Based on Phelan et al CRISPR-Cas9 screen, authors identified the DNA repair factors CHEK1, WEE1, ATR, and RAD51 as essential genes in DLBCL cell lines.
They investigated the effect of 8 small molecules targeting DNA replication stress and DNA repair mechanism.

From Supplementary Table S1 would be a plus to show which are the more resistant (and sensitive) cell lines to different DDR inhibitors and find an explanation.

In line 233 one bracket is missing.

3/8 inhibitors showed a dose-response ratio in the nanomolar order: Weei1 (AZD_1775/Adavosertib), ATRi (AZD_6738/Ceralasertib) and Chk1i (AZD_8776) that were further investigate.
Actually, it was further investigate Chk1/(2)i PF-477736 instead of AZD_8776 why?

In DLBCL Wee1i AZD1775/Adavosertib is well and recently studied, while others ATRi should be consider or mentioned like BAY-1895344/Elimusertib (PMID: 38011941, PMID: 32988960). In solid cancers Wee1i ZN-c3/Azenosertib (PMID: 40231599) or APR-105 (https://doi.org/10.1158/1538-7445.AM2024-CT195) and among ATRi camosertib (PMID: 37277454) and tuvusertib (PMID: 38407317).

In 2 cell lines OCI-LY3 and DB, which belong to the ABC- and GCB-DLBCL, treatment with the inhibitors of ATR, Chk1 and Wee1 induced a significant increase in PARP cleavage.
While Chk1 and Wee1 inhibitors led to a significant increase of γH2AX this is not true for AZD_6738/Ceralasertib; actually another stronger ATRi (BAY-1895344/Elimusertib) was reported to led to γH2AX increase (PMID: 38011941).
Are these experiment of Fig.3 all performed with Apoptosis, DNA Damage, and Cell Proliferation Kit? Western blot is mentioned in material and methods, but images/analysis are not reported.

In lines 258 and 259 Wee1 inhibitor is mentioned instead of 4-OH-Cyclophosphamide and ATRi instead of etoposide.

All 8 small molecules targeting DNA replication (IC20) were combined with doxorubicin, etoposide and 4-OH-Cyclophosphamide in U2932 ABC-DLBCL. Why not etoposide? It was just used as a cnt in monotherapie?

U2932 seems to be resistant to ATR inhibitor due to the presence of a WT CDKN2a (PMID: 38011941), are U2932 FANC HRR or BER mutated/inactivated?

Here both Chk1/2 (PF-477736), Chk1 (AZD-8776) were included.

Considering a standard threshold of 2 standard deviations and not of 3 (as reported in reference 36) below the IC50 they found synergism (synthetic lethality) with four DDR inhibitors with genotoxic agents: Chk1 inhibitor PF-477736, the ATR inhibitor AZD-6738, and the ATM inhibitor KU-55933 with both 4-OH-Cyclophosphamide and etoposide, and the DNA-PK inhibitor NU-7441 with doxorubicin. Data in U2932 with all other combinations is not reported.

Validation was performed in two (not three) cell lines DB (GCB-DLBCL) and SUDHL10 (GCB-DLBCL). Here an additional (to U2932) resistant ABC cell line would be ideal (OCI-LY3).
Validation of combination with Western blot or with Apoptosis, DNA Damage, and Cell Proliferation Kit would be a plus.

The combination of 4-OH-Cyclophosphamide with AZD-6738 (ATRi) and PF-477736 (Chk1i), and of doxorubicin with NU-7441 (DNA-PKi) was tested in primary lymph node (LN) cells coming from 6 DLBCL patients co-cultured with the non-malignant LN microenvironment. Co-treatments reduced the number of tumor cells but not of non-malignant cells (except for DNA-PK/doxorubicin). This result seems to avoid toxicity of ATRi that should be further discussed.

Lanes 336-338 discussion/conclusion by which data is supported?

R-CHOP (doxorubicin/4-OH-Cyclophosphamide) treatment was presented in the introduction but not etoposide and gemcitabine. Actually, not even in discussion.

The link between genotoxic stress and RCHOP (cyclophosphamide and doxorubicin) is clear but the rationale to combine DDRi with etoposide is note reported and for gemcitabine should be reported in introduction in addition to result (line 231).

Finally, I suggest to introduce and discuss the difference/similarity between synergism and synthetic lethality in the combination reported.

In conclusion authors tested DNA repair inhibitors as monotherapies but especially in enhancing the effects of standard chemotherapy, suggesting decreasing doses of single inhibitors but further clarifications are needed. Additional experiments will be appreciated.