Further Evolution of Metronomic Therapy Extended to 28 Days (Metro28) for Relapsed Refractory Multiple Myeloma (RRMM)
Authors: Papanikolaou Xenofon , Khan Rashid Z , Rosenthal Adam , Bailey Clyde , Jethava Yogesh , Heuck Christoph , Panozzo Susan B. , Zangari Maurizio , van Rhee Frits , Schinke Carolina , Davies Faith E , Morgan Gareth J , Barlogie Bart 
Published: October 2019

Abstract
Despite the increasing availability of novel agents for RRMM, many patients run out of treatment options due to disease refractoriness and/or progressive toxicities, both hematological (cytopenia) and non-hematological (cachexia, asthenia, renal and cardiopulmonary).Patients who are refractory to both proteasome inhibitors and immunomodulatory agents (IMIDs) carry an ominous prognosis with a median overall survival (OS) of 9 months (Leukemia, Kumar 2013). We previously reported on the efficacy and toxicity profiles of a metronomically scheduled chemotherapy regimen administered over the course of 16 days (Haematologica, Papanikolaou 2014). Encouraged by the results of that treatment, we have since modified metronomic chemotherapy to cover a 28-day period (metro28). The regimen consisted largely of bortezomib 1.0mg/m2 on days 1, 4, 7, 10, 13,16,19, 22,25,28; along with dexamethasone 12mg on days 1-4, 7-10, 13-16, 19-22, 25-28; thalidomide 100mg days 1-28, continuous 28 day infusion of doxorubicin 1.0mg/m2 (0.5mg/m2 for Ejection Fraction <40%) and cis-platinum 1.0mg/m2 (0.5mg/m2 for creatinine >2mg/dL), with the addition of arsenic trioxide (ATO) at 0.1mg/kg on each day after bortezomib; and lately vincristine (VCR) at 0.07mg daily dose by continuous infusion for 28 days. Patient characteristics included age >65yr, 46%; female, 33%; cytogenetic abnormalities at any time prior to therapy (CA), 86%; Gene Expression Profile (GEP) 70-defined high risk, 44%. The median number of prior therapies was 8 (1-64), prior transplants, 83% (1, 2, >=3), 20%, 32%, 31%; prior exposure to novel agents including Carfilzomib/Pomalidomide was 81%. Thrombocytopenia prior to treatment was present in 75% including thrombocytopenia <50,000/uL in 15%. Clinical outcomes are depicted in Figure 1. At a median follow up of 8.1 months, the median number of metro 28 cycles administered was 1 (1-5), with 37% achieving a partial response and median OS not yet reached. Interestingly, the 6 month - partial response duration estimate for the patients achieving PR was 53% (Figure 1A), while the one year OS estimate for all patients receiving metro 28 was 59% (Figure 1B). Prognostic factors that held statistical significance in univariate analysis for overall survival were albumin <3.5 g/dl (HR 2.56, P=0.009), beta-2-microglobulin (B2M) ≥3.5 mg/L (HR 3.03, P=0.003), LDH≥ 190 U/L (HR 2.81, P=0.003), GEP-70 High Risk (HR 2.32, P=0.048), GEP-5 High Risk (HR 5.75, P<0.001) (Figure 1C) and GEP PR subgroup designation (HR 3.71, P=0.003). In multivariate analysis, albumin < 3.5 g/dL (HR 2.81, P=0.035), B2M≥ 3.5 mg/L (HR 3.4, P=0.017), GEP PR subgroup (HR 3.8, P=0.012), and GEP-5 High Risk (HR 8.58, P<0.001) (Figure 1C) achieved statistical significance. The majority of cycles administered in the patient population were done in the outpatient setting (81%), while secondary admissions due to regimen toxicity occurred in 36% of the cycles administered. Grade 3 & 4 neutropenia and thrombocytopenia within 3 months from the start of the metronomic treatment were evident in 64% and 78% respectively of the cases. Treatment related mortality was 2%, due to one instance each of grade 5 infection and cerebrovascular event. In conclusion 28 day metronomic therapy is a feasible treatment with acceptable toxicity and encouraging preliminary results both in terms of ORR and OS for RRMM.
Table 1: Patient characteristics at start of Metro28 therapy Factor n/N (%) Age >= 65 yr 56/122 (46%) IgA Isotype 28/110 (25%) Female 40/122 (33%) White 108/122 (89%) Albumin < 3.5 g/dL 47/122 (39%) B2M >= 3.5 mg/L 46/93 (49%) B2M > 5.5 mg/L 26/93 (28%) CRP >= 8 mg/L 54/122 (44%) Creatinine >= 2 mg/dL 15/122 (12%) Hb < 10 g/dL 57/122 (47%) LDH >= 190 U/L 36/121 (30%) Platelet Count < 150 x 10^9/L 92/122 (75%) Cytogenetic abnormalities 105/122 (86%) CA within 1 year of therapy 84/121 (69%) CA within 90 days of therapy 65/119 (55%) New Kit GEP Sample 91/91 (100%) GEP 70 High Risk 40/91 (44%) GEP 5 High Risk 39/91 (43%) GEP CD-1 subgroup 5/91 (5%) GEP CD-2 subgroup 17/91 (19%) GEP HY subgroup 14/91 (15%) GEP LB subgroup 6/91 (7%) GEP MF subgroup 9/91 (10%) GEP MS subgroup 9/91 (10%) GEP PR subgroup 31/91 (34%) GEP proliferation index >= 10 28/91 (31%) GEP centrosome index >= 3 26/91 (29%) n/N (%): n- Number with factor, N- Number with valid data for factor ND: No valid observations for factor
Figure 1A Figure 1A.
Figure 1B Figure 1B.
Figure 1C: OS by GEP5 Figure 1C:. OS by GEP5

Disclosures
Zangari: Norvartis: Membership on an entity's Board of Directors or advisory committees; Onyx: Research Funding; Millennium: Research Funding. van Rhee:Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Millenium: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees. Morgan:Celgene Corp: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Myeloma UK: Membership on an entity's Board of Directors or advisory committees; International Myeloma Foundation: Membership on an entity's Board of Directors or advisory committees; The Binding Site: Membership on an entity's Board of Directors or advisory committees; MMRF: Membership on an entity's Board of Directors or advisory committees.