Periodic Reporting for period 2 - NECTAR (NEutron Capture-enhanced Treatment of neurotoxic Amyloid aggRegates)
Reporting period: 2022-04-01 to 2023-03-31
Neutron Capture Therapy (NCT) is a radiotherapy mainly used for cancer treatment. Its effectiveness relies on the highly localised energy deposition carried out by the charged high LET secondaries set in motion by the so called neutron capture reactions. The two most used capture isotopes are boron-10, B10, and gadolinium-157, Gd157. The range in tissue of the secondaries spans from few tens of nm (comparable to the DNA strand) up to less than 10 μm, that is the mean diameter of cells. The reactions probability is maximised at neutron low energy when modest side effects on normal tissues are expected. NCT cell-level selectivity, i.e. the biological damaging effect is active only inside the cancer cell, is due to the exploitation of the described physical properties together with the use of B10 or Gd157 enriched molecules, which are loaded only or preferentially by the neoplastic tissue.
Starting from the robust experience in oncology, NECTAR wants to evaluate and prove the feasibility, safety and effectiveness of the physical principles of NCT in the treatment of a completely different disease: Alzheimer’s disease (AD).
AD is the most common form of dementia (50-60% of all cases) and it destroys nerve cells thus limiting or abolishing higher functions. In the most advanced stages, patients will be unable to care for themselves and need constant help with their daily life.
Currently over 55 million people worldwide live with dementia. The number is expected to rise up to 139 million by 2050. Statistics say a new case of dementia arise somewhere in the world every 3 seconds. If we consider dementia as a country it would be the 14th largest economy worldwide, with a US$ 1.3 trillion current cost.
Pathogenesis and mechanisms involved in AD are still under investigation. Despite the huge amount of studies, including clinical trials, there is currently no definitive and rehab cure. In summer 2021, a new approved FDA drug, the monoclonal antibody Aducanumab was approved for AD treatment in humans with a specific action against the beta amyloid (Aβ) protein. Anyway, the very same approval was not released by EMA due to controversy in the outcomes of the trials.
Aβ is a protein normally produced by neurons, In AD this protein assumes an insoluble form leading to its abnormal aggregation and accumulation in the extracellular compartment. In this forms, Aβ is toxic for neurons and in the “amyloid cascade” hypothesis its accumulation is identified as the primum movens of the disorder. It was demonstrated that one of the very first aggregation stages, the oligomeric phase, is the most toxic for neurons. In addition, other processes are ongoing in AD, such as accumulation of iper phosphorylated tau protein and inflammation. In this context, several doubts and criticisms hover around Aducanumb, in particular because of the minimal evidences of clinical benefit from a single study (the EMERGE trial) and due to the expected high costs of using the new drug. In addition, although Aducanumab reduces the proportion of senile plaques (the last stage of Aβ aggregation), it may be ineffective against the oligomers or it may not stop the decline process connected with the tau protein. In this scenario, the investigation of new therapeutic options, in particular those proposing a completely different principle of action, deserve attention and NECTAR sets exactly at this point.
NECTAR can’t simply take the molecules and the irradiation protocols used in the NCT of cancer because in that case it faces an acute disease by an acute procedure. In AD, the treatment must address a chronic disease spreading in the whole brain, known to be radio sensitive. Only NCT basic physical principles can be translated to AD. Indeed a completely new class of neutron capture agents must be developed, in particular able to cross an almost intact blood-brain barrier. Considering the radio-sensitivity of brain, it is absolutely impossible to translate the acute irradiation protocols of NCT of cancer into an AD therapy and indeed NECTAR must identify a completely new treatment based on low doses and low dose rates. In this frame, NECTAR objectives are:
(1) to study and prove the effectiveness of the highly localised energy deposition induced by the neutron capture reactions on B10 and Gd157 to depolymerise the Aβ aggregates or to modify their structures in such a way that their toxicity is reduced or silenced;
(2) to evaluate the stimulation on the glia cell compartment by the penetrating photons emitted by the exploited capture reactions, in particular to assess if the radio-activated glia can promote the clearance of the Aβ aggregates.
If these hypothesis will be confirmed, NECTAR will test: (1) the safety of the brain pan-irradiation by low energy neutrons in presence and absence of the neutron capture agent, and (2) the effectiveness of the irradiation in slowing down the neuron degeneration and possibly the restoration of mental functions in particular connected with memory and mobility using normal and transgenic animal models.
NECTAR pursues also a technological goal, that is the identification, development and characterisation of the optimised neutron beam to perform the brain irradiation. In particular, NECTAR addresses the development and prototyping of innovative neutron spectrometers and micro- and nano-dosimeters to quantify the physical quantities of relevance down to Aβ dimension aggregates.
Starting from the robust experience in oncology, NECTAR wants to evaluate and prove the feasibility, safety and effectiveness of the physical principles of NCT in the treatment of a completely different disease: Alzheimer’s disease (AD).
AD is the most common form of dementia (50-60% of all cases) and it destroys nerve cells thus limiting or abolishing higher functions. In the most advanced stages, patients will be unable to care for themselves and need constant help with their daily life.
Currently over 55 million people worldwide live with dementia. The number is expected to rise up to 139 million by 2050. Statistics say a new case of dementia arise somewhere in the world every 3 seconds. If we consider dementia as a country it would be the 14th largest economy worldwide, with a US$ 1.3 trillion current cost.
Pathogenesis and mechanisms involved in AD are still under investigation. Despite the huge amount of studies, including clinical trials, there is currently no definitive and rehab cure. In summer 2021, a new approved FDA drug, the monoclonal antibody Aducanumab was approved for AD treatment in humans with a specific action against the beta amyloid (Aβ) protein. Anyway, the very same approval was not released by EMA due to controversy in the outcomes of the trials.
Aβ is a protein normally produced by neurons, In AD this protein assumes an insoluble form leading to its abnormal aggregation and accumulation in the extracellular compartment. In this forms, Aβ is toxic for neurons and in the “amyloid cascade” hypothesis its accumulation is identified as the primum movens of the disorder. It was demonstrated that one of the very first aggregation stages, the oligomeric phase, is the most toxic for neurons. In addition, other processes are ongoing in AD, such as accumulation of iper phosphorylated tau protein and inflammation. In this context, several doubts and criticisms hover around Aducanumb, in particular because of the minimal evidences of clinical benefit from a single study (the EMERGE trial) and due to the expected high costs of using the new drug. In addition, although Aducanumab reduces the proportion of senile plaques (the last stage of Aβ aggregation), it may be ineffective against the oligomers or it may not stop the decline process connected with the tau protein. In this scenario, the investigation of new therapeutic options, in particular those proposing a completely different principle of action, deserve attention and NECTAR sets exactly at this point.
NECTAR can’t simply take the molecules and the irradiation protocols used in the NCT of cancer because in that case it faces an acute disease by an acute procedure. In AD, the treatment must address a chronic disease spreading in the whole brain, known to be radio sensitive. Only NCT basic physical principles can be translated to AD. Indeed a completely new class of neutron capture agents must be developed, in particular able to cross an almost intact blood-brain barrier. Considering the radio-sensitivity of brain, it is absolutely impossible to translate the acute irradiation protocols of NCT of cancer into an AD therapy and indeed NECTAR must identify a completely new treatment based on low doses and low dose rates. In this frame, NECTAR objectives are:
(1) to study and prove the effectiveness of the highly localised energy deposition induced by the neutron capture reactions on B10 and Gd157 to depolymerise the Aβ aggregates or to modify their structures in such a way that their toxicity is reduced or silenced;
(2) to evaluate the stimulation on the glia cell compartment by the penetrating photons emitted by the exploited capture reactions, in particular to assess if the radio-activated glia can promote the clearance of the Aβ aggregates.
If these hypothesis will be confirmed, NECTAR will test: (1) the safety of the brain pan-irradiation by low energy neutrons in presence and absence of the neutron capture agent, and (2) the effectiveness of the irradiation in slowing down the neuron degeneration and possibly the restoration of mental functions in particular connected with memory and mobility using normal and transgenic animal models.
NECTAR pursues also a technological goal, that is the identification, development and characterisation of the optimised neutron beam to perform the brain irradiation. In particular, NECTAR addresses the development and prototyping of innovative neutron spectrometers and micro- and nano-dosimeters to quantify the physical quantities of relevance down to Aβ dimension aggregates.
During year 1 the main topics have been: (1) development and synthesis of B10-enriched molecules (UNITO) and (2) preliminary measurements (Raylab+UNIPV) exploiting the NCT low energy neutron facilities of the UNIPV LENA lab (Applied Nuclear Energy Laboratory).
The best candidates among several boronated formulations have been tested in preliminary irradiation experiments involving water solutions of Aβ aggregates tagged by the new molecules and irradiated at LENA. The structural modifications induced in the aggregates have been observed by several techniques and in collaboration between UNITO and IRFMN.
During year 2, the scientific activity focused on:
the study of the effect/s induced by the high LET radiations emitted by B10 neutron capture reaction on synthetic beta amyloid fibrils; the study has been performed using water solutions of synthetically formed Aβ fibrils marked by B10-enriched molecules under patent by UNITO and UNIPV and irradiating the samples at the research nuclear reactor of UNIPV; the main effort has been to create a dose response curve varying the thermal neutron fluence administered to the samples to identifying the minimum irradiation conditions to induce a significant modification in the toxicity of the fibrils once exposed to in vitro neuronal cells. The techniques adopted for the post-irradiation analysis were FESEM and TEM, dot-blot, SPR.
The best candidates among several boronated formulations have been tested in preliminary irradiation experiments involving water solutions of Aβ aggregates tagged by the new molecules and irradiated at LENA. The structural modifications induced in the aggregates have been observed by several techniques and in collaboration between UNITO and IRFMN.
During year 2, the scientific activity focused on:
the study of the effect/s induced by the high LET radiations emitted by B10 neutron capture reaction on synthetic beta amyloid fibrils; the study has been performed using water solutions of synthetically formed Aβ fibrils marked by B10-enriched molecules under patent by UNITO and UNIPV and irradiating the samples at the research nuclear reactor of UNIPV; the main effort has been to create a dose response curve varying the thermal neutron fluence administered to the samples to identifying the minimum irradiation conditions to induce a significant modification in the toxicity of the fibrils once exposed to in vitro neuronal cells. The techniques adopted for the post-irradiation analysis were FESEM and TEM, dot-blot, SPR.
Despite the project is almost at its half time, NECTAR results are still quite preliminary and it is difficult to state a clear progress beyond the state of the art. This apparent slowness in achieving clear therapeutic indications should not be frightening or surprising: in fact, one must take into account the very high level of innovation and absolutely groundbreaking science carried out within the NECTAR project. Anyway, the expected impact of the project remains huge and tremendous considering the economical, social and psychological burdens of the present condition of AD care.