Tailored Low Dose Lenalidomide with Low Dose Dexamethasone (len/dex) in Previously Treated Patients with Multiple Myeloma Older Than 70 Years Requiring Treatment.
Authors: Ruedas Angel , Perez Ricardo , Garcia Valentin , Smucler Alicia , Bravo Pilar , Martinez Joaquin , Sabin Pilar , Guisado Pablo , Montalban Carlos 
Published: October 2019

Abstract
Abstract 4950

Background & Aims
The management of elderly patients with Multiple Myeloma (MM) previously treated requiring further therapy (although in most cases palliative) is very difficult due to the presence of concomitant diseases, decreased bone marrow reserve, systemic toxicity, relatively decreased renal function and general problems of old age. As in this setting the tolerability of standard doses of conventional chemotherapy, high doses of dexamethasone or IMiDs is a concern, we report the preliminary results of the combination of tailored low doses of lenalidomide (len) and low doses of dexamethasone (dex).

Methods
We retrospective analyze the results of the combination of low dose lenalidomide and low dose of dexamethasone (len/dex) in 14 patients aged over 70 years with pretreated MM and progressive disease. Low doses of len (5-10 mg daily for 21days) were initially given and flexibly modified in subsequent cycles according to response and toxicity, along with low doses of dex (20-40 mg/day for 4 days) in most (12) patients. G-CSF and red cell transfusions were used when needed. Patient risk was stratified following the Salmon and Durie (S&D) score and the International Staging System (ISS). Response was assessed with the IMWG criteria.

Results
Median age was 80 years (70-90). All patients had received between 2-5 different previous modality treatments (m=2), including bortezomib (7), thalidomide (4) or PBSCT (2). 11 pts had IgG, m=3397mg/dl (868-4990), 2 IgA m=1460 (1050-1870) and another one BJ. 9 pts had κ and 4 » light chains. Median Hemoglobin level was 10 gr/dl (7.2-11.4) and median creatinine level 1.19 mg/dl (0.75-1.63). 11 (78%) had bone disease. 9 pts had S&D stage II, 4 stage III and another one stage I. 7 pts had ISS stage II, 4 had stage I and 2 stage III. Patients received between 2 and 13 cycles of len/dex (m=6.8). 11 pts (78%) achieved Partial Remission (PR) and 2 (14%) achieved significant, but lesser that 50%, reduction of the M-component (Stable Disease: Std). Overall response (PR+Std) occurred in 13/14 patients (92.8%). The best response occurred between 2-12 cycles of len/dex. Grade III-IV bone marrow toxicity occurred in 5 pts (35 %) and neurological toxicity (PNP) in 5 pts (35%) (all of them had received previous bortezomib or thalidomide). Treatment was stopped in 6 pts: for unrelated causes (1), due to neurological (3) or haematological (1) toxicity and in 2 pts after achieving Std and both relapsed after 3 months.

Conclusions
Treatment with tailored low doses of lenalidomide and low doses of dexamethasone (len/dex) is an active and tolerable option for previously treated elderly patients with symptomatic MM. Low lenalidomide doses can be flexibly modified according to the quality of the response and the hematological toxicity that is expectable and manageable. Previous treatments with bortezomib or thalidomide is associated with neurotoxicity.

Disclosures
No relevant conflicts of interest to declare.