Incidence of Second Primary Malignancies and Peripheral Sensory Neuropathy in Patients with Multiple Myeloma Receiving Daratumumab Containing Regimen
Authors: Htut Thura Win , Quick Donald P. , Win Myint Aung , Swarup Sriman , Sultan Anita , Ball Somedeb , Phyu Ei Moe , Yu Nyein Htway , Han Myat Min , Myat Yin Mon , Hardwicke Fred , D'Cunha Nicholas , Awasthi Sanjay , Thein Kyaw Zin 
Published: November 2019

Introduction:
Proteasome inhibitors-based regimens are the mainstay of initial therapy for most patients with multiple myeloma. Daratumumab is a human IgGκ monoclonal antibody that targets CD38 with direct antitumor effects and has an immunomodulatory component. Recent studies have demonstrated that addition of daratumumab to standard regimens enhance direct cytotoxicity on myeloma cells and have shown survival benefits. Yet, there are notable safety concerns. We performed a combined analysis of randomized controlled trials (RCT) to determine the risk of second primary malignancies (SPM) and peripheral sensory neuropathy (PSN) with newer daratumumab combination regimens.
Methods:
We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts from inception through June 2019. Phase III RCTs utilizing daratumumab in patients with multiple myeloma that mention SPM and PSN as adverse effects were incorporated in the analysis. Mantel-Haenszel (MH) method was used to calculate the estimated pooled risk ratio (RR), and risk difference (RD) with 95% confidence interval (CI). Heterogeneity was assessed with Cochran's Q- statistic. Random effects model was applied.
Results:
A total of 3,547 patients with multiple myeloma from 5 phase III RCTs were eligible. Studies compared daratumumab (D) + bortezomib (V) + melphan (M) + prednisone (P) vs VMP, D + lenalidomide (R) + dexamethasone (d) vs Rd, DVd vs Vd and DVd + thalidomide (T) vs VTd. The randomization ratio was 1:1 in all studies. Daratumumab was utilized in relapsed and refractory multiple myeloma in the POLLUX study (n= 564) and the CASTOR study (n= 480) and as first-line treatment for patients with multiple myeloma in the ALCYONE study (n= 700), the CASSIOPEIA study (n= 1085) and the MAIA study (n= 737). The I2 statistic for heterogeneity was 25, suggesting some heterogeneity among RCT. The SPM incidence was 76 (4.29%) in study group vs 77 (4.34%) in control group. The RR for SPM was 1.12 (95% CI: 0.74 - 1.69; P = 0.58) and RD was 0.01 (95% CI: -0.01 to 0.02; P = 0.34). The RR for SPM was noted at 2.56 (95% CI: 0.26 - 25.46; P = 0.42) in a subset of relapsed and refractory multiple myeloma. Any-grade PSN was reported in 527 (46.84%) in daratumumab arm vs 550 (48.72%) in control arm with the RR of 0.98 (95% CI: 0.80 -1.21; P = 0.88). High-grade PSN was noted in 63 (5.6%) vs 76 (6.73%) in control group with the RR of 0.73 (95% CI: 0.42 -1.27; P = 0.27).
Conclusions:
Our meta-analysis depicted that there was no significant increase in the risk of second primary malignancies and peripheral sensory neuropathy in patients on daratumumab combination regimen, in newly diagnosed and relapsed refractory multiple myeloma, compared to control arm. However, long-term follow-up of these patients is required to determine the actual relation with second primary malignancies.

Disclosures
No relevant conflicts of interest to declare.