Zachary Bunjo

General Surgery Trainee | PhD Candidate @ Adelaide University

[Zachary Bunjo @zacbunjo]

@tarik_sammour

[Craig F̶o̶s̶t̶e̶r̶ @Craig_Foster]

‘I don’t know the first thing about Bosnia, and I don’t want to know.’

Yeah.

Exactly.

That’s the problem with the world, right there.

[Zachary Bunjo @zacbunjo]

@tarik_sammour Congrats @drtfitz_littleT !!

[Tarik Sammour @tarik_sammour]

https://t.co/lEJSSn1sQz

[Tarik Sammour @tarik_sammour]

Prof Clark presenting the tremendously successful @CentralAdlLHN @UniofAdelaide Clinician PhD pathway (CPP)

We now have 12 fully funded future clinical leaders actively enrolled in PhDs through this pathway!

It really is a great initiative, and Im honoured to be part of it!

[Tarik Sammour @tarik_sammour]

Very pleased to report that the pelvic exenteration team at @RAHcolorectal has secured significant internal funding to expand the service.

As part of this we are actively recruiting for a dedicated pelvic exenteration nurse role.

Please apply!
https://t.co/IT1iHZ4erH

[Journal of Clinical Oncology @JCO_ASCO]

Watch and Wait for Rectal Cancer: A Risky Gamble or a Safe Strategy for Patients With a Near-Complete Response? Co-authored by @fdossa.

Read the full article. https://t.co/Uc3mfOxyXW

[Nicholas Hornstein @GIMedOnc]

#ASCO26

Observation vs maintenance PD-1 after cCR in dMMR/MSI-H CRC managed nonoperatively
Abstract #3502
Presentation: May 31, 2026

This is absolutely essential data.

MSI-H CRC has rapidly evolved from aggressive and hard to treat to curable without surgery.

We are suddenly dealing with questions that would have sounded absurd a few years ago:

If a patient with dMMR/MSI-H CRC has a clinical complete response after PD-1 therapy, do we need to keep treating?

This Chinese multicenter cohort looked at exactly that.

Quick hits:

📌 Study design
318 patients with dMMR/MSI-H CRC treated with PD-1 therapy
191 achieved cCR in the presented flow 129 entered non-operative management

👀 Groups
Observation: n=66, stopped PD-1 after cCR
Maintenance: n=63, received ≥2 post-cCR PD-1 cycles

🧬 Included both rectal and colon cancer
Rectal: 58
Colon: 61
Synchronous dual primaries: 10

🔎 cCR assessment was not casual
Endoscopy + imaging: 100%
Confirmatory biopsy: 80/129, 62%
Rectal cancer: DRE 100%, pelvic MRI 89.7%

⏱️ Time to cCR
Median cycles to cCR: 8 in both groups
Median treatment duration to cCR: 6 months
69.8% reached cCR within 8 cycles
93.8% reached cCR within 16 cycles

📈 3-year DFS
Observation: 96.4%
Maintenance: 98.2%
P=0.560

🙌 3-year OS
Observation: 100%
Maintenance: 98.4%
P=0.313

🔥 Consistent sensitivity analyses
Overlap-weighted 3-year DFS: 98.5% vs 99.6%
6-week landmark 3-year DFS: 96.0% vs 98.2%

⚠️ The toxicity tradeoff matters
Maintenance did not clearly improve outcomes, but continuing PD-1 means continuing exposure, cost, visits, and immune toxicity risk.

This is the kind of dataset that changes conversations in clinic.

Not definitive. But incredibly useful.

For a patient with dMMR/MSI-H CRC who achieves a high-quality cCR and is being followed closely, observation after stopping PD-1 looks very reasonable.

The remaining question is duration.

Does it depend on colon vs rectum? Localized vs metastatic? Disease burden? Quality of cCR assessment? Patient anxiety?

Almost certainly yes.

But the big message is clear:

In dMMR/MSI-H CRC with cCR after PD-1, more treatment is not automatically better.

Sometimes the win is knowing when to stop.

Plenary-worthy.

@TheGutonclab @UGrewalMD @TimothyJBrownMD @OncoAlert @Onco_Nexus @ASCO
@NazliDizman @LauraAlderMD @DVAraujoMD @DrBarbiOnc @LauraEsfeller @FunchainMD @YGaritaonaindia @DrSAHaddad @jgong15 @iandresmeraz @SakditadMD @RamilaShilpakar @RohitBanwar @lungoncdoc

[Mark Lewis, MD, FASCO @marklewismd]

Cheers, chills, and a standing ovation when RASolute 302 showed unprecedented survival on daraxonrasib for patients with progressive pancreatic cancer

Seldom do you sense you’re witnessing a historic moment in cancer care but this feels like ras targeting has arrived

#ASCO26

[The EARLY-TNT Trial @earlytnt]

@earlytnt has recently crossed the halfway mark for recruitment! More updates in Newsletter #7 ⤵️

[Nicholas Hornstein @GIMedOnc]

#ASCO26
MSI-H feels like the wild west out there. We have nonoperative management, dual checkpoint inhibitors and everything in between.
Key questions remain:
How long should we treat for? Is NOM safe?

https://t.co/HzlYtECcq9
Observation vs maintenance PD-1 after cCR in dMMR/MSI-H CRC managed with NOM

Abstract #3502
Presentation: May 31, 2026, 8:00 AM

This multicenter China cohort asks a very practical question:
If a patient with dMMR/MSI-H CRC achieves cCR on PD-1 therapy and enters NOM, do they need maintenance PD-1?

Quick hits:

📌 318 treated with PD-1
195 achieved cCR
129 analyzed in NOM cohort

🧬NOM Population
58 rectal
61 colon
10 synchronous dual primaries
14 had distant metastases at diagnosis

⏱️ Median PD-1 exposure to cCR
8 cycles in both groups (?cycle length?)
69.8% achieved cCR within 8 cycles

📈 3-year DFS
Observation: 96.4%
Maintenance: 98.4%
p=0.55

🙌 3-year OS
Observation: 100%
Maintenance: 98.4%
p=0.34

🔥 Regrowth was rare
ONLY 2 local regrowths with observation
No distant metastases

⚠️ Toxicity difference was significant
Grade 3 irAEs: 3.0% vs 11.1%
One third!

My take: if MSI-H CRC achieves cCR on PD-1 and is managed non-operatively, observation looks very reasonable. (And overall this is more evidence that NOM is safe for MSI-H CRC).

Maintenance added toxicity without a clear DFS or OS signal.

Still a lot we do not know. Almost certainly this depends on patient, disease site, disease burden, and quality of cCR assessment.

But this is fascinating data.
Honestly, plenary-worthy?

@TheGutonclab @UGrewalMD @TimothyJBrownMD @OncoAlert @Onco_Nexus @ASCO
@NazliDizman @LauraAlderMD @DVAraujoMD @DrBarbiOnc @LauraEsfeller @FunchainMD @YGaritaonaindia @DrSAHaddad @jgong15 @iandresmeraz @SakditadMD @RamilaShilpakar @RohitBanwar @lungoncdoc

[Sergei Bedrikovetski @bedrikovetski]

🔔New publication alert🔔

Excited to share our new paper just published in the ANZ Journal of Surgery

https://t.co/yaGFyvyhrj

[DCRjournal @DCRjournal]

This week's edition of Letter to the Editor "Local Excision After Total Neoadjuvant Therapy in Locally Advanced Rectal Cancer: more questions than answers?" Read now in #DCRJournal: https://t.co/e2qbjuCZLm

[Annals of Surgical Oncology @AnnSurgOncol]

May Issue: Clinical Benefit and Cost-Effectiveness of FOLFOX Versus LCCRT in Neoadjuvant Treatment for Patients with Locally Advanced #RectalCancer : An Economic Analysis of the FOWARC and PROSPECT Trial

https://t.co/9yaibBrhxN

@AMVillanoMD
@SyedAAhmad5
@SocSurgOnc

[Nicholas Hornstein @GIMedOnc]

#AACR
NEOPRISM-CRC adds to the MSI-H colon cancer story. 🧬

And this one matters because everyone got 1 cycle of pembrolizumab.

Not dual IO.
Not a year up front.
One cycle.

Then ctDNA starts doing the thing we all want it to do:

• Baseline ctDNA detected in 100%
• Pre-op ctDNA clearance predicted pCR in 13/14
• Persistent pre-op ctDNA predicted residual disease in 8/9
• ctDNA cleared before cycle 2 → 6/6 pCR 👀
• No relapses at median follow-up ~29 months

Now put this next to the field:

NICHE-2:
nivo + ipi
pCR ~67%
near-universal response
no recurrences

IMHOTEP:
pembro alone
pCR 53% overall
68% after 2 cycles
only 3 recurrences at ~2 years

NEOPRISM:
pembro alone
pCR ~59%
early ctDNA clearance looks highly predictive
no relapses so far

This is starting to feel like the actual decision point in resectable MSI-H colon cancer (in addition to non-operative management):

Do you really need dual checkpoint for everyone?

Or do you start with PD-1 alone, check early ctDNA, and only escalate the patients who are not clearing?

Pembro first.
ctDNA-guided escalation.
Save CTLA-4 for the patients who actually need it.
Or maybe we just throw dual agent at everyone (100% DFS is unbeatable)…

@TheGutOncLab @OncoAlert @Onco_Nexus

https://t.co/gfOWgSLSJK

[Zachary Bunjo @zacbunjo]

Rectal Cancer Survey Opportunity! 🇦🇺🇳🇿

This study explores treatment preferences for early rectal cancer amongst colorectal surgeons, oncologists, patients and the general public.

Only open to Australia + New Zealand, takes <5 mins and can go into the running to win a $100 gift card!

You can find more info and the survey here: https://t.co/9ogUWmyTT3

[Zachary Bunjo @zacbunjo]

Awesome course in top condition - can appreciate why they call @BonvilleGolf Australia’s Augusta!

[Zachary Bunjo @zacbunjo]

In a historical cohort of 39 patients with early-stage rectal cancer opting for TNT rather than standard care upfront surgery, 79.5% achieved cCR, 16.1% had regrowth and all were alive following a median f/u of 41 mo.

Very grateful to my co-authors and collaborating hospitals across South Australia for making this important paper possible!

https://t.co/zqu8rvvd6x

[Tarik Sammour @tarik_sammour]

Not all early stage rectal cancers are actually early stage.
=&gt; The lower the cancer, the more likely it is under-staged.
=&gt; Especially concerning given adjuvant chemotherapy doesn't work well for low rectal cancer.

https://t.co/YLD1dNorU7

[Annals of Surgical Oncology @AnnSurgOncol]

#AudioVisualAbstract : Compliance and Toxicity of Total Neoadjuvant Therapy in Locally Advanced #RectalCancer : A Systematic Review and Network Meta-analysis @warren_seow

https://t.co/F5bEOGPgCS

@AMVillanoMD
@SyedAAhmad5