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Keywords:

  • immune thrombocytopenia;
  • ITP ;
  • CD20;
  • antibody;
  • subcutaneous therapy;
  • hA20

Summary

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

Low doses of the humanized anti-CD20 monoclonal antibody, veltuzumab, were evaluated in 41 patients with immune thrombocytopenia (ITP), including 9 with ITP ≤1 year duration previously treated with steroids and/or immunoglobulins, and 32 with ITP >1 year and additional prior therapies. They received two doses of 80–320 mg veltuzumab 2 weeks apart, initially by intravenous (IV) infusion (N = 7), or later by subcutaneous (SC) injections (N = 34), with only one Grade 3 infusion reaction and no other safety issues. Thirty-eight response-assessable patients had 21 (55%) objective responses (platelet count ≥30 × 109/l and ≥2 × baseline), including 11 (29%) complete responses (CRs) (platelet count ≥100 × 109/l). Responses (including CRs) occurred with both IV and SC administration, at all veltuzumab dose levels, and regardless of ITP duration. Responders with ITP ≤1 year had a longer median time to relapse (14·4 months) than those with ITP >1 year (5·8 months). Three patients have maintained a response for up to 4·3 years. SC injections resulted in delayed and lower peak serum levels of veltuzumab, but B-cell depletion occurred after first administration even at the lowest doses. Eight patients, including 6 responders, developed anti-veltuzumab antibodies following treatment (human anti-veltuzumab antibody, 19·5%). Low-dose SC veltuzumab appears convenient, well-tolerated, and with promising clinical activity in relapsed ITP.(Clinicaltrials.gov identifier: NCT00547066.)

Corticosteroids with or without intravenous (IV) immunoglobulins remain conventional first-line therapy for adult immune thrombocytopenia (ITP), but most patients either do not respond or relapse once steroids are tapered (George et al, 1996; British Committee for Standards in Haematology General Haematology Task Force, 2003; Cines & Bussel, 2005; Provan et al, 2010; Neunert et al, 2011). Splenectomy can be curative, but patients who do not have lasting responses to first-line therapies or even splenectomy require further therapy. Unfortunately, chemotherapy or other immunosuppressive agents typically produce responses only while they are continued. While thrombopoetin-receptor (TPO) agonists may postpone splenectomy, continued use is required and relapse is common if discontinued (Bussel et al, 2006, 2007; Newland et al, 2006; Kuter et al, 2008).

Anti-CD20 immunotherapy is a promising alternative, given that approximately one-third of patients with chronic ITP achieved durable responses to single-agent rituximab (Cooper et al, 2004; Braendstrup et al, 2005; Peñalver et al, 2006; Arnold et al, 2007; Godeau et al, 2008; Medeot et al, 2008; Patel et al, 2012). Also, combining anti-CD20 agents with high-dose steroids appears promising as a first-line regimen for achieving long-lived remissions (Zaja et al, 2010; Elstrom et al, 2011; Gudbrandsdottir et al, 2013). However, the need for an infusion suite, the time required for repeated intravenous administration, and the occurrence of intravenous infusion reactions with rituximab potentially limits more widespread use.

Veltuzumab (hA20) is a 2nd-generation, humanized, anti-CD20 antibody with important structure-function differences from rituximab. These include limited amino acid differences in the complementarity-determining and framework regions, which result in both a slower off-rate as well as increased complement-dependent cytotoxicity seen in comparative in vitro studies with rituximab (Stein et al, 2004; Goldenberg et al, 2009, 2010). Veltuzumab was first administered under compassionate use to a patient not in this study with life-threatening thrombocytopenia and anaemia refractory to standard medications and rituximab (Tahir et al, 2005). Despite extremely high serum levels of anti-rituximab antibodies (human anti-chimeric antibodies 43,000 ng/ml), veltuzumab effectively depleted B cells and the patient responded rapidly (Tahir et al, 2005). A study in non-Hodgkin lymphoma (NHL) then demonstrated that 4 weekly intravenous (IV) doses of veltuzumab up to 750 mg/m2 (twice the standard rituximab dose) were not only well-tolerated, but achieved objective responses, including durable complete responses, at all dose levels, even 80 mg/m2, the lowest dose tested (Morschhauser et al, 2009). These findings with low doses of veltuzumab were particularly significant, as 375 mg/m2 doses or higher are typically used with rituximab. As such, veltuzumab was subsequently reformulated in a more concentrated form for subcutaneous (SC) injection, and a study in indolent lymphoma showed that low-dose SC veltuzumab was well-tolerated and achieved responses comparable to that obtained by IV delivery (Negrea et al, 2011). The SC route of administration may be particularly convenient in the treatment of autoimmune disease despite thrombocytopenia. Thus, this study was undertaken to evaluate low doses of veltuzumab in ITP delivered initially by IV infusion but after amendment by SC injection.

Methods

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

Study design

This was an open-label, multi-centre, Phase I study to evaluate safety, obtain preliminary evidence of efficacy, and assess the pharmacodynamics, pharmacokinetics, and immunogenicity of low-dose veltuzumab administered to patients with ITP. Treatment consisted of two identical doses of veltuzumab administered 2 weeks apart. A conventional dose escalation design was used with escalation proceeding to the next level only after three patients were treated on a dose level without dose-limiting toxicity (DLT, defined below) or, if one patient encountered DLT, after an additional three patients were treated without a second DLT. Initially, veltuzumab was to be administered by IV infusion at one of 3 planned dose levels of 80, 120, or 200 mg, resulting in a total treatment dose after two infusions of 160, 240, or 400 mg, respectively. After a higher concentration formulation of 80 mg/ml became available, the study protocol was changed with veltuzumab administered by SC injection at one of 3 planned dose levels of 80, 160 or 320 mg (delivered by 1 ml, 2 ml, or two 2-ml injections given separately several minutes apart, respectively) and resulting in a total treatment dose of 160, 320 or 640 mg, respectively. Following successful dose escalation to the 320 mg dose level, additional patients were enrolled to provide more experience with SC dosing at all dose levels and with a goal of at least 15 patients at the maximal 320 mg SC dose level.

Study population

Eligible patients were ≥18 years old with primary ITP by American Society of Hematology guidelines (George et al, 1996; Neunert et al, 2011), with or without splenectomy, who failed ≥1 standard ITP therapy and presented with platelets <30 × 109/l on two occasions at least one week apart. To avoid the risk of spontaneous improvement, the protocol initially required a history of ITP with platelet levels <150 × 109/l for >6 months, but because all patients had been previously treated, this was later considered unnecessary and removed by amendment. Patients with major bleeding, defined as >1 bleeding assessment score using a multiple body system 0–2 grading scale (Page et al, 2007), were excluded because of the delayed effects of anti-CD20 therapy and the likelihood that any rescue treatment needed would interfere with assessment of the response to veltuzumab. Patients with other significant cytopenias (Evans' syndrome, etc.) were also excluded because they did not have primary ITP. Patients had to be off ITP medications, except for prednisone ≤20 mg/d and danazol, which were allowed if on stable doses to be maintained during the 12-week study period. Prior rituximab was allowed only if the patient had achieved at least a partial response for at least 6 months and was now either one year beyond rituximab or had evidence of B-cell recovery. Using an International Working Group (IWG) categorization (Rodeghiero et al, 2009), patients were classified by the duration of their disease from diagnosis as having newly-diagnosed (<3 months), persistent (3–12 months), or chronic (>1 year) ITP. At each participating institution, the governing ethics committee approved the study, and written informed consent was obtained from all patients.

Study procedures

Following treatment, patients were initially evaluated weekly over a 12-week period. Safety was assessed with adverse events (AEs) classified by the Medical Dictionary for Regulatory Activities (MedDRA) system organ class and preferred terms (Brown et al, 1999), vital signs and physical examinations, serum chemistries, haematology, urinalysis, serum immunoglobulins, and T-cell levels (CD3+). Laboratory and AE toxicity was graded according to National Cancer Institute (NCI) Common Terminology Criteria (CTC), version 3.0 (http://ctep.cancer.gov/protocolDevelopment/electronic_applications/docs/ctcaev3.pdf), with DLT defined as any treatment-related Grade 3 or 4 events. Efficacy was assessed by peripheral blood platelet level responses and clinical bleeding assessment. Pharmacodynamics was determined by blood B-cell levels (CD19+). For pharmacokinetics (PK) and immunogenicity, enzyme-linked immunosorbent assay (ELISA) tests were performed by the sponsor and measured serum levels of veltuzumab [lower level of quantitation (LLQ), 0·5 μg/ml] and any human anti-veltuzumab antibody (HAHA) titres (LLQ, 50 ng/ml), respectively. Pharmacokinetic parameters following last injection were determined by WinNonLin 2.1 (Pharsight Corporation, Mountain View, CA, USA) using a single compartment model.

Outcome assessments

Treatment responses based on a patient's best platelet levels in the absence of bleeding and independent of rescue and supportive care regimens were classified by IWG criteria (Rodeghiero et al, 2009). An objective response (OR) was defined as a platelet count ≥30 × 109/l measured twice at least one week apart with at least a two-fold increase from the baseline count. ORs were categorized as a complete response (CR) if ≥100 × 109/l, and otherwise as a partial response (PR). Time to response was measured from treatment initiation to onset of OR. Time to relapse was defined from treatment initiation to first occurrence of platelet levels <30 × 109/l on two separate occasions at least one day apart, initiation of other therapy, or loss of follow-up. Study results were summarized using descriptive statistics.

Results

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

A total of 41 patients were treated between March 2008 and October 2011, the first 7 receiving veltuzumab by IV infusion and the last 34 by SC injection. Only 2 patients had newly-diagnosed disease and 7 had persistent disease. As these 9 patients were previously treated only with steroids and/or immunoglobulins, they were combined into one group (ITP ≤1 year) to compare results with the remaining 32 patients who had chronic disease (ITP >1 year) for up to 31 years and had also received additional and often more toxic therapies. Demographics and baseline characteristics are summarized in Table 1, while patient treatment information is summarized in Table 2.

Table 1. Demographics and baseline characteristics
 All patientsITP ≤1 yearITP >1 year
  1. ITP, immune thrombocytopenia; IVIG, intravenous immunoglobulin; TPO-R, thrombopoietin receptor.

  2. a

    29 patients with 37 sites involved: skin (1–5 bruises and/or scattered petechiae, N = 22); epistaxis (<5 min per episode, N = 7); gynecological (spotting outside normal period, N = 3); oral (gum bleeding <5 min or 1 blood blister or >5 petechiae, N = 2);subconjunctival haemorrhage, microscopic haematuria (N = 1 each).

  3. b

    Three patients granted waivers for heavy menses, epistaxis (>5 min), and bruising (>5 bruises with size >2 cm) not serious enough to preclude participation.

  4. c

    Seven patients on prednisone (none on danazol) at study entry subsequently discontinued doses prior to receiving veltuzumab (N = 1), transiently increased doses to 20 mg/d for 5 d for 6 × 109/l platelets at start of treatment (N = 1), or continued unchanged or tapered (N = 5).

Patients treated (N)41932
Sex (male/female)16/253/613/19
Median age (years)515451
Maximum bleeding score
01239
1a29326
2b330
Currently on prednisonec734
Prior treatment (N)
Steroids37928
IVIG or anti-Rho(D)27324
Azathioprine or Danazol12210
Splenectomy808
Platelets606
Rituximab606
TPO-R agonists606
Chemotherapy404
Table 2. Veltuzumab treatmenta
 All patientsITP ≤1 yearITP >1 year
  1. ITP, immune thrombocytopenia.

  2. a

    Dosing levels for initial treatment.

Treated41932
Intravenous infusions716
80 mg312
120 mg303
200 mg101
Subcutaneous injections34826
80 mg936
160 mg1019
320 mg15411

Adverse events

Seven patients treated intravenously received premedication with oral antipyretics and antihistamine, but no steroids. One serious adverse event occurred, with one patient having a Grade 3 hypersensitivity reaction with dyspnea and discontinuing further treatment after receiving ~100 mg of the first dose. Five other patients had treatment-related adverse events, but all were transient Grade 1–2 infusion reactions (throat discomfort, N = 2; fever, body aches, and nausea, 1 each). Minor infections occurred in five patients, none attributed to study treatment, and there were no bleeding events.

Thirty-four patients treated by SC injections did not receive premedication. There were no serious adverse events and only one Grade 3 event was considered possibly treatment-related (generalized pain not otherwise specified, developing 10 d after first injection). Table S1 summarizes their most frequent adverse events. Twenty-four patients had mild-moderate (Grade 1–2) treatment-related adverse events, including 17 patients with local injection site reactions (pain, burning or discomfort, erythema, swelling, bruising, cellulitis) and 11 patients having constitutional symptoms (myalgia, fever, chills, headache, nausea, pruritus, vomiting, fatigue, cold-like symptoms). The frequency of injection-site reactions or constitutional symptoms did not increase with dose level, with second injection, or with retreatment (data not shown). Nine patients had minor infections (predominantly upper respiratory or sinusitis), and four had minor bleeding events (conjunctival × 2, gingival, haemoptysis); all were considered unrelated to study treatment. Electocardiogram required by protocol at second injection detected atrial fibrillation of uncertain aetiology in one asymptomatic patient with a history of hypertension and mild ventricular hypertrophy, which resolved spontaneously without recurrence on subsequent exam. Two other patients had brief episodes of tachycardia 3 and 10 weeks after treatment considered unrelated to veltuzumab (one while starting rescue medication, the other with prior history of arrhythmias).

Laboratory values

Routine haematology and serum chemistry laboratories showed no consistent pattern of change from baseline except platelet increases (Tables S2 and S3). Three patients had isolated Grade 2–3 chemistries (elevated alanine transaminase, elevated creatinine, and partial thromboplastin time prolongation, attributed to anti-parasitic medication, chronic renal failure, and antiphospholipid antibody antibodies, respectively), while one asymptomatic patient had Grade 3 liver enzymes of unknown aetiology, which resolved by the next evaluation. Haemoglobin levels vacillated between Grade 2 and baseline levels for 3 patients and progressively decreased to Grade 2 levels for another patient with chronic renal failure. Two patients were enrolled with Grade 3 neutropenia (one further deteriorating to Grade 4, neither developing infections), three patients had occasional Grade 2 absolute neutrophil counts, and 4 asymptomatic patients developed Grade 2 lymphopenia of uncertain aetiology, which resolved by the next evaluation. Other than these cases, all laboratory values remained at Grade 0–1 levels or were unchanged from baseline grades over the 12 week post-treatment evaluation period. No cases of delayed neutropenia developed, including 38 patients monitored for 3 months, and 25 patients for ≥1 year.

Response to initial treatment

One patient withdrew after an infusion reaction during the first veltuzumab dose, receiving only 100 mg and initiating alternative ITP treatment soon thereafter. Two other patients, while receiving SC injections, initiated high-dose dexamethasone with ciclosporin or TPO-receptor agonists for extremely low platelet levels, which continued to decrease while starting treatment. This very early onset of rescue therapy precluded assessment of response to veltuzumab treatment or lack thereof in these three patients, but the other 38 patients all had assessable responses to treatment with veltzumab. This included 25 patients who did not receive any rescue medications or other treatment interventions until relapse, seven patients who received limited platelet transfusions, immunoglobulins or brief steroids for low platelet levels during treatment but were followed substantially beyond any expected transient response with no further interventions, and six patients without improvement 4–6 weeks following veltuzumab treatment who were classified as non-responders after initiating high-dose dexamethasone, ciclosporin, TPO-receptor agonists, or rituximab at that time.

Of the 38 response-assessable patients, there were 21 (55%) ORs, including 11 (29%) CRs. Responses (including CRs) occurred with both IV and SC administration, at even the lowest dose levels, and regardless of whether patients had undergone splenectomy, had previously received rituximab, or had ITP for ≤1 year duration or longer (Table 3), with none of these differences statistically significant. For the 21 responders, the median time from first veltuzumab dose to response onset was 23 d (range, 14–264), with a median of 33 d (14–91) to first occurrence of platelets ≥100 × 109/l for those 11 patients achieving CRs. The 21 responders had a median time to relapse of 8·0 months, with 10 patients continuing relapse-free for >1 year, including 3 responses still ongoing at 1·2, 3·5 and 4·3 years. Although not statistically significant, responders with ITP ≤1 year had a longer median time to relapse (14·4 months) than those with ITP >1 year (5·8 months); CRs were more durable than PRs, and responses at the highest dose level appeared more durable than those achieved with lower doses (Table 4).

Table 3. Treatment responsea
 PatientsORCRPR
  1. Treatment response categories by International Working Group criteria; ITP, immune thrombocytopenia; OR objective response; CR, complete response; PR, partial response.

  2. a

    Data from 38 patients with assessable responses.

Overall3855% (21/38)29% (11/38)26% (10/38)
Subgroup:
Administration route
IV667% (4/6)33% (2/6)33% (2/6)
SC3253% (17/32)28% (9/32)25% (8/32)
Veltuzumab dose level (mg)
801173% (8/11)46% (5/11)27% (3/11)
120–1601242% (5/12)17% (2/12)25% (3/12)
3201553% (8/15)27% (4/15)28% (4/15)
Prior splenectomy
Yes757% (4/7)57% (4/7)0% (0/7)
No3155% (17/31)23% (7/31)32% (10/31)
Prior rituximab
Yes633% (2/6)33% (2/6)0% (0/6)
No3259% (19/32)28% (9/32)31% (10/32)
ITP duration (year)
≤1978% (7/9)33% (3/9)44 (4/9)
>12948% (14/29)28% (8/29)21% (6/29)
Table 4. Time to relapsea
 PatientsMedian (months)Range (months)
  1. CR, complete response; PR; partial response; IV, intravenous; SC, subcutaneous; ITP, immune thrombocytopenia.

  2. a

    Based on 21 patients who achieved an objective response by International Working Group criteria (Rodeghiero et al, 2009). Time to relapse measured from start of treatment to relapse, initiation of rescue medications, or study withdrawal. Includes three patients with responses ongoing at last evaluation at 14·2, 42·4 and 51·1 months.

Overall218·02·1–51·1
Subgroup
Response
CR1114·23·4–51·1
PR103·52·1–17·4
Administration route
IV48·72·7–51·1
SC178·02·1–43·7
Veltuzumab dose level (mg)
8086·72·1–43·7
120–16053·42·1–51·1
320814·22·5–42·4
ITP duration (year)
≤1714·42·1–43·7
>1145·82·1–51·1

Retreatment

One patient whose platelet levels rapidly fell two weeks after the initial treatment received additional veltuzumab, but withdrew consent after no immediate improvement following the first of the 2 planned doses. Retreatment was allowed at investigator discretion for patients who had responded to treatment and then relapsed. Eight such patients were retreated at their initial or higher veltuzumab dose level. Five patients did not respond to the second round of therapy, including all three patients with HAHA prior to or following retreatment (see Immunogenicity below). However, two patients with initial PRs again responded with a duration similar to their initial treatment (~3 months), and the remaining patient who initially had achieved a CR ultimately was retreated a total of 4 times, each time receiving two 320-mg SC doses and responding with a duration similar to the initial treatment (~6 months).

Haematological changes

The first dose of veltuzumab effectively depleted B cells in most patients with overall median B-cell levels decreasing from 0·282 × 109 cells/l pretreatment to 0·004 × 109 cells/l by the second dose. Only three patients failed to decrease B-cell levels below 0·02 × 109 cells/l by 4 weeks post-treatment, although still decreasing 74–90% from baseline. B-cell depletion and recovery appeared generally comparable across veltuzumab dose levels (Fig 1). Quantitative serum immunoglobulins (Ig) and T-cell levels were measured at baseline and every 4 weeks post-treatment. For IgG, IgA, and T cells, there was no consistent pattern of change from baseline. IgM levels were consistently decreased, but not clinically significantly, with mean decreases at each time point between 16% and 22% (Table S4) and most patients remaining within normal limits.

image

Figure 1. Median B-cell blood levels. Patients received veltuzumab twice, two weeks apart, with blood levels measured at each administration (Adm), then periodically 4–48 weeks later for patients remaining on study or up to initiation of retreatment, if retreated. Two patients without initial B-cell levels and one patient without post-treatment B-cell levels were excluded. Results are shown for patients treated at 320 mg × 2 by subcutaneous (SC) injection, but for simplicity have been pooled for patients receiving either 120 mg × 2 by intravenous (IV) infusion or 160 mg × 2 by SC injection, and have also been pooled for patients receiving 80 mg × 2 by either SC injection or IV infusion.

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Pharmacokinetics

Figure 2 summarizes the mean serum levels for each dose group at the scheduled times for serum sampling, whereas Table 5 summarizes the mean pharmacokinetic parameters after the second administration. As seen, the SC route generated delayed and lower serum levels of veltzumab than the peak values obtained following IV infusions, but the terminal half-life and clearance from the blood appeared generally comparable.

Table 5. Veltuzumab pharmacokinetics after second administration (Mean ± SD)
Dose LevelCmax (μg/ml)T1/2 (d)AUC (0-∞) (d × mg/l)CL (ml/d)
  1. Patients received veltuzumab twice, two weeks apart. Results based on serum samples collected at time of second administration and then 1, 2, 3, 4, 8, and 12 weeks later, as well as additional samples which were to be obtained on days 1, 2, 3–5, 6–8 post-treatment in at least three patients in each dose group at investigator discretion. Excludes six patients with too few data points for analysis. T1/2 and AUC(0-∞) were determined by a non-compartmental model, with CL calculated as veltuzumab dose divided by AUC(0-∞). Abbreviations: SD, standard deviation; Cmax, maximum observed serum level over the sampling period; T1/2, terminal half-life; AUC(0-∞), area under the curve of serum levels over the sampling period; CL, clearance; IV, intravenous; SC, subcutaneous.

80 mg SC (n = 6)11·7 ± 7·410·3 ± 6·2338 ± 197293 ± 134
160 mg SC (n = 9)19·3 ± 7·910·6 ± 2·7508 ± 231402 ± 264
320 mg SC (n = 14)40·6 ± 17·919·1 ± 13·01645 ± 903250 ± 124
80 mg IV (n = 3)20·3 ± 7·19·8 ± 3·3236 ± 32344 ± 49
120 mg IV (n = 3)46·0 ± 14·06·6 ± 1·2473 ± 204303 ± 173
image

Figure 2. Mean serum levels of veltuzumab for each dose group. Patients received veltuzumab twice, two weeks apart, with serum samples obtained at each administration, then 1, 2, 3, 4, 8, and 12 weeks later. Additional samples were to be obtained on days 1, 2, 3–5, 6–8 after each administration in at least three patients in each dose group at investigator discretion. Veltuzumab serum levels were determined by enzyme-linked immunosorbent assay. Three patients were excluded due to lack of post-administration data and one additional patient due to assay interference from pre-existing human anti-veltuzumab antibodies (HAHA). Serum levels were censored at initiation of any veltuzumab retreatment or rescue rituximab or at the onset of any HAHA. For plotting purposes, values too low to be measured were assigned the minimum detectable level of the assay (0·5 μg/ml). (A) Results from the 3 dose cohorts treated by subcutaneous (SC) injection. (B) Results from the 2 dose cohorts treated by intravenous (IV) infusion.

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Immunogenicity (HAHA)

Nine patients had elevated HAHA titres, which subsequently resolved or decreased with available follow-up, without apparent clinical sequelae. One patient previously treated with rituximab was already HAHA-positive at baseline (titre, 1006 ng/ml). Otherwise, eight patients, including 6 responders, developed elevated titres after receiving veltuzumab (HAHA 19·5%). This includes seven patients at lower dose levels (≤160 mg × 2) who developed HAHA after initial treatment (peak titres, 61–2190 ng/ml), and one patient at the highest dose level (320 mg × 2) who developed HAHA only after being retreated with a second course of veltuzumab (peak titre, 152 ng/ml). While most patients with HAHA achieved ORs with initial treatment, including 5 CRs, none of three patients retreated responded to a second course of treatment (Table S5).

Discussion

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

Although initially developed to treat B-cell NHL, anti-CD20 rituximab has been extensively studied in autoimmune diseases, including ITP, with good results in a sizable fraction of patients (Cooper et al, 2004; Braendstrup et al, 2005; Peñalver et al, 2006; Arnold et al, 2007; Godeau et al, 2008; Medeot et al, 2008; Patel et al, 2012). Veltuzumab is a humanized anti-CD20 with in vitro differences from rituximab. The potential advantages over rituximab include its ability to be administered subcutaneously with small-volume injections, slower off rate, and increased complement-mediated cytotoxicity, as well as higher efficacy in NHL xenograft models (Stein et al, 2004; Goldenberg et al, 2009). Veltuzumab is clinically active in NHL even at low weekly doses, achieving comparable objective tumour responses, including complete responses, when administered by SC injection or intravenous infusion (Morschhauser et al, 2009; Negrea et al, 2011). Given that the antigen burden in autoimmune disease was assumed to be less than in B-cell malignancies and rituximab had shown activity in ITP, it was anticipated that low doses of veltuzumab would probably also be effective in this disease.

For ITP, we followed a dosing schedule used for anti-CD20 antibodies in other autoimmune diseases, with two identical doses of veltuzumab given two weeks apart. Of 41 patients enrolled, the initial seven patients were treated by IV infusion and the subsequent 34 patients were treated by SC injection. One patient had an infusion reaction to IV dosing and was withdrawn from the study, but otherwise, veltuzumab was well tolerated with no other substantial safety issues. In particular, the majority of patients who received SC injections had only transient mild-moderate local site reactions and occasional constitutional symptoms. As expected, low-dose veltuzumab had no significant impact on routine laboratories, including serum immunoglobulins and T-cell levels. Although immunogenicity with veltuzumab was almost negligible (~1%) in NHL (Morschhauser et al, 2009; Negrea et al, 2011), after receiving veltuzumab in this study, eight patients developed elevated HAHA titres (HAHA, 19·5%), 7 after initial treatment with lower doses ≤160 mg and only one at the higher dose of 320 mg, occurring after retreatment. This appears comparable to immunogenicity rates in autoimmune diseases reported with lower doses of other humanized and even recombinant human antibodies, such as anti-CD20 ocrelizumab and anti-TNF adalimumab (Genovese et al, 2008; Bartelds et al, 2011), the latter also administered by SC injection. Interestingly, most of these patients responded to veltuzumab with initial treatment, consistent with earlier reports correlating immunogenicity with anti-B-cell antibodies to enhanced outcomes in cancer patients (Miotti et al, 1999; Azinovic et al, 2006).

Consistent with prior studies in NHL, one administration of veltuzumab at the lower dose levels utilized in this study effectively caused B-cell depletion in most patients, regardless of whether delivered IV or SC. Although patients here received only 2 doses, the pharmacokinetics also appeared generally consistent to that seen earlier with four veltuzumab doses given in NHL (Morschhauser et al, 2009; Negrea et al, 2011). In particular, IV infusions generated immediate peak levels while SC injections took several days to reach lower peak levels, but with both routes of administration, serum levels declined slowly after the last dose, with a clearance half-life of 1–2 weeks.

Two low doses of veltuzumab, regardless of whether delivered IV or SC, were clearly active in patients with ITP, achieving treatment responses, including individual complete responses with normalization of platelet levels, at all dose levels, including the lowest dose tested, 80 mg given twice. Furthermore, 10 responders achieved durable responses for >1 year with this veltuzumab regimen, including 3 patients still continuing in remission up to 4·3 years after treatment. Similar to veltuzumab as well as other anti-CD20 antibody studies in NHL, there was little evidence of a dose-response in this study, and consistent with the pharmacodynamic findings as well, the generally complete B-cell depletion indicates that even the lowest dosing here may be sufficient to be effective. Retreatment was also shown to be feasible, with no additional safety issues and several patients again having comparable responses, including one retreated a total of 4 times, similar to what has been reported with rituximab (Hasan et al, 2009). However, the development of HAHA that occurred primarily at lower dose levels may have abrogated efficacy in other patients who failed to respond when retreated.

Given that this was the first study of this new antibody in ITP, it is not surprising that investigators entered only a minority of patients with limited-duration disease, and thus generally more heavily pretreated patients with longstanding and potentially more difficult disease were studied. Therefore, it is not possible to compare our overall responses (55% ORs, 29% CRs) with rituximab, where the duration of ITP is not often reported or factored into the response result, as is now being recommended (Rodeghiero et al, 2009). As suggested in a general review (Arnold et al, 2007), patient heterogeneity, publication bias, and different response criteria may account for the wide variability of response rates (25% - 75%, CRs 15% - 50%) reported for rituximab treatment of ITP (Cooper et al, 2004; Braendstrup et al, 2005; Peñalver et al, 2006; Godeau et al, 2008; Medeot et al, 2008) although one study identified reasonable consistency (Patel et al, 2012).

Cox regression analyses combining multiple rituximab studies recently confirmed that CRs were important for maintaining long-term responses, but that ITP duration was not predictive (Patel et al, 2012). The ability to obtain platelet normalization with veltuzumab appears equally important to that with rituximab, as patients with CRs appeared to have more durable responses than PRs (14·2 vs. 3·5 months, respectively). Furthermore, the median time to relapse was 14·4 months for responders with ITP for ≤1 year compared to 5·8 months for those with ITP >1 year. Thus, in this study, longer-standing chronic disease appears to be less responsive to antibody therapy, as has been reported for rituximab in at least one study (Cooper et al, 2004), although in contrast to findings elsewhere (Patel et al, 2012). Given the relatively small number of patients enrolled in this phase I study and the very small percentage of cases with ITP of short duration, larger studies will be required to clarify the treatment outcome expected with SC veltuzumab in newly-diagnosed, persistent, and chronic immune thrombocytopenia. Interestingly, even though there was no overall evidence of a dose-response relationship, the highest dose level of 320 mg × 2 appeared to provide more durable responses, having a median of 14·2 months compared to ≥6·7 months at lower doses levels. This also deserves consideration in subsequent studies.

In conclusion, low-dose veltuzumab delivered by SC injection appears convenient, well-tolerated, and with promising activity in relapsed immune thrombocytopenia. B-cell depletion was demonstrated after one dose at all levels of veltuzumab, suggesting that even the lowest dose (80 mg) is sufficient to achieve the expected biological effect of anti-CD20 therapy. Further studies of this agent are warranted, including the more extended SC dosing regimens currently being explored.

Acknowledgements

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

The authors acknowledge the late Zale P. Bernstein, MD, from the Erie County Medical Center, Buffalo, NY, who had been an active investigator in this study. We thank Robert M. Sharkey, PhD, Preeti Trisal, MS, and Kiril Gordeyev, BS, for their contributions to the pharmacokinetic and immunoassay analyses.

Authors' contributions

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

David M. Goldenberg and William A. Wegener were responsible for study design, data analysis and the initial manuscript. Howard Liebman, Mansoor N. Saleh, James B. Bussel, and O. George Negrea were responsible for provision of patients and reviewing the results. Heather Horne oversaw study conduct and data collection. All authors were responsible for review, revision and approval of the manuscript.

Disclosures

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information

Research grants from Immunomedics were provided to each participating institution to support this study. Heather Horne, David M. Goldenberg and William A. Wegener have employment, stock, and/or stock options with Immunomedics, Inc. The other authors have no conflicts of interest to declare.

References

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information
  • Arnold, D.M., Dentali, F., Crowther, M.A., Meyer, R.M., Cook, R.J., Sigouin, C., Fraser, G.A., Lim, W. & Kelton, J.G. (2007) Systematic review: efficacy and safety of rituximab for adults with idiopathic thrombocytopenic purpura. Annals of Internal Medicine, 146, 2533.
  • Azinovic, I., DeNardo, G.L., Lamborn, K.R., Mirick, G., Goldstein, D., Bradt, B.M. & DeNardo, S.J. (2006) Survival benefit associated with human anti-mouse antibody (HAMA) in patients with B-cell malignancies. Cancer Immunology and Immunotherapy, 55, 14511458.
  • Bartelds, G.M., Krieckaert, C.L., Nurmohamed, M.T., van Schouwenburg, P.A., Lems, W.F., Twisk, J.W., Dijkmans, B.A., Aarden, L. & Wolbink, G.J. (2011) Development of antidrug antibodies against adalimumab and association with disease activity and treatment failure during long-term follow-up. The Journal of the American Medical Association, 305, 14601468.
  • Braendstrup, P., Bjerrum, O.W., Nielsen, O.J., Jensen, B.A., Clausen, N.T., Hansen, P.B., Andersen, I., Schmidt, K., Andersen, T.M., Peterslund, N.A., Birgens, H.S., Plesner, T., Pedersen, B.B. & Hasselbalch, H.C. (2005) Rituximab chimeric anti-CD20 monoclonal antibody treatment for adult refractory idiopathic thrombocytopenic purpura. American Journal of Hematology, 78, 275280.
  • British Committee for Standards in Haematology General Haematology Task Force. (2003) Guidelines for the investigation and management of idiopathic thrombocytopenic purpura in adults, children and in pregnancy. British Journal of Haematology, 120, 574596.
  • Brown, E.G., Wood, L. & Wood, S. (1999) The medical dictionary for regulatory activities (MedDRA). Drug Safety, 20, 109117.
  • Bussel, J.B., Kuter, D.J., George, J.N., McMillan, R., Aledort, L.M., Conklin, G.T., Lichtin, A.E., Lyons, R.M., Nieva, J., Wasser, J.S., Wiznitzer, I., Kelly, R., Chen, C.F. & Nichol, J.L. (2006) AMG 531, a thrombopoesis-stimulating protein, for chronic ITP. The New England Journal of Medicine, 355, 16721681.
  • Bussel, J.B., Cheng, G., Saleh, M.N., Psaila, B., Kovaleva, L., Meddeb, B., Kloczko, J., Hassani, H., Mayer, B., Stone, N.L., Arning, M., Provan, D. & Jenkins, J.M. (2007) Eltrombopaq for the treatment of chronic idiopathic thrombocytopenic purpura. The New England Journal of Medicine, 357, 22372247.
  • Cines, D.B. & Bussel, J.B. (2005) How I treat thrombocytopenic purpura (ITP). Blood, 106, 22442251.
  • Cooper, N., Stasi, R., Cunningham-Rundles, S., Feuerstein, M.A., Leonard, J.P., Amadori, S. & Bussel, J.B. (2004) The efficacy and safety of B-cell depletion with anti-CD20 monoclonal antibody in adults with chronic immune thrombocytopenic purpura. British Journal of Haematology, 125, 232239.
  • Elstrom, R., Ghanima, W., Lee, S.Y., Turenne, I. & Bussel, J.B. (2011) Standard dose rituximab plus 2–4 cycles of pulse dexamethasone is effective and tolerable in treatment of immune thrombocytopenia (ITP). Blood, 118, 527 (abstract 1166).
  • Genovese, M.C., Kaine, J.L., Lowenstein, M.B., Del Giudice, J., Baldassare, A., Schechtman, J., Fudman, E., Kohen, M., Gujrathi, S., Trapp, R.G., Sweiss, N.J., Spaniolo, G. & Dummer, W.; ACTION Study Group. (2008) Ocrelizumab, a humanized anti-CD20 monoclonal antibody, in the treatment of patients with rheumatoid arthritis: a phase I/II randomized, blinded, placebo-controlled, dose-ranging study. Arthritis & Rheumatism, 58, 26522661.
  • George, J.N., Woolf, S.H., Raskob, G.E., Wasser, J.S., Aledort, L.M., Ballem, P.J., Blanchette, V.S., Bussel, J.B., Cines, D.B., Kelton, J.G., Lichtin, A.E., McMillan, R., Okerbloom, J.A., Regan, D.H. & Warrier, I. (1996) Idiopathic thrombocytopenic purpura: a practice guideline developed by explicit methods for the American Society of Hematology. Blood, 88, 340.
  • Godeau, B., Porcher, R., Fain, O., Lefrère, F., Fenaux, P., Cheze, S., Vekhoff, A., Chauveheid, M.P., Stirnemann, J., Galicier, L., Bourgeois, E., Haiat, S., Varet, B., Leporrier, M., Papo, T., Khellaf, M., Michel, M. & Bierling, P. (2008) Rituximab efficacy and safety in adult splenectomy candidates with chronic immune thrombocytopenic purpura – results of a prospective multicenter phase 2 study. Blood, 112, 9991004.
  • Goldenberg, D.M., Rossi, E.A., Stein, R., Cardillo, T.M., Czuczman, S. & Hernandez-Ilizaliturri, F.J. (2009) Properties and structure-function relationship of veltuzumab (hA20), a humanized anti-CD20 monoclonal antibody. Blood, 113, 10621070.
  • Goldenberg, D.M., Morschhauser, F. & Wegener, W.A. (2010) Veltuzumab (humanized anti-CD20 monoclonal antibody): characterization, current clinical results, and future prospects. Leukemia & Lymphoma, 51, 747755.
  • Gudbrandsdottir, S., Birgens, H.S., Jensen, B.A., Jensen, M.K., Kjeldsen, L., Klausen, T.W., Larsen, H., Mourits-Andersen, H.T., Nielsen, C.H., Nielsen, O.J., Plesner, T., Pulczynski, S., Rasmussen, I.H., Rønnov-Jessen, D. & Hasselbalch, H.C. (2013) Rituximab and dexamethasone vs dexamethasone monotherapy in newly diagnosed patients with primary immune thrombocytopenia. Blood, 121, 19761981.
  • Hasan, A., Michel, M., Patel, V., Stasi, R., Cunningham-Rundles, S., Leonard, J. & Bussel, J. (2009) Repeated courses of rituximab in chronic ITP: three different regimens. American Journal of Hematology, 84, 661665.
  • Kuter, D.J., Bussel, J.B., Lyons, R.M., Pullarkat, V., Gernsheimer, T.B., Senecal, F.M., Aledort, L.M., George, J.N., Kessler, C.M., Sanz, M.A., Liebman, H.A., Slovick, F.T., de Wolf, J.T., Bourgeois, E., Guthrie, T.H. Jr, Newland, A., Wasser, J.S., Hamburg, S.I., Grande, C., Lefrère, F., Lichtin, A.E., Tarantino, M.D., Terebelo, H.R., Viallard, J.F., Cuevas, F.J., Go, R.S., Henry, D.H., Redner, R.L., Rice, L., Schipperus, M.R., Guo, D.M. & Nichol, J.L. (2008) Efficacy of romiplostim in patients with chronic immune thrombocytopenic purpura: a double-blind randomized controlled trial. Lancet, 371, 395403.
  • Medeot, M., Zaja, F., Vianelli, N., Battista, M., Baccarani, M., Patriarca, F., Soldano, F., Isola, M., De Luca, S. & Fanin, R. (2008) Rituximab therapy in adult patients with relapsed or refractory immune thrombocytopenic purpura: long-term follow up results. European Journal of Haematology, 81, 165169.
  • Miotti, S., Negri, D.R., Valota, O., Calabrese, M., Bolhuis, R.L., Gratama, J.W., Colnaghi, M.I. & Canevari, S. (1999) Level of anti-mouse-antibody response induced by bi-specific monoclonal antibody OC/TR in ovarian-carcinoma patients is associated with longer survival. International Journal of Cancer, 84, 6268.
  • Morschhauser, F., Leonard, J.P., Fayad, L., Coiffier, B., Petillon, M.O., Coleman, M., Schuster, S.J., Dyer, M.J., Horne, H., Teoh, N., Wegener, W.A. & Goldenberg, D.M. (2009) Humanized anti-CD20 antibody, veltuzumab, in refractory/recurrent non-Hodgkin's lymphoma: phase I/II results. Journal of Clinical Oncology, 27, 33463353.
  • Negrea, G.O., Elstrom, R., Allen, S.L., Rai, K.R., Abbasi, R.M., Farber, C.M., Teoh, N., Horne, H., Wegener, W.A. & Goldenberg, D.M. (2011) Subcutaneous injections of low-dose veltuzumab (humanized anti-CD20 antibody) are safe and active in patients with indolent non-Hodgkin's lymphoma. Haematologica, 96, 567573.
  • Neunert, C., Lim, W., Crowther, M., Cohen, A., Solberg, L. Jr & Crowther, M.A. (2011) The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood, 117, 41904207.
  • Newland, A., Cauolier, M.T., Kappers-Klunne, M., Schipperus, M.R., Lefrere, F., Zwaginga, J.J., Christal, J., Chen, C.F. & Nichol, J.L. (2006) An open-label, unit dose-finding study of AMG 531, a novel thrombopoesis-stimulating peptibody, in patients with immune thrombocytopenic purpura. British Journal of Haematology, 135, 547553.
  • Page, L., Psaila, B., Provan, D., Hamilton, J.M., Jenkins, J.M., Elish, A.S., Lesser, M.L. & Bussel, J.B. (2007) The immune thrombocytopenic purpura (ITP) bleeding score: assessment of bleeding in patients with ITP. British Journal of Haematology, 138, 245248.
  • Patel, V.L., Mahévas, M., Lee, S.Y., Stasi, R., Cunningham-Rundles, S., Godeau, B., Kanter, J., Neufeld, E., Taube, T., Ramenghi, U., Shenoy, S., Ward, M.J., Mihatov, N., Patel, V.L., Bierling, P., Lesser, M., Cooper, N. & Bussel, J.B. (2012) Outcomes 5 years after response to rituximab therapy in children and adults with immune thrombocytopenia. Blood, 119, 59895995.
  • Peñalver, F.J., Jiménez-Yuste, V., Almagro, M., Alvarez-Larrán, A., Rodríguez, L., Casado, M., Gallur, L., Giraldo, P., Hernández, R., Menor, D., Rodríguez, M.J., Caballero, D., González, R., Mayans, J., Millán, I. & Cabrera, J.R. (2006) Rituximab in the management of chronic immune thrombocytopenic purpura: an effective and safe therapeutic alternative in refractory patients. Annals of Hematology, 85, 400406.
  • Provan, D., Stasi, R., Newland, A.C., Blanchette, V.S., Bolton-Maggs, P., Bussel, J.B., Chong, B.H., Cines, D.B., Gernsheimer, T.B., Godeau, B., Grainger, J., Greer, I., Hunt, B.J., Imbach, P.A., Lyons, G., McMillan, R., Rodeghiero, F., Sanz, M.A., Tarantino, M., Watson, S., Young, J. & Kuter, D.J. (2010) International consensus report on the investigation and management of primary immune thrombocytopenia. Blood, 115, 168186.
  • Rodeghiero, F., Stasi, R., Gernsheimer, T., Michel, M., Provan, D., Arnold, D.M., Bussel, J.B., Cines, D.B., Chong, B.H., Cooper, N., Godeau, B., Lechner, K., Mazzucconi, M.G., McMillan, R., Sanz, M.A., Imbach, P., Blanchette, V., Kühne, T., Ruggeri, M. & George, J.N. (2009) Standardization of terminology, definitions, and outcome in idiopathic thrombocytopenic purpura (ITP) of adults and children: report from an international working group. Blood, 113, 23862393.
  • Stein, R., Qu, Z., Chen, S., Rosario, A., Shi, V., Hayes, M., Horak, I.D., Hansen, H.J. & Goldenberg, D.M. (2004) Characterization of a new humanized anti-CD20 monoclonal antibody, IMMU-106, and its use in combination with the humanized anti-CD22 antibody, epratuzumab, for the therapy of non-Hodgkin's lymphoma. Clinical Cancer Research, 10, 28682878.
  • Tahir, H., Bhatia, A., Wegener, W.A. & Isenberg, D.A. (2005) Humanised anti-CD20 monoclonal antibody in the treatment of severe resistant systemic lupus erythematosus in a patient with antibody against rituximab. Rheumatology, 44, 561562.
  • Zaja, F., Baccarani, M., Mazza, P., Bocchia, M., Gugliotta, L., Zaccaria, A., Vianelli, N., Defina, M., Tieghi, A., Amadori, S., Campagna, S., Ferrara, F., Angelucci, E., Usala, E., Cantoni, S., Visani, G., Fornaro, A., Rizzi, R., De Stefano, V., Casulli, F., Battista, M.L., Isola, M., Soldano, F., Gamba, E. & Fanin, R. (2010) Dexamethasone plus rituximab yields higher sustained response rates than dexamethasone monotherapy in adults with primary immune thrombocytopenia. Blood, 115, 27552762.

Supporting Information

  1. Top of page
  2. Summary
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgements
  7. Authors' contributions
  8. Disclosures
  9. References
  10. Supporting Information
FilenameFormatSizeDescription
bjh12448-sup-0001-TableS1-S5.docWord document94K

Table S1. Incidence of adverse events occurring in 2 or more patients receiving subcutaneous injections (N = 34).

Table S2. Hematology laboratories (Mean ± SD).*

Table S3. Serum chemistry laboratories (Mean ± SD).*

Table S4. Serum immunoglobulins and T cells (Mean ± SD).*

Table S5. Patients with Measurable Serum Levels of Human Anti-Veltuzumab Antibodies (HAHA).

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