KRD-PACE Mobilization for Multiple Myeloma Patients With Significant Residual Disease Before Autologous Stem-Cell Transplantation

Optimizing Autologous Stem Cell Transplantation in Multiple Myeloma: The Impact of Intensive Chemomobilization

Most transplant-eligible multiple myeloma (MM) patients undergo autologous peripheral blood stem cell collection (PBSC) using G-CSF with on-demand plerixafor (G ± P). Chemomobilization (CM) can be used as a salvage regimen after G ± P failure or for debulking residual tumor burden ahead of autologous peripheral blood stem cell transplantation (ASCT). Prior studies utilizing cyclophosphamide-based CM have not shown long-term benefits. At our center, intensive CM (ICM) using a PACE- or HyperCVAD-based regimen has been used to mitigate "excessive" residual disease based on plasma cell (PC) burden or MM-related biomarkers. Given the lack of efficacy of non-ICM, we sought to determine the impact of ICM on event-free survival (EFS), defined as death, progressive disease, or unplanned treatment escalation. We performed a retrospective study of newly diagnosed MM patients who collected autologous PBSCs with the intent to proceed immediately to ASCT at our center between 7/2020 and 2/2023. Patients were excluded if they underwent a tandem autologous or sequential autologous-allogeneic transplant, had primary PC leukemia, received non-ICM treatment (i.e., cyclophosphamide and/or etoposide), or had previously failed G ± P mobilization. To appropriately evaluate the impact of ICM among those who potentially could have received it, we utilized a propensity score matching (PSM) approach whereby ICM patients were compared to a cohort of non-CM patients matched on pre-ASCT factors most strongly associated with the receipt of ICM. Of 451 patients identified, 61 (13.5%) received ICM (PACE-based, n = 45; hyper-CVAD-based, n = 16). Post-ICM/pre-ASCT, 11 patients (18%) required admission for neutropenic fever and/or infection. Among 51 evaluable patients, the overall response rate was 31%; however, 46 of 55 evaluable patients (84%) saw a reduction in M-spike and/or involved free light chains. Among those evaluated with longitudinal peripheral blood flow cytometry (n = 8), 5 patients (63%) cleared circulating blood PCs post-ICM. Compared to patients mobilized with non-CM, ICM patients collected a slightly greater median number of CD34+ cells (10.8 versus 10.2 × 10⁶/kg, P = .018). The median follow-up was 30.6 months post-ASCT. In a PSM multivariable analysis, ICM was associated with significantly improved EFS (hazard ratio [HR] 0.30, 95% CI 0.14 to 0.67, P = .003), but not improved OS (HR 0.38, 95% CI 0.10 to 1.44, P = .2). ICM was associated with longer post-ASCT inpatient duration (+4.1 days, 95% CI, 2.4 to 5.8, P < .001), more febrile days (+0.96 days, 95% CI 0.50 to 1.4, P < .001), impaired platelet engraftment (HR 0.23, 95% CI 0.06 to 0.87, P = .031), more bacteremia (OR 3.41, 95% CI 1.20 to 9.31, P = .018), and increased antibiotic usage (cefepime: +2.3 doses, 95% CI 0.39 to 4.1, P = .018; vancomycin: +1.0 doses, 95% CI 0.23 to 1.8, P = .012). ICM was independently associated with improved EFS in a matched analysis involving MM patients with excessive disease burden at pre-ASCT workup. This benefit came at the cost of longer inpatient duration, more febrile days, greater incidence of bacteremia, and increased antibiotic usage in the immediate post-ASCT setting. Our findings suggest that ICM could be considered for a subset of MM patients, but its use must be weighed carefully against additional toxicity.

Real-world clinical outcomes in patients with relapsed and refractory multiple myeloma receiving VTD-PACE treatment in the era of monoclonal antibodies

Bortezomib (Velcade), thalidomide, dexamethasone, platinum (cisplatin), adriamycin (doxorubicin), cyclophosphamide, and etoposide (VTD-PACE) are commonly used as salvage treatment for patients with relapsed/refractory multiple myeloma (RRMM). However, its outcomes in the era of monoclonal antibodies remain unclear. Therefore, this retrospective cohort study assessed the clinical outcomes of 60 patients with RRMM (median four prior treatment lines) administered VTD-PACE. The median follow-up period was 11.1 months, during which they received a median of two cycles of VTD-PACE. The overall response rate (ORR) was 66.7%; ORRs of 53.1 and 82.1% were noted in patients with ≥ 4 and ≤ 3 prior lines (P = 0.027), respectively. The median overall survival (OS) was 17 months, with a median progression-free survival (PFS) of 9.8 months. Using the 3-month time point after VTD-PACE treatment as a landmark, 54 patients were still alive. Landmark analysis was conducted for PFS and OS of patients who received or did not receive HSCT or CART after VTD-PACE treatment. Patients who underwent subsequent hematopoietic stem cell transplantation (HSCT) or chimeric antigen receptor T-cell therapy (CART) following VTD-PACE showed a trend of longer PFS and OS than those who did not undergo subsequent HSCT or CART. The median OS in patients with and without renal dysfunction was 10.7 months and 21.5 months, respectively (P = 0.0091). Therefore, VTD-PACE is useful as a bridging therapy for HSCT or CART, as a response can be expected regardless of organ damage, disease risk, or history of anti-CD38 antibody use.

VTd-PACE and VTd-PACE-like regimens are effective salvage therapies in difficult-to-treat relapsed/refractory multiple myeloma: a single-center experience

Although treatment options for multiple myeloma (MM) are rapidly evolving, there still remain difficult-to-treat situations, especially in relapsed and/or refractory (r/r) disease. When modern therapies are exhausted, or emergency treatment is needed for high tumor burden, classic chemotherapy combination regimens like the VTd-PACE regimen and its modifications (PACE-M) may also be beneficial as bridging to subsequent treatment options. This single-center retrospective analysis aimed to investigate the outcome of VTd-PACE and PACE-M salvage therapy in 31 heavily pretreated r/r MM patients. The primary objective was the overall response rate (ORR). Secondary objectives were median progression-free survival (mPFS), median overall survival (mOS), safety, and renal response. Median age was 59 years (range 39-75), and 71% of patients were male. R-ISS stratification showed high-risk MM in 48%. The median number of prior therapies was 3, with 23 patients being triple- and 12 penta-refractory (74% and 39%). ORR was 71%, including 23% of patients achieving a very good partial response. Median duration of follow-up was 15 months (range 0-29 months). mPFS and mOS were 3 months (95% CI 0.27-5.74) and 11 months (95% CI 3.66-18.35), respectively. In 26 patients (83.9%), at least one subsequent treatment (stem cell transplant or BCMA-directed) was administered. Renal function significantly improved after VTd-PACE or PACE-M treatment (p = 0.032). Non-hematological adverse events ≥ grade 3 were predominantly infections. VTd-PACE and PACE-M are effective salvage therapies in difficult-to-treat situations in heavily pre-treated r/r MM, including patients with impaired renal function. VTd-PACE and PACE-M can be successfully used as bridging therapy for subsequent treatment.

The Efficacy and Safety of Chemotherapy-Based Stem Cell Mobilization in Multiple Myeloma Patients Who Are Poor Responders to Induction: The Mayo Clinic Experience

We report the outcomes of 117 patients with newly diagnosed multiple myeloma who received novel agent induction, had a poor response to induction, and were mobilized using intravenous intermediate-dose cyclophosphamide (82%) or VD-PACE (18%) plus granulocyte colony-stimulating factor (G-CSF) and on-demand plerixafor. The median progression-free survival and overall survival of the chemo-mobilized cohort were 21 months (95% confidence interval [CI], 15-71) and 58 months (95% CI, 47-80), respectively. We compared our cohort to a 117-patient cohort matched by the level of response at pretransplant evaluation. The matched patients were mobilized with G-CSF and on-demand plerixafor without chemotherapy. Patients receiving chemo-mobilization had higher stem cell yields than the growth-factor-only cohort (median, 10.7 × 10⁶ cells/kg vs. 8.77 × 10⁶ cells/kg, respectively; P < .001). The safety profile of chemo-mobilization was favorable, and there was no difference between the two groups in length of hospitalization during autologous stem cell transplantation (P = .95), days to neutrophil engraftment (P = .22), days to platelet engraftment (P = .27), or risk of bacteremia (P = .52). Twenty-nine percent of the chemo-mobilized cohort and 65% of the matched cohort required plerixafor for adequate mobilization (P < .001). Chemo-mobilization enhances stem cell collection without adversely impacting the post-transplant clinical course.

Prolonged Lenalidomide Therapy Does Not Impact Autologous Peripheral Blood Stem Cell Mobilization and Collection in Multiple Myeloma Patients: A Single-Center Retrospective Analysis

Since the introduction of lenalidomide into induction therapy for multiple myeloma (MM), there have been conflicting reports about its impact on autologous peripheral blood stem cell (PBSC) mobilization. We evaluated the impact of previous lenalidomide exposure in a large cohort of patients with MM undergoing mobilization and collection at a tertiary stem cell transplantation center. We hypothesized that collection of PBSCs is feasible even with a prolonged duration of previous lenalidomide therapy. We examined patients with MM who attempted stem cell mobilization and collection, seen at our center between January 2012 and July 2015. The patients were categorized into 3 groups for analysis: (1) patients with previous receipt of >6 cycles lenalidomide, (2) patients with previous receipt of ≤6 cycles of lenalidomide, and (3) patients without previous lenalidomide exposure. We compared collection yields and days of apheresis among the 3 groups using linear regression analysis. We identified 297 patients with MM who underwent mobilization of PBSCs. Of these, 35 had received >6 cycles of lenalidomide (median, 8 cycles; range, 7 to 25 cycles), 156 had received ≤6 cycles of lenalidomide (median, 4 cycles; range, 1 to 6 cycles), and 106 had received no lenalidomide. Prior lenalidomide exposure did not have a statistically significant impact on the absolute number of CD34⁺ cells collected or on the duration of collection based on a multivariate linear regression analysis for association between receipt of >6 cycles of lenalidomide. In this retrospective analysis of MM patients undergoing autologous PBSC transplantation, we show that the duration of previous lenalidomide exposure does not impact the total number of PBSCs collected or the number of days of apheresis. These data suggest that longer courses of induction therapy with lenalidomide-containing regimens to achieve a maximum response can be safe without impairing the ability to collect PBSCs, and that limiting lenalidomide use before mobilization does not appear warranted in all cases.