GNG11, GNA15, RHOB, GNB2, ARPC4 3/236 (1%) ITGB1, DIAPH3, PPP1R12A Agranulocyte Adhesion and Diapedesis 13/190 (7%) ICAM1, PPBP, ITGA5, CXCL5, SDC4, CCL3, GNAI2, MYL9, CLDN5, CCL3L3, IL1B, CXCL1, CXCL2 1/190 (1%) ITGB1 TREM1 Signaling 7/76 (9%) ICAM1, AKT1, NLRP12, ITGA5, IL1B, CD83, CCL3 2/76 (3%) ITGB1, NLRC3 Figure 1. Differentially expressed genes post-ECP between responders and non-responders Figure 1. Differentially expressed genes post-ECP between responders and non-responders Disclosures Duvic: Therakos: Research Funding. Ni:Therakos: Research Funding.

Description: Background: Romidepsin is a bicyclic peptide that inhibits Class I and II HDACs. Piekarz et al noted responses to romidepsin in CTCL (ASCO, 2004). This pivotal phase II study sought to confirm the activity. Methods: This single arm, open label study enrolled CTCL (Stages 1B–1VA), including MF and Sézary syndrome (SS) patients (pts) from ∼40 sites in Europe, Russia, Ukraine, Georgia and the US. Pts with biopsy-proven CTCL (centrally reviewed) who failed ≥1 prior systemic therapy received romidepsin at 14 mg/m2 as a 4-hour IV infusion on Days 1, 8, and 15 q 28 days for up to 6 cycles but could continue if deriving benefit. Eligibility criteria included adequate organ function and ECOG PS ≤ 1. Exclusions included significant CV abnormality or treatment with QTc-prolonging or CYP3A4-inhibiting drugs. The primary endpoint is response rate measured by a combination of imaging, circulating malignant T-cell counts and a weighted scoring instrument to determine skin involvement (confirmed by photography). Target accrual of 64 evaluable pts (i.e. received 2 courses) has been reached and the study will close. Results: 92 pts were eligible with 68 evaluable for efficacy per protocol. Responses in evaluable pts are 1 CR, 3 CCRs, 20 PRs, 40 SD and 4 PD for an ORR of 35% (duration 2–21 months). Of pts who received ≥1 dose, the ORR is 26% (24/92) but includes 5 too early to be assessed. Median time to response is 8 weeks (range 4 – 20). Responses by stage at entry in evaluable pts, as available: Stage IB-IIA 7/23 (30%); Stage IIB-IVA 15/37 (41%). In pts with pruritus at baseline i.e. score of ≥ 30 mm on a 100 mm visual analogue scale (VAS), relief of ≥ 30 mm from baseline or a VAS score of 0 (no itching) for at least 2 cycles, was seen in 18/38 pts (47%). In those pts with severe pruritus (VAS score ≥70 mm), 14/24 (58%) experienced relief of itching. Adverse event (AE) data are available for 75 pts. AEs were reported in 54/75 (72%) of dosed pts but Grade (G) 3/4 events in only 12/75 (16%). Most frequent AEs are nausea/vomiting (G2) fatigue (G2/3), myelosuppression (G2/3), and asymptomatic ECG changes (transient mild QTc prolongation and nonspecific ST-T wave abnormalities). Thirteen pts withdrew due to AEs but there were no treatment-related deaths although 4 pts died of PD and 1 from right ventricular failure. Serious AEs considered possibly, probably or likely related to treatment were reported in 12 pts. Of these, 8 had ≥G3 events: tumor lysis, cardiac tamponade, sepsis, constipation, oral candidiasis, dermatitis, hyperglycemia/vomiting/nausea and bradyarrhythmia/atrial fibrillation. Conclusions: This study confirms the efficacy of romidepsin in treatment-refractory CTCL including relief of pruritus and an encouraging response rate with 4 CCR (1 pathology-confirmed). The low rate of discontinuation due to AEs and prolonged treatment duration of some patients illustrate that toxicity has been manageable.