Pomalidomide-dexamethasone in refractory multiple myeloma: long-term follow-up of a multi-cohort phase II clinical trial

Despite therapeutic advances, multiple myeloma remains incurable, with limited options for patients with refractory disease. We conducted a large, multi-cohort clinical trial testing various doses and treatment schedules of pomalidomide and dexamethasone (Pom/dex) in patients with refractory multiple myeloma. Overall, 345 patients were enrolled to six cohorts based on number and type of prior lines of therapy, pomalidomide dose and schedule. Median prior lines of therapy were three with near universal prior exposure to proteasome inhibitors and/or immunomodulatory drugs. A confirmed response rate of 35% was noted for all cohorts (range 23-65%) with higher responses in cohorts with fewer prior lines of therapy. Median time to confirmed response was ⩽2 months and the longest progression-free survival and overall survival seen in any cohort were 13.1 and 47.9 months, respectively. Observed adverse reactions were as expected, with myelosuppression and fatigue being the most common hematologic and non-hematologic adverse events (AEs), respectively. Longer durations of treatment and response, higher response rates and fewer AEs were noted with the 2 mg pomalidomide dose. This is the longest follow-up data for Pom/dex in refractory multiple myeloma and will help shape the real-world utilization of this regimen.

Pomalidomide: the new immunomodulatory agent for the treatment of multiple myeloma

In this report, we provide a comprehensive review on the preclinical and clinical investigations conducted in development of the next-generation immunomodulatory drug (IMiD) pomalidomide for the treatment of relapsed/refractory multiple myeloma (MM). We consulted PubMed, MEDLINE, ASH, ASCO annual symposium abstracts and http://clinicaltrials.gov/ for the purpose of this literature review. Twenty-six preclinical and 11 clinical studies were examined. These studies delineate the mechanisms of action of pomalidomide and attest to the robust clinical activity in relapsed/refractory MM. MM is the second most common hematological malignancy in the US. Despite availability of several therapeutic agents, MM remains incurable. Thus, the development of new therapies remains a priority. Pomalidomide is the newest member of the IMiDs class of drugs, and in preclinical and clinical investigations, it has demonstrated an improved efficacy and toxicity profile in comparison to its sister compounds, lenalidomide and thalidomide. Importantly, recent clinical studies have demonstrated its activity in relapsed or refractory myeloma, particularly in lenalidomide and bortezomib-refractory patients. Thus, the addition of pomalidomide to the anti-myeloma armamentarium is widely anticipated to have a significant impact on the overall clinical outcome of advanced stage relapsed and refractory MM patients.

Lenalidomide (L) induces high response rates with molecular remission in patients (pts) with relapsed (rel) or refractory (ref) chronic lymphocytic leukemia (CLL)

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Background: Tumor microenvironment (ME) is critical in CLL pathogenesis. Targeting the ME is a novel approach in CLL therapeutics. Lenalidomide (Revlimid, L) is an immunomodulating agent (IMiD), approved for pts with transfusion-dependent low or intermediate-1 risk myelodysplastic syndrome with deletion 5q cytogenetic abnormality. Its antitumor activity is possibly mediated through (a) downregulation of cytokine(s) - TNF-α, VEGF, PDGF and IL-6 and/or (b) activation of immune effector cells (T & NK cells). We investigated its antitumor activity in rel/ref CLL pts. Here we present the final results of the first cohort of pts treated with 25mg daily dose of L. Methods: Oral L was given at 25mg/day for 21 out of a 28 day cycle. Anti-leukemic effects were recorded after each cycle using NCI-WG 1996 criteria. Treatment was continued until molecular complete response (mCR) or progressive disease (PD). Those with PD were then treated with L in combination with rituximab (reported separately). Polymerase chain reaction (PCR) for immunoglobulin heavy chain gene was used to determine molecular remission (mCR). Results: Twenty-nine pts (median age 64 years; range: 47–75) have been enrolled. Toxicity is reported on all, while response on 19 evaluable pts. Nine pts are inevaluable (2 withdrew consent and 5 received < 2 months of therapy due to toxicity). Major response was noted in 13 of 19 evaluable pts (68%) with 3 CR (2 mCR) and 10 PR. Toxicity: Most common grade 3/4 adverse effects (AE) were neutropenia (60%) and thrombocytopenia (55%). Another common AE was tumor flare (79%); characterized by tender swelling of lymph nodes and/or rash, noted in almost all pts. Conclusions: L at 25mg/day dose given on days 1–21 in a 28 day cycle yields high ORR including mCR in rel/ref CLL. Hematologic toxicity was the most common AE requiring dose reduction. Overall safety profile was predictable and manageable. A slow dose escalation schema, starting at 15mg is being investigated.

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Incidence of venous thromboembolic (VTE) in chronic lymphocytic leukemia (CLL) patients (pts) treated with immunomodulating agents (IMiDs)

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Introduction: We recently reported the clinical activity of IMiDs (both thalidomide (T) and lenalidomide (L)) in pts with CLL. VTE is a commonly reported complication of these agents requiring prophylaxis. Most available information is in pts treated for multiple myeloma (MM), a disease with a high baseline incidence of VTE. To determine whether the incidence of IMiDs associated VTE is similar in CLL pts we reviewed all CLL pts treated with IMiDs at our institute. Method: All CLL pts treated at our institute with T or L either alone or in combination with other antileukemic agents such as rituximab (R) or fludarabine (F)) were evaluable for this analysis. All pts were treated on IRB approved clinical trials and signed informed consent. Prophylaxis for VTE was recorded. Dose range for T was 100–300mg/day, while that of L was 5–25mg/day. Results: To date a total of 55 pts (35 on L and 20 on T) are treated with IMiDs at our center. All pts treated with L received single agent L while those treated with T received concurrent F (FT). All T treated pts also received low-dose warfarin (1 or 2 mg for body weight ≤ or > than 70 kg respectively) for VTE prophylaxis. No prophylaxis was given to L treated pts. VTE was noted in 2 (6%) pts on L and 2 (10%) on FT. Thus the cumulative incidence of IMiDs associated VTE in CLL pts at our center was 7% (4/55). Conclusion: VTE is a known side effect of IMiDs. Its incidence in CLL treated pts is unknown. Our experience with both T and L in CLL pts suggest that VTE remains a concern in this pt population as well though the incidence may be lower. Three other studies investigated T either alone (n=28)1, with F (n=18)2 or with dexamethasone/cyclophosphamide (n=3)3. Only 1 episode of VTE was reported in these studies.3 Our current analysis failed to reveal any apparent risk factors for VTE in CLL pts treated with IMiDs. Several pts on the L clinical trial continue to be on therapy. Updated results with prolonged L treatment will be presented at the meeting. 1. Kay N et al: ASH 2003 2. Furman RR et al: ASCO 2005 3. Trompeter S et al: IWCLL 2005

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Clinical characterization of first cycle reactions in patients with chronic lymphocytic leukemia treated with oblimersen

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Background: Serious adverse reactions during the first treatment cycle characterize many drugs used for chronic lymphocytic leukemia (CLL), including rituximab, alemtuzumab, flavopiridol, lenalidomide, and oblimersen. Termed cytokine release reactions (CRRs), these events have occurred more commonly in pts with bulky disease and elevated leukocyte counts, and some have been fatal. Rapid increases in serum levels of tumor necrosis factor-α, interleukin-6, interleukin-2, interferon-γ, and other cytokines may result in symptoms including fever, chills, nausea, vomiting, hypotension, and dyspnea. Ex vivo treatment of CLL cells with oblimersen induce release of vasoactive interleukin-8. First cycle reactions, including tumor lysis syndrome (TLS), proved dose-limiting in a phase 1–2 trial of oblimersen in pts with relapsed or refractory CLL. To characterize these reactions, we evaluated data from this single-agent study and from a phase 3 randomized clinical trial of oblimersen with fludarabine and cyclophosphamide (Flu/Cy). Methods: Data on investigator assessment of CRR and TLS were obtained from both studies, which included 155 pts; 40 were treated with oblimersen alone (3–7mg/kg/d by CIV for 5–7 days) and 115 with oblimersen (3 mg/kg/d × 7 days) in combination with Flu/Cy. Results: Of 145 pts treated with oblimersen 3mg/kg/d, either alone or with Flu/Cy, 2 pts (1.3%) experienced CRR and TLS, respectively. Two CRRs occurred in 10 pts treated with 4–7mg/kg/d. Reactions typically began 24–48 hours after starting treatment. CCR was usually associated with spiking fever, nausea, dehydration, rigors, and back pain. Rarely pts developed hypotension, acidosis, or reversible renal insufficiency, usually with a reduction in WBC. Symptoms lasted 1 day to several weeks (1 pt). In most cases, reactions were reversible with intensive supportive care, including IV fluids, pressors, and antibiotics; 1 death from TLS and 1 from CCR occurred during cycle 1. There was no definitive correlation with baseline measures of disease burden. Conclusion: First cycle oblimersen reactions are uncommon but represent a risk. Early symptoms (fever, nausea, and dehydration) require aggressive treatment, which may prevent progression of the reaction.

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Prednisone (P) prophylaxis decreases incidence and severity of lenalidomide (L) induced flare reaction (flr) in patients with relapse (rel) or refractory (ref) chronic lymphocytic leukemia

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Background: Flare reaction (flr) is a new side effect unique to CLL pts treated with immunomodulating agents both thalidomide (T) and L. It is characterized by tender swelling of disease involved lymph nodes (LN), spleen, rash, low-grade fever and/or increase in absolute lymphocyte counts (ALC). Underlying biologic process remains unknown though it is postulated to be mediated through activation of immune effector cells and/or change in serum concentration of pro-inflammatory cytokines. In a phase II clinical trial of L in rel/ref CLL pts we noted a high incidence of flr. Here we report treatment schema for flr and a new preventive approach employed in this study. Methods: A total of 35 pts are enrolled. No prophylaxis given to initial cohort (A). Pts were treated at onset of symptoms with (1) ibuprofen (Ib) 600 mg po q6 hours (2) oxycodone (oxy) 5–10 mg po prn q 6 hours. In subsequent cohort (B) we are investigating prophylactic use of P 20 mg PO QD starting day −1 × 5 days followed by 10 mg QD × 5 days. Results: All pts had rel or ref disease. Median age 63 (range 48–76) year. In cohort A (n = 29) overall incidence of flr was 79% (n = 23). Of these the severity was graded as I, II and III in 48%, 24%, and 7% respectively. There was no grade IV flr. Symptoms initiated within hours of intake of the 1st dose of L lasting for a median of 14 days (cycle 1 only). Pts were adequately managed with symptom resolution using Ib/oxy. Recurrence in cycle 2 was noted in 1 pt. Pain in LN was the most common complaint. Increase ALC noted in 2 pts. Serum cytokine analysis (n = 5) pre and post 7-days of L treatment showed significant increase in TNF-α, IL-10 and MIG. In cohort B (n = 6) 2 pts had flr (grade I) lasting ≤ 10 days. Conclusions: Prophylactic use of P results in decrease incidence, severity and duration of flr. There was no correlation with clinical response. Elevation of ALC can be part of the flr, pts response should be interpreted cautiously for disease progression. Our findings suggest that use of P may be an effective prophylactic maneuver for prevention of L induced flr. Updated results of cohort B will be presented at this meeting.

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Acute renal failure requiring dialysis after allogeneic blood and marrow transplantation identifies very poor prognosis patients

We examined the incidence, risk factors and associated mortality of acute renal failure requiring dialysis (Renal Bearman Grade [BG] 3) in a 3-year cohort of 97 consecutive allogeneic blood and marrow transplantation (alloBMT) patients. In all, 20 (21%) developed Renal BG3 (all died by day +132) and 77 (79%) developed renal insufficiency (Renal BG1-2). Renal BG3 was a contributing or primary cause of death in 18 (90%) patients who continued to require dialysis at time of death. The two Renal BG3 patients whose deaths were not related to renal failure died on day +103 of hemorrhage and day +132 of underlying disease. By univariate analysis, age, unrelated donor, veno-occlusive disease (VOD) and grade III-IV acute graft-versus-host disease with hepatic involvement were significantly associated with Renal BG3. The multivariate model of time to Renal BG3 determined only a prior diagnosis of severe acute GVHD (RR=4.1, 95% CI 1.6-10.3, P=0.003) and VOD (RR=9.1, 95% CI 3.5-23.7, P<0.001) as significant independent predictors. Renal BG3 is generally considered a conditioning regimen-related toxicity. This study demonstrates that Renal BG3 is most commonly a complication of hepatic co-morbidities after allogeneic blood and marrow transplantation and identifies patients with a very poor prognosis.

Effect of rituximab on peripheral blood stem cell mobilization and engraftment kinetics in non-Hodgkin's lymphoma patients

Rituximab is used for in vivo tumor cell purging for non-Hodgkin's lymphoma (NHL) patients prior to autologous peripheral blood stem cell transplantation (PBSCT). However, its effects on PBSC mobilization and function are poorly understood. We compared the mobilization characteristics and engraftment kinetics of 13 NHL patients receiving and 34 NHL patients not receiving rituximab 6 months before PBSC mobilization. In the rituximab group, there was a significantly longer time to neutrophil engraftment (P=0.0466), a trend toward the need for BM harvest to supplement low-yield PBSC collections (31 vs 9%, P=0.08) and a significantly increased rate of bacteremia episodes (62 vs 26%, P=0.025). Median progression-free survival (PFS) and overall survival (OS) were significantly longer in the rituximab compared to the nonrituximab patients (P=0.049 and 0.042, respectively). However, patients in the nonrituximab group were at high risk for recurrence and expected to have shorter survival. Rituximab used within 6 months prior to collection may have a detrimental effect on PBSC mobilization and engraftment. However, rituximab is a major therapeutic breakthrough for NHL treatment and this negative effect may be offset by improved survival. Further studies are warranted in larger populations to determine the impact of rituximab on engraftment, PFS and OS.