Novel Enhancement of Pulsing involved-field Radiotherapy and CPI for LAHNSCC in elderly patients.
PD-0396
Abstract
Novel Enhancement of Pulsing involved-field Radiotherapy and CPI for LAHNSCC in elderly patients.
Authors: Adam Raben1, Olga Russial2, Sujong Park3, Neil Hockstein4
1Christiana Care Health System, Radiation Oncology, Newark, USA; 2Thomas Jefferson University Hospital, Radiation Oncology, Philadelphia, USA; 3Christiana Care Health System, Medical Oncology, Newark, USA; 4Christiana Care Health System, ENT, Newark, USA
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Purpose or Objective
Purpose: To combine pulsing RT schedule (QUAD shot) directed only to gross HNSCC to enhance response to immunotherapy in elderly patient’s ineligible for conventional RT approaches.
Material and Methods
Materials/Method: 23 Patients, with a mean age 82, were evaluated in an MDC-HN clinic with non-metastatic either recurrent or unresectable cutaneus SCC (cSCCC) or mucosal SCC (mSCC), 21/23 were HPV- , 52% Male, 48% Female. These patients were prohibitive candidates for curative ERT +/- chemotherapy due to age, Poor KPS or ECOG PS, or co-morbidities. Patients were treated with a pulsed recurring ERT schedule (QUAD SHOT) using VMAT , delivering 14.8 Gy/4 fxs/BID, repeated q 3 weeks. Based on imaging, ONLY Gross Primary/LN’s were treated, while END were excluded. PD-1 CPI’s were administered either day 2 of the QUAD shot or day 1-3 after each QUAD shot. (either Pembrolizumab, Cemilipumab, Nivolumab) and continued adjuvantly at the discretion of the Medical Oncologist.
Patients were evaluated at conclusion of QUAD Shots for response and at 3 months with PET/CT and then till death. Primary endpoint for this study: LRC and RC-END (elective LNs not treated) Secondary endpoints: DMFS, DFS.
Results
Results: With a median FU of 17 mos (1-39 mos) 72% of pts (16/22) achieved a CR based on clinical and radiologic evaluation, with 22% achieving a PR. 1 pt showed POD, and 1 not evaluable due to Covid death. The KM overall LRC estimate at 1 year was 78%. The KM LRC-END estimate at 1 year was 93% (untreated elective LN’s). The KM DM rate estimate at 1 year was 85%. The KM curve estimate for overall DFS at 1 year was 59% (67% cSCC, 55% mSCC)
LRC for gross recurrent/unresectable/regional parotid/nodal cSCC was especially encouraging with QUAD+CPI with a 1 year KM rate of 100% versus 70% for mucosal SCC (p=.17). KM LRC-END estimate at 1 year for cSCC versus mSCC was 100% versus 91% (p=.27) DM estimate at 1 year for cSCC was 100% versus 79@ mSCC.
The combined QUAD SHOT schedule was well tolerated when combined with a CPI, with only 1/23 pts requiring treatment interruption and admission for FTT (Failure to Thrive) but resumed and completed therapy. Gr 3 mucositis occurred in 1 pt on the lower lip that resolved. Gr 1 fatigue, xerostomia, and anorexia were noted in 1 patient. Gr 3/ 4 IMAR’s were observed in 3 patients and included infusion reaction, colitis, and fatigue/FTT and were discontinued. 4 pts (23%) required post QUAD PEG’s unrelated to radiation toxicity and due to POD.
Conclusion
Conclusions: This feasibility study, is one of the first utilizing a pulsing radiotherapy in elderly patients with LAHNSCC combined with a CPI. This regimen was well tolerated with very encouraging response LRC at 1 year. More encouraging, was the lack of significant END failure suggesting that this may be excluded from treatment particularly in elderly patients with cSCC. This unique approach is a potential means to release neoantigens, prime the TME and evolve away from ENI that engender greater toxicity and cost.