Goyal, Gaurav

Abstract Erdheim-Chester disease (ECD) and Rosai-Dorfman disease (RDD) are rare non-Langerhans cell histiocytoses (non-LCHs), for which therapeutic options are limited. MAPK pathway activation through BRAFV600E mutation or other genomic alterations is a histiocytosis hallmark and correlates with a favorable response to BRAF inhibitors and the MEK inhibitor cobimetinib. However, there has been no systematic evaluation of alternative MEK inhibitors. To assess the efficacy and safety of the MEK inhibitor trametinib, we retrospectively analyzed the outcomes of 26 adult patients (17 with ECD, 5 with ECD/RDD, 3 with RDD, and 1 with ECD/LCH) treated with orally administered trametinib at 4 major US care centers. The most common treatment-related toxicity was rash (27% of patients). In most patients, the disease was effectively managed at low doses (0.5-1.0 mg trametinib daily). The response rate of the 17 evaluable patients was 71% (73% [8/11] without a detectable BRAFV600E achieving response). At a median follow-up of 23 months, treatment effects were durable, with a median time-to-treatment failure of 37 months, whereas the median progression-free and overall survival were not reached (at 3 years, 90.1% of patients were alive). Most patients harbored mutations in BRAF (either classic BRAFV600E or other BRAF alterations) or alterations in other genes involved in the MAPK pathway, eg, MAP2K, NF1, GNAS, or RAS. Most patients required lower than standard doses of trametinib but were responsive to lower doses. Our data suggest that the MEK inhibitor trametinib is an effective treatment for ECD and RDD, including those without the BRAFV600E mutation.

AbstractClinical trials of novel salvage therapies have encouraging outcomes for relapsed/refractory transplant‐eligible classic Hodgkin lymphoma (R/R cHL) but comparison with conventional chemotherapy is lacking. Herein, we report the final analysis of a multicenter retrospective cohort of R/R cHL assessing outcomes by type of salvage therapy before autologous stem cell transplant (ASCT). R/R cHL patients who underwent ASCT at 14 institutions across the United States were included. Outcomes were compared among patients receiving conventional chemotherapy, brentuximab vedotin (BV) + chemotherapy, BV alone, and a checkpoint inhibitor (CPI)‐based regimens before ASCT. Study endpoints included event‐free survival (EFS), progression‐free survival (PFS), and overall survival (OS). All endpoints are defined from relapse. Of 936 patients, 728 received conventional chemotherapy, 73 received BV + chemotherapy, 70 received BV alone, and 65 received CPI‐based regimens prior to ASCT. When adjusted for time to relapse, pre‐ASCT response and use of BV maintenance, patients receiving CPI‐based regimens had superior 2‐year EFS compared to conventional chemotherapy, BV + chemotherapy, and BV alone (79.7, 49.6, 62.3, and 36.9%, respectively, p < .0001). Among 649 patients transplanted after 1 line of salvage therapy, CPI‐based regimens were associated with superior 2‐year PFS compared to conventional chemotherapy (98% vs. 68.8%, hazard ratio: 0.1, 95% confidence interval: 0.03–0.5, p < .0001). OS did not differ by pre‐ASCT salvage regimen. In this large multicenter retrospective study, CPI‐based regimens improved EFS and PFS compared to other salvage regimens independent of pre‐ASCT response. These data support earlier sequencing of CPI‐based regimens in R/R cHL in the pre‐ASCT setting.

ImportanceRosai-Dorfman disease (RDD) is a rare histiocytic neoplasm with recent studies showing alterations in the MAPK pathway, most commonly in the KRAS and MEK genes in about 40% of patients. Reports on the use of MEK-inhibitor therapy in RDD have been limited to small case studies. There are no approved treatments for this neoplasm, and therefore patients with RDD need efficacious treatments.ObjectiveTo study the outcomes after treatment with cobimetinib based on MAPK pathway alterations in patients with RDD.Design, Setting, and ParticipantsThis retrospective cohort study conducted at 2 tertiary care centers included patients with RDD who underwent treatment with cobimetinib between January 1, 2013, and December 1, 2021. Cobimetinib was administered at a dosage of 20 to 60 mg orally once daily as a single agent for 21 days in a 28-day cycle. Pathology was centrally reviewed. Response assessment was centrally conducted and was based on the established positron emission radiography response criteria used for clinical trials of targeted therapies in histiocytosis.Main Outcomes and MeasuresMain outcomes were overall response rate (ORR), progression-free survival (PFS), adverse events (AEs) of cobimetinib in the entire cohort, and ORRs and PFS based on MAPK pathway alterations in patients with RDD.ResultsA total of 16 patients (median [range] age at cobimetinib initiation, 57 [31-74] years; 11 [69%] women) were included in the study. The median follow-up duration was 19.0 months (95% CI, 8.4-27.8 months). The ORR was 63% (n = 10), including 5 complete responses and 5 partial responses. Somatic alterations in the KRAS or MEK genes were detected in 8 (50%) patients. Patients with KRAS or MEK alterations had significantly higher ORR (88% vs 38%; P = .03), deeper responses (complete responses among responders: 71% vs 0%; P = .002), and better PFS (at 1 year, 100% vs 29% were free from progression or death, respectively; P &amp;lt; .001) compared with those without such alterations. Grade 2 or higher AEs occurred in 12 (75%) patients, and 9 (56%) required dose reduction or temporary/permanent treatment discontinuation due to AEs.Conclusions and RelevanceIn this cohort study, treatment with cobimetinib was associated with positive outcomes in KRAS- or MEK-variant RDD. However, AEs requiring dose modifications were common.

7515 Background: Primary refractory disease (PRD) and early relapse (ER) are predictors of poor prognosis in classic Hodgkin lymphoma (cHL). In this multicenter retrospective study, we describe outcomes of PRD and ER in pts with relapsed/refractory (R/R) cHL treated with salvage therapy (ST) and autologous stem cell transplant (ASCT). Methods: Of 14 sites, adult patients with R/R cHL who received ST and underwent ASCT were enrolled. PRD was defined as progression on frontline chemoimmunotherapy or within 6 months of diagnosis. ER was defined as relapse from 6 months-1 yr of diagnosis. Pts who relapsed >1 yr of diagnosis were called late relapses (LR). Study objectives were Overall response rates (ORR), CR rates, PFS, and OS. Results: Of 986 total pts, 160 had PRD, 365 had ER and 461 had LR. Significantly higher number of pts with PRD, but not ER, had bulky disease (41% vs 27%, p<0.01) and B symptoms (53% vs 38%, p<0.001) than LR. Higher proportions of pts with PRD and ER required >1 line of ST (44% vs 30% vs 23%, p<0.001) before ASCT and received BV maintenance (25% vs 24% vs 16%, p<0.05). When adjusted for B symptoms and Bulky disease, PRD and ER had significantly lower ORR (65% vs 76% vs 84%, p<0.001) and CR (37% vs 46% vs 57%, p<0.001) to first ST than LR. Pts with PRD and ER had significantly lower PFS (56.3%, 61.4%, vs 77.6%, p<.0001) and OS (93% vs 89% vs 94%, p=0.01) than LR. In pts with ER, Brentuximab/bendamustine (BBV) and brentuximab vedotin/nivolumab (BV/nivo) had a trend towards higher ORR (92% vs 92% vs 75%) but significantly higher CR (79.2% vs 76% vs 42%, p<0.01) than platinum based chemotherapy (PBC). In pts with PRD, BBV and BV/Nivo had a statistically insignificant trend towards higher ORR and CR than PBC. The table shows 2 yr PFS by type of ST in PRD, ER, LR. There was no difference in PFS by time to relapse in BV/nivo, CPI and miscellaneous agents. BV/Nivo had a significantly higher PFS than PBC in PRD (88% vs 48%, p<0.05) and ER (95% vs 57%, p<0.05). There was no difference in PFS of PBC and other ST in PRD, ER or LR. OS was not significantly associated with type of ST in either group. Conclusions: PRD and ER are associated with lower response to ST and survival after ASCT compared to late relapse. In pts with PRD and ER, BV/Nivo has high ORR and CR and leads to significantly higher PFS comparable to pts with late relapse and may be preferable ST regardless of time to relapse. [Table: see text]