Dermatologists and Oncologists Discuss Referral Gaps in Advanced CSCC Care

Neal Bhatia, MD, director of clinical dermatology at Therapeutics Clinical Research in San Diego, California, led a recent Dermatology Times Evolving Paradigms event in San Diego, guiding a discussion among dermatologists and oncologists on advancing multidisciplinary care in cutaneous squamous cell carcinoma (CSCC). The program centered on a single advanced patient case, which prompted a broader conversation comparing 3 available systemic immunotherapies and the referral pathways that connect dermatology and oncology.

Building the Case for Systemic Therapy in Advanced CSCC

The patient case involved a 72-year-old man with a left central frontal scalp lesion, no immunosuppression, and no prior skin cancers, whose workup revealed a parotid-region lymph node concerning for metastasis. Mohs surgery cleared the tumor in 1 stage, but pathology showed poorly differentiated histology with extensive perineural invasion, and parotidectomy found 1 of 18 lymph nodes positive for metastatic disease. The patient went on to adjuvant radiation. Attendees largely agreed surgery and radiation alone would not be sufficient.

"Super aggressive case, but radiation alone is not enough for this gentleman," an attendee said. Another noted the patient had far advanced local disease and floated downsizing the tumor before further treatment. "You could consider neoadjuvant therapy downsize and then you do Mohs or follow up with whatever adjuvant or radiation, depending on what you come up with," the attendee said. Bhatia agreed, prompting a discussion of why neoadjuvant systemic therapy is not yet standard thinking for many dermatologists managing high-risk CSCC.

Discussing Cemiplimab, Pembrolizumab, and Cosibelimab

Bhatia walked the group through indications, dosing, and trial data for the 3 approved PD-1 and PD-L1 inhibitors. He noted cemiplimab (Libtayo; Regeneron) carries an added adjuvant indication,¹ while cosibelimab (Unloxcyt; Sun Pharma), which blocks the ligand rather than the receptor, launched more recently.² Pembrolizumab (Keytruda; Merck) blocks the PD-1 protein on immune cells, and was first approved for recurrent or metastatic cSCC in 2020.³ Reviewing response and duration-of-response data from EMPOWER-CSCC-1 (NCT02760498), KEYNOTE-629 (NCT03284424), and CK-301-101 (NCT03212404), attendees compared outcomes across the agents in both locally advanced and metastatic disease.

"Cosibelimab looks like a winner here," one attendee said, pointing to its locally advanced results. Bhatia agreed the agent performed somewhat better at 6 months and held up at 12 and 24 months, though he cautioned the comparison crossed 3 separate trials with different populations. Safety data drew similar scrutiny: cosibelimab showed fewer treatment discontinuations than pembrolizumab, with cemiplimab in between. Attendees floated a few theories, including smaller, less treatment-experienced patient cohorts in the cosibelimab trial and differences in receptor versus ligand blockade, but no one reached a firm mechanistic explanation.

Bridging Referral Gaps Between Dermatology and Oncology

Discussion turned to how patients move between specialties once systemic therapy becomes a consideration. Several dermatologists described inconsistent referral timelines shaped by insurance networks, multidisciplinary access, and how quickly pathology results trigger a phone call. Clinicians in closed health systems described faster turnaround through regular tumor boards, while those in single-specialty private practice described more friction.

"I think the problem is….the sequencing. You're trying to [get this] hot potato out of your hands," an attendee said. Another, describing a multidisciplinary tumor board that meets weekly, said referrals there move within 3 to 4 weeks. Bhatia pushed the group to consider whether dermatologists are sending enough clinical detail, not just a diagnosis, when referring out. He also raised the use of gene expression profile testing for risk stratification in borderline cases, which drew mixed reception, with several oncologists noting it is not validated or guideline-supported for CSCC.

The discussion closed on monitoring and adverse event management once systemic therapy starts. Bhatia emphasized that dermatologists should stay engaged even after referring a patient out, both for adverse event recognition and ongoing skin surveillance. "The key for the dermatologist is not to think this is not our disease and to stay involved," he said, adding that oncologists should keep referring clinicians looped in through notes and continued tumor board participation.

Attendees ended the discussion on a shared theme: dermatologists and oncologists each rely on the other to fill gaps neither specialty can close alone. Bhatia concluded by framing referrals as a 2-way relationship rather than a handoff, urging dermatologists to stay engaged through tumor boards and follow-up notes while asking oncologists to keep referring clinicians informed of treatment progress. "That'll lead to more exchange of ideas and exchange of business also," he said.

This event recap has been produced independently by Dermatology Times and supported through an educational grant by Sun Pharmaceuticals.

For more upcoming Dermatology Times events, click here.

References

1. Libtayo (cemiplimab-rwlc). Prescribing information. Regeneron Pharmaceuticals. Accessed June 17, 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/761097s014lbl.pdf
2. Unloxcyt (cosibelimab-ipdl). Prescribing information. Sun Pharmaceuticals. Accessed June 17, 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/761297s000lbl.pdf
3. Keytruda (pembrolizumab). Prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125514s096lbl.pdf