Pharmacologic insights into the future of trastuzumab

Population pharmacokinetic analysis of phase 1 bemarituzumab data to support phase 2 gastroesophageal adenocarcinoma FIGHT trial

Purpose

To report population pharmacokinetic (PK) analysis of the phase 1 study (FPA144-001, NCT02318329) and to select a clinical dose and schedule that will achieve an empirical target trough concentration (C_trough) for an anti-fibroblast growth factor receptor 2b antibody, bemarituzumab.

Methods

Nonlinear mixed-effect modeling was used to analyse PK data. In vitro binding affinity and receptor occupancy of bemarituzumab were determined. Simulation was conducted to estimate dose and schedule to achieve an empirical target C_trough in a phase 2 trial (FIGHT, NCT03694522) for patients receiving first-line treatment combined with modified 5-fluourouracil, oxaliplatin and leucovorin (mFOLFOX6) for gastric and gastroesophageal junction adenocarcinoma.

Results

Bemarituzumab PK is best described by a two-compartment model with parallel linear and nonlinear (Michaelis–Menten) elimination from the central compartment. Albumin, gender, and body weight were identified as the covariates on the linear clearance and/or volume of distribution in the central compartment, and no dose adjustment was warranted. An empirical target of bemarituzumab C_trough of ≥ 60 µg/mL was projected to achieve > 95% receptor occupancy based on in vitro data. Fifteen mg/kg every 2 weeks, with a single dose of 7.5 mg/kg on Cycle 1 Day 8, was projected to achieve the target C_trough on Day 15 in 98% of patients with 96% maintaining the target at steady state, which was confirmed in the FIGHT trial.

Conclusion

A projected dose and schedule to achieve the target C_trough was validated in phase 1 of the FIGHT trial which supported selection of the phase 2 dose and schedule for bemarituzumab.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04139-4) contains supplementary material, which is available to authorized users.

Trastuzumab: More than a Guide in HER2-Positive Cancer Nanomedicine

HER2 overexpression, which occurs in a fifth of diagnosed breast cancers as well as in other types of solid tumors, has been traditionally linked to greater aggressiveness. Nevertheless, the clinical introduction of trastuzumab has helped to improve HER2-positive patients' outcomes. As a consequence, nanotechnology has taken advantage of the beneficial effects of the administration of this antibody and has employed it to develop HER2-targeting nanomedicines with promising therapeutic activity and limited toxicity. In this review, the molecular pathways that could be responsible for trastuzumab antitumor activity will be briefly summarized. In addition, since the conjugation strategies that are followed to develop targeting nanomedicines are essential to maintaining their efficacy and tolerability, the ones most employed to decorate drug-loaded nanoparticles and liposomes with trastuzumab will be discussed here. Thus, the advantages and disadvantages of performing this trastuzumab conjugation through adsorption or covalent bindings (through carbodiimide, maleimide, and click-chemistry) will be described, and several examples of targeting nanovehicles developed following these strategies will be commented on. Moreover, conjugation methods employed to synthesized trastuzumab-based antibody drug conjugates (ADCs), among which T-DM1 is well known, will be also examined. Finally, although trastuzumab-decorated nanoparticles and liposomes and trastuzumab-based ADCs have proven to have better selectivity and efficacy than loaded drugs, trastuzumab administration is sometimes related to side toxicities and the apparition of resistances. For this reason also, this review focuses at last on the important role that newer antibodies and peptides are acquiring these days in the development of HER2-targeting nanomedicines.

mRNA Delivery for Therapeutic Anti-HER2 Antibody Expression In Vivo

Antibody-based drugs are a leading class of biologics used to treat a variety of diseases, including cancer. However, wide antibody implementation is hindered by manufacturing challenges and high production cost. Use of in-vitro-transcribed mRNA (IVT-mRNA) for endogenous protein expression has the potential to circumvent many of the shortcomings of antibody production and therapeutic application. Here, we describe the development of an IVT-mRNA system for in vivo delivery of a humanized anti-HER2 (also known as ERBB2) antibody, trastuzumab, and demonstrate its anticancer activity. We engineered the IVT-mRNA sequence to maximize expression, then formulated the IVT-mRNA into lipid-based nanoparticles (LNPs) to protect the mRNA from degradation and enable efficient in vivo delivery. Systemic delivery of the optimized IVT-mRNA loaded into LNPs resulted in antibody serum concentrations of 45 ± 8.6 μg/mL for 14 days after LNP injection. Further studies demonstrated an improved pharmacokinetic profile of the produced protein compared to injection of trastuzumab protein. Finally, treatment of tumor-bearing mice with trastuzumab IVT-mRNA LNPs selectively reduced the volume of HER2-positive tumors and improved animal survival. Taken together, the results of our study demonstrate that using IVT-mRNA LNPs to express full-size therapeutic antibodies in the liver can provide an effective strategy for cancer treatment and offers an alternative to protein administration.

Gene therapy using plasmid DNA-encoded anti-HER2 antibody for cancers that overexpress HER2

Plasmid DNA-encoded antibodies, or DNA-based monoclonal antibodies (dMAbs), are delivered by intramuscular injection and in vivo electroporation (EP) and are effective in virus neutralization, although they have not been evaluated for tumor gene therapy. Here we investigated whether a dMAb was appropriate for tumor gene therapy. We constructed the expression plasmids coding for the heavy or light chain of a parental murine antibody of Herceptin with the antibody genes codon- and RNA-optimized and fused to the Kozak-IgE leader sequence in pVax1. Transfection of the plasmids into human muscle RD cells resulted in functional expression of the antibody, and this exhibited the same in vitro antiproliferative activity as Herceptin. A single intramuscular injection and in vivo EP of the plasmids (100 μg per head) resulted in high and sustained antibody expression in the sera of normal mice and in effective inhibition of tumor growth in nude mice bearing HER2-positive human breast carcinoma BT474 xenografts. The antitumor efficacy of the anti-HER2 dMAb was similar to that of four doses of intravenously injected 10 mg kg⁻¹ Herceptin. The results demonstrate that the dMAb is effective in the treatment of HER2-positive breast cancer, suggesting that this dMAb may be applicable for tumor gene therapy.

Engineering humoral immunity as prophylaxis or therapy

PURPOSE OF THE REVIEW

In this review, we will discuss the field of engineered humoral immunity with an emphasis on recent work using viral vectors to produce antibodies in vivo. As an alternative to passive transfer of monoclonal antibody protein, a transgene encoding an antibody is delivered to cells via vector transduction, resulting in expression and secretion by the host cell. This review will summarize the evidence in support of this strategy as an alternative to traditional vaccines against infection and as novel therapeutics for a variety of diseases.

RECENT FINDINGS

Historically, humoral immunity has been engineered through vaccination and passive transfer of monoclonal antibodies. However, recent work suggests that vectors can be used to deliver transgenes encoding broadly neutralizing antibodies to non-hematopoietic tissues and can mediate long-term expression that is capable of preventing or treating infectious diseases. The production of engineered monoclonal antibodies allows for precise targeting and elimination of aberrant self-proteins that are characteristic of certain neurodegenerative disease. This approach has also been successfully used to combat cancer and addiction in several animal models. Despite the wide array of expression platforms that have been described, adeno-associated virus vectors have emerged as the frontrunner for rapid clinical translation.

SUMMARY

Recent advances in vector-mediated antibody expression have demonstrated the potential for such interventions to prevent infection and treat disease. As such, it offers an alternative to immunogen-based vaccine design and a novel therapeutic intervention by enabling precise manipulation of humoral immunity. Success translating these approaches to patients may enable the development of effective prevention against previously intractable pathogens that evade immunity such as HIV, influenza, malaria or HCV and may also enable new treatment options for neurodegenerative diseases such as Alzheimer's disease.

Persistent expression of biologically active anti-HER2 antibody by AAVrh.10-mediated gene transfer

Trastuzumab (Herceptin) is a recombinant humanized monoclonal antibody directed against an extracellular region of the HER2 protein. We hypothesized that a single adeno-associated virus mediated genetic delivery of an anti-HER2 antibody should be effective in mediating long term production of anti-HER2 and in suppressing the growth of human tumors in a xenograft model in nude mice. The adeno-associated virus gene transfer vector AAVrh.10αHER2 was constructed based on non-human primate AAV serotype rh.10 to express the cDNAs for the heavy and light chains of monoclonal antibody 4D5, the murine precursor to trastuzumab. The data demonstrates that genetically transferred anti-HER2 selectively bound human HER2 protein and suppressed proliferation of HER2 positive tumor cell lines. A single administration of AAVrh.10αHER2 provided long term therapeutic levels of anti-HER2 antibody expression without inducing anti-idiotype response, suppressed the growth of HER2 positive tumors and increased survival of the tumor-bearing mice. In the context that trastuzumab therapy requires frequent, repeated administration, this strategy might be developed as an alternate platform for delivery anti-HER2 therapy.

Pharmacokinetics and pharmacokinetic/pharmacodynamic associations of ofatumumab, a human monoclonal CD20 antibody, in patients with relapsed or refractory chronic lymphocytic leukaemia: a phase 1-2 study

The purpose of this phase 1-2 study was to investigate the association between the pharmacokinetic properties of ofatumumab, a human monoclonal CD20 antibody, and outcomes in 33 patients with relapsed/refractory chronic lymphocytic leukaemia receiving 4 weekly infusions of ofatumumab. The ofatumumab concentration profiles were fitted well by a two-compartment model with different elimination rate constant at first infusion compared to the remaining infusions in line with the observed rapid and sustained B-cell depletion. Exposure to ofatumumab was linked to clinical outcomes: high exposure was associated with higher probability of overall clinical response and longer progression-free survival. This association still remained statistically significant even when adjusting for relevant baseline covariates including tumour burden.

Outcome of patients with HER2-positive advanced breast cancer progressing during trastuzumab-based therapy

We sought to describe patterns of treatment and clinical outcome in patients with HER2-positive advanced breast cancer progressing on trastuzumab-based therapy. One hundred eighty-four consecutive HER2-positive advanced breast cancer patients received trastuzumab-based therapy between September 1999 and September 2004. Patients were followed up until death or May 2005. For patients progressing on trastuzumab-based therapy, we calculated the response rate (RR) to the first post-progression treatment, overall survival (OS) from the first administration of trastuzumab, time to second progression (TT-SP), and post-progression survival (PPS), according to treatment. At the time of this analysis, 132 patients had progressed on trastuzumab-based therapy, and 89 had died. Of the progressing patients, 21 experienced rapid progression and could not receive additional anticancer treatments;40 patients continued trastuzumab either alone (12 patients with isolated central nervous system progression), with chemotherapy (23 patients), or with endocrine therapy (5 patients); and 71 stopped trastuzumab and received chemotherapy (61 patients) or endocrine therapy (10 patients) as the first post-progression treatment. Excluding patients with rapid progression, clinical outcomes were similar whether trastuzumab was continued or not, in terms of RR (18% and 27%, respectively), OS (31 and 30 months, respectively), TT-SP (6 and 7 months, respectively), and PPS (21 and 19 months, respectively). The clinical outcome of patients with HER2-positive advanced breast cancer progressing during trastuzumab-based therapy might not be influenced by continuing trastuzumab. The optimal therapeutic strategy in this setting of patients needs evaluation in randomized trials.

Gemcitabine and Trastuzumab Combinations for Patients with Metastatic Breast Cancer Overexpressing HER2/neu

In HER2/neu-positive metastatic breast cancer, the combination of chemotherapy and trastuzumab has become a standard of care. This review discusses HER2/neu overexpression in breast cancer and the use of trastuzumab-based therapies. Specifically, the rationale for a gemcitabine/trastuzumab combination in this disease entity and the available clinical data on the use of the combination are discussed. Response rates of 12%-42% have been seen with single-agent gemcitabine and 37%-62% with trastuzumab/gemcitabine combinations. Further work is currently ongoing to examine this promising combination.