Combining Evolution and Cancer therapy: A review of the Mathematical Approach

: Conventional cancer therapy kills tumors by applying the maximum tolerable dose of therapy. However, it leads to the development of tumoral heterogeneity and resistance, hence leading to therapy failure and progression. It is necessary to design therapies keeping in mind the evolutionary dynamics of tumors to minimize resistance and delay progression. Mathematical models are of great importance in oncology as they assist in the recreation of the tumor microenvironment, predict the outcomes of treatment strategies and elucidate fundamentals of tumor growth and resistance development. The body of literature covering models which incorporate evolutionary dynamics is vast. This paper provides an overview of existing models of “evolutionary therapy”, including ordinary differential equations, fitness, and probability functions.

Evolutionary Dynamics of Treatment-Induced Resistance in Cancer Informs Understanding of Rapid Evolution in Natural Systems

Rapid evolution is ubiquitous in nature. We briefly review some of this quite broadly, particularly in the context of response to anthropogenic disturbances. Nowhere is this more evident, replicated and accessible to study than in cancer. Curiously cancer has been late - relative to fisheries, antibiotic resistance, pest management and evolution in human dominated landscapes - in recognizing the need for evolutionarily informed management strategies. The speed of evolution matters. Here, we employ game-theoretic modeling to compare time to progression with continuous maximum tolerable dose to that of adaptive therapy where treatment is discontinued when the population of cancer cells gets below half of its initial size and re-administered when the cancer cells recover, forming cycles with and without treatment. We show that the success of adaptive therapy relative to continuous maximum tolerable dose therapy is much higher if the population of cancer cells is defined by two cell types (sensitive vs. resistant in a polymorphic population). Additionally, the relative increase in time to progression increases with the speed of evolution. These results hold with and without a cost of resistance in cancer cells. On the other hand, treatment-induced resistance can be modeled as a quantitative trait in a monomorphic population of cancer cells. In that case, when evolution is rapid, there is no advantage to adaptive therapy. Initial responses to therapy are blunted by the cancer cells evolving too quickly. Our study emphasizes how cancer provides a unique system for studying rapid evolutionary changes within tumor ecosystems in response to human interventions; and allows us to contrast and compare this system to other human managed or dominated systems in nature.

A Phase I Dose Escalation Study of Oxaliplatin, Cisplatin and Doxorubicin Applied as PIPAC in Patients with Peritoneal Carcinomatosis

Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is an innovative laparoscopic intraperitoneal chemotherapy approach with the advantage of a deeper tissue penetration. Thus far, oxaliplatin has been administered at an arbitrary dose of 92 mg/m2, cisplatin at 7.5 mg/m2 and doxorubicin 1.5 mg/m2. This is a model-based approach phase I dose escalation study with the aim of identifying the maximum tolerable dose of the three different drugs. The starting dose of oxaliplatin was 100 mg/m2; cisplatin was used in association with doxorubicin: 15 mg/m2 and 3 mg/m2 were the respective starting doses. Safety was assessed according to Common Terminology Criteria for Adverse Events (CTCAE version 4.03). Thirteen patients were submitted to one PIPAC procedure. Seven patients were treated with cisplatin and doxorubicin and 6 patients with oxaliplatin; no dose limiting toxicities and major side effects were found. Common adverse events included postoperative abdominal pain and nausea. The maximum tolerable dose was not reached. The highest dose treated cohort (oxaliplatin 135 mg/m2; cisplatin 30 mg/m2 and doxorubicin 6 mg/m2) tolerated PIPAC well. Serological analyses revealed no trace of doxorubicin at any dose level. Serum levels of cis- and oxaliplatin reached a peak at 60–120 min after PIPAC and were still measurable in the circulation 24 h after the procedure. Cisplatin and doxorubicin may be safely used as PIPAC at a dose of 30 mg/m2 and 6 mg/m2, respectively; oxaliplatin can be used at an intraperitoneal dose of 135 mg/m2. The dosages achieved to date are the highest ever used in PIPAC.

Efficacy of a novel lantibiotic, CMB001, against MRSA

Objectives To evaluate the efficacy of a novel lantibiotic, CMB001, against MRSA biofilms in vitro and in an in vivo experimental model of bacterial infection. Methods Antibacterial activity of CMB001 was measured in vitro after its exposure to whole blood or to platelet-poor plasma. In vitro efficacy of CMB001 against a Staphylococcus aureus biofilm was studied using scanning electron microscopy. The maximum tolerable dose in mice was determined and a preliminary pharmacokinetic analysis for CMB001 was performed in mice. In vivo efficacy was evaluated in a neutropenic mouse thigh model of infection. Results CMB001 maintained its antibacterial activity in the presence of blood or plasma for up to 24 h at 37°C. CMB001 efficiently killed S. aureus within the biofilm by causing significant damage to the bacterial cell wall. The maximum tolerable dose in mice was established to be 10 mg/kg and could be increased to 30 mg/kg in mice pretreated with antihistamines. In neutropenic mice infected with MRSA, treatment with CMB001 reduced the bacterial burden with an efficacy equivalent to that of vancomycin. Conclusions CMB001 offers potential as an alternative treatment option to combat MRSA. It will be of interest to evaluate the in vivo efficacy of CMB001 against infections caused by other pathogens, including Clostridioides difficile and Acinetobacter baumannii, and to expand its pharmacokinetic/pharmacodynamic parameters and safety profile.

TOOTH (The Open study Of dental pulp stem cell Therapy in Humans): Study protocol for evaluating safety and feasibility of autologous human adult dental pulp stem cell therapy in patients with chronic disability after stroke

Rationale Stroke represents a significant global disease burden. As of 2015, there is no chemical or biological therapy proven to actively enhance neurological recovery during the chronic phase post-stroke. Globally, cell-based therapy in stroke is at the stage of clinical translation and may improve neurological function through various mechanisms such as neural replacement, neuroprotection, angiogenesis, immuno-modulation, and neuroplasticity. Preclinical evidence in a rodent model of middle cerebral artery ischemic stroke as reported in four independent studies indicates improvement in neurobehavioral function with adult human dental pulp stem cell therapy. Human adult dental pulp stem cells present an exciting potential therapeutic option for improving post-stroke disability. Aims TOOTH (The Open study Of dental pulp stem cell Therapy in Humans) will investigate the use of autologous stem cell therapy for stroke survivors with chronic disability, with the following objectives: (a) determine the maximum tolerable dose of autologous dental pulp stem cell therapy; (b) define that dental pulp stem cell therapy at the maximum tolerable dose is safe and feasible in chronic stroke; and (c) estimate the parameters of efficacy required to design a future Phase 2/3 clinical trial. Methods and design TOOTH is a Phase 1, open-label, single-blinded clinical trial with a pragmatic design that comprises three stages: Stage 1 will involve the selection of 27 participants with middle cerebral artery ischemic stroke and the commencement of autologous dental pulp stem cell isolation, growth, and testing in sequential cohorts (n = 3). Stage 2 will involve the transplantation of dental pulp stem cell in each cohort of participants with an ascending dose and subsequent observation for a 6-month period for any dental pulp stem cell-related adverse events. Stage 3 will investigate the neurosurgical intervention of the maximum tolerable dose of autologous dental pulp stem cell followed by 9 weeks of intensive task-specific rehabilitation. Advanced magnetic resonance and positron emission tomography neuro-imaging, and clinical assessment will be employed to probe any change afforded by stem cell therapy in combination with rehabilitation. Sample size estimates Nine participants will step-wise progress in Stage 2 to a dose of up to 10 million dental pulp stem cell, employing a cumulative 3 + 3 statistical design with low starting stem cell dose and subsequent dose escalation, assuming that an acceptable probability of dose-limiting complications is between 1 in 6 (17%) and 1 in 3 (33%) of patients. In Stage 3, another 18 participants will receive an intracranial injection with the maximum tolerable dose of dental pulp stem cell. Outcomes The primary outcomes to be measured are safety and feasibility of intracranial administration of autologous human adult DPSC in patients with chronic stroke and determination of the maximum tolerable dose in human subjects. Secondary outcomes include estimation of the measures of effectiveness required to design a future Phase 2/3 clinical trial.