Don't Delay: Patients With Cancer Need Both Doses of COVID Vax

Liam Davenport

March 15, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

The first report on responses to COVID-19 vaccination among patients with cancer suggests that the immune response that occurs after the first dose of vaccine is reduced in comparison with the response that occurs in healthy individuals. The new findings, which were published as a preprint on medRxiv, cast doubt on the current UK policy of delaying the second dose of the vaccine. The article, with first author Leticia Monin-Aldama, PhD, has not been peer reviewed.

Delaying the second dose can leave most patients with cancer wholly or partially unprotected. Moreover, such a delay has implications with respect to the transmission of virus in the cancer parient's environs as well as with respect to the evolution of virus variants that could be of concern, the researchers conclude.

The data come from a British study that included 151 patients with cancer and 54 healthy control persons. All participants received the COVID-19 mRNA BNT162b2 vaccine (Pfizer-BioNTech).

This vaccine requires two doses. The first few participants in this study were given the second dose 21 days after they had received the first dose, but then national guidelines changed, and the remaining participants had to wait 12 weeks to receive their second dose.

The team reports that among healthy control persons, the immune efficacy of the first dose was very high (97% efficacious); by contrast, among patients with solid cancers, the immune efficacy of a single dose was strikingly low (39%), and it was even lower in patients with hematologic cancers (13%).

The second dose of vaccine greatly and rapidly increased the immune efficacy in patients with solid cancers (95% within 2 weeks of receiving the second dose), the researchers add.

Too few patients with hematologic cancer had received the second dose before the study ended for clear conclusions to be drawn. Nevertheless, the available data suggest that 50% of patients with hematologic cancers who had received the booster at day 21 were seropositive at 5 weeks, vs only 8% of those who had not received the booster.

"Our data provide the first real-world evidence of immune efficacy following one dose of the Pfizer vaccine in immunocompromised patient populations [and] clearly shows that the poor one-dose efficacy in cancer patients can be rescued with an early booster at day 21," commented senior author Sheeba Irshad, MD, senior clinical lecturer, King's College London, London, United Kingdom.

"Based on our findings, we would recommend an urgent review of the vaccine strategy for clinically extremely vulnerable groups. Until then, it is important that cancer patients continue to observe all public health measures in place, such as social distancing and shielding when attending hospitals, even after vaccination," Irshad added.

These data are "of immediate importance" to patients with cancer, commented Shoba Amarnath, PhD, Newcastle University research fellow, Laboratory of T cell Regulation, Newcastle University Center for Cancer, Newcastle upon Tyre, United Kingdom. "These findings are consistent with our understanding.... We know that the immune system within cancer patients is compromised as compared to healthy controls.

"The data in the study support the notion that in solid cancer patients, a considerable delay in second dose will extend the period when cancer patients are at risk of SARS-CoV-2 infection," she added.

Although more data are required, "this study does raise the issue of whether patients with cancer, other diseases, or those undergoing therapies that affect the body's immune response should be fast-tracked for their second vaccine dose," commented Lawrence Young, PhD, professor of molecular oncology and director of the Warwick Cancer Research Center, University of Warwick, Coventry, United Kingdom.

Stephen Evans, MSc, professor of pharmacoepidemiology, London School of Hygiene and Tropical Medicine, underlined that the study is "essentially" observational and "inevitable limitations must be taken into account.

"Nevertheless, these results do suggest that the vaccines may well not protect those patients with cancer as well as those without cancer." He noted that it is "important that this population continues to observe all COVID-19-associated measures, such as social distancing and shielding when attending hospitals, even after vaccination."

Study Details

Previous studies have shown that some patients with cancer have prolonged responses to SARS-CoV-2 infection, with ongoing immune dysregulation, inefficient seroconversion, and prolonged viral shedding.

There are few data, however, on how these patients respond to COVID-19 vaccination. The authors point out that among the 18,860 individuals who received the Pfizer vaccine during its development trials, "none with an active oncological diagnosis was included."

To investigate this issue, they launched the Sars-CoV-2 for Cancer Patients (SOAP-02) study.

The 151 patients with cancer who participated in this study were mostly elderly, the authors note (75% were older than 65 years; the median age was 73 years). The majority (63%) had solid malignancies; of those, 8% had late-stage disease and had been living with their cancer for more than 24 months.

The healthy control persons were vaccine-eligible primary healthcare workers who were not age-matched to the cancer patients.

All participants received the first dose of vaccine; 31 (of 151) patients with cancer and 16 (of 54) healthy control persons received the second dose on day 21.

The remaining participants were scheduled to receive their second dose 12 weeks later (after the study ended), in line with the changes in the national guidelines.

The team reports that approximately 21 days after receiving the first vaccine dose, the immune efficacy of the vaccine was estimated to be 97% among health control persons, vs 39% for patients with solid tumors and only 13% for those with hematologic cancers (P < .0001 for both).

T-cell responses, as assessed via interferon-gamma and/or interleukin-2 production, were observed in 82% of healthy control persons, 71% of patients with solid tumors, and 50% of those with hematologic cancers.

Vaccine boosting at day 21 resulted in immune efficacy of 100% for healthy control persons and 95% for patients with solid cancers. In contrast, only 43% of those who did not receive the second dose were seropositive 2 weeks later.

Further analysis suggested that participants who did not have a serologic response were "spread evenly" across different cancer types, but the reduced responses were more frequent among patients who had received the vaccine within 15 days of cancer treatment, especially chemotherapy, and had undergone intensive treatments.

The UK's vaccination policy is different from the policy in the United States, pointed out Lee Greenberger, PhD, chief scientific officer, the Leukemia and Lymphoma Society (LLS). In the United States, the Pfizer and Moderna vaccines are being administered as they were intended to be — with second dose administered 21 and 28 days after first dose, respectively, he told Medscape Medical News.

Greenberger also noted that cancer patients are at risk for more severe COVID-19 outcomes, including more prolonged periods of illness and higher death rates, "so they must take every measure to protect their health.... The LLS and other cancer organizations are encouraging cancer patients to discuss COVID-19 vaccination with their doctor as early as possible. It’s also important for this population to maintain recommended preventative measures, like wearing a mask, social distancing, and hand washing, even after vaccination," he said.

The SOAP study is sponsored by King's College London (KCL) and Guy's and St. Thomas Trust Foundation NHS Trust. It is funded from grants from the KCL Charity, Cancer Research UK, and program grants from Breast Cancer Now. The investigators have disclosed no relevant financial relationships.

medRrxiv. Published online March 17, 2021. Full text

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