Ctni-53. Radiation Treatment Volumes Before and After Braf/mek Therapy in Newly Diagnosed Papillary Craniopharyngiomas: a Correlative Analysis of the Alliance A071601 Phase Ii Trial
Year: 2021
Type: conference-abstract
Abstract: PURPOSE Standard of care for craniopharyngiomas is surgery with or without radiotherapy (RT). Cohort A of Alliance A071601 evaluated the efficacy of BRAF/MEK inhibition with vemurafenib/cobimetinib in patients with previously untreated papillary craniopharyngiomas (PCP), which carry the BRAF V600E mutation. Cohort B is currently enrolling patients with recurrence after RT. In a correlative analysis, we examined changes in RT volumes after BRAF/MEK therapy in Cohort A. METHODS Previously unirradiated patients with BRAF-mutated PCP were treated with vemurafenib/cobimetinib. Sixteen patients had scans available before starting vemurafenib/cobimetinib (“pre-therapy”) and after completing therapy (“post-therapy”). Two patients went off study treatment after 8 and 9 days due to side-effects and were excluded for this analysis. Gross target volumes (GTV) were contoured on pre-therapy and post-therapy scans. On post-therapy scans, an additional target comprising gross disease and at-risk regions for microscopic residual disease (GTV-micro) was defined and considered the treatment volume. Clinical target volume (CTV) was a 5-mm uniform expansion on pre-therapy GTV and post-therapy GTV-micro. Volumes were independently reviewed by two radiation oncologists. Changes in volumes from pre- versus post-therapy were compared using the Wilcoxon signed rank test. RESULTS In 14 patients evaluated, 57% were female and median age at enrollment was 49.5 years (range 33-83). Median time on treatment was 8.9 months (range 4.0-18.0). Median GTV pre-therapy was 3.8 mL (range 0.2-23.4) versus 0.3 mL (range 0.0-3.2) post-therapy (p=0.0001) and 1.7 mL (range 0.1-8.0) post-therapy GTV-micro (p=0.0001). Median CTV pre-therapy was 13.7 mL (range 2.8-51.8) versus 9.1 mL (range 2.2-27.5) post-therapy (p=0.0001). All tumors abutted the optic chiasm pre-therapy, only 6 did post-therapy. CONCLUSIONS Vemurafenib/cobimetinib resulted in smaller RT volumes. BRAF/MEK inhibitors could reduce RT volumes and spare dose to surrounding normal structures. Enrollment to Cohort B of Alliance A071601 should be considered for patients with recurrent tumors after RT. SUPPORT https://acknowledgments.alliancefound.org
Source: Neuro-Oncology
Authors: Helen Shih, Shervin Tabrizi, Brian Kabat, Erin Twohy, Susan Geyer, Shivangi Vora, Elizabeth Gerstner, Timothy Kaufmann, Michael Ruff, David Reardon, Adam Cohen, Daniela Bota, Pankaj Agarwalla, Macarena De la Fuente, Glen Lesser, Jian Campian, Priya Kumthekar, Michael Knopp, Daniel Cahill, Sandro Santagata, Fred Barker, Evanthia Galanis, Priscilla Brastianos, Paul Brown
Institutions: Harvard University, Massachusetts General Hospital, Mayo Clinic, The Ohio State University, Dana-Farber Cancer Institute, Inova Fairfax Hospital, University of California, Irvine, Rutgers New Jersey Medical School, University of Miami Hospital, Sylvester Comprehensive Cancer Center, Atrium Health Wake Forest Baptist, Wake Forest Baptist Comprehensive Cancer Center, Washington University in St. Louis, Northwestern University, Brigham and Women's Hospital
Language: English
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W3216022266