Company: DRTSW
Filing Date: 2025-03-12
Form Type: 20-F
Source: 0001213900-25-023187
Chunk: 142

Company: Alpha Tau Medical Ltd.
Filing Date: 2025-03-12
Form: 20-F
Item: Item 4
Chunk 142
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inoma      X                     X                         
  Breast Carcinoma             X                     X                         
  Glioblastoma Multiforme      X                     X                         
  Cervical Carcinoma                                 X                         
  Melanoma                     X                     X                         
  Colon Carcinoma              X                     X                         
  Sarcoma                      X                                               

In vitrostudies were
performed to evaluate the impact of alpha particles on tumor cell viability. Cell lines investigated in vitroincluded squamous
cell, lung, colon, prostate, breast, pancreatic and cervical carcinomas, glioblastoma and melanoma. All cell lines were sensitive to alpha
particles (typically dying within days after exposure), with a mean lethal dose in the range 0.7 - 1.5 Gy. In vivostudies using
various tumor types were consistent with the in vitrofindings and showed that Alpha DaRT sources destroyed tumors and achieved
a high degree of local control.

As shown in the figure below
regarding observed tumor growth in mice, in a pre-clinical study using a sealed Alpha DaRT source designed to prevent radon recoil, no
ablative effect was observed, suggesting that the ablation was caused primarily by alpha radiation from the recoiling alpha emitters,
rather than the low level of gamma/beta radiation emitted from the source, which had a minor effect.

The
complex DNA damage induced by alpha radiation, namely clustered double-strand breaks, is nearly impossible to repair and is largely unaffected
by the presence of oxygen or by cell cycle phase, which may indicate the potential for alpha particles to kill hypoxic cells which might
otherwise be resistant to conventional radiation treatments based on photons or electrons. Consistent with this understanding, mouse
and human cells showed lower survival following treatment with alpha radiation compared to x-ray in the same dose. The figure below demonstrates in vitrosurvival curves for Panc1 (A) and FaDu (B) cancer cell lines after exposure to X-rays or to alpha particles generated
from Thorium-228.

Alpha DaRT sources were observed
to have killed multiple types of mouse and human tumors in vivo. The extent of the tumor killing varied between tumor types and
was dependent on the ability of the radioactive atoms to diffuse inside the tumor and on the intrinsic sensitivity of the cancer cells
to DNA damage induced by the radiation, but all tumor types showed responsiveness to Alpha DaRT, i. e., there was no observed resistance.
The figure below compares the growth of tumors in groups of mice who