Concurrent Radiation and Biological Therapy is Safe in Multiple Myeloma

Abstract

The management of multiple myeloma (MM) has evolved in the modern era partially owing to the increasing number of biological therapeutics. Bortezomib, Daratumumab and Carfizomib have become standard of care treatments for MM. Nonetheless radiation continues to be an important treatment in the management of painful lytic lesions from MM. There is a concern for increased toxicity of treatment when given concurrently with biologicals. The goal of this study is to evaluate the side effect profile of radiation therapy while patients are concurrently being treated with biological agents. We conducted a retrospective study based on data collected from patients receiving radiotherapy at our institute from 2007 to 2017. A total of 130 patients (279 treatment sites) were included in this study with a median follow up time of 14 months. Patients had to be receiving a biological agent at least within one month prior to start and up to one month post receiving radiation therapy. Generalized estimating equations were used to assess difference in the probability of onset of acute side effects (within 4 weeks of treatment), sub-acute side effects (during 4 weeks and 6 months of treatment) and hematological events (Grade 3 or higher anemia, need for PRBC transfusion, need for platelet (Plt) transfusion and need for neupogen) between patient groups receiving or not receiving concurrent biological agents with RT. A compound symmetric covariance structure was assumed to control for intra-subject correlation. Linear mixed models were used to estimate the change in blood counts before and after treatment while adjusting for pre-treatment values. The mean age of all the patients in our cohort was 63.1 years (SD: 8.7), with 53 (58.9%) males and 37 (41.1%) females. The mean KPS score of all the cohort was 76. Further patient demographic information can be found in table 1. No significant difference in incidence of acute [OR = 1.65, 95% CI, (0.87, 3.13), p = 0.1270] or subacute [OR = 0.90, 95% CI, (0.40, 2.04), p = 0.8068] toxicities was found between patients with or without biological agents concurrently with RT. Furthermore, no significant difference in incidence of anemia and Neupogen requirement was noted between patients with or without biological agents concurrently with RT. However, patients receiving biological agents were more likely to have PRBC transfusion [OR = 5.05, 95% CI, (1.09, 23.44), p<0.05] and Plt transfusion [OR = 2.26, 95% CI, (1.01, 5.06), p<0.05]. Our study did not detect any significant toxicity rates from palliative radiation while patients were concurrently receiving biological agents. Palliative radiation therapy may be safely administered while patients are concurrently being treated with biological agents, without any major adverse effects. Biological therapies do not need to be held during RT.Abstract MO_35_2798; Table 1Treatment SiteNumber of PatientsSpine49Pelvis23Skull18Shoulder6Arm6Dose (Gy)Number of Patients≤ 20Gy5420-30Gy31≥ 30Gy17 Open table in a new tab