Early response to anti-TNF predicts long-term outcomes including sustained remission: an analysis of the BSRBR-RA.

OBJECTIVE: To identify different trajectories of disease activity in patients with RA following initiation of a first anti-TNF. METHODS: Patients with RA starting their first anti-TNF between 2001 and 2013 were selected from the British Society for Rheumatology Biologics Register for RA. Six-monthly DAS28-ESR scores were used to identify trajectories of disease activity using latent class modelling. Data were included for six follow-ups after registration (approximately 3 years). Subgroup analysis examined changes in disease activity profiles over time. RESULTS: A total of 14 436 patients with RA starting their first anti-TNF were enrolled between 2001 and 2013 (13 115 between 2001 and 2008, 1321 between 2010 and 2013). The mean number of DAS28-ESR scores was 3.5/patient (s.d. 2.1), with a mean of 184.9 days (s.d. 69.9) between scores. The DAS28-ESR nadir was achieved within 250 days of commencing anti-TNF, although apparent trajectory divergence emerged by first 6-monthly follow-up at 180 days. Four distinct response trajectories comprised the most stable model. Most patients fitted into 'modest' (7986 patients; 55.3%) or 'substantial' (4676 patients; 32.4%) response trajectories. Of the remainder, 1254 (8.7%) and 520 (3.6%) fitted 'maximal' and 'minimal' response trajectories, respectively. There was a significant (P < 0.01) increase in proportion achieving 'maximal' response between 2001-2008 and 2010-2013. CONCLUSION: This is the largest study to identify long-term response trajectories with anti-TNF. By 6 months, longer-term trajectory profiles of DAS28 could already be identified, with many patients identified earlier. The majority of patients had persistent moderate response, equivalent to maintained DAS28-ESR moderate disease activity. The maximal response trajectory (equivalent to sustained DAS2-ESR remission) was only achieved by approximately one-third of patients.

Gender stratified adjustment of the DAS28-CRP improves inter-score agreement with the DAS28-ESR in rheumatoid arthritis.

OBJECTIVES: To evaluate determinants of discordance between DAS28-ESR and DAS28-CRP and resulting impact on disease activity stratification in RA. METHODS: Paired DAS28-ESR and DAS28-CRP readings (n = 31 074) were obtained from the British Society for Rheumatology Biologics Register for RA. Factors influencing discordance between DAS28-ESR and DAS28-CRP were evaluated alongside the resulting effect on disease activity stratification. The impact of gender adjustment to the DAS28-CRP was evaluated. RESULTS: DAS28-CRP scores were ∼0.3 lower than DAS28-ESR overall, with greatest differences for women (-0.35) and patients over 50 years old (-0.34). Mean male DAS28-CRP scores were 0.15 less than corresponding DAS28-ESR scores. Discordance between DAS28-ESR and DAS28-CRP significantly impacted disease activity stratification at low disease activity and remission thresholds (32.0% and 66.6% concordance, respectively). Adjusting DAS28-CRP scores by gender significantly (P < 0.001) improved agreement with the DAS28-ESR. CONCLUSION: Discordance between DAS28-ESR and DAS28-CRP is greatest for women and patients over 50 years of age, and influences disease activity stratification. The proposed gender-adjusted DAS28-CRP improves inter-score agreement with DAS28-ESR, supporting more reliable disease activity stratification in treat-to-target approaches for RA.

Predictors, demographics and frequency of sustained remission and low disease activity in anti-tumour necrosis factor-treated rheumatoid arthritis patients.

OBJECTIVES: To investigate the frequency and predictors of sustained 28-joint DAS (DAS28) remission and low disease activity (LDA) in patients receiving anti-TNF therapy and changes in responses over a 12 year period. METHODS: Data from the British Society for Rheumatology Biologics Registry for Rheumatoid Arthritis were used. Sustained remission and LDA were defined according to DAS28-ESR thresholds sustained for 6 months. The dataset was dichotomized into sequential chronological subgroups (2001-2010 and 2010-2013). Predictive variables were identified from a previous systematic review and modelled using multivariable logistic regression. RESULTS: Overall, 2144 (14.9%) and 3802 (26.3%) patients achieved sustained remission or LDA, respectively. Positive predictors of sustained remission/LDA included adalimumab (vs etanercept), greater patient global assessment, never- and ex-smoker status (vs current smoking), greater swollen joint count, more recent commencement of anti-TNF and MTX co-prescription (except in the 2010-2013 subgroup). Negative predictors of sustained remission and LDA included poor baseline functional status (HAQ), female gender, older age at starting anti-TNF, infliximab use (vs etanercept), increasing BMI and greater baseline ESR. Increasing tender joint count was negatively associated with sustained LDA only. The overall proportion of patients achieving sustained remission and LDA has increased significantly over time. CONCLUSION: Sustained remission/LDA on anti-TNF treatment remains uncommon. Adalimumab use, greater patient global assessment, never- and ex-smoker status, greater swollen joint count, more recent commencement of anti-TNF and MTX co-prescription are associated with achievement of sustained remission/LDA. However, co-prescription of MTX was not associated with an increased likelihood of achieving sustained remission or LDA in the analysis of more recent anti-TNF responses.

Recommendation to implementation of remote patient monitoring in rheumatology: lessons learned and barriers to take.

Remote patient monitoring (RPM) leverages advanced technology to monitor and manage patients' health remotely and continuously. In 2022 European Alliance of Associations for Rheumatology (EULAR) points-to-consider for remote care were published to foster adoption of RPM, providing guidelines on where to position RPM in our practices. Sample papers and studies describe the value of RPM. But for many rheumatologists, the unanswered question remains the 'how to?' implement RPM.Using the successful, though not frictionless example of the Southmead rheumatology department, we address three types of barriers for the implementation of RPM: service, clinician and patients, with subsequent learning points that could be helpful for new teams planning to implement RPM. These address, but are not limited to, data governance, selecting high quality cost-effective solutions and ensuring compliance with data protection regulations. In addition, we describe five lacunas that could further improve RPM when addressed: establishing quality standards, creating a comprehensive database of available RPM tools, integrating data with electronic patient records, addressing reimbursement uncertainties and improving digital literacy among patients and healthcare professionals.

Availability of and use of Intralipid (lipid rescue therapy, lipid emulsion) in England and Wales.

There is increasing evidence for the use of Intralipid in the management of acute local anaesthetic toxicity. This is supported by the recent Association of Anaesthetists of Great Britain and Ireland (AAGBI) guidelines for the management of local anaesthetic toxicity. Acute hospitals in England and Wales were surveyed to determine the proportion that currently stocked Intralipid, the locations of stocks within the hospital, guidelines related to its use and previous use in the last 12 months. The majority of hospitals surveyed stocked Intralipid in multiple locations, although not in all areas using high volumes of local anaesthetics. Guidelines were typically in place, although these were often local rather than those from the AAGBI. Use in the last 12 months was uncommon, but typically information was not available on indications for its use. More systematic data collection is required on the safety and efficacy of Intralipid in the management of acute drug toxicity.

Determination of pharmacokinetic values of calicheamicin-antibody conjugates in mice by plasmon resonance analysis of small (5 microl) blood samples.

PURPOSE: The present study aims to establish a method that provides fast, precise and reproducible pharmacokinetic (PK) parameters of antibody-calicheamicin conjugates. The method should discriminate between PK of the antibody moiety and PK of the conjugated calicheamicin (CM). METHODS: The conjugates gemtuzumab ozogamicin (CMA-676, Mylotarg) or inotuzumab ozogamicin (CMC-544) were injected in the tail vein of nude mice. At regular time intervals, 5 mul whole blood samples were taken from the tail artery. Concentrations of conjugated CMA-676 or CMC-544 as well as concentrations of their respective antibody moiety were determined by sandwich plasmon resonance. This detection system measures changes in the plasma resonance angle caused by the interaction of macromolecules on biosensor chips. We determined as a first measure the binding of CMA-676 or CMC-544 to their respective antigens, CD33 or CD22. As a second measure we determined the amount of CM on the antigen-bound conjugates. This was done by determination of changes in plasma resonance angle after binding of an anti-CM antibody. RESULTS: Sandwich plasmon resonance allowed detection of both conjugates in blood of mice in a range of 100-1,000 ng/ml protein. Due to the precision of the sampling and detection methods, PK values of each conjugate were determined in individual mice. Calicheamicin bound to antibody was eliminated faster than the antibody alone. The presence of a CD22-expressing tumour in mice reduced the plasma levels of the CD22-targeting conjugate but not of the CD33-targeting one. CONCLUSIONS: Using small blood samples from a mouse, the sandwich plasmon resonance method provided PK-values of CM-conjugates and information about the stability of the linkage in vivo. Comparison between the PK-values of CM-conjugates in tumour-bearing and tumour-free mice suggested that retention of the conjugate in tumour tissue due to antigen targeting could be deduced from the plasma levels.

Antitumor efficacy of a combination of CMC-544 (inotuzumab ozogamicin), a CD22-targeted cytotoxic immunoconjugate of calicheamicin, and rituximab against non-Hodgkin's B-cell lymphoma.

PURPOSE: CMC-544 is a CD22-targeted cytotoxic immunoconjugate, currently being evaluated in B-cell non-Hodgkin's lymphoma (B-NHL) patients. Rituximab is a CD20-targeted antibody commonly used in B-NHL therapy. Here, we describe antitumor efficacy of a combination of CMC-544 and rituximab against B-cell lymphoma (BCL) in preclinical models. EXPERIMENTAL DESIGN: BCLs were cultured in vitro with CMC-544, rituximab, or their combination. BCLs were injected either s.c. or i.v. to establish localized s.c. BCL in nude mice or disseminated BCL in severe combined immunodeficient mice, respectively. I.p. treatment with CMC-544 or rituximab was initiated at various times either alone or in combination and its effect on s.c. BCL growth or survival of mice with disseminated BCL was monitored. RESULTS: In vitro growth-inhibitory activity of CMC-544 combined with rituximab was additive. Rituximab but not CMC-544 exhibited effector functions, such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. Rituximab was less effective in inhibiting growth of established BCL xenografts than developing xenografts. In contrast, CMC-544 was equally effective against both developing and established BCL xenografts. Although CMC-544 and rituximab individually caused partial inhibition of the growth of BCL xenografts at suboptimal doses examined, their combination suppressed xenograft growth by >90%. In a disseminated BCL model, 60% of CMC-544-treated mice and 20% of rituximab-treated mice survived for 125 days. In contrast, 90% of mice treated with the combination of CMC-544 and rituximab survived for longer than 125 days. CONCLUSION: The demonstration of superior antitumor activity of a combination of CMC-544 and rituximab described here provides the preclinical basis for its clinical evaluation as a treatment option for B-NHL.

Factors Associated With Sustained Remission in Rheumatoid Arthritis in Patients Treated With Anti-Tumor Necrosis Factor.

OBJECTIVE: Anti-tumor necrosis factor (anti-TNF) antibody has revolutionized the treatment of rheumatoid arthritis (RA), and remission is now a realistic possibility for patients. Despite widespread use of anti-TNFs, predicting which patients are most likely to attain a sustained good response to these treatments remains challenging. Our objective was to undertake a systematic review of the literature to evaluate existing evidence for demographic and clinical factors associated with the achievement of sustained remission in individuals with RA treated with anti-TNF therapy. METHODS: Embase, Medline, and the Cochrane Controlled Trials Register were searched along with studies identified from reference lists. Quality of studies was assessed using Newcastle-Ottawa criteria. Meta-analysis was undertaken where unadjusted odds ratios were available for the same demographic or clinical factors from at least 3 studies. RESULTS: Six studies were identified. Concomitant methotrexate use was associated with an increased likelihood of achieving sustained remission. Greater baseline disease activity, tender joint count, age, disease duration, baseline functional impairment, and female sex were associated with reduced likelihood of achieving sustained remission. CONCLUSION: Factors predicting sustained remission are seldom reported. Evidence identified in this review supports current recommendations for methotrexate coprescription and highlights the negative impact of particular clinical and demographic features on the likelihood of achieving optimal response to anti-TNF treatment. Sustained remission is clinically more relevant than point remission in RA. More widespread reporting of sustained remission will help clinicians set realistic expectations on likely long-term treatment efficacy and could be an important tool for identifying patients suitable for dose optimization.

Transcriptional profiling identifies differential expression of long non-coding RNAs in Jo-1 associated and inclusion body myositis.

Myositis is characterised by muscle inflammation and weakness. Although generally thought to be driven by a systemic autoimmune response, increasing evidence suggests that intrinsic changes in the muscle might also contribute to the pathogenesis. Long non-coding RNAs (lncRNAs) are a family of novel genes that regulate gene transcription and translation. To determine the potential role of lncRNAs, we employed next generation sequencing to examine the transcriptome in muscle biopsies obtained from two histologically distinct patient populations, inclusion body myositis (IBM) and anti-Jo-1-associated myositis (Jo-1). 1287 mRNAs and 1068 mRNAs were differentially expressed in the muscle from Jo-1 and IBM patients, respectively. Pathway analysis showed the top canonical pathway in both Jo-1 and IBM was oxidative phosphorylation and mitochondrial dysfunction. We identified 731 known and 325 novel lncRNAs in the muscles biopsies. Comparison with controls showed 55 and 46 lncRNAs were differentially expressed in IBM and Jo-1 myositis, respectively. Of these, 16 lncRNAs were differentially expressed in both IBM and Jo-1 myositis and included upregulated H19, lncMyoD and MALAT1. Given that these are known to regulate muscle proliferation and differentiation, we speculate that changes in lncRNAs might contribute to the phenotypic changes in Jo-1 and IBM myositis.

Tumoricidal effect of calicheamicin immuno-conjugates using a passive targeting strategy.

Calicheamicin is a potent chemotherapeutic with a low therapeutic index that requires targeting to tumor cells for its use in the clinic. To treat acute myeloid leukemia, calicheamicin has been conjugated to an antibody that recognizes CD33 (gemtuzumab ozogamicin). The application range of this 'active' targeting strategy is limited since it depends on specific antigen expression by tumor cells. This limitation could be reduced by using an antigen-independent 'passive targeting' strategy for calicheamicin. 'Passive targeting' relies on the dysfunctional vasculature of a neoplastic tumor that allows enhanced retention of macromolecules. We studied the efficacy of calicheamicin conjugated to various carrier molecules: i.e. immunoglobulin, albumin or PEGylated Fc fragments. In nude mice, a conjugate of anti-CD33 and calicheamicin accumulates in human tumor xenografts in the absence of detectable amounts of targeting antigen. Passive targeting provided sufficient accumulation of this conjugate to inhibit tumor growth of 10 different CD33-negative xenograft models. This efficacy depended on the use of an acid-labile linker between antibody and calicheamicin. Substitution of immunoglobulin as a carrier with either albumin or PEGylated Fc reduced or eliminated the efficacy of the conjugate. The results showed that using 'non-specific' immunoglobulin for passive targeting of calicheamicin might be an effective mode of cancer therapy.

Potent and specific antitumor efficacy of CMC-544, a CD22-targeted immunoconjugate of calicheamicin, against systemically disseminated B-cell lymphoma.

PURPOSE: CMC-544 is a CD22-targeted immunoconjugate of calicheamicin and exerts a potent cytotoxic effect against CD22+ B-cell lymphoma. This study evaluated antitumor efficacy of CMC-544 against systemically disseminated B-cell lymphoma. EXPERIMENTAL DESIGN: Scid mice received i.v. injections of CD22+ Ramos B-cell lymphoma cells for their systemic dissemination. CMC-544, G5/44, CD33-targeted CMA-676 (control conjugate) or rituximab were given i.p. 3, 9, 15, or 21 days after B-cell lymphoma dissemination. Diseased mice were monitored daily for hind-limb paralysis and death. Histopathological examination of CMC-544-treated and vehicle-treated diseased mice was also performed. RESULTS: Mice with disseminated B-cell lymphoma developed hind-limb paralysis within 35 days. When given up to 15 days after B-cell lymphoma dissemination, CMC-544 extended survival of the diseased mice to >100 days, and these mice were considered cured. CMC-544 was efficacious when given during both the early initiation phase and the late established phase of the disease. A single dose of CMC-544 was effective in delaying the occurrence of hind-limb paralysis. In contrast, neither CMA-676 nor unconjugated G5/44 was effective. Rituximab was effective when given early in the disease process but not when the disease was established. Histopathological analysis revealed B-cell lymphoma infiltration in brain, spinal cord, bone marrow, and kidney in vehicle-treated but not in CMC-544-treated diseased mice. Consistent with its efficacy against the disseminated B-cell lymphoma, CMC-544 also caused regression of established Ramos B-cell lymphoma xenografts in scid mice. CONCLUSIONS: CMC-544 confers strong therapeutic activity against systemic disseminated B-cell lymphoma and protects mice from hind-limb paralysis and death. These results support clinical evaluation of CMC-544 in the treatment of CD22+ lymphoid malignancies.

Antibody-targeted chemotherapy with the calicheamicin conjugate hu3S193-N-acetyl gamma calicheamicin dimethyl hydrazide targets Lewisy and eliminates Lewisy-positive human carcinoma cells and xenografts.

PURPOSE: Linking a cytotoxic anticancer drug to an antibody that recognizes a tumor-associated antigen can improve the therapeutic index of the drug. We asked whether a conjugate of the cytotoxic antibiotic N-acetyl gamma calicheamicin dimethyl hydrazide (CalichDMH) and an antibody recognizing Lewis(y) (Le(y)) antigen could eliminate carcinomas that express Le(y). Because Le(y) is highly expressed on carcinomas of colon, breast, lung, ovary, and prostate, a CalichDMH conjugate targeting Le(y) could provide a treatment option for various cancers. EXPERIMENTAL DESIGN: The humanized anti-Le(y) antibody hu3S193 was conjugated to CalichDMH via the bifunctional AcBut linker. Selectivity and avidity of the conjugate (hu3S193-CalichDMH) for Le(y)-BSA or Le(y+) cells was tested by BIAcore or flow cytometry. Cytotoxicity of hu3S193-CalichDMH was compared with toxicity of a control conjugate on monolayers of Le(y+) and Le(y-) carcinoma cells. Inhibition of tumor growth by hu3S193-CalichDMH was assessed on three types of s.c. xenografts. RESULTS: Hu3S193-CalichDMH had similar selectivity as hu3S193. The conjugate had lower affinity for Le(y)-BSA but not for Le(y+) cells. When tested on monolayers of human Le(y+) carcinoma cells, hu3S193-CalichDMH was more cytotoxic than a control conjugate. This difference in efficacy was not noted on Le(y-) cells. Efficacy of hu3S193-CalichDMH depended on the expression of Le(y) and on the sensitivity of the cells to CalichDMH. In vivo, hu3S193-CalichDMH inhibited growth of xenografted human gastric (N87), colon (LOVO), and prostate carcinomas (LNCaP). When used against N87 xenografts, hu3S193-CalichDMH arrested tumor growth for at least 100 days. CONCLUSION: Hu3S193-CalichDMH can specifically eliminate Le(y+) tumors. These results support development of this conjugate for treatment of carcinomas.

Reactivity in ELISA with DNA-loaded nucleosomes in patients with proliferative lupus nephritis.

Autoantibodies against nucleosomes are considered a hallmark of systemic lupus erythematosus (SLE). We compared in patients with proliferative lupus nephritis the diagnostic usefulness of a dsDNA-loaded nucleosome ELISA (anti-dsDNA-NcX) with ELISAs in which dsDNA or nucleosomes alone were coated. First, we analysed whether DNA loading on nucleosomes led to masking of epitopes by using defined monoclonal anti-DNA, anti-histone and nucleosome-specific autoantibodies to evaluate the accessibility of nucleosomal epitopes in the anti-dsDNA-NcX ELISA. Second, autoantibody levels were measured in these 3 ELISAs in 100 patients with proliferative lupus nephritis (LN) before immunosuppressive treatment and in 128 non-SLE disease controls. In patients with LN inter-assay comparisons and associations with clinical and serological parameters were analysed. The panel of monoclonal antibodies revealed that all epitopes were equally accessible in the anti-dsDNA-NcX ELISA as in the two other ELISAs. Patients with proliferative lupus nephritis were positive with dsDNA-loaded nucleosomes in 86%, with DNA in 66% and with nucleosomes in 85%. In the non-lupus disease control group these frequencies were 1.6% (2 out of 128) for both the anti-dsDNA-NcX and the anti-dsDNA ELISA and 0% in the anti-nucleosome ELISA. The levels in the anti-dsDNA-NcX ELISA were high in a group of patients with LN that showed absent reactivity in the anti-DNA or low levels in the anti-nucleosome ELISA. Anti-dsDNA-NcX positivity was associated with higher SLEDAI scores within this group. Within nucleosome-based ELISAs, we propose the anti-dsDNA-NcX ELISA as the preferred test system.

Statin-induced necrotizing myositis - a discrete autoimmune entity within the "statin-induced myopathy spectrum".

Statin-induced necrotizing myositis is increasingly being recognised as part of the "statin-induced myopathy spectrum". As in other immune-mediated necrotizing myopathies, statin-induced myositis is characterised by proximal muscle weakness with marked serum creatinine kinase elevations and histological evidence of myonecrosis, with little or no inflammatory cell infiltration. Unlike other necrotizing myopathies, statin-induced myopathy is associated with the presence of autoantibodies directed against 3-hydroxy-3-methylglutaryl- coenzyme A reductase (the enzyme target of statin therapies), and with Human Leukocyte Antigen-DRB1*11. This article summarises the clinical presentation, investigations and management of this rare, but serious complication of statin therapy.

Delineation of a cellular hierarchy in lung cancer reveals an oncofetal antigen expressed on tumor-initiating cells.

Poorly differentiated tumors in non-small cell lung cancer (NSCLC) have been associated with shorter patient survival and shorter time to recurrence following treatment. Here, we integrate multiple experimental models with clinicopathologic analysis of patient tumors to delineate a cellular hierarchy in NSCLC. We show that the oncofetal protein 5T4 is expressed on tumor-initiating cells and associated with worse clinical outcome in NSCLC. Coexpression of 5T4 and factors involved in the epithelial-to-mesenchymal transition were observed in undifferentiated but not in differentiated tumor cells. Despite heterogeneous expression of 5T4 in NSCLC patient-derived xenografts, treatment with an anti-5T4 antibody-drug conjugate resulted in complete and sustained tumor regression. Thus, the aggressive growth of heterogeneous solid tumors can be blocked by therapeutic agents that target a subpopulation of cells near the top of the cellular hierarchy.

Selection of reaction additives used in the preparation of monomeric antibody-calicheamicin conjugates.

The formation of protein aggregates can be a major problem during the preparation of antibody-drug conjugates. Herein is described the methods by which reaction additives were selected, which reduce the tendency of antibodies to aggregate during the attachment of the cytotoxic agent calicheamicin to form an immunoconjugate. Reaction conditions were delineated that produced optimized yields of monomeric conjugates. These conditions were used in the preclinical preparations of gemtuzumab ozogamicin (Mylotarg), the first commercially available chemotherapeutic immunoconjugate.

CD20-specific antibody-targeted chemotherapy of non-Hodgkin's B-cell lymphoma using calicheamicin-conjugated rituximab.

Tumor-targeted delivery of a potent cytotoxic agent, calicheamicin, using its immunoconjugates is a clinically validated therapeutic strategy. Rituximab is a human CD20-specific chimeric antibody extensively used in B-NHL therapy. We investigated whether conjugation to calicheamicin can improve the anti-tumor activity of rituximab against human B-cell lymphoma (BCL) xenografts in preclinical models. BCL cells were cultured with rituximab or its calicheamicin conjugates and their in vitro growth was monitored. BCL cells were injected s.c. to establish localized xenografts in nude mice or i.v. to establish disseminated BCL in severe combined immunodeficient (scid) mice. I.p. treatment with rituximab or its calicheamicin conjugates was initiated and its effect on s.c. BCL growth or survival of mice with disseminated BCL was monitored. Conjugation of calicheamicin to rituximab vastly enhanced its growth inhibitory activity against BCL in vitro. Conjugation to calicheamicin had no deleterious effect on the effector functional activity of rituximab. Calicheamicin conjugated to rituximab with an acid-labile linker exhibited greater anti-tumor activity against s.c. BCL xenografts and improved survival of mice with disseminated BCL over that of unconjugated rituximab. Anti-tumor activities of rituximab conjugated to calicheamicin via an acid-stable linker were similar to that of unconjugated rituximab. Superior anti-tumor efficacy exhibited by a calicheamicin immunoconjugate of rituximab with an acid-labile linker over that of rituximab demonstrates the therapeutic potential of CD20-specific antibody-targeted chemotherapy strategy in the treatment of B-NHL.

A calicheamicin conjugate with a fully humanized anti-MUC1 antibody shows potent antitumor effects in breast and ovarian tumor xenografts.

Murine CTM01 is an internalizing murine IgG(1) monoclonal antibody that recognizes the MUC1 antigen expressed on many solid tumors of epithelial origin. Calicheamicin conjugates of this antibody have previously been shown to be potent, selective antitumor agents in preclinical models. A conjugate has now been made with a genetically engineered human version of this antibody, hCTM01. The hCTM01 is an IgG(4) isotype, has an immunoaffinity approximately 30% higher than mCTM01 by competitive RIA, and is efficiently internalized into target cells. The hCTM01-NAc-gamma calicheamicin DM amide conjugate, referred to as CMB-401, shows targeted killing of MUC1-expressing cells in vitro and produces pronounced dose-related antitumor effects over an 8-fold dose range against a MUC1-expressing, ovarian xenograft tumor, OvCar-3. The specificity of CMB-401 was confirmed by comparing its antitumor effects with those of an isotype-matched nonspecific conjugate against the MX-1 breast carcinoma. CMB-401, given either ip or iv, was highly active in these models in single and multiple dose regimens and gave complete regressions at the highest doses examined with good overall therapeutic ratios. CMB-401 also gave good antitumor effects at similar doses with a cisplatin-resistant MUC1-expressing cell line.

An anti-MUC1 antibody-calicheamicin conjugate for treatment of solid tumors. Choice of linker and overcoming drug resistance.

The anti-MUC1 antibody, CTM01, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to solid tumors of epithelial origin that express this antigen. Earlier calicheamicin conjugates relied on the attachment of a hydrazide derivative to the oxidized carbohydrates that occur naturally on antibodies. This produced a "carbohydrate conjugate" capable of releasing active drug by hydrolysis in the lysosomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin derivative containing an activated ester with the lysines of antibodies. This gives an "amide conjugate" that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the only likely site of drug release from the conjugate. As previously shown for the carbohydrate conjugate, this amide conjugate of CTM01 produces complete regressions of xenograft tumors at doses of 300 microg/kg (calicheamicin equivalents) given three times. This indicates that hydrolytic drug release is not necessary for potent, selective cytotoxicity for calicheamicin conjugates of CTM01. Although the unconjugated calicheamicins are in general less active in cells expressing the multidrug resistance phenotype, both in vitro and in vivo results of studies reported here suggest that the efficacy of the calicheamicins toward such tumors is unexpectedly enhanced by antibody conjugation, especially for the "amide conjugate". These hydrolytically stable conjugates are also active toward cisplatin-resistant ovarian carcinoma cells as well. Such studies indicate that the calicheamicin amide conjugate of CTM01 may have potential for the treatment of MUC1-positive solid tumors, including some types of resistant tumors.